To evaluate patellofemoral congruity after opening wedge high tibial osteotomy (OWHTO) and hybrid HTO.
Twenty-four knees with hybrid HTO and 24 with OWHTO were evaluated in this study. The Caton-Deschamps and modified Miura-Kawamura indices were used to evaluate pre- and post-operative patellar heights for both types of surgery. Tibial tuberosity-trochlear groove (TT-TG) distance, patellar tilt, and medial and lateral joint space at the patellofemoral joint were compared. Anterior knee pain was assessed using the Kujala anterior knee pain scale.
There was no significant difference between the correction angles of the hybrid HTO and OWHTO. Pre- and post-operative values for the Caton-Deschamps and modified Miura-Kawamura indices in patients who underwent hybrid HTO changed from 0.90 to 0.94 and from 0.95 to 1.03, respectively, with no significant differences noted. Following OWHTO, these values decreased significantly from 0.91 to 0.73 and from 1.06 to 0.84, respectively (p < 0.01). The post-operative patellar height after OWHTO was significantly lower than that after hybrid HTO (p < 0.01). After hybrid HTO, the TT-TG distance decreased significantly from 11.4 to 7.4 (p < 0.01), but it did not change significantly after OWHTO. Although pre- and post-operative patellar tilt were not altered significantly in either group, the medial joint space of the patellofemoral joint was significantly increased post-operatively following hybrid HTO (p = 0.035). The pre-operative Kujala scores were significantly lower in the hybrid HTO group, but post-operative scores improved in both groups.
Retrospective comparative study, Level III.
Hybrid HTO provides a better post-operative patellofemoral joint than does OWHTO with regard to patellar position and reduction of the TT-TG distance, as well as improved clinical outcomes. Hybrid HTO, rather than OWHTO, is the preferred technique for the treatment of varus knees combined with patellofemoral osteoarthritis.