High-risk factors for subjective discomfort due to lower limb discrepancy after medial open wedge high tibial osteotomy

BACKGROUND: Medial open wedge high tibial osteotomy (OWHTO) may result in lower limb discrepancy (LLD), and some patients experience uncomfortable symptoms. Studies have found that the degree of LLD is one but not the only high-risk factor for inducing symptoms. The main purpose of this study is to explore the risk factors for symptomatic LLD. METHODS: Sixty-four patients who underwent OWHTO in our hospital between June 2018 and January 2020 were included in the study. Changes in tibia length, lower limb length, femorotibial angle (FTA), LLD, and KOOS score were evaluated before and 1 year after surgery. Questionnaire was used to investigate whether patients had uncomfortable symptoms of LLD after surgery. Binary logistic regression was applied to analyze the risk factors of symptomatic LLD. RESULTS: There were 18 patients with subjective LLD uncomfortableness, 13 of them were occasional and 5 were frequent. Patients had a mean correction angle of 11.7° ± 4.6°, with a mean increase in tibial length of 6.0 ± 3.5 mm, lower limb length of 7.5 ± 2.3 mm, and LLD of 6.9 ± 4.2 mm at 1 year post-operation. Preoperative and postoperative changes in tibia length and lower limb length were statistically significant (P < 0.0001).There were statistically significant differences in pain, symptoms, ADL, sports/recreations, QOL of KOOS subclassification before and after surgery (P < 0.0001). Binary logistic regression revealed that age ≥ 55, BMI ≥ 28, and LLD ≥ 10 mm were high-risk factors for symptomatic LLD (P = 0.031, OR = 4.82; P = 0.012, OR = 6.251; P = 0.006, OR = 6.836). CONCLUSION: Patients with age ≥ 55, BMI ≥ 28, and postoperative LLD ≥ 10 mm are more likely to develop symptomatic LLD. Older or heavier patients, who are expected to have an LLD greater than 10 mm after OWHTO should be fully informed of the possibility of postoperative LLD symptoms.