Analysis of reduction status and lag screw direction in intertrochanteric fractures treated with intramedullary nailing: Possible influence of anterior femoral head–neck offset
Clinical and Medical Investigations
Aim: There are many evaluations of lag screw tip position. However, there is no comprehensive report on the evaluation of the alignment of the lag screw position relative to the cervical axis from the nail hole to the femoral head. Purpose of this study is to analyze the relationship between the reduction status and the alignment of the lag screw in patients with intertrochanteric fractures treated with intramedullary nails (IHN), using postoperative computed tomography (CT). Patients and
... s: Postoperative CT evaluation was performed in 100 intertrochanteric fractures (23 men and 77 women), which were randomly selected from 237 cases, treated with IHN. The mean patients' age at the time of surgery was mean age 83.9±8.9 years (61 to 96). The position of the nail, fracture reduction status, and direction of the screw relative to the femoral neck were assessed by axial plane CT. The angle between the screw and the femoral neck axis (deviation angle) was measured and deemed positive with the presence of anterior deviation. Results: The proximal fragment was posteriorly displaced in 82 patients, anteriorly displaced in one patient, and nondisplaced in 17 patients. The lag screw was positioned at the anterior third relative to the femoral neck in eight patients, the middle third in 15 patients, and the posterior third in 77 patients. The lag screw was deviated in 61 patients, with a mean deviation angle of 11.6±10.9° (7.2 to 37.5). When the screw was inserted parallel with the femoral neck, 84.6% (34/39) of the patients had displaced fragments, and most (33 patients) were posteriorly displaced. In 17 nondisplaced cases, posterior to anterior deviation of the lag screw direction was observed in 12 patients (70.6%). Discussion: Anatomical reduction and proper positioning of the lag screw were rarely achieved simultaneously in IHN surgeries, possibly because of anterior offset of the femoral neck relative to the femoral shaft. New concepts in intramedullary nail design such as nails with an anterior offset will be required to achieve better CT results with IHN.