Osteochondral Autograft Transfer Versus Microfracture in the Knee: A Meta-analysis of Prospective Comparative Studies at Midterm

Purpose: To compare microfracture (MFX) and osteochondral autograft transfer (OAT) surgical techniques to determine (1) postoperative activity level, (2) subjective patient outcomes, (3) failure rates, and (4) assess if any lesion characteristics favored one technique over the other. Methods: A comprehensive review of literature was performed of all studies comparing MFX and OAT. Studies included were all prospective studies that reported on activity-based outcome measures such as Tegner activity scores and subjective outcomes such as the International Knee Documentation Committee score. Failure rates, as determined by the publishing authors, were recorded for each study. Meta-analyses were conducted using a random-effects model. Paired standardized mean differences (Hedges's g to account for small sample bias) were used for continuous outcome measures, and risk ratios (Mantel-Haenszel method for small sample bias) for dichotomous outcome measures. Results: Six prospective studies satisfied the eligibility criteria and included 249 patients (186 male, 120 female) with an average age of 26.4 years and follow-up of 67.2 months. Tegner scores were superior in patients treated with OAT compared with MFX (DOAT-MFX for pre-post scores = 0.94 Tegner points, standardized mean difference [SMD] = 0.469, P =.005). Failure rates of MFX were higher than OAT (OAT = 11%, MFX = 32%, risk ratio = 2.42, P <.036). OAT was superior to MFX at 3 years in relation to subjective outcome scores (SMD = 0.404, P =.008). When assessing OAT lesions larger than 3 cm(2), OAT was superior to MFX with respect to activity level (SMD = 0.506, P =.001). Conclusions: OAT may achieve higher activity levels and lower risk of failure when compared with MFX for cartilage lesions greater than 3 cm2 in the knee, although there was no significant difference for lesions less than 3 cm2 at midterm. However, because of variability in patient-specific factors such as age, preinjury activity level, lesion location and size, the superiority of OAT over MFX cannot be generalized to all patient populations and therefore requires individualized patient care. Level of Evidence: Level II, meta-analysis of Level I and II studies.