2015 ISAKOS Biennial Congress ePoster #1129
Contributors to Limb Alignment in Patients with Varus Knee Osteoarthritis Undergoing HTO
Chong Bum Chang, MD, PhD, Seongnam-Si, Gyeonggi-do KOREA, REPUBLIC OF
Seung-Baik Kang, MD, PhD, Prof., Seoul KOREA, REPUBLIC OF
Sang Cheol Seong, MD, PhD, mapo-gu, Seoul city KOREA, REPUBLIC OF
Myung Chul Lee, MD, PhD, Prof., Seoul KOREA, REPUBLIC OF
Sahnghoon Lee, MD, PhD, Seoul KOREA, REPUBLIC OF
Hyuk-Soo Han, MD, PhD, Seoul KOREA, REPUBLIC OF
Yong-Seuk Lee, MD, PhD, Prof., Seongnam, Kyung-gi KOREA, REPUBLIC OF
Woo Young Hwang, MD, Seoul, Seoul KOREA, REPUBLIC OF
Su Jin Kim, MS, Seoul, Seoul KOREA, REPUBLIC OF
Ja-Young Choi, MD, PhD, Seoul, Seoul KOREA, REPUBLIC OF
Seoul National University Boramae Hospital, Seoul, Seoul, KOREA
FDA Status Cleared
Summary: A knee surgeon needs to consider status of contribution of 3 factors (femoral condylar orientation, tibia plateau inclination, and joint space tilt angle) to overall limb alignment and joint tilt angle changes after HTO in his/her preoperative planning for patients warranting HTO.
The aims of this study were 1) to determine the contributions of three major anatomical sites (femur, tibia, and joint space) to the overall limb alignment in patients undergoing high tibial osteotomy (HTO) for medial tibiofemoral osteoarthritis (OA), 2) to determine the changes in knee joint space tilt angle after HTO, which would be a potentially important factor for preoperative planning, and 3) to identify factors for the changes of the knee joint space.
Three parameters including femoral condylar orientation, tibia plateau inclination, and joint space tilt angle were measured on a whole limb standing radiograph preoperatively and postoperatively in 66 patients undergoing HTO (the HTO group) for medial tibiofemoral OA with varus deformity. Two control groups including the normal knee group (132 normal knees) and the TKA group (132 knees with severe OA undergoing total knee arthroplasty [TKA]) were developed for comparison with the HTO group. In the HTO group, the amounts of changes in the joint space tilt angle between pre- and post-HTO were computed and analyzed. Then, the factors associated with the postoperative changes in the joint space tilt angle were examined.
The three study groups showed significant differences in the alignment parameters and their contributions to the overall limb alignment. In the HTO group, the tibial plateau inclination (-5.8 degrees on average) was the strongest contributor to the varus limb alignment followed by the joint space tilt angle (-4.2 degrees). Besides the tibia plateau inclination, the joint space tilt angle was significantly changed after HTO; decreased by 1.9º on average. Further multivariate regression analyses revealed that the greater preoperative joint space tilt angle (JTA) and more severe preoperative varus mechanical TFA (MTFA) were significantly associated with a greater decrease in the joint space tilt angle after HTO (ß = -0.36, p = 0.005 and ß = -0.32, p = 0.011, respectively; R2 for regression model = 0.362). The equation for estimating the amount of joint space tilt angle change after HTO is -0.65 - 0.23 x (preoperative JTA) - 0.18 x (preoperative MTFA).
We found that that the tibial plateau inclination was the most significant contributor to overall varus limb alignment in the HTO group, which would validate the appropriateness of HTO. Nevertheless, the joint space tilt angle was also a considerable contributor limb alignment in the HTO group, and the angle would significantly decrease after HTO, which should be considered in targeting a correction angle in HTO.