Does modern nail geometry affect positioning in the distal femur of elderly patients with hip fractures? A comparison of otherwise identical intramedullary nails with a 200 versus 150 cm radius of curvature.

Abstract

To compare implant positioning in the distal femur between 2 cohorts of elderly patients treated for a hip fracture with a long 200- or 150-cm radius of curvature (ROC) cephalomedullary nail. We theorized that the 150-cm ROC nails would more closely approximate the femoral bow and result in fewer implant-related complications. Retrospective Comparative Study. Single Level II Trauma Center. Fifty-eight geriatric patients with a hip fracture (26 in 200-cm nail cohort and 32 in 150-cm nail cohort). Long cephalomedullary nailing using single hip fracture nail and instrumentation system (InterTAN) before and after transition from a 200- to 150-cm ROC long hip nail. Anteroposterior position of distal nail tip on intraoperative lateral radiograph (where 0.50 indicates midaxial, perfectly central placement) and implant-related complications (anterior cortical abutment, perforation, or fracture). The average position of nails with a 150-cm ROC was closer to the midaxial line of the distal femur compared with 200-cm nails (0.63 vs. 0.55, P = 0.02). Only 1 of 26 (3.8%) 200-cm ROC nails was placed at the midaxial line and none were posterior, whereas 9 of 32 (28%) 150-cm ROC nails were positioned at or posterior to this line (P = 0.006). Only 1 nail with a 150-cm ROC abutted the distal femur's anterior cortex compared with 3 in the 200-cm cohort-including one that caused a fracture. Femoral nails with a 150-cm ROC more closely approximate the femoral bow of geriatric hip fracture patients than 200-cm ROC nails, appearing less likely to cause complications such as anterior cortical abutment, perforation, or fracture. Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.