Increased symptoms of stiffness after opening-wedge high tibial osteotomy are associated with worse postoperative knee function outcomes and lower patient satisfaction rate.

BACKGROUND: Symptoms of knee stiffness after open wedge high tibial osteotomy (OW-HTO) can significantly affect surgical effectiveness, but no studies have reported risk factors for knee stiffness after OW-HTO.

METHODS: Patients treated with OW-HTO for the first time between 2018 and 2021 were included. Data were collected on patient demographics, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Short Form (SF) 12 scores, hip-knee-ankle angle (HKA) and patient satisfaction before and after surgery. Patients with worse WOMAC stiffness scores at 1 year were defined as the 'increased stiffness' group and the other cohort as the 'non-stiffness' group. The primary outcome of the study was to compare postoperative knee function scores (WOMAC and SF-12), HKA and patient satisfaction rate between the two groups. The secondary outcome was the use of logistic regression to analyze independent predictors of increased postoperative stiffness symptoms.

RESULTS: At 1 year postoperatively, 95 (11.3%) patients had a significant increase in stiffness. Patients had significantly ( p < .001) less improvement in pain, function, and total WOMAC scores, and SF-12 score than those in the non-stiffness group ( n = 745). However, the differences in WOMAC and SF-12 scores in increased stiffness group at 1 year post-operatively were statistically significant ( p < .001) compared to the non-stiffness group. There was no statistically significant difference in HKA in the increased stiffness group (172.9° ± 2.3°) compared to non-stiffness group (173.4° ± 2.6°) at 1 year postoperatively ( p = .068). Patient satisfaction was significantly lower in the increased stiffness group ( p < .001). Logistic regression analysis showed that diabetes (odds ratio (OR) 1.809, p = .034) and preoperative WOMAC stiffness score of 44 or less (OR 4.255 p < .001) were predictors of increased stiffness.

CONCLUSIONS: Patients with increased stiffness after OW-HTO had worse functional outcomes and lower patient satisfaction rates and patients at risk of being in this group should be informed pre-operatively.