Frequency and Causes of Failure of Dynamic Hip Screw Fixation for Interochanteric Fracture

Background: Hip fractures are a leading cause of death and disability among elderly. Approximately half of these injuries are intertrochanteric fractures and the incidence is continuously increasing. It is estimated that the incidence of intertrochanteric fractures will be doubled by the year 2040. Different types of implants were tried at different times for internal fixation of these fractures, of which dynamic hip screw has remained the most popular one. But with the advent of some newer implants, the efficacy of dynamic hip screw is being questioned. Aims: To determine the frequency of failure after dynamic hip screw fixation of intertrochanteric fracture and to identify causes (instability, increased tip apex distance and high angle side plate) leading to failure after dynamic hip screw fixation of intertrochanteric fracture. Design: Descriptive case series. Setting: The study was conducted in Orthopaedic ward of Ghurki Trust Teaching Hospital/Lahore Medical & Dental College, Lahore. Duration of study: Six months (15 th November, 2008 to 15 th May, 2009) Methods: Forty five cases of intertrochanteric fractures were included and operated for internal fixation with dynamic his screw under fluoroscopic guidance. Pre, per and post-operative findings during hospital stay and follow-up period were recorded. Results: There were 32 males and 13 females with male to female ratio were 2.5:1. The mean±SD between the ages was 71.91±10.40 years. Thirty one patients were admitted through emergency and 14 patients through outdoor patient department. The size of lag screw in 12 patients of 85 mm screw and 33 patients of 900 mm screw were used. Three types of interlocking nail of 45 mm, 50 mm and 55 mm sizes were used. The failure rate was found in 22 patients of grade III, 15 patients of grave IV and 8 patients of grade V of dynamic hip screw fixation through Hammer et al radiological assessment of callus formation. At Sirkoski and Barrington pain scale, the failure rate was found in 28 patients of grade III and 17 patients of grade IV. Conclusion: The use of this implant is associated with satisfactory result and acceptable complication rate, given the poor physical status of many of these elderly patients before the injury.