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The tibial tubercle osteotomy (TTO) is a versatile tool for unloading patellar and trochlear focal chondral defects as well as treating patellofemoral arthritis with or without patellofemoral instability. The TTO indirectly functions to address chondral defects in the patellofemoral joint (PFJ) by unloading compressive forces in the affected area and preventing further chondral deterioration and pain. Since its inception, the TTO technique has undergone iterative modification and refinement. The Fulkerson anteromedialization has persisted as the workhorse of modern TTO procedures with good surgical results, though it is not without limitations. Recently, the use of novel surgical systems such as the multidirectional tibial tubercle transfer as well as concomitant soft tissue balancing procedures have been implemented to address challenges posed by the classic Fulkerson technique and improve TTO customizability and reproducibility. In addition, TTO has increasingly been used in conjunction with concomitant procedures such as autologous chondrocyte implantation and osteochondral allograft transfer in the PFJ, to protect the restored cartilage from repeat injury. Though the anteriorization TTO has long been supported to help alleviate pathologic joint compression, recent advancements in surgical guides as well as combined procedures involving multiplane TTO, cartilage restoration, and soft tissue balancing allow for customization of treatment that more thoroughly addresses the complex anatomy and pathology in the PFJ. This article aims to provide an overview of the rationale and recent advancements in the use of TTO to unload and treat chondral defects in the PFJ.
the tibial tubercle osteotomy (TTO) is a versatile tool for treating and unloading patellar and trochlear focal chondral defects as well as patellofemoral arthritis with or without patellofemoral instability. Chondral lesions of the patellofemoral joint (PFJ) are common and may be seen in isolation or with other concomitant PFJ pathologies. The spectrum of chondral disease ranges from focal cartilage defects to diffuse patellofemoral arthritis and can develop secondary to patellar instability, patellar maltracking, trauma, idiopathic (ie, osteochondritis dissecans), or a combination of these entities.
PFJ pathologies are typically multifactorial and require individualized diagnosis and treatment.
Current surgical treatment options may directly address cartilage defects by restoring their function or indirectly by shifting the load from the affected area (ie, unloading) and preventing further deterioration and pain. For example, TTO is one tool that, when used in isolation, addresses chondral defects indirectly by shifting the vector of the extensor mechanism away from the affected area, thus functionally unloading it.
Increasingly, however, TTO has been used in conjunction with concomitant procedures such as autologous chondrocyte implantation (ACI) and osteochondral allograft transfer (OCA) in the PFJ, to protect the restored cartilage from repeat injury.
Since its inception, the TTO technique has undergone iterative modification and refinement, and a range of strategies continue to be used. Notably, the Maquet anteriorization,
anteromedialization (AMZ), and distalization type TTO each utilize unique approaches to correct PFJ pathology. More recently, the evolution of the TTO has continued with the use of concomitant soft tissue and cartilage replacement procedures as well as novel surgical systems to improve customizability and reproducibility. This article aims to provide an overview of the rationale and recent advancements in the use of TTO to unload and treat chondral defects in the PFJ.
Rationale for TTO in the setting of knee preservation
Operative indications for TTO to unload the PFJ include focal patellar and trochlear articular cartilage defects or isolated patellofemoral arthritis. Typically the presenting symptoms are pain, swelling, or mechanical symptoms that are refractory to conservative management. The type of TTO indicated to unload the PFJ and combat chondral defects depends on the patient's specific pathoanatomy and location of the chondral defects. Isolated anteriorization, anteriorization with distalization, and AMZ with or without distalization are used to unload the PFJ. Isolated medialization and distalization without anteriorization do little to unload the joint and are typically useful only for instability without chondrosis, which is outside the scope of this article.
In patients with overload syndromes, anteriorization may serve as a powerful tool to decrease joint compressive forces. For instance, anteriorization of 2 cm can reduce joint compression forces by 50%, though more significant elevations may increase the risk of wound healing complications.
Furthermore, in patients with an elevated tibial tuberosity to trochlear groove distance measurement (>15 mm), combined AMZ is usually indicated to both correct the lateralized force vector and unload the joint, with the aim of achieving a tibial tuberosity to trochlear groove distance closer to 10 to 12 mm. Finally, distalization can be used to achieve a postsurgical Caton-Deschamps Index of 1.1 to 1.2 in patients with patella alta, as this will more evenly distribute forces that were concentrated on the distal aspect of the PFJ. However, care should be taken not to overdistalize into patella baja as this would increase compressive forces.
In some instances, tibial tubercle (TT) transfer can be used in isolation to address chondral lesions; however, this depends on the lesion size and location which is determined by cartilage mapping. Pidoriano et al
demonstrated that isolated TTO AMZ could be adequate to address focal distal lateral patellar lesions, with 87% of patients reporting positive outcomes at 3.9 years follow-up. In contrast, medial, central, panpatellar, and bipolar chondral lesions are inherently more extensive and typically require combined anteriorization or AMZ TTO with concomitant cartilage restoration. Combined TTO and cartilage replacement in these patients showed favorable outcomes in 75% of patients at 1.2-year follow-up.
TTO techniques and use have evolved. Elmslie and Trillat's modification to the original Roux procedure (ie, Elmslie-Trillat procedure) involves transferring the tibial tuberosity medially without posterior translation.
A 10 to 15-year follow-up of the Elmslie-Trillat procedure showed 62.5% good to excellent results, and this technique continues to be used widely. Hauser later described a distal and medial transfer of the tibial tuberosity in 1938.
This procedure was generally effective in resolving instability, with a reported 67% to 74% of patients having good or excellent outcomes. However, several authors eventually reported a high incidence of patellofemoral arthritis, believed to be caused primarily by the posterior translation of the tuberosity, which generated higher patellofemoral compressive force, ultimately leading to this method falling out of favor.
later modified this technique by elevating the tibial tuberosity anteriorly using a bone graft, though this procedure was complicated by soft tissue injury and wound breakdown.
The Fulkerson AMZ is now widely used to address PFJ pathology. Even though classic TTO techniques such as the Elmslie-Trillat medialization and the Fulkerson AMZ have proven effective over time, an opportunity exists to improve surgical precision, reproducibility, and customization for multiplane corrections. In 2016, Sarin et al
published a biomechanical study that used a novel surgical technique to perform TT transfer procedures. This technique utilized a proprietary saw guide to ensure reproducibility, precision, and therefore highly customized anterior, medial, and distal tubercle transfers. Results of the biomechanical analysis suggested that fixation using the novel tubercle transfer technique is as strong as traditional Elmslie–Trillat and Fulkerson AMZ with procedures and supported further investigation through use in clinical practice. Early results presented by Merchant
demonstrated a low complication rate, flexible osteotomy placement, and early return to full weightbearing. Early results from a subsequent cohort study (N = 39) investigating the safety of the proprietary saw guide system demonstrated good safety outcomes and low complication rates at short- and midterm follow-ups, with 1 case (3%) of hardware removal due to stiffness.
Early safety report on the novel multi-direction tibial tubercle transfer system (MD3T) for tibial tubercle osteotomy: a cohort study [Abstract].
in: International Society of Arthroscopy, Knee Surgery and Orthopaedic Sports Medicine, Boston, MA, USA2023
This supports further clinical investigation with a larger cohort and long-term follow-up.
Core principles and concepts underpinning current strategies
During flexion and extension, suboptimal alignment of the patella in the trochlear groove can lead to patellar maltracking and cause patellofemoral pathologies, including instability and pathologic PFJ compression. Such pathologies may lead to accelerated PFJ degeneration due to abnormal load distribution. Current TTO techniques used for joint preservation aim to address these aberrant force vectors to mechanically unload areas of high stress and prevent further damage to the joint. Though the Fulkerson AMZ is often used to address patellar instability, it was initially described to specifically unload the patella's lateral and distal articular regions in individuals with pathologic chondral wear.
This is accomplished through realignment of the extensor mechanism, which in turn improves overall patellar tracking, allowing for earlier patella-trochlear contact in flexion, and shifts the contact area proximal and medial, away from the distal lateral patella.
Distalization in cases of patella alta is also effective in reducing the distal load on the patella and works to improve stability by providing earlier engagement of the patella in the trochlear groove.
Note that isolated distalization is rarely performed for PFJ unloading, but instead, distalization is typically performed in conjunction with either anteriorization or AMZ to unload chondrosis. When considering TTO for PFJ unloading, it is important to remember that the bony morphology and specific pathology can vary widely between patients, necessitating TTO customization and so-called “tailor-made” treatment to address the patient's specific anatomy and pathology.
What is state of the art in 2023?
Though the Fulkerson AMZ has largely persisted as the workhorse of modern TTO procedures, it is not without limitations. Here we discuss similarities and differences between the classic Fulkerson AMZ technique and a novel TT transfer system, the multidirectional tibial tubercle transfer (MD3T) System (KINAMED Inc) that aims to address some of the relative shortcomings of the original Fulkerson technique. Surgical setup and initial arthroscopic evaluation are similar across both TTO techniques such that, before the osteotomy, the patient is brought to a supine position under general anesthesia with a high-thigh tourniquet on the operated leg. After a focused clinical examination, including a comparison to the opposite limb, a comprehensive diagnostic arthroscopy is performed to evaluate the articular cartilage, additional soft tissue injuries, and dynamic patellar tracking.
