Govardhan Praveen Ramia, Harigovindarao Govardhan Ramia
Department of Orthopaedics, Vasanthi Orthopaedic Hospital, Chennai, Tamil Nadu, India.
J Orthop Case Rep. 2020 Aug-Sep;10(5):37-42. doi: 10.13107/jocr.2020.v10.i05.1830.
Flexion of the femoral component has been described as a theoretical possibility to balance flexion and extension gap. Computer navigation has made it possible to intentionally flex the femoral component in a controlled fashion to take advantage of the same.Aim:The aim of this study was to assess whether intentional femoral component flexion is helpful in balancing flexion and extension gaps and in restoring sagittal diameter.
One hundred and forty-six total knee replacements performed in a navigated, gap-balanced, and tibia-first technique were included in this study. The femoral component flexion needed to equal flexion to extension gap was calculated based on the navigation data. The sagittal diameter, the anterior, and posterior offset were measured pre- and postoperatively based on the lateral radiographs. Flexion/extension gap differences pre- and postoperatively were analyzed. In addition, pre- and post-operative knee society scores were analyzed.
To achieve equal flexion and extension gap, the femoral component was flexed in 95% of patients showing mean flexion of 3.6°. The sagittal diameter was restored in 89%; however, the anterior offset was significantly reduced by 1.3 mm, and the posterior offset was significantly increased by 1.6 mm. The average knee society score improved from 33 preoperatively to 88 postoperatively.
Flexion of the femoral component is indeed an option to balance flexion and extension gap and to restore sagittal diameter in navigated total knee replacement. At present, it is possible only in a navigated technique, but an addition instrument should be made available in the future to reap the benefits of the same in the conventional technique.
股骨假体的屈曲被描述为平衡屈伸间隙的一种理论可能性。计算机导航使得以可控方式有意屈曲股骨假体成为可能，从而利用这一特性。
本研究的目的是评估有意屈曲股骨假体是否有助于平衡屈伸间隙以及恢复矢状径。
本研究纳入了146例采用导航、间隙平衡和胫骨优先技术进行的全膝关节置换术。根据导航数据计算使屈伸间隙相等所需的股骨假体屈曲度。基于侧位X线片测量术前和术后的矢状径、前后偏移。分析术前和术后屈伸间隙的差异。此外，还分析了术前和术后的膝关节协会评分。
为了实现屈伸间隙相等，95%的患者股骨假体发生屈曲，平均屈曲度为3.6°。89%的患者矢状径得以恢复；然而，前偏移显著减少了1.3mm，后偏移显著增加了1.6mm。膝关节协会平均评分从术前的33分提高到术后的88分。
在导航全膝关节置换术中，屈曲股骨假体确实是平衡屈伸间隙和恢复矢状径的一种选择。目前，这仅在导航技术中可行，但未来应提供一种附加器械，以便在传统技术中也能从中受益。
