Breakage of sliding hip screw after fixation of pertrochanteric hip fracture: A rare complication.

Introduction: The authors report a rare case of lag screw breakage in a patient treated using locking DHS with home-made trochanteric stabilizing plate (TSP) for pertrochanteric hip fracture.

Case Presentation: A 67 year-old female was operated for pertrochanteric hip fracture with incompetent lateral wall using locking DHS with home-made TSP. At seven months postoperative, there was radiographic nonunion with breakage of the sliding lag screw. Patient was consequently scheduled for total hip replacement.

Discussion: Breakage of DHS lag screw has been attributed to multiple-cycle, low-stress fatigue failure associated with nonunion. Predisposing factors are: situation of the medial edge of the barrel at the level of the fracture site prohibiting fracture compression, and mechanical obstacle to the lag screw back sliding into the barrel. In our case, the use of handmade TSP interdicted lag screw back sliding and prevented fracture impaction which was already impaired by the location of the medial edge of the barrel at the fracture level. Additionally our fixation construct was very rigid because of the use of locking screws in the DHS side plate.

Conclusion: When DHS fixation is planned for unstable or potentially unstable trochanteric hip fracture the surgeon should be prepared by making available a TSP from the manufacturer in the operative room rather than improvising intra-operatively with handmade TSP; this augmentation device shouldn't interfere with lag screw back sliding. Furthermore the DHS barrel should ideally not impinge with the fracture site, and the use of locking screws in the DHS plate should be cautious.