The remainder of this section will detail the unique characteristics of each technique.
The Fulkerson AMZ
The innovative concepts behind this procedure include moving the entire tibial tuberosity with the patellar tendon, creating a relatively wide and flat bone-to-bone healing surface with primary compressive fixation, and allowing for simultaneous 2-plane correction by means of adjusting the angle of the osteotomy to alter the amount of anteriorization and medialization achieved.
involves a lateral incision running halfway between Gerdy's tubercle and the tibial tuberosity to the distal patellar pole, followed by exposure of the patellar tendon and lateral retinacular release. Once adequate exposure is achieved, the periosteum and the anterior compartment muscle belly are peeled off the tibia, exposing 10 to 12 cm of the lateral tibia. The freehand cutting angle is determined using predrilling holes adjacent to the medial side of the anterior tibial crest, leaving the drill bits to be used as a template for the final cut. The oblique drilling is directed posterolaterally, penetrating the proximal part of the lateral tibial cortex. The bone cut is completed using a reciprocating saw and osteotomes to add an oblique lateral bony cut to release the patellar tendon along with its bony distal insertion. The osteotomized bony fragment is then mobilized and repositioned according to the preoperative plan. After temporary fixation and dynamic assessment through the knee range of motion, the bony fragment is fixated with a bicortical lag screw in its new position to create compression
Since the Fulkerson AMZ was first published in 1983, the technique has undergone several modifications, including custom osteotomy systems with designated jigs such as Tracker (DePuy Mitek, Inc) and the T3 System (Arthrex, Inc) to facilitate and control the osteotomy angle.
Different fixation methods were also introduced, such as headless screws, cancellous lag screws, lag screw vs lag effect, various screw materials (ie, metal, magnesium, etc.), osteotomy site augmentations using cerclage wire or plate, and different numbers of screws (2 or 3) with or without additional bone grafting. Finally, several biologic enhancements to facilitate bone healing were also introduced in recent decades, including local use of platelet-rich plasma or autologous conditioned plasma.
Chronic patellofemoral instability and pain treated effectively by anteromedial tibial tubercle transfer (Fulkerson osteotomy) with or without medial patellofemoral ligament reconstruction.
Table 1The Fulkerson osteotomy: pearls and pitfalls.
Pearls
Meticulous preoperative planning:
•
Adequate imaging and measurements, ruling out other factors such as limb rotational mal-alignment.
•
Coherent pre- and postoperative rehabilitation protocols.
Tailor-made surgery—addressing other pathologies/concomitant surgeries.
Pitfalls
Breaching and breaking of the tibial lateral cortex during drilling/sawing of the tibial tuberosity.
Insufficient or overcorrection of the tibial tuberosity translation, especially with multidirectional correction (ie, AMZ and distalization).
Fixed degree of anteriorization and medialization determined by the slope of the osteotomy. Inability to change the slope in real time.
Intraoperative injury to the neurovascular structures, including the popliteal artery, its trifurcation, and the deep peroneal nerve.
Neurovascular injuries:
•
Stripping the muscles and periosteum of the anterior compartment to expose the entire tibial lateral side may cause soft tissue injury (muscle) and the perineal nerve.
•
Penetration of the posterior tibial cortex (“far cortex”) during the tibial tuberosity fixation can jeopardize the peroneal nerve where it turns medially from the fibular head, and may also endanger the popliteal artery and its trifurcation.
The integrity of the bony structure:
•
Inadequate surface contact between the osteotomised tibial tuberosity and its bone pedicle and the tibia may cause a medial tilt of the bone fragment, malunion or nonunion.
•
Iatrogenic fracture of the proximal part of the bone pedicle, specifically with a low cutting angle.
•
Bone gap formation without bone substituted, or lack of integration of the bone substituted.
The length of this bone pedicle should provide good surface contact and avoid tilting the fragment medially. It is imperative not to fracture the pedicle itself except at its most distal point.
Proximal tibial fracture due to early weight bearing before adequate bone healing.
Wound healing problems due to extreme anteriorization of the tibial tuberosity.
AMZ with distalization is associated with a higher complication rate and less stability.
Sagital plan patellar rotation with clinical manifestation due to excessive tibial tuberosity transfer.
Although the Fulkerson technique has become the mainstay of modern TTO procedure with good surgical results, it poses challenges, such as a long learning curve resulting from the freehand cut, especially when a precise and multiplanar correction is needed. Other drawbacks include extensive stripping of the anterior compartment, fracture risk, and the potential for rare but devastating neurovascular injuries, as described in Table 1.
This system was designed to standardize a technique he had performed freehand for years prior. Furthermore, it addressed some of the challenges experienced with the original Fulkerson technique, making it possible to design a TT transfer in which anteriorization, medialization, and/or distalization can be performed independently or combined with a technique that is accurate, reproducible, and simple to learn even in complex multiplanar corrections.
After the initial skin incision and exposure of the tibial tuberosity and the patellar tendon, a customed jig with an adjustable saw-cutting guide is temporarily fastened onto the tuberosity with unicortical screw fixation (Fig. 2). Fluoroscopy is not required during the planning or execution of the osteotomy but can be utilized to confirm correction just before screw fixation. The modular jig and the transfer indicator aid in predicting the new TT position before cutting occurs. The cutting guide allows for precise multidirectional and multiplanar cuts. For AMZ, the MD3T system guides the surgeon to produce 2 compound bone wedges. Maintenance of the medial and lateral cortex improves construct stability for early weight-bearing and range of motion, reduces fracture risk, eliminates the need for anterior compartment dissection, and theoretically reduces the risk of bleeding, early postoperative pain, and neurovascular damage.
Fig. 2The intraoperative tibial tubercle osteotomy surgery using the MD3T system. A, Skin incision. B, Exposer and isolation of the patellar tendon (dotted line) and the tibial tubercle (blue star). C, MD3T cutting guide. MD3T, multidirectional tibial tubercle transfer.
The osteotomized tibial tuberosity with its attached patellar tendon is the primary (lateral) and more robust bone wedge. The second (medial) variable wedge is cut just medial to the first wedge. Transposing these 2 wedges moves the TT and patellar tendon insertion anterior and medial to their desired correction, which is precisely measured in real time. If increasing amounts of anteriorization or medialization are required, this can be facilitated by adding an autograft bone void filler posterior to the transferred TT (for anteriorization effect) or by removing more medial bone in the primary pedicle bed to further medialize (Fig. 3). Synthetic calcium phosphate filler is also placed laterally to fill the bone void in cases of AMZ (Fig. 4). This reduces the risk of stress fractures and pull-offs by nearly 50% compared to the original Fulkerson technique (from 15% to 26%).
Distalization can be easily included in any osteotomy type by removing 2 mm from the primary pedicle wedge and widening the distal kerf of the primary tubercle pedicle bed. The destabilized tubercle can be easily reduced into a stable position with excellent cortical apposition. It is critical to utilize bone graft to create a proximal buttress in cases of distalization. Additional data comparing the Fulkerson technique and the MD3T is presented in Table 2.
Fig. 3The intraoperative tibial tubercle osteotomy surgery using the MD3T system. A, Cutting the primary bone wedge. B, Primary bone wedge (blue star). C, Osteotomy site (blue arrow). MD3T, multidirectional tibial tubercle transfer.
Fig. 4The intraoperative tibial tubercle (TT) osteotomy surgery using the MD3T system. A, Secondary bone wedge (blue star) after TT transposition. B, Bone graft substitute (red asterisk). MD3T, multidirectional tibial tubercle transfer.
All orthopedic procedures may have related complications, but some are unique to TTO surgery. These complications may be divided into general surgical complications such as infection, deep vein thrombosis, compartment syndrome, etc., and orthopedic complications such as malunion, nonunion, iatrogenic fracture, and hardware failure. The latter may be further divided into AMZ-related complications, including knee stiffness and arthrofibrosis, progressive chondral damage, injury to the neurovascular structures, complex regional pain syndrome, and symptomatic hardware with or without persistent pain (Fig. 5).
Fig. 5Postoperative tibial tubercle osteotomy X-ray of the left knee using the MD3T system. A, Anteroposterior view. B, Lateral view in 30° of flexion. The red star indicates the bone graft substitute. MD3T, multidirectional tibial tubercle transfer.
To address patellofemoral chondral lesions, TTO can be used in conjunction with concomitant procedures that fall into 2 main categories: cartilage restoration and soft tissue balancing. Osteochondral autograft transplantation (OAT) or OCA, ACI, and matrix-induced ACI are among the most common cartilage restoration procedures performed with TTO to treat PFJ overload syndromes. Additionally, common soft tissue balancing techniques include lateral retinacular lengthening/lateral release and medial patellofemoral ligament (MPFL) reconstruction (Fig. 6).
Fig. 6Intraoperative tibial tubercle osteotomy surgery with concomitant procedures. A, Trochleoplasty (blue arrow). B, Osteochondral allograft transplantation (green star), C, Additional tibial osteotomy (blue star), osteochondral allograft transplantation (green star) and medial patellofemoral ligament reconstruction (yellow star).
These procedures (ie, OAT, OCA, and ACI) are useful clinical tools used with TTO to treat chondral lesions resulting from overload syndromes. Within this context, osteotomy can be utilized to significantly unload the affected compartment of the knee, normalize joint mechanics, and reduce contact pressures on the implanted graft.
