High tibial open wedge osteotomy below the tibial tubercle: clinical and radiographic results

Purpose The purpose of this study was to evaluate the clinical and radiographic results of open wedge HTO below the tubercle for genu varum in relatively young patients. Methods Thirty-seven knees in 19 patients with genu varum treated by open wedge HTO below the tubercle between 2001 and 2008 were retrospectively studied. Median follow-up was 36 months (12–108), and median patient age at the time of surgery was 26 years (16–45). Clinical results were evaluated using Lysholm knee scores and Hospital for Special Surgery knee scores. Satisfaction with the results of surgery (0–10 points) was subjectively evaluated using operative scar (1–5 points) and leg shape (1–5 points) results at follow-up. Radiographic evaluations were made using: (1) tibiofemoral angles, (2) mechanical axis deviations, (3) varus-valgus inclinations of the tibial plateau, (4) tibial slopes, and (5) Insall-Savati and (6) Blackburne-Peel ratios. Results All but one patient achieved radiographic healing and union at the osteotomy site at an average of 3 months postoperatively. Average Lysholm knee score improved from 89.4 ± 8.7 preoperatively to 98.6 ± 2.5 at final follow- up (P = 0.0001), and mean HSS score improved from 91.1 ± 5.6 preoperatively to 98.5 ± 2.0 at final follow-up (P = 0.0001). Mean patient satisfaction score at final follow-up was 8.6 ± 1.0, and mean tibiofemoral angle increased from -1.6 preoperatively to 7.7 at final followup (P\0.0001). The point where the mechanical axis crosses the tibial plateau also shifted significantly from 15.0% preoperatively to 50.6% at final follow-up (P = 0.0002). However, mean posterior tibial slope did not change significantly (9.7 preoperatively and 8.7 at final follow-up; P = NS), and neither did patella heights as measured by Insall-Savati and Blackburne-Peel ratios. Conclusion Both functional assessment and radiographic measures indicated that HTO below the tibial tubercle leads to significant improvements in radiographic parameters and knee function without changes in patellar height or posterior tibial slope. The results obtained support the hypotheses that opening wedge HTO below the tibial tubercle should be recommended in relatively young patients with genu varum. Level of evidence Therapeutic study, Level IV.