Leg length inequality following total hip replacement

Total hip replacement is a technical and demanding operation and subsequent leg length inequality (LLI) is a recognized complication. Although noted when the operation was popularized in the 1960s it was in the 1990s that it increased in prominence. LLI following total hip replacement is an independent risk factor in the outcome of total hip replacement.While not everyone with a post-total hip replacement LLI will be symptomatic, those who are can complain of mechanical problems, pain and neurological deficit. LLI also has increasing medico-legal consequences.Although any patient undergoing total hip replacement is at risk of a symptomatic LLI there are identifiable populations who are less likely to tolerate what would be otherwise considered an acceptable deformity.This paper focuses on the important elements in the history, examination and investigation with relevance to LLI and total hip replacement, particularly considering those at greater risk of symptoms. The paper also discusses the background, definitions as well as the management strategies for an unacceptable LLI.