Department of Orthopaedics and Trauma, Medical University of Graz, Auenbruggerplatz 5, 8036, Graz, Austria.
Knee Surg Sports Traumatol Arthrosc. 2023 Apr;31(4):1405-1411. doi: 10.1007/s00167-022-07147-4. Epub 2022 Sep 10.
The aim of this study was to determine the change in the long leg axis according to the preoperative knee phenotype using the mechanically aligned extension-first technique in total knee arthroplasty. The hypothesis of this study was that the knee phenotype would have an impact on the postoperative leg axis.
This was a retrospective comparative study comprising 224 whole-leg radiographs of 112 patients. The leg axes of the pre- and postoperative radiographs were measured and categorized into three preoperative limb phenotypes (based on the hip-knee-ankle angle [HKA]) according to Hirschmann et al. (varus-HKA < 178.5°, neutral-HKA 178.5°-181.5°, and valgus-HKA > 181.5°). Additionally, femoral phenotypes (based on the femoral mechanical angle [FMA], i.e., the mechanical medial distal femoral angle [mMDFA], as well as the tibial phenotypes [based on the tibial mechanical angle, i.e., the medial proximal tibial angle (MPTA)] was calculated. The change in the long leg axis was analyzed and compared with the preoperative limb phenotype.
Significantly more patients with preoperative varus alignment shifted to neutral alignment (46.3%, n = 31) than did patients with preoperative valgus alignment (38.9%; n = 14). Moreover, 43.3% of patients (n = 29) with the varus phenotype remained in a varus alignment, compared with the 58.3% of patients with preoperative valgus phenotype (n = 21) remaining in valgus alignment. These findings were similar for both females (p < 0.001) and males (p = 0.015).
Using an extension-first mechanically aligned surgical technique, varus phenotypes predominantly result in neutral leg axes or remain varus, neutral phenotypes remain neutral, and valgus phenotypes remain valgus or change to neutral phenotypes. This study showed that preoperative knee phenotypes in valgus knees influence this technique more strongly than estimated in previous investigations, which is in line with modern alignment philosophies for TKA.
Level IV, retrospective comparative study.
本研究旨在使用机械对线的伸直优先技术，在全膝关节置换术中，根据术前膝关节表型确定下肢长轴的变化。本研究的假设是膝关节表型会影响术后下肢轴。
这是一项回顾性比较研究，共纳入 112 例患者的 224 例全下肢 X 线片。测量术前和术后 X 线片的下肢轴，并根据 Hirschmann 等人的研究，根据髋膝踝角（HKA）将肢体表型分为三类（内翻-HKA<178.5°，中立-HKA 178.5°-181.5°，外翻-HKA>181.5°）。此外，还计算了股骨表型（基于股骨机械角，即机械内侧远端股骨角（mMDFA））和胫骨表型（基于胫骨机械角，即内侧近端胫骨角（MPTA））。分析并比较了下肢长轴的变化与术前肢体表型。
与术前外翻组相比，术前内翻组（46.3%，n=31）更多患者的下肢轴从内翻转为中立（38.9%，n=14）。此外，术前内翻表型的患者中有 43.3%（n=29）仍保持内翻，而术前外翻表型的患者中有 58.3%（n=21）仍保持外翻。这些发现无论是女性（p<0.001）还是男性（p=0.015）都相似。
使用伸直优先的机械对线技术，内翻表型主要导致下肢轴中立或保持内翻，中立表型保持中立，外翻表型保持外翻或转为中立。本研究表明，在外翻膝关节中，术前膝关节表型比之前研究估计的更能影响这种技术，这与现代 TKA 的对线理念一致。
IV 级，回顾性比较研究。