In addition, unloading with an osteotomy has significantly improved subjective patient outcomes of ACI and OAT compared with cartilage treatment alone.
In the setting of lateral facet overload, lateral retinacular release or lengthening may be performed in addition to TTO if there is tightness of the lateral soft tissue structures and fixed patellar tilt. This aims to unload the lateral region by mechanically shifting the compressive forces medially. Because the lateral retinaculum is a secondary stabilizer to lateral patellar translation, it should not be disturbed unless a clear lesion is present. In addition, because it does not cause complete disruption of the lateral soft tissue envelope, lengthening of the lateral retinaculum may be preferred. Furthermore, in patients with a history of patellar instability, MPFL reconstruction can be performed in conjunction with TTO surgery to provide checkreign to lateral translation after the bony alignment has been optimized. MPFL reconstruction can help prevent the patella from tracking laterally and serves to functionally unload the lateral aspect of the patella, decreasing the risk of associated chondral damage and pain.
In some cases, other underlying anatomical abnormalities can cause pathologic compression and associated chondral damage in the PFJ. For example, trochlear dysplasia, genu valgum, increased femoral antetorsion, or a combination of the latter are correlated with an increased risk of cartilage lesions in the PFJ.
Association between patellar cartilage defects and patellofemoral geometry: a matched-pair MRI comparison of patients with and without isolated patellar cartilage defects.
In cases of symptomatic chondrosis in extreme rotational or valgus deformity, with or without severe trochlear dysplasia, addressing the primary deforming force(s) makes sense. It is not clear when to include TTO alongside these other procedures. It is clearly considered in cases of severe patella alta (Caton Deschamps > 1.4) and lateralized force vector. The efficacy of combining procedures with concomitant cartilage replacement therapy has yet to be investigated in any meaningful series.
Discussion
The TTO is a dynamic tool that can be used in isolation or in conjunction with additional procedures to treat overload syndromes and resulting chondral pathologies in the PFJ. Depending on the underlying pathology and location of the chondral lesions, isolated anteriorization, anteriorization with distalization, and AMZ with or without distalization are used to unload the PFJ. TTO, along with lateral retinacular release and MPFL reconstruction, indirectly addresses chondral defects by shifting the vector of the extensor mechanism away from the affected area, thus functionally unloading it.
Specifically, anteriorization of the TT has long been supported for PFJ unloading, with a 2 cm anteriorization decreasing joint compressive forces by up to 50%.
Conversely, procedures such as OAT, OCA, ACI, and matrix-induced ACI directly address chondral damage in the PFJ. An increasing body of evidence supports the use of isolated anteriorization, anteriorization with distalization, and AMZ with or without distalization-type TTO in conjunction with a form of direct cartilage restoration procedures. In this context, TTO helps to reduce joint compression forces and supports superior graft survivorship and improved clinical outcomes.
In addition, recent advancements in TTO technology have taken steps to standardize the TTO technique while allowing for flexible, precise, and reproducible tubercle transfer
that accounts for specific patient anatomy and pathologic joint processes. This allows for a “tailor-made” treatment of PFJ overload syndromes and chondral damage.
Conclusion
Myriad approaches exist to unload and treat chondral defects in the PFJ surgically. While anteriorization TTO has long been supported to help alleviate pathologic joint compression, recent advancements in surgical guides as well as combined procedures involving multiplane TTO, cartilage restoration, and soft tissue balancing, allow for customization of treatment that more thoroughly addresses the complex anatomy and pathology in the PFJ.
Declaration of competing interest
Seth L. Sherman received royalties from CONMED Linvatec, Enovis, and Ostesys. He reported serving as a paid consultant to Arthrex, Inc, BioVentus, CONMED Linvatec, Joint Restoration Foundation Ortho, Kinamed, Smith & Nephew, and Vericel. He is a paid speaker for Arthrex, Inc, CONMED Linvatec, Joint Restoration Foundation, Kinamed, Smith & Nephew, and Vericel. He received Intellectual Properties royalties from CONMED Linvatec. He is a board or committee member at American Academy of Orthopaedic Surgeons, Anterior Cruciate Ligament Study Group, American Orthopaedic Society for Sports Medicine, Biologics Alliance, Epic Bio, International Cartilage Regeneration & Joint Preservation Society, International Society of Arthroscopy, Knee Surgery, and Orthopaedic Sports Medicine, International Sports Medicine Fellows Conference, Patellofemoral Foundation, Reparel, Sarcio, Sparta Biomedical, Vericel, Video Journal of Sports Medicine, and Icarus Bracing. He is an editorial or committee member of Arthoscopy and Current Reviews in Musculoskeletal Medicine. He received stocks or stock options from Epic Bio, Reparel, Sarcio, Vivorte, Ostesys. The remaining authors reported no financial interests.
Ethics approval
Complete informed consent was obtained from the patient for the publication of this study and accompanying images.
Chronic patellofemoral instability and pain treated effectively by anteromedial tibial tubercle transfer (Fulkerson osteotomy) with or without medial patellofemoral ligament reconstruction.
Association between patellar cartilage defects and patellofemoral geometry: a matched-pair MRI comparison of patients with and without isolated patellar cartilage defects.
Iain R. Murray and Seth L. Sherman served as Guest Editors for this issue of JCJP. They were not involved in decisions about the article they wrote, and peer review was handled independently.
The intraoperative tibial tubercle osteotomy surgery using the MD3T system. A, Skin incision. B, Exposer and isolation of the patellar tendon (dotted line) and the tibial tubercle (blue star). C, MD3T cutting guide. MD3T, multidirectional tibial tubercle transfer.
The intraoperative tibial tubercle osteotomy surgery using the MD3T system. A, Cutting the primary bone wedge. B, Primary bone wedge (blue star). C, Osteotomy site (blue arrow). MD3T, multidirectional tibial tubercle transfer.
The intraoperative tibial tubercle (TT) osteotomy surgery using the MD3T system. A, Secondary bone wedge (blue star) after TT transposition. B, Bone graft substitute (red asterisk). MD3T, multidirectional tibial tubercle transfer.
Postoperative tibial tubercle osteotomy X-ray of the left knee using the MD3T system. A, Anteroposterior view. B, Lateral view in 30° of flexion. The red star indicates the bone graft substitute. MD3T, multidirectional tibial tubercle transfer.
The tibial tubercle osteotomy (TTO) is a versatile tool for unloading patellar and trochlear focal chondral defects as well as treating patellofemoral arthritis with or without patellofemoral instability. The TTO indirectly functions to address chondral defects in the patellofemoral joint (PFJ) by unloading compressive forces in the affected area and preventing further chondral deterioration and pain. Since its inception, the TTO technique has undergone iterative modification and refinement. The Fulkerson anteromedialization has persisted as the workhorse of modern TTO procedures with good surgical results, though it is not without limitations. Recently, the use of novel surgical systems such as the multidirectional tibial tubercle transfer as well as concomitant soft tissue balancing procedures have been implemented to address challenges posed by the classic Fulkerson technique and improve TTO customizability and reproducibility. In addition, TTO has increasingly been used in conjunction with concomitant procedures such as autologous chondrocyte implantation and osteochondral allograft transfer in the PFJ, to protect the restored cartilage from repeat injury. Though the anteriorization TTO has long been supported to help alleviate pathologic joint compression, recent advancements in surgical guides as well as combined procedures involving multiplane TTO, cartilage restoration, and soft tissue balancing allow for customization of treatment that more thoroughly addresses the complex anatomy and pathology in the PFJ. This article aims to provide an overview of the rationale and recent advancements in the use of TTO to unload and treat chondral defects in the PFJ.
Introduced originally to address patellofemoral instability,1x1Roux, C. Luxation habituelle de la rotule. Rev Chir Paris. 1888;
: 682–689 Google ScholarSee all References the tibial tubercle osteotomy (TTO) is a versatile tool for treating and unloading patellar and trochlear focal chondral defects as well as patellofemoral arthritis with or without patellofemoral instability. Chondral lesions of the patellofemoral joint (PFJ) are common and may be seen in isolation or with other concomitant PFJ pathologies. The spectrum of chondral disease ranges from focal cartilage defects to diffuse patellofemoral arthritis and can develop secondary to patellar instability, patellar maltracking, trauma, idiopathic (ie, osteochondritis dissecans), or a combination of these entities.2x2Sherman, SL, Erickson, BJ, Cvetanovich, GL et al. Tibial tuberosity osteotomy: indications, techniques, and outcomes. Am J Sports Med. 2014;
42: 2006–2017https://doi.org/10.1177/0363546513507423 Crossref | PubMed | Scopus (89) | Google ScholarSee all References PFJ pathologies are typically multifactorial and require individualized diagnosis and treatment.
Current surgical treatment options may directly address cartilage defects by restoring their function or indirectly by shifting the load from the affected area (ie, unloading) and preventing further deterioration and pain. For example, TTO is one tool that, when used in isolation, addresses chondral defects indirectly by shifting the vector of the extensor mechanism away from the affected area, thus functionally unloading it.3x3Fulkerson, JP. AMZ of the tibial tuberosity for patellofemoral malalignment. Clin Orthop Relat Res. 1983;
Jul-Aug: 176–181 Google ScholarSee all References Increasingly, however, TTO has been used in conjunction with concomitant procedures such as autologous chondrocyte implantation (ACI) and osteochondral allograft transfer (OCA) in the PFJ, to protect the restored cartilage from repeat injury.
