Femoral intertrochanteric nail (fitn): a new short version design with an anterior curvature and a geometric match study using post-operative radiographs

Abstract

Objective: Femoral intertrochanteric fractures are usually fixed with short, straight cephalomedullary nails. However, mismatches between the nail and the femur frequently occur, such as tip impingement and tail protrusion. The authors designed a new type of short femoral intertrochanteric nail (fitn) with an anterior curvature (length=19.5cm, r=120cm) and herein report the geometric match study for the first of 50 cases.

Methods: A prospective case series of 50 geriatric patients suffering from unstable intertrochanteric fractures (AO/OTA 31 A2/3) were treated. There were 15 males and 35 females, with an average age of 82.3 years. Post-operatively, the nail entry point position in the sagittal greater trochanter (in three categories, anterior, central and posterior), the nail-tip position in the medullary canal (in 5-grade scale) and the nail-tail level to the greater trochanter (in 3-grade scale) were measured using X-ray films.

Results: For the nail entry point measurement, 5 cases were anterior (10%), 38 cases were central (76%), and 7 cases were posterior (14%). For the distal nail-tip position, 32 cases (64%) were located along the central canal axis, 13 cases (26%) were located anteriorly but did not contact the anterior inner cortex, 2 cases (4%) showed less than one-third anterior cortex thickness contact, and 3 cases (6%) were located posteriorly with no contact. For the proximal nail-tail level, there were no protrusions over the greater trochanter in 15 cases (30%), protrusion of less than 5mm in 29 cases (58%), and protrusion of more than 5mm in 6 cases (12%). The fitness was very high, as 96% cases showed no tip-cortex contact, and 88% cases showed less than 5mm proximal tail protrusion.

Conclusion: The newly designed femoral intertrochanteric nail has a good geometric match with the femur medullary canal and the proximal length in the Chinese population.

Keywords: Femoral intertrochanteric fracture; Femur anterior bow; Geometric match; Greater trochanter; Nail tip impingement; Short cephalomedullary nail.