2023 ISAKOS Biennial Congress ePoster
Mechanical Axis Changes and its Related Factors on the Whole Leg Preoperative Planning X-Rays under Bilateral and Unilateral Weight Bearing in HTO Patients
Tomomasa Nakamura, MD, PhD, Bunkyo-Ku, Tokyo JAPAN
Takashi Hoshino, MD, PhD, Tokyo JAPAN
Hiroki Katagiri, MD, PhD, Tokyo, Tokyo JAPAN
Aritoshi Yoshihara, MD, Tokyo, Tokyo JAPAN
Masaki Amemiya, MD, PhD, Tokyo, Tokyo JAPAN
Yusuke Nakagawa, Tokyo, 88 JAPAN
Nobutake Ozeki, Tokyo JAPAN
Hideyuki Koga, Prof., MD, PhD, Tokyo JAPAN
Tokyo Medical and Dental University, Tokyo, Tokyo, JAPAN
FDA Status Not Applicable
Summary
Since the mechanical axis deviates medially in the single-leg loading position compared to the bilateral-leg loading position, consideration should be taken in preoperative planning for high tibial osteotomy for avoiding inappropriate correction during surgery.
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Abstract
Purpose
Accurate mechanical axis evaluation is essential in high tibial osteotomy (HTO) for preoperative surgical planning. Inappropriate underestimation of the mechanical axis may lead under correction during surgery and may result in lower patient satisfaction and poor clinical outcomes. Previously the hip-knee-angle change in bilateral- and single-leg weight bearing has been reported, but the mechanical axis difference between bilateral- and single-leg weight bearing and its related factors are unknown. In this study, we compared the load axes of bilateral-leg and single-leg weight bearing in the standing position and examined the factors associated with load axis changes.
Methods
We compared the %mechanical axis (%MA) of 132 knees that underwent HTO between 2012 and 2021 using semi-automated analysis software (mediCAD) during bilateral- and single-leg weight bearing on preoperative full-length lower extremity X-rays. Multiple regression analysis was performed using the medial change in %MA during single-leg weight bearing compared to bilateral-leg weight bearing as the objective variable. The patient background and X-ray parameters; mechanical lateral proximal femoral angle (mLPFA), mechanical lateral distal femoral angle (mLDFA), medial proximal tibial angle (MPTA), lateral distal tibial angle (LDTA), and joint line convergence angle (JLCA) during bilateral-leg weight bearing were considered as explanatory variables.
Results
The %MA was significantly lower (p<0.01) at 15.7±2.7% during single-leg weight bearing compared to 22.2±2.4% during bilateral-leg weight bearing. One hundred seventeen of 132 knees (88.6%) had a medial deviation of the mechanical axis during single-leg weight bearing. Multiple regression analysis showed that MPTA during bilateral-leg weight bearing was an associated factor for change in %MA (p<0.01).
Discussion
Patients with a lower MPTA during bilateral-leg weight bearing are more likely to have a medial deviation of the load axis during single-leg weight bearing, which should be considered in preoperative planning.