Paper 22: High Tibial Osteotomy: Return to Duty in an Active Duty Military Population

OBJECTIVES: Evidence on both return to sport and work following high tibial osteotomy (HTO) has been limited, especially in a young, military population with high occupational demands. The purpose of this study was two-fold: 1) to identify if objective measures of preoperative knee condition severity or intraoperative correction were associated with successful return to duty and 2) to assess if postoperative complications and return to the operating room were associated with successful return to duty. METHODS: A retrospective cohort study was performed of patients in the Military Health System who underwent HTO between 2003 and 2018. All patients were between 18 and 55 years and presented with osteoarthritis isolated to the medial compartment with or without other knee injuries. Concomitant meniscal and cartilage procedures were included while ligamentous procedures were excluded as they were viewed as a separate pathology. The inclusion criteria were as follows: active duty status at the time of the index procedure and two-year minimum follow-up with both preoperative knee radiographs and pre- and postoperative long-leg alignment radiographs. Preoperative Kellgren-Lawrence grade, pre- and postoperative hip-knee-ankle angle, and postoperative weightbearing axis were collected. The primary outcome was return to duty, stratified by failure defined as medical separation from the military or conversion to total knee arthroplasty. Success was defined as remaining on active duty without restriction while modified success was defined as remaining on active duty with permanent activity restrictions. The secondary outcome was reoperation for any reason. RESULTS: Fifty-five HTOs were performed in 50 patients with a mean age of 39.0 years (range 22.8-55.0). Mean follow up was 5.0 years (range 2.1-10.7). 18.2% (10/55 knees) failed HTO (one conversion to TKA, nine medical separations), 27.3% (15/55 additional knees) had permanent activity restrictions, and 54.5% (30/55 knees) returned to active duty without restriction. 34.5% of HTOs had reoperation at any time point and return to the operating room was associated with medical separation (p=0.027). Reoperation occurred for unplanned removal of hardware (7), irrigation and debridement (4), revision HTO (3), meniscal transplant (2), meniscal repair (1), spinal cord stimulator placement (1), and decompressive fasciotomies (1). Younger age was associated with both medical separation (p=0.003) and permanent restrictions (p=0.006) following HTO and was the only significant variable identified on multiple logistic regression analysis. Patients with residual postoperative varus deformity >5 degrees were more likely to undergo medical separation (p=0.023). CONCLUSIONS: When performed in a military population, HTO succeeded in returning 54.5% of knees to full duty without restriction despite 34.5% of knees requiring reoperation for complications. However, HTOs with residual varus deformity or complications requiring additional procedures were associated with lower return to duty rates. No correlation was identified between return to duty and osteoarthritis grading or amount of deformity.