2015 ISAKOS Biennial Congress ePoster #1706

Closing Wedge Versus Opening Wedge Technique in High Tibial Osteotomy Comparison of Proximal Tibia Deformity

Umito Kuwashima, MD, PhD, Tokyo JAPAN
Yasutaka Tashiro, MD, PhD, Kitakyushu JAPAN
Ken Okazaki, MD, PhD, Tokyo JAPAN
Hideki Mizu-uchi, MD, PhD, Fukuoka City, Fukuoka JAPAN
Satoshi Hamai, MD, Fukuoka JAPAN
Hiroyuki Nakahara, MD, PhD, Fukuoka JAPAN
Shigetoshi Okamoto, MD, Fukuoka JAPAN
Koji Murakami, MD, Fukuoka JAPAN
Yukihide Iwamoto, MD, PhD, Fukuoka, Fukuoka JAPAN
Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Fukuoka, JAPAN

FDA Status Cleared

Summary: The deviation of mechanical axis from anatomical axis was greater after CW-HTO than that after OW-HTO, however the difference was small and not clinically significant when TKA conversion.

Abstract:

«Purpose»
High tibial osteotomy (HTO) is a useful treatment option for osteoarthritis of the knee. Closing-wedge HTO (CW-HTO) had been mostly performed previously. Recently, opening-wedge HTO (OW-HTO) is becoming more popular, but the difference of the two surgical techniques about the influence on proximal tibia deformity and difficulties in Total Knee Arthroplasty (TKA) conversion are not fully understood. The purpose of this study was to clarify the influence of two surgical techniques with CW-HTO and OW-HTO on the tibial bone deformity using computer simulation and to evaluate the difficulties when TKA conversion should be required in the future. We hypothesized that the effect of deformity was greater in CW-HTO due to the resection of proximal tibia.
«Methods»
In thirty knees with medial osteoarthritis, the 3D bone models were created from the series of 2 mm slices two-dimensional contours using the 3D reconstruction algorithm. The 3-D imaging software (Mimics, materialize NV, Leuven, Belgium) was applied and simulated surgical procedure of each CW-HTO and OW-HTO were performed on the same knee models. The correction angle was determined so that the postoperative femorotibial angle would be 170 degrees. The distance between the center of resection surface and anatomical axis, and the angle of anatomical axis and mechanical axis were measured in each procedure. Secondly, a simulated TKA conversion was operated on the each tibial bone models after HTO. The distance between the nearest points of tibial implant and cortical bone was assessed as the index of the bone-implant interference.
«Results»
The distance between the center of resection surface and anatomical axis was significantly shifted to the lateral side in CW-HTO group (0.01 ±3.27 mm lateral shift) than in OW-HTO group (1.61 ± 4.07 mm medial shift) (P<0.01). The difference of two procedure was 1.6mm. The angle of anatomical axis and mechanical axis was significantly increased in the CW-HTO group (CW-HTO: 0.46 ± 0.93 degrees, OW-HTO: 0.22 ± 0.93 degrees, P<0.01). The difference of two procedure was 0.3 degrees. In the simulation of TKA conversion, if thickness of the lateral cortical bone was 3mm, it was showed that the tibial implant was more interfered with the cortical bone in CW-HTO group (2.80 ± 1.54 mm) than in OW-HTO group (7.40 ± 1.84 mm) (P<0.01).
«Conclusions»
The deviation of mechanical axis from anatomical axis was greater after CW-HTO than that after OW-HTO. And the risk of interference between implant and cortical bone was greater after CW-HTO than that after OW-HTO. However, the difference was small and not clinically significant when TKA conversion, although it needed attention to select the implant.