Since its inception, the TTO technique has undergone iterative modification and refinement, and a range of strategies continue to be used. Notably, the Maquet anteriorization,4x4Maquet, P. Advancement of the tibial tuberosity. Clin Orthop Relat Res. 1976;
Mar-Apr: 225–230 Google ScholarSee all References Roux-Elmslie-Trillat medialization,5x5Cox, JS. Evaluation of the Roux-Elmslie-Trillat procedure for knee extensor realignment. Am J Sports Med. 1982;
10: 303–310https://doi.org/10.1177/036354658201000509 Crossref | PubMed | Scopus (135) | Google ScholarSee all References Fulkerson3x3Fulkerson, JP. AMZ of the tibial tuberosity for patellofemoral malalignment. Clin Orthop Relat Res. 1983;
Jul-Aug: 176–181 Google ScholarSee all References anteromedialization (AMZ), and distalization type TTO each utilize unique approaches to correct PFJ pathology. More recently, the evolution of the TTO has continued with the use of concomitant soft tissue and cartilage replacement procedures as well as novel surgical systems to improve customizability and reproducibility. This article aims to provide an overview of the rationale and recent advancements in the use of TTO to unload and treat chondral defects in the PFJ.
Rationale for TTO in the setting of knee preservation
Operative indications for TTO to unload the PFJ include focal patellar and trochlear articular cartilage defects or isolated patellofemoral arthritis. Typically the presenting symptoms are pain, swelling, or mechanical symptoms that are refractory to conservative management. The type of TTO indicated to unload the PFJ and combat chondral defects depends on the patient's specific pathoanatomy and location of the chondral defects. Isolated anteriorization, anteriorization with distalization, and AMZ with or without distalization are used to unload the PFJ. Isolated medialization and distalization without anteriorization do little to unload the joint and are typically useful only for instability without chondrosis, which is outside the scope of this article.
In patients with overload syndromes, anteriorization may serve as a powerful tool to decrease joint compressive forces. For instance, anteriorization of 2 cm can reduce joint compression forces by 50%, though more significant elevations may increase the risk of wound healing complications.4x4Maquet, P. Advancement of the tibial tuberosity. Clin Orthop Relat Res. 1976;
Mar-Apr: 225–230 Google ScholarSee all References Furthermore, in patients with an elevated tibial tuberosity to trochlear groove distance measurement (>15 mm), combined AMZ is usually indicated to both correct the lateralized force vector and unload the joint, with the aim of achieving a tibial tuberosity to trochlear groove distance closer to 10 to 12 mm. Finally, distalization can be used to achieve a postsurgical Caton-Deschamps Index of 1.1 to 1.2 in patients with patella alta, as this will more evenly distribute forces that were concentrated on the distal aspect of the PFJ. However, care should be taken not to overdistalize into patella baja as this would increase compressive forces.
In some instances, tibial tubercle (TT) transfer can be used in isolation to address chondral lesions; however, this depends on the lesion size and location which is determined by cartilage mapping. Pidoriano et al6x6Pidoriano, AJ, Weinstein, RN, Buuck, DA, and Fulkerson, JP. Correlation of patellar articular lesions with results from anteromedial tibial tubercle transfer. Am J Sports Med. 1997;
25: 533–537https://doi.org/10.1177/036354659702500417 Crossref | PubMed | Scopus (182) | Google ScholarSee all References demonstrated that isolated TTO AMZ could be adequate to address focal distal lateral patellar lesions, with 87% of patients reporting positive outcomes at 3.9 years follow-up. In contrast, medial, central, panpatellar, and bipolar chondral lesions are inherently more extensive and typically require combined anteriorization or AMZ TTO with concomitant cartilage restoration. Combined TTO and cartilage replacement in these patients showed favorable outcomes in 75% of patients at 1.2-year follow-up.6x6Pidoriano, AJ, Weinstein, RN, Buuck, DA, and Fulkerson, JP. Correlation of patellar articular lesions with results from anteromedial tibial tubercle transfer. Am J Sports Med. 1997;
25: 533–537https://doi.org/10.1177/036354659702500417 Crossref | PubMed | Scopus (182) | Google ScholarSee all References,7x7Rue, LJPH, Colton, A, Zare, SM et al. Trochlear contact pressures after straight anteriorization of the tibial tuberosity. Am J Sports Med. 2008;
30: 1953–1959https://doi.org/10.1177/0363546508317125 Crossref | Scopus (53) | Google ScholarSee all References This supports the notion that TTO can be used with or without concomitant cartilage restoration procedures to treat chondral damage in the PFJ.
TTO: A historical perspective
Since Roux first described the medial transfer of the patellar tendon in 1888 to address recurrent patellar dislocation,1x1Roux, C. Luxation habituelle de la rotule. Rev Chir Paris. 1888;
: 682–689 Google ScholarSee all References TTO techniques and use have evolved. Elmslie and Trillat's modification to the original Roux procedure (ie, Elmslie-Trillat procedure) involves transferring the tibial tuberosity medially without posterior translation.5x5Cox, JS. Evaluation of the Roux-Elmslie-Trillat procedure for knee extensor realignment. Am J Sports Med. 1982;
10: 303–310https://doi.org/10.1177/036354658201000509 Crossref | PubMed | Scopus (135) | Google ScholarSee all References A 10 to 15-year follow-up of the Elmslie-Trillat procedure showed 62.5% good to excellent results, and this technique continues to be used widely. Hauser later described a distal and medial transfer of the tibial tuberosity in 1938.8x8Hauser, EDW. The classic: total tendon transplant for slipping patella: a new operation for recurrent dislocation of the patella. Clin Orthop Relat Res. 2006;
452: 7–16https://doi.org/10.1097/01.blo.0000238831.50186.87 Crossref | PubMed | Scopus (33) | Google ScholarSee all References This procedure was generally effective in resolving instability, with a reported 67% to 74% of patients having good or excellent outcomes. However, several authors eventually reported a high incidence of patellofemoral arthritis, believed to be caused primarily by the posterior translation of the tuberosity, which generated higher patellofemoral compressive force, ultimately leading to this method falling out of favor.9x9Chrisman, OD, Snook, GA, and Wilson, TC. A long-term prospective study of the Hauser and Roux-Goldthwait procedures for recurrent patellar dislocation. Clin Orthop Relat Res. 1979;
Oct: 27–30 Google ScholarSee all References,10x10Insall, J, Falvo, KA, and Wise, DW. Chondromalacia patellae. A prospective study. JBJS. 1976;
58: 1–8 Crossref | PubMed | Scopus (344) | Google ScholarSee all References,11x11Decesare, WF. Late results of Hauser procedure for recurrent dislocation of the patella. Clin Orthop Relat Res. 1979;
May: 137–144https://doi.org/10.1097/00003086-197905000-00026 Crossref | Scopus (36) | Google ScholarSee all References,12x12Juliusson, R and Markhede, G. A modified Hauser procedure for recurrent dislocation of the patella. A long-term follow-up study with special reference to osteoarthritis. Arch Orthop Trauma Surg (1978). 1984;
103: 42–46https://doi.org/10.1007/BF00451317 Crossref | PubMed | Scopus (37) | Google ScholarSee all References Maquet4x4Maquet, P. Advancement of the tibial tuberosity. Clin Orthop Relat Res. 1976;
Mar-Apr: 225–230 Google ScholarSee all References,13x13Maquet, P. Mechanics and osteoarthritis of the patellofemoral joint. Clin Orthop Relat Res. 1979;
Oct: 70–73 Google ScholarSee all References later modified this technique by elevating the tibial tuberosity anteriorly using a bone graft, though this procedure was complicated by soft tissue injury and wound breakdown.2x2Sherman, SL, Erickson, BJ, Cvetanovich, GL et al. Tibial tuberosity osteotomy: indications, techniques, and outcomes. Am J Sports Med. 2014;
42: 2006–2017https://doi.org/10.1177/0363546513507423 Crossref | PubMed | Scopus (89) | Google ScholarSee all References
In 1983, Fulkerson introduced and popularized the AMZ3x3Fulkerson, JP. AMZ of the tibial tuberosity for patellofemoral malalignment. Clin Orthop Relat Res. 1983;
Jul-Aug: 176–181 Google ScholarSee all References technique and, later, straight anteriorization without bone grafts.3x3Fulkerson, JP. AMZ of the tibial tuberosity for patellofemoral malalignment. Clin Orthop Relat Res. 1983;
Jul-Aug: 176–181 Google ScholarSee all References The Fulkerson AMZ is now widely used to address PFJ pathology. Even though classic TTO techniques such as the Elmslie-Trillat medialization and the Fulkerson AMZ have proven effective over time, an opportunity exists to improve surgical precision, reproducibility, and customization for multiplane corrections. In 2016, Sarin et al14x14Sarin, VK, Camisa, W, Leasure, JM, and Merchant, AC. Multidirectional tibial tubercle transfer technique: rationale and biomechanical investigation. J Surg Orthop Adv. 2016;
25: 157–164https://doi.org/10.3113/JSOA.2016.0157 Crossref | PubMed | Google ScholarSee all References published a biomechanical study that used a novel surgical technique to perform TT transfer procedures. This technique utilized a proprietary saw guide to ensure reproducibility, precision, and therefore highly customized anterior, medial, and distal tubercle transfers. Results of the biomechanical analysis suggested that fixation using the novel tubercle transfer technique is as strong as traditional Elmslie–Trillat and Fulkerson AMZ with procedures and supported further investigation through use in clinical practice. Early results presented by Merchant15x15Merchant, T. Preliminary experience with the MD3T, a novel tibial tubercle transfer. Presented at: Meeting of the International Patellofemoral Study Group. Banff,
Alberta, Canada; September 26, 2019 Google ScholarSee all References demonstrated a low complication rate, flexible osteotomy placement, and early return to full weightbearing. Early results from a subsequent cohort study (N = 39) investigating the safety of the proprietary saw guide system demonstrated good safety outcomes and low complication rates at short- and midterm follow-ups, with 1 case (3%) of hardware removal due to stiffness.16x16Atzmon, R, Steen, A, Pierre, K, Vel, M, Lin, K, and Sherman, SL. Early safety report on the novel multi-direction tibial tubercle transfer system (MD3T) for tibial tubercle osteotomy: a cohort study [Abstract]. in: International Society of Arthroscopy, Knee Surgery and Orthopaedic Sports Medicine. ; 2023 Google ScholarSee all References This supports further clinical investigation with a larger cohort and long-term follow-up.
