To identify arthroscopic findings and gait parameters associated with improvement in 5-year clinical outcomes after OWHTO in patients with knee osteoarthritis (KOA).
A total of 50 consecutive knees from 50 patients with KOA who underwent OWHTO between 2016 and 2018 were retrospectively reviewed. Those who underwent second-look arthroscopy and were followed up for 5 years were enrolled. The knee injury and osteoarthritis outcome score (KOOS), hip-knee-ankle angle, and gait parameters were assessed using a three-dimensional motion analyzer (VICON MX, Oxford Metrics, Oxford, UK) and electromyography (DELSYS Trigno, DELSYS Lab, Natick, USA). Specific parameters included varus thrust (the amount of knee varus angle in the stance phase), knee adduction moment (first peak in the stance phase, normalized by body weight and height), and muscle activity (vastus medialis, normalized by maximum voluntary contraction) at 1 year postoperatively. Cartilage status was graded at the time of osteotomy (first look) and plate removal (second look) according to the International Cartilage Repair Society (ICRS) grading system. The KOOS knee subscale score was assessed separately. Patients were divided into two groups based on changes in preoperative and 5-year postoperative parameters using the minimal clinically significant difference (MCID) to define improvement (improved score ≥ MCID) and non-improvement (improved score MCID).
The study included 40 knees. The mean knee score improved significantly for symptom, activities of daily living (ADL), sports, and quality of life at 1 year (P .001) and at 5 years (P .001) postoperatively. No patient underwent conversion to total knee arthroplasty within 5 years after surgery. The improved KOOS Symptom, Pain, and ADL group showed significantly improved ICRS grades in the medial compartment, low varus thrust, and high vastus medialis muscle activation compared with the non-improved KOOS Symptom, Pain, and ADL group (P .01). Multivariate logistic regression analysis identified improved ICRS grade of the medial compartment at secondary arthroscopy, low varus thrust, and high medial vastus activation as the factors most strongly associated with improved knee joint score (odds ratio, 11.2; P = .03).
The presence of cartilage improvement in the knee medial compartment at second-look arthroscopy, low varus thrust, and high vastus medialis muscle activity were associated with improved long-term clinical outcomes after OWHTO.
Our findings suggest that improvements in the medial compartment cartilage and optimized gait mechanics, which are characterized by low varus thrust and high vastus medialis muscle activity, are critical for enhancing long-term clinical outcomes after OWHTO in patients with knee osteoarthritis. These insights can aid the development of targeted rehabilitation strategies and postoperative monitoring, ultimately contributing to more effective treatment plans and better patient quality of life.
high tibial osteotomy
clinical outcome
