2023 ISAKOS Biennial Congress ePoster
Appropriate Patient Selection Based on Joint Line Convergence Angle Minimizes Difference in Mechanical Axis between Standing and Supine Positions after High Tibial Osteotomy
Naosuke Nagata, MD, Kobe JAPAN
Takehiko Matsushita, MD, PhD, Kobe, Hyogo JAPAN
Kyohei Nishida , MD, PhD, Kobe, Hyogo JAPAN
Kanto Nagai, MD, PhD, Kobe, Hyogo JAPAN
Noriyuki Kanzaki, MD, PhD, Kobe, Hyogo JAPAN
Yuichi Hoshino, MD, PhD, Kobe, Hyogo JAPAN
Ryosuke Kuroda, MD, PhD, Kobe, Hyogo JAPAN
Kobe University Graduate School of Medicine, Kobe, JAPAN
FDA Status Not Applicable
Summary
This study showed that the differences in mechanical axis between the standing and supine positions in patient with preoperative JLCA< 6° and the difference in JLCA supine and standing positions < 3° were minimal after HTO. Appropriate surgical indication and patient selection may minimize the difference in mechanical axis between standing and supine position.
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Abstract
Purpose
Appropriate alignment correction is one of the key points to obtain successful outcomes after high tibial osteotomy (HTO). It has been reported that a large difference in limb alignment between the standing and supine positions due to soft tissue laxity could cause correction error after HTO. However, it has not yet been clear to what extent of the soft tissue laxity needs to be considered to obtain acceptable difference. The purpose of this study was to evaluate the differences in mechanical axis between the standing and supine positions in patient who received HTO under the surgical indication based on joint convergence angle (JLCA), which is an indicator of soft tissue laxity.
Methods
Patients who underwent medial open-wedge HTO or distal tuberosity osteotomy between 2016 August and 2021 December under the following surgical indication were examined. The surgical indication were patients with varus knee, medial compartmental osteoarthritis and cartilage injuries, medial meniscus tears, JLCA < 6° in standing position, and the difference in JLCA between standing and supine positions < 3°. Anteroposterior long-leg-view radiographs in the double-leg standing and supine positions before and after surgery and preoperative planning was performed using preoperative supine long-leg-view x-rays. The %mechanical axis (%MA) and JLCA in standing and supine positions were measured using preoperative and postoperative long-leg-view x-rays taken within one year after surgery. %MA and JLCA were evaluated on both standing and supine radiographs (%MAst and %Map, JLCAst, and JLCAsp, respectively). The difference in %MA and JLCA between the standing and supine positions (d-%MA and d-JLCA, respectively) was calculated as the measurement value in standing position – that in supine position.
Results
In total, 71 knees in 69 patients were included in this study. Preoperative %MAst, %MAsp, JLCAst and JLCAsp (95% CI) were (21.6% - 26.1%), (26.9 - 30.6%), (2.6° - 3.2°) and (1.3° - 1.9°). There were significant differences in preoperative %MA. The preoperative d-%MA and d-JLCA were (-6.3% - -3.5%) and (1.1° - 1.6°), respectively. Postoperative %MAst, %MAsp, JLCAst, and JLCAsp were (57.2% - 60.5%), (57.6% - 60.5%), (1.5° - 2.0°), and (1.2° - 1.7°), respectively. There were no significant differences in postoperative %MAst and %MAsp, the postoperative d-%MA and d-JLCA were (-0.9% - 0.5%) and (0.1° - 0.4°) respectively. d-%MA was < 5% in 68 knees (95.8%) while it was =5% in three knees (4.2%).
Discussion
The differences in mechanical axis between the standing and supine positions after HTO were minimal in patient with preoperative JLCAst <6° and d-JLCA <3°. Appropriate surgical indication and patient selection may minimize the difference in mechanical axis between standing and supine position.