Medical College of Wisconsin, Milwaukee, WI, USA.
J Trauma Acute Care Surg. 2012 Jul;73(1):249-54. doi: 10.1097/TA.0b013e318256a0b6.
Intramedullary nail (IMN) perforation through the cortex of the distal femur is a risk of intramedullary stabilization of proximal femur fractures. This study was performed to identify information that is available before operation that can pick out patients at risk for this complication.
A retrospective review of records and roentgenograms of 150 patients treated with intramedullary stabilization of a proximal femur fracture during a 4-year period at a Level I trauma center was performed. The position of the tip of the IMN in the distal femur was measured on postoperative lateral roentgenograms and grouped into anterior, middle, or posterior one third positions. Patients in whom the tip of the nail contacted or penetrated through the anterior cortex were designated as having cortical impingement.
Nail tip position was in the anterior one third of the distal femur in 71 (47%) of 150 patients, and 38 (25%) of these patients fit the definition for cortical impingement. The radiographic femoral angle of incidence strongly correlated with an anterior nail tip position (p < 0.0001) and cortical impingement (p < 0.0001). Shorter patients were also more likely to have cortical impingement (p < 0.005), and patients less than 160 cm in height had a 49% likelihood of impingement. A starting point in the posterior one third of the greater trochanter increased the likelihood of having an anterior nail tip position as well (p < 0.007).
Of the 150 patients in whom an IMN was used for stabilization of a proximal femur fracture, 71 (47%) had the distal part of their nail positioned in the anterior one third of the distal femur. Patients who are shorter and/or had an increased femoral bow as measured on a lateral roentgenogram are more likely to have an anterior nail tip position or cortical impingement. Posterior starting points should be avoided to prevent this complication.
Prognostic study, level III; therapeutic study, level IV.
髓内钉（IMN）穿透股骨远端皮质是髓内固定股骨近端骨折的风险。本研究旨在确定术前可识别出发生这种并发症风险的患者的信息。
对 150 例在一级创伤中心接受髓内固定股骨近端骨折治疗的患者的病历和 X 线片进行回顾性分析，随访时间为 4 年。术后侧位 X 线片测量髓内钉尖端在股骨远端的位置，并分为前、中、后三分之一。将钉尖接触或穿透前皮质的患者定为皮质撞击。
150 例患者中，71 例（47%）髓内钉尖端位于股骨远端前 1/3，其中 38 例（25%）符合皮质撞击定义。射线照相股骨入射角与髓内钉尖端前位呈强烈相关性（p<0.0001）和皮质撞击（p<0.0001）。身材矮小的患者也更容易发生皮质撞击（p<0.005），身高低于 160cm 的患者发生撞击的可能性为 49%。大转子后 1/3 作为起始点也增加了髓内钉尖端前位的可能性（p<0.007）。
在 150 例行髓内固定股骨近端骨折的患者中，71 例（47%）的髓内钉远端位于股骨远端前 1/3。身高较矮和/或侧位 X 线片上股骨弯曲增加的患者更容易发生髓内钉尖端前位或皮质撞击。应避免后起始点以防止这种并发症。
预后研究，III 级；治疗研究，IV 级。
