Background
Time-dependent changes in lower extremity alignment after an open wedge high tibial osteotomy (OWHTO) was poorly investigated. Moreover, few studies investigated risk factors of postoperative alignment change.
Purpose
To investigate time-dependent alignment changes and identify predictive factors for postoperative alignment change after OWHTO.
Methods
This study included patients who underwent OWHTO between March 2010 and September 2018. A total of 142 knees were enrolled with a mean follow-up of 42 months and classified as the ‘change’ group when the amount of hip-knee-ankle (HKA) angle change was more than 1°; if otherwise, then as the ‘no change’ group. HKA angle was obtained at six time points: preoperatively, at 3 months, 6 months, 1 year, 2 years, and final follow-up postoperatively. Multiple regression analysis was performed to identify the factors that were correlated with the changes in the HKA angle from 3 months to the final follow-up.
Results
Among the 142 knees, 59 (42%) were enrolled in the change group. The overall postoperative HKA angles progressed serially toward varus after OWHTO. The mean angles of the six time points were 8.5°/-3.7°/-3.6°/-3.3°/-3.1°/-2.7°, respectively. The mean HKA angles of change and no change group were 9.1°/-4.3°/-3.4°/-2.8°/-2.0°/-1.4°/ and 8.1°/-3.3°/-3.8°/-3.6°/-3.8°/-3.7°, respectively. Greater change in the HKA angle was predicted by preoperative greater valgus stress joint line convergence angles (JLCA) and less medial joint space width.
Conclusion
Forty-two percent of OWHTO showed correction loss of more than 1° at a mean follow-up of 42 months. The overall postoperative HKA angles progressed serially to varus angles after OWHTO. Preoperative greater valgus stress JLCA and less medial joint space width were predictive factors for greater change in alignment toward varus after OWHTO.