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Commentary & Perspective | ||||||||
Commentary & Perspective on Following hip fracture surgery, an ipsilateral femoral fracture is an important complication not only because of the associated increased morbidity to the patient and the increased medical expense but also because its prevalence may increase with the increasing number of hip fractures that are occurring worldwide. All of these types of fractures have occurred in the elderly population that is at risk because of recurrent falls and poor general health. Robinson et al. studied a "captured" population in which the true prevalence of ipsilateral femoral fracture could be tracked. When analyzing the results, it is easy to see that the most significant predictors of ipsilateral fracture were type of implant and choice of procedure. The highest incidence of fracture occurred in the group of patients who had had a cemented arthroplasty after failure of a primary implant. At first, this result seems surprising, but I have observed an increase in ipsilateral fractures in an extremity even in younger patients who have had disuse osteoporosis because of a previous ipsilateral injury, and this phenomenon has been documented in the literature1,2. The highest incidence of fracture was in patients who had had immobilization and disuse osteopenia as a result of their original injury and then had a secondary procedure, which exacerbates the cycle of immobilization and disuse osteopenia. This group of patients, with weaker bone from inactivity and also weak musculature that increases the risk of falls, subsequently develops one of the highest rates of ipsilateral femoral fracture. In the study by Robinson et al., the second highest incidence of ipsilateral fracture occurred in the patients who had been treated with a Gamma nail and a distal locking screw. Use of this device has resulted in a high incidence of femoral fracture3, which seems to be related to the device as well as to the procedure. The combination of a short intramedullary rod with a distal screw mechanically weakens the femur. It has been well documented that stress risers in any mechanical device in a long bone result in a lower force to fracture4, which puts the bone at risk for refracture. This is particularly a risk in a patient population that is prone to repeated falls. The third highest incidence of ipsilateral fracture occurred in the patients who had had a primary uncemented hemiarthroplasty. Again, this at first seems surprising, but this population of patients may be the most debilitated and therefore likely to be treated with the most expeditious procedure. Fractures in these patients generally occur in the supracondylar area of the femur and are not necessarily related to a stress riser created by the implant. The lowest incidence of ipsilateral femoral fracture occurred in the patients whose hip fractures were treated with cannulated screws or compression hip screws. Yet, subtrochanteric fractures can occur through the distal hole placed at or below the lesser trochanter for insertion of cannulated screws5. Such fractures generally occur as a result of torsional forces, and the importance of the mechanics involved is further borne out by the fact that these subtrochanteric fractures occur early after index surgery before the stress riser has had a chance to heal. In this study, some of the ipsilateral fractures occurred at the tip of the hip-screw plate, but the ratio of supracondylar fractures to fractures at the tip of the implant, which would be useful information, was not reported. Many of these ipsilateral femoral fractures can be prevented by an awareness of the biomechanical effects of the implant that lead to creation of a substantial stress riser in the femur. This is particularly true in regard to use of the Gamma nail with distal locking screws and cannulated screws inserted through drill-holes at or below the lesser trochanter. Procedures that leave the patient with a painful hip, such as a hemiarthroplasty6 or multiple procedures, further increase the risk of disuse osteoporosis. In these patients, fractures occur more commonly in the supracondylar region and may not be directly related to a stress riser but rather to weakness, falls, and severe disuse osteoporosis. The supracondylar fractures that follow treatment with a compression hip screw are similar in nature, but their incidence is much lower. In summary, Robinson et al. studied the incidence of ipsilateral femoral fracture after hip fracture surgery, which is an increasing problem because of the increasing numbers of hip fractures. Recognizing this problem and identifying the risk factors involved will decrease morbidity for our patients. I look forward to further excellent work by the group in Edinburgh concerning implant-related ipsilateral femoral fractures after surgical treatment of a fractured hip. *The author did not receive grants or outside funding in support of the research or preparation of this manuscript. He did not receive payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity. No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, educational institution, or other charitable or nonprofit organization with which the author is affiliated or associated. References 1. Finsen V, Haave O, Benum P. Fracture interaction in the extremities. The possible relevance of post-traumatic osteopenia. Clin Orthop. 1989;240:244-9. | ||||||||
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