Moderate Return to High Impact Function after Fresh Osteochondral Allograft Transplantation for Chondral Defects of the Knee

OBJECTIVES: The purpose of this investigation was to report the patient-reported and occupational outcomes of military servicemembers after fresh osteochondral allograft transplantation (OCA) of the knee at mid-term follow-up. METHODS: A query of the Military Health System was performed to identify all United States Army service members undergoing OCA for Outerbridge grade 3 or 4 chondral lesions between January 2009 and June 2013 with minimum 2-year follow-up. Exclusion criteria were applied to individuals with the following: insufficient follow-up or documentation; treatment of bipolar lesions; and use of cryopreserved, fresh-frozen, or fresh osteochondral allografts used greater than 28 days after harvest. Demographic information, lesion characteristics, and clinical outcomes (Visual Analog Scale for pain, functional duty limitations, and/or revision rates) were extracted from the military electronic medical records system. Statistical measures such as the Chi square test and Poisson multivariable regression analysis were utilized to evaluate for variables associated with rate-limiting, knee disability and/or surgical revision. RESULTS: At 3.8 follow-up, 61 patients met the inclusion criteria with an average age was 32 yrs±8.0. Medial femoral condyles were most common (n=40;65.6%), followed by the patella (n=11;18.0%), lateral femoral condyle (n=8;13.1%), and trochlea (3;5.0%). The average cross-sectional size of treated lesions was 364 mm(2)±193 (48-707 mm(2)). Thirty-seven knees (61.7%) were treated without concomitant procedure, and 21 knees (34.4%) had staged or simultaneous periarticular osteotomies. Average VAS pain scores significantly decreased from 4.1 to 2.5 postoperatively (p<0.01). At final follow up, 65.6% of patients returned to unrestricted or modified military function, whereas 21(34.4%) individuals were unable to return due to persistent knee limitations. Nine (14.7%) patients experienced preoperative complications, Seven patients (11.5%) required secondary revision after OCA, 3 patients underwent chondroplasty, and 1 patient (1.6%) underwent subsequent total knee arthroplasty. Lesion size was not associated with any adverse clinical or surgical outcomes (p>0.05), and lateral femoral condyle and trochlear lesions had a higher rates of revision, although this failed to achieve significance (p=0.22;p=0.26, respectively). Higher preoperative BMI (OR 1.15;p=0.045) and postoperative VAS(OR 1.36;p<0.01) values were associated with increased risk of knee disability. CONCLUSION: Fresh OCA can reliably decrease knee pain in a highly-active population, with nearly two-thirds of all patients return to military function. However, approximately one in eight individuals may undergo revision after return to preoperative activities, and individuals of high BMI may be at heightened risk of clinical failure.