Core principles and concepts underpinning current strategies
During flexion and extension, suboptimal alignment of the patella in the trochlear groove can lead to patellar maltracking and cause patellofemoral pathologies, including instability and pathologic PFJ compression. Such pathologies may lead to accelerated PFJ degeneration due to abnormal load distribution. Current TTO techniques used for joint preservation aim to address these aberrant force vectors to mechanically unload areas of high stress and prevent further damage to the joint. Though the Fulkerson AMZ is often used to address patellar instability, it was initially described to specifically unload the patella's lateral and distal articular regions in individuals with pathologic chondral wear.3x3Fulkerson, JP. AMZ of the tibial tuberosity for patellofemoral malalignment. Clin Orthop Relat Res. 1983;
Jul-Aug: 176–181 Google ScholarSee all References,6x6Pidoriano, AJ, Weinstein, RN, Buuck, DA, and Fulkerson, JP. Correlation of patellar articular lesions with results from anteromedial tibial tubercle transfer. Am J Sports Med. 1997;
25: 533–537https://doi.org/10.1177/036354659702500417 Crossref | PubMed | Scopus (182) | Google ScholarSee all References This is accomplished through realignment of the extensor mechanism, which in turn improves overall patellar tracking, allowing for earlier patella-trochlear contact in flexion, and shifts the contact area proximal and medial, away from the distal lateral patella.17x17Fulkerson, JP. Diagnosis and treatment of patients with patellofemoral pain. Am J Sports Med. 2002;
30: 447–456https://doi.org/10.1177/03635465020300032501 Crossref | PubMed | Scopus (393) | Google ScholarSee all References Distalization in cases of patella alta is also effective in reducing the distal load on the patella and works to improve stability by providing earlier engagement of the patella in the trochlear groove.18x18Leite, CBG, Santos, TP, Giglio, PN, Pécora, JR, Camanho, GL, and Gobbi, RG. Tibial tubercle osteotomy with distalization is a safe and effective procedure for patients with patella alta and patellar instability. Orthop J Sports Med. 2021;
9: 2325967120975101https://doi.org/10.1177/2325967120975101 Crossref | PubMed | Scopus (15) | Google ScholarSee all References Note that isolated distalization is rarely performed for PFJ unloading, but instead, distalization is typically performed in conjunction with either anteriorization or AMZ to unload chondrosis. When considering TTO for PFJ unloading, it is important to remember that the bony morphology and specific pathology can vary widely between patients, necessitating TTO customization and so-called “tailor-made” treatment to address the patient's specific anatomy and pathology.
What is state of the art in 2023?
Though the Fulkerson AMZ has largely persisted as the workhorse of modern TTO procedures, it is not without limitations. Here we discuss similarities and differences between the classic Fulkerson AMZ technique and a novel TT transfer system, the multidirectional tibial tubercle transfer (MD3T) System (KINAMED Inc) that aims to address some of the relative shortcomings of the original Fulkerson technique. Surgical setup and initial arthroscopic evaluation are similar across both TTO techniques such that, before the osteotomy, the patient is brought to a supine position under general anesthesia with a high-thigh tourniquet on the operated leg. After a focused clinical examination, including a comparison to the opposite limb, a comprehensive diagnostic arthroscopy is performed to evaluate the articular cartilage, additional soft tissue injuries, and dynamic patellar tracking.19x19Farr, J, Cole, BJ, Kercher, J, Batty, L, and Bajaj, S. Anteromedial tibial tubercle osteotomy (Fulkerson osteotomy). in: V Sanchis-Alfonso
(Ed.)
Anterior Knee Pain and Patellar Instability. Springer,
; 2011: 455–462https://doi.org/10.1007/978-0-85729-507-1_40 Crossref | Google ScholarSee all References,20x20Ferrari, MB, Sanchez, G, Kennedy, NI, Sanchez, A, Schantz, K, and Provencher, MT. Osteotomy of the tibial tubercle for AMZ. Arthrosc Tech. 2017;
6: e1341–e1346https://doi.org/10.1016/j.eats.2017.05.012 Abstract | Full Text | Full Text PDF | PubMed | Scopus (5) | Google ScholarSee all References The remainder of this section will detail the unique characteristics of each technique.
The Fulkerson AMZ
The innovative concepts behind this procedure include moving the entire tibial tuberosity with the patellar tendon, creating a relatively wide and flat bone-to-bone healing surface with primary compressive fixation, and allowing for simultaneous 2-plane correction by means of adjusting the angle of the osteotomy to alter the amount of anteriorization and medialization achieved.3x3Fulkerson, JP. AMZ of the tibial tuberosity for patellofemoral malalignment. Clin Orthop Relat Res. 1983;
Jul-Aug: 176–181 Google ScholarSee all References,19x19Farr, J, Cole, BJ, Kercher, J, Batty, L, and Bajaj, S. Anteromedial tibial tubercle osteotomy (Fulkerson osteotomy). in: V Sanchis-Alfonso
(Ed.)
Anterior Knee Pain and Patellar Instability. Springer,
; 2011: 455–462https://doi.org/10.1007/978-0-85729-507-1_40 Crossref | Google ScholarSee all References The Fulkerson technique3x3Fulkerson, JP. AMZ of the tibial tuberosity for patellofemoral malalignment. Clin Orthop Relat Res. 1983;
Jul-Aug: 176–181 Google ScholarSee all References involves a lateral incision running halfway between Gerdy's tubercle and the tibial tuberosity to the distal patellar pole, followed by exposure of the patellar tendon and lateral retinacular release. Once adequate exposure is achieved, the periosteum and the anterior compartment muscle belly are peeled off the tibia, exposing 10 to 12 cm of the lateral tibia. The freehand cutting angle is determined using predrilling holes adjacent to the medial side of the anterior tibial crest, leaving the drill bits to be used as a template for the final cut. The oblique drilling is directed posterolaterally, penetrating the proximal part of the lateral tibial cortex. The bone cut is completed using a reciprocating saw and osteotomes to add an oblique lateral bony cut to release the patellar tendon along with its bony distal insertion. The osteotomized bony fragment is then mobilized and repositioned according to the preoperative plan. After temporary fixation and dynamic assessment through the knee range of motion, the bony fragment is fixated with a bicortical lag screw in its new position to create compression3x3Fulkerson, JP. AMZ of the tibial tuberosity for patellofemoral malalignment. Clin Orthop Relat Res. 1983;
Jul-Aug: 176–181 Google ScholarSee all References (Fig. 1Fig. 1).
Fig. 1
Postoperative Fulkerson tibial tubercle osteotomy X-ray of the right knee. A, Anteroposterior view. B, Lateral view.
Table 1The Fulkerson osteotomy: pearls and pitfalls.
Pearls
Meticulous preoperative planning:
•
Adequate imaging and measurements, ruling out other factors such as limb rotational mal-alignment.
•
Coherent pre- and postoperative rehabilitation protocols.
Tailor-made surgery—addressing other pathologies/concomitant surgeries.
Pitfalls
Breaching and breaking of the tibial lateral cortex during drilling/sawing of the tibial tuberosity.
Insufficient or overcorrection of the tibial tuberosity translation, especially with multidirectional correction (ie, AMZ and distalization).
Fixed degree of anteriorization and medialization determined by the slope of the osteotomy. Inability to change the slope in real time.
Intraoperative injury to the neurovascular structures, including the popliteal artery, its trifurcation, and the deep peroneal nerve.
Neurovascular injuries:
•
Stripping the muscles and periosteum of the anterior compartment to expose the entire tibial lateral side may cause soft tissue injury (muscle) and the perineal nerve.
•
Penetration of the posterior tibial cortex (“far cortex”) during the tibial tuberosity fixation can jeopardize the peroneal nerve where it turns medially from the fibular head, and may also endanger the popliteal artery and its trifurcation.
The integrity of the bony structure:
•
Inadequate surface contact between the osteotomised tibial tuberosity and its bone pedicle and the tibia may cause a medial tilt of the bone fragment, malunion or nonunion.
•
Iatrogenic fracture of the proximal part of the bone pedicle, specifically with a low cutting angle.
