Stevens Jarrad, Clement Nicholas, Nasserallah Michael, Millar Michael, Joseph Sam
Department of Surgery, Orthopaedics, Peninsula Health, Frankston Hospital, Frankston, Australia.
Department of Surgery, Orthopaedics, Royal Infirmary Edinburgh, Edinburgh, UK.
Eur J Orthop Surg Traumatol. 2018 May;28(4):659-665. doi: 10.1007/s00590-018-2141-y. Epub 2018 Feb 8.
Periprosthetic fractures of the proximal femur place a significant burden on the patients who endure them, as well as the medical health system that supports them. The purpose of this study was to determine whether femoral cortical thickness, as an absolute measurement, is a predictor of periprosthetic fracture pattern.
A cohort of 102 patients who had sustained a periprosthetic hip fracture were retrospectively identified. This included 58 males and 44 females with a mean age of 79.8 years. The femoral periprosthetic fracture pattern was classified based on the Vancouver classification system. Stem fixation was recorded and femoral cortical thickness measured. Patients were grouped into cemented and cementless stems. The relationship between cortical thickness and periprosthetic fracture pattern was assessed using the primary stem fixation method. Receiver operating characteristic (ROC) curve analysis was used to identify a threshold in the cortical thickness that predicted fracture pattern. Multinomial logistic regression analysis was used to adjust for confounding variables to assess the independent influence of cortical thickness on the risk of sustaining a Vancouver type A, B or C.
There were 65 (63.7%) patients in the cemented group and 37 (36.3%) in the cementless group. The pattern of periprosthetic fractures around cemented stems was significantly (p < 0.001) influenced by the femoral cortical thickness, with a thinner cortical thickness associated with a type A fracture pattern. In contrast, no association between femoral cortical thickness and fracture pattern assessment was demonstrated in the cementless group (p = 0.82 Chi square). Comparing the rate of type A fracture patterns between the groups illustrated a significantly decreased risk in the cemented group with a cortical thickness of > 7 mm (odds ratio 0.03, p < 0.001). ROC curve analysis of the cemented group demonstrated a threshold value of 6.3 mm, offering a sensitivity of 83.3% and a specificity of 78.9% in predicting an A type fracture. Using this threshold, patients with a cortical thickness of 6.3 mm or less were significantly more likely to sustain a Vancouver type A fracture (OR 18.9, 95% CI 2.0-166.7, p < 0.001) when compared to patients with a cortical thickness of > 6.3 mm. In contrast, the ROC curve analysis did not find cortical thickness to be a predictor of fracture pattern in the cementless group. When adjusting for confounding variables, multinomial logistic regression demonstrated a cortical thickness of 6.3 mm or less was a significant predictor of a type A fracture (OR 3.28, 95% CI 1.06-10.16, p = 0.04) relative to those sustaining a type B fracture.
Cortical thickness was found to influence the periprosthetic fracture pattern around cemented femoral stems, but this was not observed with cementless stems. Type A fracture patterns were significantly more likely to occur with a cortical thickness of 6.3 mm or less around cemented stems.
股骨近端假体周围骨折给承受此类骨折的患者以及支持他们的医疗保健系统带来了沉重负担。本研究的目的是确定股骨皮质厚度作为一种绝对测量值，是否是假体周围骨折类型的预测指标。
回顾性纳入了102例发生假体周围髋部骨折的患者。其中包括58例男性和44例女性，平均年龄为79.8岁。根据温哥华分类系统对股骨假体周围骨折类型进行分类。记录柄的固定方式并测量股骨皮质厚度。患者分为骨水泥型柄和非骨水泥型柄两组。使用主要的柄固定方法评估皮质厚度与假体周围骨折类型之间的关系。采用受试者工作特征（ROC）曲线分析来确定能够预测骨折类型的皮质厚度阈值。使用多项逻辑回归分析对混杂变量进行校正，以评估皮质厚度对发生温哥华A型、B型或C型骨折风险的独立影响。
骨水泥型组有65例（63.7%）患者，非骨水泥型组有37例（36.3%）患者。骨水泥型柄周围假体周围骨折的类型受股骨皮质厚度的显著影响（p < 0.001），皮质厚度越薄与A型骨折类型相关。相比之下，在非骨水泥型组中未显示股骨皮质厚度与骨折类型评估之间存在关联（p = 0.82，卡方检验）。比较两组之间A型骨折类型的发生率表明，皮质厚度> 7 mm的骨水泥型组风险显著降低（比值比0.03，p < 0.001）。骨水泥型组的ROC曲线分析显示阈值为6.3 mm，在预测A型骨折时敏感性为83.3%，特异性为78.9%。使用该阈值，与皮质厚度> 6.3 mm的患者相比，皮质厚度为6.3 mm或更小的患者发生温哥华A型骨折的可能性显著更高（比值比18.9，95%可信区间2.0 - 166.7，p < 0.001）。相比之下，ROC曲线分析未发现皮质厚度是非骨水泥型组骨折类型的预测指标。在对混杂变量进行校正时，多项逻辑回归表明，相对于发生B型骨折的患者，皮质厚度为6.3 mm或更小是A型骨折的显著预测指标（比值比3.28，95%可信区间1.06 - 10.16，p = 0.04）。
发现皮质厚度会影响骨水泥型股骨柄周围的假体周围骨折类型，但在非骨水泥型柄中未观察到这种情况。在骨水泥型柄周围，皮质厚度为6.3 mm或更小的情况下，A型骨折类型发生的可能性显著更高。
