Review Question - QID 219788

Anteriorizarion of the tibial tubercle by greater than 1 cm can lead to skin necrosis and wound breakdown (Answer 2).

Anterior knee pain and patellofemoral chondral lesions are common and can result from malalignment, mechanical overload, unique surface anatomy, and instability. The patellofemoral joint experiences forces up to 6.5 times body weight with increased knee flexion. Patients with symptomatic patellofemoral chondral lesions experience significant pain and decreased quality of life. These patients are often young or active, making them less suitable for arthroplasty and often involve complex surgical decision-making. While a tibial tubercle osteotomy (TTO) is well-established for patellofemoral instability, its indications for cartilage defects are less clear. Experts generally agree that an unloading TTO should be considered for patients with bipolar patellofemoral lesions undergoing cartilage procedures, but the specific type of TTO is still debated. An isolated anteriorization of the tibial tubercle (Maquet) was historically used for isolated distal pole lesions but carried an additional risk of skin necrosis and wound issues with excessive anteriorization.

Middleton et al. review patellofemoral disorders and emphasize the challenging diagnosis and management of this condition. They summarize the causes of instability, which include trochlear dysplasia, patella alta, patellar tilt, and an elevated tibial tuberosity and trochlea groove distance. The authors then describe the various tibial tubercle transfer (TTT) options based on lesion location, patellar tracking, and/or patellar height. In summary, a thorough understanding of the anatomy and biomechanics of the patellofemoral joint is essential for optimizing results after TTT.

Patel et al. reviewed specific indications and techniques for performing a tibial tubercle anteriorization. The authors propose that while indications for TTO in the setting of patellar instability are well established, they are less strictly defined in the setting of chondral defects. They describe their technique for performing a direct anterior transfer of the tibial tubercle and compare it to the historical Maquet osteotomy. They conclude that their modified technique prevents wound breakdown secondary to lateralization of the incision a less extensive osteotomy cut, and less pronounced anteriorization (<1 cm).

Figure A demonstrates an inferolateral patellar chondral lesion. Figure B shows an arthroscopic view of grade III chondromalacia of the distal lateral patella.

Incorrect answers:
Answer 1: Isolated anteriorization is not indicated in the setting of instability and is not associated with new instability.
Answer 3: While nonunion is a risk with any TTO, skin necrosis is a more likely scenario.
Answer 4: TTO is not associated with progression of osteochondral lesions.
Answer 5: Fracture is not associated with excessive anteriorization.