•
Bone gap formation without bone substituted, or lack of integration of the bone substituted.
The length of this bone pedicle should provide good surface contact and avoid tilting the fragment medially. It is imperative not to fracture the pedicle itself except at its most distal point.
Proximal tibial fracture due to early weight bearing before adequate bone healing.
Wound healing problems due to extreme anteriorization of the tibial tuberosity.
AMZ with distalization is associated with a higher complication rate and less stability.
Sagital plan patellar rotation with clinical manifestation due to excessive tibial tuberosity transfer.
Although the Fulkerson technique has become the mainstay of modern TTO procedure with good surgical results, it poses challenges, such as a long learning curve resulting from the freehand cut, especially when a precise and multiplanar correction is needed. Other drawbacks include extensive stripping of the anterior compartment, fracture risk, and the potential for rare but devastating neurovascular injuries, as described in Table 1Table 1.3x3Fulkerson, JP. AMZ of the tibial tuberosity for patellofemoral malalignment. Clin Orthop Relat Res. 1983;
Jul-Aug: 176–181 Google ScholarSee all References,19x19Farr, J, Cole, BJ, Kercher, J, Batty, L, and Bajaj, S. Anteromedial tibial tubercle osteotomy (Fulkerson osteotomy). in: V Sanchis-Alfonso
(Ed.)
Anterior Knee Pain and Patellar Instability. Springer,
; 2011: 455–462https://doi.org/10.1007/978-0-85729-507-1_40 Crossref | Google ScholarSee all References,20x20Ferrari, MB, Sanchez, G, Kennedy, NI, Sanchez, A, Schantz, K, and Provencher, MT. Osteotomy of the tibial tubercle for AMZ. Arthrosc Tech. 2017;
6: e1341–e1346https://doi.org/10.1016/j.eats.2017.05.012 Abstract | Full Text | Full Text PDF | PubMed | Scopus (5) | Google ScholarSee all References,25x25Fulkerson, JP. Fracture of the proximal tibia after Fulkerson anteromedial tibial tubercle transfer. A report of four cases. Am J Sports Med. 1999;
27: 265 Crossref | PubMed | Google ScholarSee all References,26x26Bellemans, J, Cauwenberghs, F, Brys, P, Victor, J, and Fabry, G. Fracture of the proximal tibia after Fulkerson anteromedial tibial tubercle transfer. Am J Sports Med. 1998;
26: 300–302https://doi.org/10.1177/03635465980260022401 Crossref | PubMed | Scopus (49) | Google ScholarSee all References With these challenges in mind, Merchant and colleagues developed the MD3T System (KINAMED incorporated).14x14Sarin, VK, Camisa, W, Leasure, JM, and Merchant, AC. Multidirectional tibial tubercle transfer technique: rationale and biomechanical investigation. J Surg Orthop Adv. 2016;
25: 157–164https://doi.org/10.3113/JSOA.2016.0157 Crossref | PubMed | Google ScholarSee all References This system was designed to standardize a technique he had performed freehand for years prior. Furthermore, it addressed some of the challenges experienced with the original Fulkerson technique, making it possible to design a TT transfer in which anteriorization, medialization, and/or distalization can be performed independently or combined with a technique that is accurate, reproducible, and simple to learn even in complex multiplanar corrections.
After the initial skin incision and exposure of the tibial tuberosity and the patellar tendon, a customed jig with an adjustable saw-cutting guide is temporarily fastened onto the tuberosity with unicortical screw fixation (Fig. 2Fig. 2). Fluoroscopy is not required during the planning or execution of the osteotomy but can be utilized to confirm correction just before screw fixation. The modular jig and the transfer indicator aid in predicting the new TT position before cutting occurs. The cutting guide allows for precise multidirectional and multiplanar cuts. For AMZ, the MD3T system guides the surgeon to produce 2 compound bone wedges. Maintenance of the medial and lateral cortex improves construct stability for early weight-bearing and range of motion, reduces fracture risk, eliminates the need for anterior compartment dissection, and theoretically reduces the risk of bleeding, early postoperative pain, and neurovascular damage.
Fig. 2
The intraoperative tibial tubercle osteotomy surgery using the MD3T system. A, Skin incision. B, Exposer and isolation of the patellar tendon (dotted line) and the tibial tubercle (blue star). C, MD3T cutting guide. MD3T, multidirectional tibial tubercle transfer.
The osteotomized tibial tuberosity with its attached patellar tendon is the primary (lateral) and more robust bone wedge. The second (medial) variable wedge is cut just medial to the first wedge. Transposing these 2 wedges moves the TT and patellar tendon insertion anterior and medial to their desired correction, which is precisely measured in real time. If increasing amounts of anteriorization or medialization are required, this can be facilitated by adding an autograft bone void filler posterior to the transferred TT (for anteriorization effect) or by removing more medial bone in the primary pedicle bed to further medialize (Fig. 3Fig. 3). Synthetic calcium phosphate filler is also placed laterally to fill the bone void in cases of AMZ (Fig. 4Fig. 4). This reduces the risk of stress fractures and pull-offs by nearly 50% compared to the original Fulkerson technique (from 15% to 26%).14x14Sarin, VK, Camisa, W, Leasure, JM, and Merchant, AC. Multidirectional tibial tubercle transfer technique: rationale and biomechanical investigation. J Surg Orthop Adv. 2016;
25: 157–164https://doi.org/10.3113/JSOA.2016.0157 Crossref | PubMed | Google ScholarSee all References Distalization can be easily included in any osteotomy type by removing 2 mm from the primary pedicle wedge and widening the distal kerf of the primary tubercle pedicle bed. The destabilized tubercle can be easily reduced into a stable position with excellent cortical apposition. It is critical to utilize bone graft to create a proximal buttress in cases of distalization. Additional data comparing the Fulkerson technique and the MD3T is presented in Table 2Table 2.
Fig. 3
The intraoperative tibial tubercle osteotomy surgery using the MD3T system. A, Cutting the primary bone wedge. B, Primary bone wedge (blue star). C, Osteotomy site (blue arrow). MD3T, multidirectional tibial tubercle transfer.
The intraoperative tibial tubercle (TT) osteotomy surgery using the MD3T system. A, Secondary bone wedge (blue star) after TT transposition. B, Bone graft substitute (red asterisk). MD3T, multidirectional tibial tubercle transfer.
All orthopedic procedures may have related complications, but some are unique to TTO surgery. These complications may be divided into general surgical complications such as infection, deep vein thrombosis, compartment syndrome, etc., and orthopedic complications such as malunion, nonunion, iatrogenic fracture, and hardware failure. The latter may be further divided into AMZ-related complications, including knee stiffness and arthrofibrosis, progressive chondral damage, injury to the neurovascular structures, complex regional pain syndrome, and symptomatic hardware with or without persistent pain (Fig. 5Fig. 5).3x3Fulkerson, JP. AMZ of the tibial tuberosity for patellofemoral malalignment. Clin Orthop Relat Res. 1983;
Jul-Aug: 176–181 Google ScholarSee all References,19x19Farr, J, Cole, BJ, Kercher, J, Batty, L, and Bajaj, S. Anteromedial tibial tubercle osteotomy (Fulkerson osteotomy). in: V Sanchis-Alfonso
(Ed.)
Anterior Knee Pain and Patellar Instability. Springer,
; 2011: 455–462https://doi.org/10.1007/978-0-85729-507-1_40 Crossref | Google ScholarSee all References,25x25Fulkerson, JP. Fracture of the proximal tibia after Fulkerson anteromedial tibial tubercle transfer. A report of four cases. Am J Sports Med. 1999;
27: 265 Crossref | PubMed | Google ScholarSee all References
Fig. 5
Postoperative tibial tubercle osteotomy X-ray of the left knee using the MD3T system. A, Anteroposterior view. B, Lateral view in 30° of flexion. The red star indicates the bone graft substitute. MD3T, multidirectional tibial tubercle transfer.
To address patellofemoral chondral lesions, TTO can be used in conjunction with concomitant procedures that fall into 2 main categories: cartilage restoration and soft tissue balancing. Osteochondral autograft transplantation (OAT) or OCA, ACI, and matrix-induced ACI are among the most common cartilage restoration procedures performed with TTO to treat PFJ overload syndromes. Additionally, common soft tissue balancing techniques include lateral retinacular lengthening/lateral release and medial patellofemoral ligament (MPFL) reconstruction (Fig. 6Fig. 6).
Fig. 6
Intraoperative tibial tubercle osteotomy surgery with concomitant procedures. A, Trochleoplasty (blue arrow). B, Osteochondral allograft transplantation (green star), C, Additional tibial osteotomy (blue star), osteochondral allograft transplantation (green star) and medial patellofemoral ligament reconstruction (yellow star).
