Return to Preoperative Function After Autologous Cartilage Implantation of the Knee in Active Military Servicemembers

BACKGROUND: Autologous chondrocyte implantation (ACI) has been shown to provide adequate durability, pain relief, and improved long-term functional outcomes in the average patient, but proof of its efficacy in individuals with greater than average physical demands is scarce. Further knowledge is required to understand which patients may benefit from ACI and to identify which risk factors are associated with failure to return to the preinjury activity level. PURPOSE: To determine the occupational outcomes, rates of reoperation, and variables predictive of suboptimal outcomes after ACI. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: All active-duty military servicemembers in the United States who underwent ACI of the knee between 2004 and 2014 were identified. Demographic information, injury characteristics, surgical variables, and clinical and surgical outcomes were extracted from the medical record. Univariate and multivariate analyses were used to determine significant independent predictors of clinical and surgical failures. RESULTS: A total of 90 patients (91 knees) met the inclusion criteria. The cohort was predominantly male (86%), with a mean age of 34.5 ± 6.3 years (range, 20-50 years). The most common location of the articular cartilage lesion was the patellofemoral compartment (54 lesions, 59%), and the mean Outerbridge grade and size were 3.8 ± 0.4 and 4.00 ± 2.77 cm(2) (range, 1.2-15.0 cm(2)), respectively. A total of 72 patients (79%) had at least 1 previous knee procedure. Nearly three-quarters of patients (71%) underwent concomitant procedures. At a mean follow-up of 59.9 ± 27.1 months (range, 24.0-140.1 months), 60% of our patients reported significant improvement in knee pain and did not require further surgical intervention. Multivariate analysis identified age <30 years as the only significant independent predictor of both clinical (P = .011) and overall failure (P = .014). Moderate-demand military occupational specialties (P = .036), exclusive involvement of the patellofemoral compartment (P = .045), and use of a periosteal patch (P = .0173) were additionally found to be independent predictors of surgical failure. CONCLUSION: Treatment of articular cartilage defects of the knee with ACI in physically active young individuals can return nearly two-thirds of individuals to daily activity with decreased pain and improved function. Risk factors for failure after ACI surgery were age younger than 30 years, lower demand occupation, exclusive involvement of the patellofemoral compartment, prior microfracture, and use of a periosteal patch.