Abstract
Purpose
Successful outcome after opening wedge high tibial osteotomy (HTO) has been correlated with obtaining and maintaining angular correction while achieving union. Magnitude of correction, type of fixation and use of bone graft have been implicated as variables which can affect maintenance of correction.
The purpose of this study was to determine whether loss of coronal plane correction occurs over time following opening wedge HTO using our standard surgical techniques (unlocked plate with allograft). Our aim was also to correlate clinical outcome measures and radiographic findings. Our hypothesis was that no significant loss of correction would occur.
Method
We conducted a retrospective case series with prospectively obtained clinical and radiographic follow-up. The study population was drawn from surgical data bases of 4 fellowship trained surgeons and included all patients who underwent opening wedge HTO between 2007 and 2009, allowing a minimum of 1 year follow-up. Chart data collected included the model and size of opening wedge fixation plate, type of bone graft, concomitant procedures performed as well as patient factors such as smoking status, medical co-morbidities and body mass index (BMI).
Patients underwent follow-up including documentation of complications and physical examination for range of motion and stability. Outcome scores obtained included the validated, disease-specific KOOS score (5 domains measured out of 100) and the SF-36 as a validated assessment of health related quality of life (8 domains averaged and reported using norm based scoring with population mean = 50). Full length weight bearing X-rays were obtained and measured and then compared with pre-operative and early post-operative X-rays. Measurements were performed with PACS digital imaging software.
Results
Forty-one patients with 44 osteotomies were identified as being eligible for the study. Ten patients were lost to follow-up and 7 patients (8 knees) did not agree to participate in prospective evaluation. The total study population with complete retrospective and prospective data included 24 patients with 26 knees. Complications occurred in 4 cases (15%) with 2 patients who developed superficial infections treated with antibiotics and wound care. Two patients developed deep infections requiring multiple additional procedures. One additional patient underwent plate removal. All osteotomies united. No loss of significant loss of coronal plane correction occurred. Mean alignment was 1.1 degrees of mechanical valgus. Mean KOOS (pain) was 78.9 and SF-36 was 50.7
Conclusion
Our results demonstrate that no significant loss of correction occurred in our series after opening wedge HTO using unlocked plates and either allograft or no bone graft. Successful clinical and radiographic outcomes were demonstrated with mean health related quality of life scores equal to population norms. Patients with BMI < 30 and those who did not develop infections had superior results.
