Treatment of Cartilage Defects of the Knee: Expanding on the Existing Algorithm

Objective: The purpose of this review is to survey the literature regarding factors used in determining a course of surgical treatment for symptomatic cartilage lesions of the knee to determine which factors affect treatment outcomes and should be incorporated in the treatment algorithm. Methods: A systematic review was performed using PubMed, Cochrane Review, and SportDiscus databases for studies investigating factors affecting cartilage lesion treatment and outcomes. Inclusion criteria were clinical and basic science studies in English, on human or animal specimens that focus on factors affecting the initiation, progression, and treatment of focal knee chondral defects. Results: Twenty-seven studies examining 1450 human (1416 in vivo; 34 cadaveric) and 90 animal subjects met inclusion criteria. Female sex and higher body mass index (BMI) significantly predicted cartilage loss rates and recovery after microfracture (MFx) and autologous matrix-induced chondrogenesis. Defect size and location significantly predicted treatment outcomes. Sizes >2 to 4 cm(2) demonstrated worse outcomes after MFx treatment. Defect size did not consistently affect autologous chondrocyte implantation or osteochondral autograft transplantation outcomes. Intra-articular lesion location was related to intralesional subchondral bone contact and MFx outcome. Corrected patellofemoral and tibiofemoral alignment improved clinical outcome when realignment procedures were done concurrently with cartilage repair. Conclusions: Choice of the appropriate repair technique for focal knee cartilage defects is multifactorial. A treatment algorithm should consider frequently used factors such as defect size, location, knee alignment, and patient demand. However, patient sex and BMI could also be considered. Patient age was not significantly associated with clinical outcome.