In the setting of lateral facet overload, lateral retinacular release or lengthening may be performed in addition to TTO if there is tightness of the lateral soft tissue structures and fixed patellar tilt. This aims to unload the lateral region by mechanically shifting the compressive forces medially. Because the lateral retinaculum is a secondary stabilizer to lateral patellar translation, it should not be disturbed unless a clear lesion is present. In addition, because it does not cause complete disruption of the lateral soft tissue envelope, lengthening of the lateral retinaculum may be preferred. Furthermore, in patients with a history of patellar instability, MPFL reconstruction can be performed in conjunction with TTO surgery to provide checkreign to lateral translation after the bony alignment has been optimized. MPFL reconstruction can help prevent the patella from tracking laterally and serves to functionally unload the lateral aspect of the patella, decreasing the risk of associated chondral damage and pain.7x7Rue, LJPH, Colton, A, Zare, SM et al. Trochlear contact pressures after straight anteriorization of the tibial tuberosity. Am J Sports Med. 2008;
30: 1953–1959https://doi.org/10.1177/0363546508317125 Crossref | Scopus (53) | Google ScholarSee all References,29x29Stephen, JM, Lumpaopong, P, Dodds, AL, Williams, A, and Amis, AA. The effect of tibial tuberosity medialization and lateralization on patellofemoral joint kinematics, contact mechanics, and stability. Am J Sports Med. 2015;
43: 186–194https://doi.org/10.1177/0363546514554553 Crossref | PubMed | Scopus (80) | Google ScholarSee all References,33x33Ramappa, AJ, Apreleva, M, Harrold, FR, Fitzgibbons, PG, Wilson, DR, and Gill, TJ. The effects of medialization and AMZ of the tibial tubercle on patellofemoral mechanics and kinematics. Am J Sports Med. 2006;
34: 749–756https://doi.org/10.1177/0363546505283460 Crossref | PubMed | Scopus (81) | Google ScholarSee all References
In some cases, other underlying anatomical abnormalities can cause pathologic compression and associated chondral damage in the PFJ. For example, trochlear dysplasia, genu valgum, increased femoral antetorsion, or a combination of the latter are correlated with an increased risk of cartilage lesions in the PFJ.34x34Ambra, LF, Hinckel, BB, Arendt, EA, Farr, J, and Gomoll, AH. Anatomic risk factors for focal cartilage lesions in the patella and trochlea: a case-control study. Am J Sports Med. 2019;
47: 2444–2453https://doi.org/10.1177/0363546519859320 Crossref | PubMed | Scopus (29) | Google ScholarSee all References,35x35Flury, A, Hoch, A, Andronic, O, Fritz, B, Imhoff, FB, and Fucentese, SF. Increased femoral antetorsion correlates with higher degrees of lateral retropatellar cartilage degeneration, further accentuated in genu valgum. Knee Surg Sports Traumatol Arthrosc. 2021;
29: 1760–1768https://doi.org/10.1007/s00167-020-06223-x Crossref | PubMed | Scopus (10) | Google ScholarSee all References,36x36Macri, E, Felson, D, Ziegler, M et al. The association of frontal plane alignment to MRI-defined worsening of patellofemoral osteoarthritis: the MOST study. Osteoarthritis Cartilage. 2019;
27: 459–467https://doi.org/10.1016/j.joca.2018.11.004 Abstract | Full Text | Full Text PDF | PubMed | Scopus (10) | Google ScholarSee all References,37x37Mehl, J, Feucht, MJ, Bode, G, Dovi-Akue, D, Südkamp, NP, and Niemeyer, P. Association between patellar cartilage defects and patellofemoral geometry: a matched-pair MRI comparison of patients with and without isolated patellar cartilage defects. Knee Surg Sports Traumatol Arthrosc. 2016;
24: 838–846https://doi.org/10.1007/s00167-014-3385-7 Crossref | PubMed | Scopus (59) | Google ScholarSee all References Data supports that failure to correct underlying anatomical copathology in PFJ chondral lesions leads to poorer outcomes.38x38Brittberg, M, Lindahl, A, Nilsson, A, Ohlsson, C, Isaksson, O, and Peterson, L. Treatment of deep cartilage defects in the knee with autologous chondrocyte transplantation. N Engl J Med. 1994;
331: 889–895https://doi.org/10.1056/NEJM199410063311401 Crossref | PubMed | Scopus (4648) | Google ScholarSee all References,39x39Peterson, L, Minas, T, Brittberg, M, Nilsson, A, Sjögren-Jansson, E, and Lindahl, A. Two- to 9-year outcome after autologous chondrocyte transplantation of the knee. Clin Orthop Relat Res. 2000;
May: 212–234https://doi.org/10.1097/00003086-200005000-00020 Crossref | Scopus (1234) | Google ScholarSee all References,40x40Peterson, L, Brittberg, M, Kiviranta, I, Åkerlund, EL, and Lindahl, A. Autologous chondrocyte transplantation: biomechanics and long-term durability. Am J Sports Med. 2002;
30: 2–12https://doi.org/10.1177/03635465020300011601 Crossref | PubMed | Scopus (743) | Google ScholarSee all References In cases of symptomatic chondrosis in extreme rotational or valgus deformity, with or without severe trochlear dysplasia, addressing the primary deforming force(s) makes sense. It is not clear when to include TTO alongside these other procedures. It is clearly considered in cases of severe patella alta (Caton Deschamps > 1.4) and lateralized force vector. The efficacy of combining procedures with concomitant cartilage replacement therapy has yet to be investigated in any meaningful series.
Discussion
The TTO is a dynamic tool that can be used in isolation or in conjunction with additional procedures to treat overload syndromes and resulting chondral pathologies in the PFJ. Depending on the underlying pathology and location of the chondral lesions, isolated anteriorization, anteriorization with distalization, and AMZ with or without distalization are used to unload the PFJ. TTO, along with lateral retinacular release and MPFL reconstruction, indirectly addresses chondral defects by shifting the vector of the extensor mechanism away from the affected area, thus functionally unloading it.3x3Fulkerson, JP. AMZ of the tibial tuberosity for patellofemoral malalignment. Clin Orthop Relat Res. 1983;
Jul-Aug: 176–181 Google ScholarSee all References Specifically, anteriorization of the TT has long been supported for PFJ unloading, with a 2 cm anteriorization decreasing joint compressive forces by up to 50%.4x4Maquet, P. Advancement of the tibial tuberosity. Clin Orthop Relat Res. 1976;
Mar-Apr: 225–230 Google ScholarSee all References Conversely, procedures such as OAT, OCA, ACI, and matrix-induced ACI directly address chondral damage in the PFJ. An increasing body of evidence supports the use of isolated anteriorization, anteriorization with distalization, and AMZ with or without distalization-type TTO in conjunction with a form of direct cartilage restoration procedures. In this context, TTO helps to reduce joint compression forces and supports superior graft survivorship and improved clinical outcomes.6x6Pidoriano, AJ, Weinstein, RN, Buuck, DA, and Fulkerson, JP. Correlation of patellar articular lesions with results from anteromedial tibial tubercle transfer. Am J Sports Med. 1997;
25: 533–537https://doi.org/10.1177/036354659702500417 Crossref | PubMed | Scopus (182) | Google ScholarSee all References,30x30Gallo, RA and Feeley, BT. Cartilage defects of the femoral trochlea. Knee Surg Sports Traumatol Arthrosc. 2009;
17: 1316–1325https://doi.org/10.1007/s00167-009-0799-8 Crossref | PubMed | Scopus (23) | Google ScholarSee all References,31x31Trinh, TQ, Harris, JD, Siston, RA, and Flanigan, DC. Improved outcomes with combined autologous chondrocyte implantation and patellofemoral osteotomy versus isolated autologous chondrocyte implantation. Arthroscopy. 2013;
29: 566–574https://doi.org/10.1016/j.arthro.2012.10.008 Abstract | Full Text | Full Text PDF | PubMed | Scopus (74) | Google ScholarSee all References,32x32Calcei, JG, Varshneya, K, Sochacki, KR, Safran, MR, Abrams, GD, and Sherman, SL. Concomitant osteotomy reduces risk of reoperation following cartilage restoration procedures of the knee: a matched cohort analysis. Cartilage. 2021;
13: 1250S–1257Shttps://doi.org/10.1177/19476035211011515 Crossref | PubMed | Scopus (1) | Google ScholarSee all References In addition, recent advancements in TTO technology have taken steps to standardize the TTO technique while allowing for flexible, precise, and reproducible tubercle transfer14x14Sarin, VK, Camisa, W, Leasure, JM, and Merchant, AC. Multidirectional tibial tubercle transfer technique: rationale and biomechanical investigation. J Surg Orthop Adv. 2016;
25: 157–164https://doi.org/10.3113/JSOA.2016.0157 Crossref | PubMed | Google ScholarSee all References,15x15Merchant, T. Preliminary experience with the MD3T, a novel tibial tubercle transfer. Presented at: Meeting of the International Patellofemoral Study Group. Banff,
Alberta, Canada; September 26, 2019 Google ScholarSee all References that accounts for specific patient anatomy and pathologic joint processes. This allows for a “tailor-made” treatment of PFJ overload syndromes and chondral damage.
Conclusion
Myriad approaches exist to unload and treat chondral defects in the PFJ surgically. While anteriorization TTO has long been supported to help alleviate pathologic joint compression, recent advancements in surgical guides as well as combined procedures involving multiplane TTO, cartilage restoration, and soft tissue balancing, allow for customization of treatment that more thoroughly addresses the complex anatomy and pathology in the PFJ.
