Zhang Wei, Antony Xavier Rex Premchand, Decruz Joshua, Chen Ying Dong, Park Derek Howard
Department of Orthopaedics, Khoo Teck Puat Hospital, 90 Yishun Central, Singapore, 768828, Singapore.
Arch Orthop Trauma Surg. 2021 Apr;141(4):569-575. doi: 10.1007/s00402-020-03399-2. Epub 2020 Apr 15.
Intertrochanteric hip fractures pose a significant health problem. The proximal femur nail anti-rotation (PFNA IIDePuySynthes) is the most commonly used implant for intramedullary nailing of unstable intertrochanteric fractures at our institution. We aim to identify the risk factors predisposing to mechanical failure of intertrochanteric hip fractures fixation with PFNAII in our Southeast Asian population.
We retrospectively reviewed 295 consecutive patients who underwent PFNA fixation for intertrochanteric fractures of the proximal femur between January 2014 and June 2018 at our institution. Exclusion criteria included a follow-up period of less than 4 months and patients with polytrauma. 204 patients were eligible for analysis, of which 22 had mechanical failure of PFNAII. We compared these patients with respect to their demographics, medical co-morbidities, quality of reduction according to the Baumgartner scale, calcar restoration, blade position according to Cleveland Zones, the stability of fracture according to OTA/AO classification, neck-shaft-angle, tip-apex distance, as well as neck of femur bone mineral density T-score. Patients were followed up for a minimum of 4 months and until fracture union or complication had occurred. Logistic regression analysis was performed to determine the odds ratio for mechanical failure for selected variables.
Good quality of reduction reduced risk of mechanical failure whilst posterior blade position in lateral hip X-ray predicted it, with odds ratios of 0.147 (95% confidence interval, 0.030-0.733; p = 0.019) and12.12 (95% confidence interval, 1.583-92.825; p = 0.016) respectively. On univariate analysis, the mechanical failure group were older, had poorer calcar restoration, more unstable fracture patterns, more varus neck-shaft angle, and trochanteric starting points that were lateral to or on the tip of the greater trochanter. However, these were not significant in multivariate analysis. Tip apex distance, the severity of osteoporosis, presence of diabetes, chronic kidney disease and serum vitamin D levels were not significant predictors of failure.
To avoid mechanical failure, one should aim to achieve a good quality of reduction and centre blade position on lateral hip X-ray. Tip apex distance did not predict mechanical failure in our study.
股骨转子间髋部骨折是一个严重的健康问题。股骨近端防旋髓内钉（PFNA II，德普伊辛迪斯公司生产）是我院治疗不稳定型股骨转子间骨折最常用的髓内固定植入物。我们旨在确定在我们的东南亚人群中，导致PFNA II固定的股骨转子间髋部骨折发生机械性失效的危险因素。
我们回顾性分析了2014年1月至2018年6月在我院接受PFNA固定治疗股骨近端转子间骨折的295例连续患者。排除标准包括随访期少于4个月以及多发伤患者。204例患者符合分析条件，其中22例发生了PFNA II的机械性失效。我们比较了这些患者的人口统计学特征、合并疾病、根据鲍姆加特纳量表评估的复位质量、股骨距恢复情况、根据克利夫兰分区评估的刀片位置、根据OTA/AO分类评估的骨折稳定性、颈干角、尖顶距以及股骨颈骨密度T值。患者至少随访4个月，直至骨折愈合或出现并发症。进行逻辑回归分析以确定所选变量发生机械性失效的比值比。
良好的复位质量可降低机械性失效风险，而髋部侧位X线片显示刀片位于后方则预示着机械性失效，比值比分别为0.147（95%置信区间，0.030 - 0.733；p = 0.019）和12.12（95%置信区间，1.583 - 92.825；p = 0.016）。单因素分析显示，机械性失效组患者年龄较大，股骨距恢复较差，骨折模式更不稳定，颈干角内翻更多，且转子起始点位于大转子尖端外侧或尖端处。然而，在多因素分析中这些因素并不显著。尖顶距、骨质疏松严重程度、糖尿病的存在、慢性肾脏病以及血清维生素D水平均不是失效的显著预测因素。
为避免机械性失效，应努力实现良好的复位质量，并使髋部侧位X线片上的刀片位于中心位置。在我们的研究中，尖顶距并不能预测机械性失效。
