Figure 1. Anteroposterior radiograph of the left hip.
Figure 2. Anteroposterior radiograph of the left femur.
An 80-year-old woman presents with pain in the left hip for several weeks. She has a history of dementia. Her surgical history is significant for fixation of a hip fracture 8 months ago. Anteroposterior radiographs of the left hip and femur are obtained (Figures 1 and 2).
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The patient’s radiographs show mechanical failure of the intramedullary nail at the junction of the compression screw and nail. Intramedullary nails are the most common devices used for fixation of peritrochanteric fractures. Once internal fixation is performed, bone healing and weight-bearing restrictions protect the implant from stress that could cause mechanical failure. A fracture that fails to heal (nonunion) is prone to cause eventual failure of the implant. Stress from weight-bearing can cause metal implants such as screws, rods, and plates to fatigue if the fracture is not healed to support the weight. Fatigue of metal hardware over time results in fracture of the implant. Mechanical failure of intramedullary devices is rare, occurring in <1% of implants; more commonly, the bone around the metal implant fractures or displaces.1 Patients with persistent hip pain and nonunion beyond 6 months are at highest risk for device failure, as most occur after 6 months postoperatively. Risk factors for nonunion and failure of the implant include poor bone quality, metastatic disease, and mal-reduction of the fracture.
Nonunion of the patient’s intertrochanteric fracture led to fatigue of the hardware. Preoperative laboratory work-up and intraoperative cultures were negative for an infectious process. The patient underwent removal of hardware, followed by hemiarthroplasty of the left hip with reconstruction of the modular stem, which allowed for immediate weight-bearing postoperatively. Observation, removal of hardware, or revision of the intramedullary nail alone would fail to address nonunion of the patient’s fracture.1,2
Dagan Cloutier, MPAS, PA-C, practices in a multispecialty orthopedic group in the southern New Hampshire region and is editor-in-chief of the Journal of Orthopedics for Physician Assistants (JOPA).
1. Najibi S, Mark L, Fehnel D. Mechanical failure of the long gamma nail in two proximal femur fractures. Iowa Orthop J. 2010;30:205-210.
2. Zafiropoulos G, Pratt DJ. Fractured gamma nail. Injury. 1994;25(5):331-336.