Department of Orthopaedic Surgery, Graduate School of Medical Science, Kanazawa University, 13-1 Takaramachi, Kanazawa, Ishikawa, 920-8641, Japan.
Int Orthop. 2019 Sep;43(9):2047-2056. doi: 10.1007/s00264-018-4158-6. Epub 2018 Sep 21.
There is no documented maximum amount that an extremity can be safely lengthened in primary total hip arthroplasty (THA) without neurologic or soft tissue complications. We retrospectively reviewed patients who underwent primary THA with acute limb lengthening and investigated the safety range for acute limb lengthening in primary THA.
This study included 61 hips in 52 patients who underwent primary THA with acute limb lengthening (more than 2.5 cm) without femoral shortening osteotomy. The amount of lengthening was measured from pre-operative and post-operative X-ray films using computer graphics software, then the ratios of the amount of lengthening to femoral length (L/F ratio = amount of lengthening / femoral shaft length × 100) were calculated. We investigated correlation with nerve and soft tissue complications at operation in regard to this index.
The average amount of lengthening was 3.0 cm (2.5 to 4.8). The average L/F ratio was 7.9 (6.2 to 12.9). There were seven nerve complications and two soft tissue complications in the whole series. In all nine complications, eight indicated higher L/F ratios than 8.7. Altogether, 12 hips indicated a higher L/F ratio than 8.7; 66% of them showed neurological or soft tissue problems. ROC curve analysis indicated that the optimal cutoff value of the L/F ratio was 8.7, which predicted acute lengthening-related complications with a sensitivity of 88.9% and a specificity of 92.3% (AUC = 0.88).
The patients who underwent THA with acute lengthening of more than 8.7% of femoral shaft length are at high risk of complications caused by acute limb lengthening in primary THA.
在初次全髋关节置换术（THA）中，肢体在不发生神经或软组织并发症的情况下，安全延长的最大程度尚未有文献记载。我们回顾性分析了接受过急性肢体延长术的初次 THA 患者，并研究了初次 THA 中急性肢体延长的安全范围。
本研究纳入了 52 例患者的 61 髋，这些患者接受了初次 THA 合并急性肢体延长（超过 2.5cm），但未行股骨缩短截骨术。使用计算机图形软件从术前和术后 X 线片上测量延长的长度，然后计算延长长度与股骨长度的比值（L/F 比值=延长长度/股骨干长度×100）。我们调查了该指标与手术中神经和软组织并发症的相关性。
平均延长长度为 3.0cm（2.5 至 4.8cm）。平均 L/F 比值为 7.9（6.2 至 12.9）。整个系列中有 7 例神经并发症和 2 例软组织并发症。在所有 9 例并发症中，8 例的 L/F 比值均高于 8.7。总共 12 髋的 L/F 比值高于 8.7，其中 66%的髋出现了神经或软组织问题。ROC 曲线分析表明，L/F 比值的最佳截断值为 8.7，其对急性延长相关并发症的预测具有 88.9%的敏感性和 92.3%的特异性（AUC=0.88）。
在初次 THA 中，股骨干延长超过 8.7%的患者发生急性肢体延长相关并发症的风险较高。
