Hybrid Lateral Closed-Wedge High Tibial Osteotomy showed Similar Accuracy in Angular Correction and Reduction of Posterior Tibial Slope Compared to Opening-wedge High Tibial Osteotomy - A Correction Angle Matched Cohort Study.
BACKGROUND
We aimed to compare accuracy of applied correction angle between hybrid lateral closed wedge high tibial osteotomy (hybrid HTO) and medial open wedge high tibial osteotomy (OWHTO), and verify previous reports on hybrid HTO by matching correction angle between groups. Change in various radiological parameters including union rate were also compared.


METHODS
A total of 50 OWHTO patients were selected for 2:1 propensity matching with 25 hybrid HTO patients. Rate of correction error was calculated by dividing the difference between change in MPTA and preoperatively planned correction angle (change of PRD) by planned correction angle. Accuracy of angular correction was assessed using change of PRD and correction error rates. Hip-knee-ankle axis, mechanical lateral distal femoral angle, medial proximal tibial angle, joint line convergence angle, and length of the entire lower limb and tibia were measured. The Caton-Deschamp index (CDI) was used to assess change in patellar height. Serial postoperative radiographic analysis was performed to assess union rate.


RESULTS
The discrepancy between planned correction angle and real correction angle was 0.8±2.3° in hybrid HTO and 1.1±3.4° in OWHTO (p>0.05), and the rate of error in osteotomy was similar between the groups approximately 6%. Postoperatively, posterior tibial slope (PTS) (p<0.001), tibia length, and CDI (p<0.001) were significantly different between groups. The amount of change in PTS (p<0.001), tibia length in hybrid HTO (p<0.001), and CDI (p<0.001) were significantly different between groups. Union rate of osteotomy site was significantly faster in hybrid HTO than in OWHTO (p<0.001).


CONCLUSION
Hybrid HTO showed similar accuracy in angular correction compared to correction angle-matched OWHTO. Reduction in PTS, tibial shortening, maintained patellar height relative to the proximal tibia, and faster osteotomy site union were also confirmed in hybrid HTO.