2018 Volume 37 Issue 4 Pages 407-412
Purpose: The purpose of this study was to investigate factors affecting Knee Injury and Osteoarthritis Outcomes Score (KOOS) in the intermediate term (more than five years) after opening-wedge high tibial osteotomy (OWHTO).
Subjects and Methods: We investigated 84 patients with 90 knees who underwent OWHTO between June 2007 and October 2010 inclusive. The patients had been followed for more than five years and comprised 21 men with 25 knees, and 63 women with 65 knees (mean age=65.7 at the time of surgery; 71 knees with medial osteoarthritis (OA), and 19 knees with osteonecrosis (ON)). The average observation period was 74.3 months (range: 60-102 months). The KOOS was calculated during the final investigation, and its relation to various factors before or after the surgery were also analyzed. Factors examined prior to surgery included the femorotibial angle (FTA), range of motion (ROM), and intraoperative correction angle, while the factors after surgery (during the final investigation) included FTA and ROM.
Results: The FTA showed optimum alignment from 168.3° to 180.4°, while the intraoperative correction angle was 12.1° on average. The ROM (flexion/extension) was unchanged overall, ranging from 125.4°/−1.1° to 126.5°/−1.0°. The KOOS during the final investigation was 82.0 for symptoms, 81.6 for pain, 85.5 for function in activities of daily living (ADL), 61.0 for function in sports and recreation, and 66.1 for quality of life (QOL). The ROM after surgery was positively correlated with all five items of the KOOS, with the score increasing as the bending angle after surgery also increased (symptoms R=0.402 P<0.01, pain R=0.399 P<0.01, ADL R=0.306 P<0.01, sports and recreation R=0.394 P<0.01, QOL R=0.271 P<0.01). The other variables were not correlated with KOOS.
Discussion: The intermediate-term results of OWHTO in our clinic were overall indicative of good outcomes for patients. ROM after surgery was also related to KOOS, suggesting that appropriate aftercare is also important.
