Abstract
Hip abductor deficiency (HAD) associated with hip arthroplasty can be a chronic, painful condition that can lead to abnormalities in gait and instability of the hip. HAD is often confused with trochanteric bursitis and patients are often delayed in diagnosis after protracted courses of therapy and steroid injection. A high index of suspicion is subsequently warranted.
Risk factors for HAD include female gender, older age, and surgical approach. The Hardinge approach is most commonly associated with HAD because of failure of repair at the time of index surgery or subsequent late degenerative or traumatic rupture. Injury to the superior gluteal nerve at exposure can also result in HAD and is more commonly associated with anterolateral approaches. Multiple surgeries, chronic infection, and chronic inflammation from osteolysis or metal debris are also risk factors especially as they can result in bone stock deficiency and direct injury to muscle. Increased offset and/or leg length can also contribute to HAD, especially when both are present.
Physical exam demonstrates abductor weakness with walking and single leg stance. There is often a palpable defect over the greater trochanter and palpation in that area usually elicits significant focal pain. Note may be made of multiple incisions. Increased leg length may be seen.
Radiographs may demonstrate avulsion of the greater trochanter or significant osteolysis. Significant polyethylene wear or a metal-on-metal implant should be considered as risk factors, as well as the presence of increased offset and/or leg length. Ultrasound or MRI are helpful in confirming the diagnosis but false negatives and positive results are possible.
Treatment is difficult, especially since most patients have failed conservative management before diagnosis of HAD is made. Surgical options include allograft and mesh reconstruction as well as autologous muscle transfers. Modest to good results have been reported, but reproducibility is challenging. In the case of increased offset and leg length, revision of the components to reduce offset and leg length may be considered. In the case of significant instability, abductor repair may require constrained or multi-polar liners to augment the surgical repair.
HAD is a chronic problem that is difficult to diagnose and treat. Detailed informed consent appropriately setting patient expectations with a comprehensive surgical plan is required if surgery is to be considered. Be judicious when offering this surgery.