Declaration of competing interest
Seth L. Sherman received royalties from CONMED Linvatec, Enovis, and Ostesys. He reported serving as a paid consultant to Arthrex, Inc, BioVentus, CONMED Linvatec, Joint Restoration Foundation Ortho, Kinamed, Smith & Nephew, and Vericel. He is a paid speaker for Arthrex, Inc, CONMED Linvatec, Joint Restoration Foundation, Kinamed, Smith & Nephew, and Vericel. He received Intellectual Properties royalties from CONMED Linvatec. He is a board or committee member at American Academy of Orthopaedic Surgeons, Anterior Cruciate Ligament Study Group, American Orthopaedic Society for Sports Medicine, Biologics Alliance, Epic Bio, International Cartilage Regeneration & Joint Preservation Society, International Society of Arthroscopy, Knee Surgery, and Orthopaedic Sports Medicine, International Sports Medicine Fellows Conference, Patellofemoral Foundation, Reparel, Sarcio, Sparta Biomedical, Vericel, Video Journal of Sports Medicine, and Icarus Bracing. He is an editorial or committee member of Arthoscopy and Current Reviews in Musculoskeletal Medicine. He received stocks or stock options from Epic Bio, Reparel, Sarcio, Vivorte, Ostesys. The remaining authors reported no financial interests.
Ethics approval
Complete informed consent was obtained from the patient for the publication of this study and accompanying images.
References
1Roux, C. Luxation habituelle de la rotule. Rev Chir Paris. 1888;
: 682–689
6Pidoriano, AJ, Weinstein, RN, Buuck, DA, and Fulkerson, JP. Correlation of patellar articular lesions with results from anteromedial tibial tubercle transfer. Am J Sports Med. 1997;
25: 533–537https://doi.org/10.1177/036354659702500417
7Rue, LJPH, Colton, A, Zare, SM et al. Trochlear contact pressures after straight anteriorization of the tibial tuberosity. Am J Sports Med. 2008;
30: 1953–1959https://doi.org/10.1177/0363546508317125
8Hauser, EDW. The classic: total tendon transplant for slipping patella: a new operation for recurrent dislocation of the patella. Clin Orthop Relat Res. 2006;
452: 7–16https://doi.org/10.1097/01.blo.0000238831.50186.87
9Chrisman, OD, Snook, GA, and Wilson, TC. A long-term prospective study of the Hauser and Roux-Goldthwait procedures for recurrent patellar dislocation. Clin Orthop Relat Res. 1979;
Oct: 27–30
12Juliusson, R and Markhede, G. A modified Hauser procedure for recurrent dislocation of the patella. A long-term follow-up study with special reference to osteoarthritis. Arch Orthop Trauma Surg (1978). 1984;
103: 42–46https://doi.org/10.1007/BF00451317
15Merchant, T. Preliminary experience with the MD3T, a novel tibial tubercle transfer. Presented at: Meeting of the International Patellofemoral Study Group. Banff,
Alberta, Canada; September 26, 2019
16Atzmon, R, Steen, A, Pierre, K, Vel, M, Lin, K, and Sherman, SL. Early safety report on the novel multi-direction tibial tubercle transfer system (MD3T) for tibial tubercle osteotomy: a cohort study [Abstract]. in: International Society of Arthroscopy, Knee Surgery and Orthopaedic Sports Medicine. ; 2023
18Leite, CBG, Santos, TP, Giglio, PN, Pécora, JR, Camanho, GL, and Gobbi, RG. Tibial tubercle osteotomy with distalization is a safe and effective procedure for patients with patella alta and patellar instability. Orthop J Sports Med. 2021;
9: 2325967120975101https://doi.org/10.1177/2325967120975101
20Ferrari, MB, Sanchez, G, Kennedy, NI, Sanchez, A, Schantz, K, and Provencher, MT. Osteotomy of the tibial tubercle for AMZ. Arthrosc Tech. 2017;
6: e1341–e1346https://doi.org/10.1016/j.eats.2017.05.012
21Mukhopadhaya, J, Gupta, A, Sinha, AK, and Bhadani, JS. Chronic patellofemoral instability and pain treated effectively by anteromedial tibial tubercle transfer (Fulkerson osteotomy) with or without medial patellofemoral ligament reconstruction. Int J Res Orthop. 2021;
7: 1026https://doi.org/10.18203/issn.2455-4510.IntJResOrthop20213163
22Unal, M, Demirayak, E, Ertan, MB, Kilicaslan, OF, and Kose, O. Bioabsorbable magnesium screw fixation for tibial tubercle osteotomy; a preliminary study. Acta Biomed. 2022;
92: e2021263https://doi.org/10.23750/abm.v92i6.11716
24Nurmi, JT, Itälä, A, Sihvonen, R et al. Bioabsorbable versus metal screw in the fixation of tibial tubercle transfer: a cadaveric biomechanical study. Orthop J Sports Med. 2017;
5: 232596711771443https://doi.org/10.1177/2325967117714433
25Fulkerson, JP. Fracture of the proximal tibia after Fulkerson anteromedial tibial tubercle transfer. A report of four cases. Am J Sports Med. 1999;
27: 265
26Bellemans, J, Cauwenberghs, F, Brys, P, Victor, J, and Fabry, G. Fracture of the proximal tibia after Fulkerson anteromedial tibial tubercle transfer. Am J Sports Med. 1998;
26: 300–302https://doi.org/10.1177/03635465980260022401
27Mina, C, Garrett, WE, Pietrobon, R, Glisson, R, and Higgins, L. High tibial osteotomy for unloading osteochondral defects in the medial compartment of the knee. Am J Sports Med. 2008;
36: 949–955https://doi.org/10.1177/0363546508315471
28Quirno, M, Campbell, KA, Singh, B et al. Distal femoral varus osteotomy for unloading valgus knee malalignment: a biomechanical analysis. Knee Surg Sports Traumatol Arthrosc. 2017;
25: 863–868https://doi.org/10.1007/s00167-015-3602-z
29Stephen, JM, Lumpaopong, P, Dodds, AL, Williams, A, and Amis, AA. The effect of tibial tuberosity medialization and lateralization on patellofemoral joint kinematics, contact mechanics, and stability. Am J Sports Med. 2015;
43: 186–194https://doi.org/10.1177/0363546514554553
30Gallo, RA and Feeley, BT. Cartilage defects of the femoral trochlea. Knee Surg Sports Traumatol Arthrosc. 2009;
17: 1316–1325https://doi.org/10.1007/s00167-009-0799-8
32Calcei, JG, Varshneya, K, Sochacki, KR, Safran, MR, Abrams, GD, and Sherman, SL. Concomitant osteotomy reduces risk of reoperation following cartilage restoration procedures of the knee: a matched cohort analysis. Cartilage. 2021;
13: 1250S–1257Shttps://doi.org/10.1177/19476035211011515
33Ramappa, AJ, Apreleva, M, Harrold, FR, Fitzgibbons, PG, Wilson, DR, and Gill, TJ. The effects of medialization and AMZ of the tibial tubercle on patellofemoral mechanics and kinematics. Am J Sports Med. 2006;
34: 749–756https://doi.org/10.1177/0363546505283460
34Ambra, LF, Hinckel, BB, Arendt, EA, Farr, J, and Gomoll, AH. Anatomic risk factors for focal cartilage lesions in the patella and trochlea: a case-control study. Am J Sports Med. 2019;
47: 2444–2453https://doi.org/10.1177/0363546519859320
35Flury, A, Hoch, A, Andronic, O, Fritz, B, Imhoff, FB, and Fucentese, SF. Increased femoral antetorsion correlates with higher degrees of lateral retropatellar cartilage degeneration, further accentuated in genu valgum. Knee Surg Sports Traumatol Arthrosc. 2021;
29: 1760–1768https://doi.org/10.1007/s00167-020-06223-x
36Macri, E, Felson, D, Ziegler, M et al. The association of frontal plane alignment to MRI-defined worsening of patellofemoral osteoarthritis: the MOST study. Osteoarthritis Cartilage. 2019;
27: 459–467https://doi.org/10.1016/j.joca.2018.11.004
37Mehl, J, Feucht, MJ, Bode, G, Dovi-Akue, D, Südkamp, NP, and Niemeyer, P. Association between patellar cartilage defects and patellofemoral geometry: a matched-pair MRI comparison of patients with and without isolated patellar cartilage defects. Knee Surg Sports Traumatol Arthrosc. 2016;
24: 838–846https://doi.org/10.1007/s00167-014-3385-7
38Brittberg, M, Lindahl, A, Nilsson, A, Ohlsson, C, Isaksson, O, and Peterson, L. Treatment of deep cartilage defects in the knee with autologous chondrocyte transplantation. N Engl J Med. 1994;
331: 889–895https://doi.org/10.1056/NEJM199410063311401
39Peterson, L, Minas, T, Brittberg, M, Nilsson, A, Sjögren-Jansson, E, and Lindahl, A. Two- to 9-year outcome after autologous chondrocyte transplantation of the knee. Clin Orthop Relat Res. 2000;
May: 212–234https://doi.org/10.1097/00003086-200005000-00020
40Peterson, L, Brittberg, M, Kiviranta, I, Åkerlund, EL, and Lindahl, A. Autologous chondrocyte transplantation: biomechanics and long-term durability. Am J Sports Med. 2002;
30: 2–12https://doi.org/10.1177/03635465020300011601
Iain R. Murray and Seth L. Sherman served as Guest Editors for this issue of JCJP. They were not involved in decisions about the article they wrote, and peer review was handled independently.
Published by Elsevier B.V. on behalf of International Cartilage Regeneration and Joint Preservation Society.
Article Info
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