How to minimize failures of fixation of unstable intertrochanteric fractures.

Sliding hip screws have improved the treatment of unstable intertrochanteric hip fractures and their success, compared with fixed devices, is in large part due to the sharing of load between the implant and the fracture fragments. In a prospective study of 100 patients with such fractures, five factors concerned with the fracture and its fixation were studied and odds ratios calculated of their relative importance in prediction of failure. The most important factor affecting the load borne by the fracture fragments was the amount of slide available within the device, and that affecting the load carried by the device was the position of the screw in the femoral head. For fractures fixed with a device allowing less than 10 mm of slide, and those with superior screw position, the risk of failure was increased by factors of 3.2 and 5.9, respectively. Anatomical reduction alone, rather than osteotomy, together with sliding hip screw fixation, has been recommended for these fractures in three prospective randomized trials. It is calculated here that to allow sufficient slide when employing this technique, it is essential to use a short barrel device when using dynamic screws of 85 mm or less. This has not been demonstrated before.