Moon Young Wan, Kim Jae Gyoon, Woo Kyung Jae, Lim Seung Jae, Seo Jai Gon
Department of Orthopedic Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Korea.
Orthopedics. 2011 May 18;34(5):355. doi: 10.3928/01477447-20110317-10.
The goal of this study was to analyze medial flexion gaps after medial release for varus deformity by navigation-guided total knee arthroplasty (TKA). In each patient, a preoperative standing anteroposterior (AP) radiograph of the lower extremity and an AP valgus stress radiograph of the knee were used to measure preoperative mechanical axis angle and valgus stress angle, respectively. The correlation between preoperative varus deformities and medial flexion gap increases as measured by navigation was examined. Patients were assigned to 2 groups: group A (25 knees), in which the difference between the lateral flexion gap (LFG) and the medial flexion gap (MFG) (LFG-MFG) was ≤ 1 mm; and group B (73 knees), with an LFG-MFG of >1 mm.Mean preoperative mechanical axis angles in groups A and B were 13.21° ± 5.01° varus (range, 3.7°-23.6°) and 10.05° ± 3.70° varus (range, 1.9° - 23.7°), respectively. Mean preoperative valgus stress angles in groups A and B were 1.72° ± 0.89° valgus (range, 0.1° - 4.0°) and 4.84° ± 2.61° valgus (range, 0.1° - 11.7°), respectively. A significant difference was observed between the groups in terms of mechanical axis angle (P = .002) and valgus stress angle (P<.001). Furthermore, valgus stress angle was found to be more strongly correlated with medial flexion gap increase than mechanical axis angle. The cutoff values of mechanical axis angle and valgus stress angle in group A were 13.4° and 2.45°, respectively.This study shows that preoperative valgus stress angle measurements can be used to predict the extent of medial release for varus deformity.
本研究的目的是通过导航引导下的全膝关节置换术（TKA）分析内翻畸形内侧松解后的内侧屈曲间隙。在每位患者中，分别使用术前下肢站立前后位（AP）X线片和膝关节AP外翻应力X线片测量术前机械轴角和外翻应力角。研究了术前内翻畸形与导航测量的内侧屈曲间隙增加之间的相关性。患者被分为两组：A组（25个膝关节），外侧屈曲间隙（LFG）与内侧屈曲间隙（MFG）之差（LFG - MFG）≤1mm；B组（73个膝关节），LFG - MFG>1mm。A组和B组术前平均机械轴角分别为内翻13.21°±5.01°（范围3.7° - 23.6°）和内翻10.05°±3.70°（范围1.9° - 23.7°）。A组和B组术前平均外翻应力角分别为外翻1.72°±0.89°（范围0.1° - 4.0°）和外翻4.84°±2.61°（范围0.1° - 11.7°）。两组在机械轴角（P = .002）和外翻应力角（P<.001）方面存在显著差异。此外，发现外翻应力角比机械轴角与内侧屈曲间隙增加的相关性更强。A组机械轴角和外翻应力角的截断值分别为13.4°和2.45°。本研究表明，术前外翻应力角测量可用于预测内翻畸形的内侧松解程度。
