Cartilage Restoration Techniques for the Patellofemoral Joint

Robert H. Brophy, MD; Robert D. Wojahn, MD; Joseph D. Lamplot, MD

Disclosures

J Am Acad Orthop Surg. 2017;25(5):321-329. 

In This Article

Abstract and Introduction

Abstract

Symptomatic osteochondral lesions of the patellofemoral joint are clinically challenging to manage because of the limited healing potential of articular cartilage; the complex morphology of the patellofemoral joint; the heterogeneity of the articular surface between patients; and high stresses across the joint, which can be altered by malalignment, tilt, or maltracking. Indications for surgery include traumatic lesions, osteochondritis dissecans, and high-grade chondromalacia in association with persistent pain despite a course of nonsurgical management. Various techniques have been described for managing symptomatic osteochondral lesions of the patellofemoral joint, including microfracture, osteochondral autograft transplantation, and biologic cell transplantation, including autologous chondrocyte implantation. Salvage techniques (eg, fresh allograft) may provide satisfactory outcomes after a failed attempt at surgical management. Irrespective of the surgical technique used, outcomes are generally worse in the patellofemoral compartment than in the tibiofemoral joint. The concomitant management of associated pathology, including patellar malalignment, is recommended because it has been shown to improve the success of cartilage restoration procedures.

Introduction

Chondral lesions of the patellofemoral joint are a common entity that is identified in >33% of patients undergoing arthroscopic surgery.[1] After the medial femoral condyle, the patella is the second most common location in the knee for the occurrence of Outerbridge grade III and IV chondral lesions.[2,3] Etiologies for patellofemoral chondral lesions include acute traumatic injuries, such as dislocation and subluxation, microtrauma, osteochondritis dissecans, and degenerative changes.

Multiple factors contribute to the increased challenges of performing patellofemoral cartilage restoration procedures compared with procedures in other areas of the knee. First, patellofemoral joint loads may reach 6.5 times body weight, and chondral injuries that alter force distribution may result in even higher loads.[4] Force distribution can be further altered by abnormal patellar tilt, malalignment, and maltracking, as well as patellar or trochlear dysplasia.[3,5] Second, the complex morphology of the patellofemoral joint and its heterogeneity between patients complicates efforts to restore the native articular surface contour. Third, the patella contains the thickest cartilage in the body, and femoral autograft has structural properties that differ from those of the adjacent native patellar cartilage. Thus, femoral autograft may not adapt well to patellofemoral joint stresses.[1,6,7] Finally, whereas most tibiofemoral defects can be managed arthroscopically, it is often necessary to perform an arthrotomy to manage patellofemoral defects.[4,7] These factors may contribute to the inferior outcomes after cartilage restoration of the patellofemoral joint compared with outcomes after cartilage restoration of the tibiofemoral joint.[1,7–11]

Untreated chondral lesions may be a contributing factor in activity-limiting anterior knee pain.[4–8,10,12–14] The main goal in managing patellar and trochlear chondral injuries is to restore cartilage surface congruity with sufficient biomechanical properties to alleviate symptoms, facilitate the return to previous level of activity, and improve quality of life.[5]

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