Opening-wedge high tibial osteotomy performed with locking plate fixation (TomoFix) and early weight-bearing but without filling the defect. A concise follow-up note of 48 cases at 10 years' follow-up.

ABSTRACT

INTRODUCTION: Use of a locking plate during medial opening high tibial osteotomy (HTO) eliminates the need to fill the defect and its associated complications. It also allows early weight-bearing. Since long-term data with this type of construct are rare, we wanted to report the outcomes of a 51-patient cohort evaluated after a mean follow-up of 10.2years. The goals were to determine (1) the HTO survival and whether the correction was maintained between 2 and 10years later, (2) the stability of the functional outcomes, (3) the complication rate related to use of locking plates. HYPOTHESIS: The correction following medial opening HTO with a Tomofix™ plate without void filling is maintained after 10years' follow-up. MATERIAL AND METHODS: Fifty-one patients ranging from 37 to 72years of age at the time of surgery between 2003 and 2005 underwent a medial opening HTO that was stabilized with a Tomofix™ locking plate (Synthes, Oberdorf, Switzerland) without void filling. Forty-eight patients were reviewed between March and September 2014; 1 patient had died and 2 were lost to follow-up. RESULTS: The mean HKA angle went from 172±3.18° (165-178°) preoperatively to 181±1.18° (176-185°) postoperatively, to 181±1.60° (176-185°) at 2years, and 180.8±2.4° (175-184°) at 10years' follow-up. This equates to a loss of correction of 0.71±1.9° (0-6°) (p=0.02) between 2 and 10years after the surgery. Five patients underwent total knee arthroplasty (TKA), thus the 10-year survival of the HTO procedure was 88% (95% CI 81-98%). If the five TKA procedures are excluded, the mean IKS knee score went from 90±7.4 (66-98) at 2years' follow-up to 77±15.3 (43-97) at 10years (p>0.05). There were four complications in all (8%), of which three occurred within 2years (2 cases of nonunion and 1 surgical site infection) and one occurred later (infection after 118months that resolved once the hardware was removed and the patient given appropriate antibiotics). There were no complications related to the five subsequent TKA procedure and no bone grafting was required. DISCUSSION: There was a small (less than 1 degree) but statistically significant loss of correction and non-significant deterioration in the functional outcomes. Conversely, the complication rate did not increase over time, despite the lack of void filling, particularly in patients who subsequently underwent TKA. The 10-year survival was similar to other HTO procedures. This locking plate construct without void filling is reliable after 10years. LEVEL OF EVIDENCE Level IV, prospective study without control group.