Brumat Peter, Pompe Borut, Antolič Vane, Mavčič Blaž
University Medical Centre Ljubljana and Faculty of Medicine, Zaloška 9, 1000, Ljubljana, Slovenia.
Arch Orthop Trauma Surg. 2018 Jan;138(1):123-129. doi: 10.1007/s00402-017-2840-6. Epub 2017 Nov 13.
The femoral stem should protrude from femur by an appropriate vertical distance to allow leg length equalization at hip arthroplasty; this distance depends on the size/shape of medullary canal and implant. The relationship between femoral morphology and achievability of leg length restoration is currently unclear. Our aim was to examine the impact of the femoral canal flare index (CFI) on the risk of leg length discrepancy (LLD) after total hip arthroplasty with different femoral stems.
The study cohort included 126 patients with unilateral primary total hip arthroplasty due to idiopathic osteoarthritis and three different types of implanted femoral stems. The impact of CFI on postoperative LLD was assessed with separate logistic regression model for each implant and covariables of age, gender, body mass index and femoral neck resection level.
Higher CFI was an independent risk factor for postoperative LLD ≥ 5 mm with odds ratio 4.5 (p = 0.03) in 49 stems with cementless metaphyseal fixation Implantcast-EcoFit®, regardless of the femoral neck resection level. CFI had no significant impact on LLD in 30 stems with cementless diaphyseal fixation EndoPlus-Zweymüller® or 47 cemented collared stems Link-SPII®. No significant difference was observed between groups in pre/postoperative WOMAC scores, postoperative radiographic LLD, subjectively reported LLD, insole use or complications after mean 6.8 years of follow-up.
Higher CFI increases the risk of clinically detectable postoperative LLD in single-wedge femoral stems with cementless metaphyseal fixation. CFI has no significant impact on LLD in femoral stems with cementless diaphyseal fixation or cemented fixation.
股骨柄应从股骨中突出适当的垂直距离，以便在髋关节置换术中实现双下肢等长；该距离取决于髓腔的大小/形状以及植入物。目前尚不清楚股骨形态与双下肢长度恢复的可实现性之间的关系。我们的目的是研究股骨髓腔扩口指数（CFI）对使用不同股骨柄的全髋关节置换术后双下肢长度差异（LLD）风险的影响。
研究队列包括126例因特发性骨关节炎接受单侧初次全髋关节置换术的患者，以及三种不同类型的植入股骨柄。针对每种植入物以及年龄、性别、体重指数和股骨颈切除水平等协变量，使用单独的逻辑回归模型评估CFI对术后LLD的影响。
在49个采用非骨水泥型干骺端固定的Implantcast-EcoFit®股骨柄中，较高的CFI是术后LLD≥5 mm的独立危险因素，优势比为4.5（p = 0.03），与股骨颈切除水平无关。CFI对30个采用非骨水泥型骨干固定的EndoPlus-Zweymüller®股骨柄或47个骨水泥固定带领圈股骨柄Link-SPII®的LLD没有显著影响。在平均6.8年的随访后，各组之间在术前/术后WOMAC评分、术后影像学LLD、主观报告的LLD、鞋垫使用情况或并发症方面均未观察到显著差异。
较高的CFI会增加采用非骨水泥型干骺端固定的单楔股骨柄术后出现临床可检测到的LLD的风险。CFI对采用非骨水泥型骨干固定或骨水泥固定的股骨柄的LLD没有显著影响。
