Hybrid HTO leads to significant improvements in radiographic parameters and knee function. In general, closed wedge HTO tends to shorten the leg length, however Hybrid HTO did not significantly influence the leg length. According to the result of JLCA change, required correction angle is almost same with bony correction angle.
High tibial osteotomy (HTO) is a reliable procedure for knee osteoarthritis and osteonecrosis. Especially, Hybrid HTO reported by Takeuchi R et.al is a novel closed wedge HTO which is applicable for the patients with severe varus knee deformity.
The aim of this study is to assess the clinical results and surgical complications of Hybrid HTO in our hospital. Intraarticular findings and changes were assessed by second-look arthroscopy before and after Hybrid HTO.
MATERIAL & METHODS:
63 knees in 53 consecutive patients who were underwent Hybrid HTO with an internal plate fixator were assessed. JOA Score (Japan Orthopedic Association Knee Score) was used to evaluate the functional results.
Radiological parameters consisted of hip-knee angle (HKA), posterior tibial slope angle (PTS), weight bearing line ratio (WBL-R) , joint line convergence angle (JLCA) ,and Caton-Deschamps-index(CDI) for checking patella height. The ratio of the leg length (RLL) between the operated side and the opposite side of each patient was calculated before and after surgery for evaluating leg length change. In 39 knees of all 34 cases, articular cartilage in medial femorotibial joint and patellofemoral joint were evaluated by arthroscopy before and about 12 months after HTO according to ICRS grading system. In all cases operative complications were recorded.
Duration of follow-up was 23.5±4.2 months. Mean JOA Score improved 47.2 ±3.8 to 82.5 ±4.0 points (P<0.001). Mean HKA was corrected 9.65±3.5° pre-operatively to 0.06±1.4°post-operatively (P<0.001). Mean WBL-R was corrected 10.2±15.5% pre-operatively to 56.2±13.8% post-operatively (P<0.001). Mean PTS decreased significantly 4.7±1.9° pre-operatively to 1.9±2.1° post-operatively (P<0.001). Mean CDI and mean JLCA did not change 0.85±0.14 pre-operatively to 0.84±0.12 post- operatively (P=0.26), 4.04°±0.26 pre-operatively to 3.87±0.29° post- operatively (P=0.31) respectively.
ICRS grade in medial femorotibial(FT) joint improved in 33 of 39 knees (84.6%)and did not change in 6 of 39 knees (15.4%).
ICRS grade in patellofemoral(PF) joint improved in 16 of 39 knees (41.1%)and did not change in 23 of 39 knees (58.9%). Mean RLL did not alter 0.994±0.013 pre-operatively to 0.995±0.008 post- operatively (P=0.79). Operative complications were non-union of the osteotomy site 2knees of 1case (3.2%), Methicillin-resistant Staphylococcus aureus (MRSA) infection 1knee of 1 case (1.6%), Pseudoaneurysm formation in the posterior tibial artery just after plate removal 1knee of 1 case (1.6%), deep peroneal nerve injury 1knee of 1 case (1.6%).
From the result of this study, Hybrid HTO leads to significant improvements in radiographic parameters and knee function. In general, closed wedge HTO tends to shorten the leg length, however Hybrid HTO did not significantly influence the leg length. According to the result of JLCA change, required correction angle is almost same with bony correction angle. Arthroscopic findings suggest that Hybrid HTO may contribute to the regeneration of cartilage in FT and PF joints.