Hybrid closed wedge high tibial osteotomy improves patellofemoral joint congruity compared with open wedge high tibial osteotomy

PurposeTo evaluate clinical outcomes and radiographic changes in patellofemoral (PF) joint congruity between open wedge high tibial osteotomy (OWHTO) and hybrid closed wedge HTO (HCWHTO).MethodsFrom 2011 to 2013, 36 knees in 31 patients who underwent OWHTO and 21 knees in 17 patients who underwent HCWHTO were evaluated in this retrospective study with a minimum 5-year follow-up. Radiological outcomes including hip-knee-ankle angle (HKA), femoral patellar height index (FPHI), preoperative PF osteoarthritis (OA) grade, medial and lateral joint spaces of the PF joint, and congruence angle were measured. Clinical parameters including the Knee injury and Osteoarthritis Outcome Score (KOOS) and the Oxford Knee Score (OKS) were also evaluated. Preoperative and final follow-up values for each procedure were compared in outcome analyses.ResultsMean preoperative HKA and the degree of PF-OA were significantly more severe for patients treated with HCWHTO compared with those treated with OWHTO (p=0.001, p=0.0001). Mean postoperative FPHI was significantly decreased with proximalization of the patella in HCWHTO (p=0.01) but showed no significant change in OWHTO (n.s.). Regarding PF joint congruity after HCWHTO, lateral joint space and congruence angle were significantly improved (p=0.0001, p=0.005), while medial joint space was not significantly changed (n.s.). After OWHTO, congruence angle showed no significant difference (n.s.), but medial and lateral joint spaces were significantly decreased (p=0.0001, p=0.018). There were no significant differences in KOOS and OKS between the groups (n.s., n.s.).ConclusionsAlthough degrees of varus knee and PF-OA were more severe in HCWHTO than those in OWHTO, HCWHTO led to improved PF joint congruity, and its mid-term clinical outcomes were equivalent to those of OWHTO. Therefore, in patients with varus knee combined with PF-OA preoperatively, HCWHTO is a more effective treatment than OWHTO.Level of evidenceTherapeutic level III.