Hip involvement in ankylosing spondylitis and poor function but successful outcome with early total hip replacement

Eduardo Collantes and Vander Cruyssen and colleagues are to be congratulated for their multicenter study focusing on hip involvement in ankylosing spondylitis (AS). The study included patients from two centers in Belgium, two in Mexico and several in Spain. It is self-evident that only a multicenter study can provide sufficient patients to answer the questions posed. For reasons that are unclear, clinicians often ignore the hip, in spite of hip disease being of paramount importance to those patients with AS who develop hip involvement complicating their spinal dysfunction. Naturally, hip disease, from the point of view of both patients and society, is very expensive in terms of cost relating to suffering, loss of work, early retirement and therapy. The authors suggest that between 24 and 36% of subjects with AS have hip involvement and in their population no less than 5% needed hip replacement surgery. Not surprisingly, overall, those with hip involvement had less function than those without hip involvement. In essence, patients with younger age of onset are most likely to require hip replacement surgery. It is not only function that is poor in those with hip involvement – as defined by the Bath AS Functional Index (BASFI) [1] – but disease activity is also worse (as defined by the Bath AS Disease Activity Index [BASDAI] [2]), given the pain and stiffness. Furthermore, there is an impact on global status (the Bath AS Global Score [BAS-G] [3]) – and not surprisingly, on the radiological status (the Bath AS Radiology Index [BASRI] [4]) considering that hip involvement is a component of the radiological score with a number ranging from 0 to 4 where 0 is normality, 1 is minor change, 2 is moderate change, 3 is severe change and 4 is end-stage hip disease, or indeed a replaced hip. In our experience, the distressing aspect of hip disease in AS relates to the fact that, as noted in this study, it is the young patient with early-onset disease who suffers most, and for decades the tragedy has been that orthopedic surgeons were reluctant to replace hips in young individuals. Of course, to the teenager with crippling disease, or the young adult aged in his or her 20s, there is no comfort being told that they are ‘too young’ for hip replacement, considering that it is now that they want to get on with their life in terms of social, family and professional activities. The survival of a replaced hip may only be 10 or 15 years, and they would then require a revision or a second hip replacement. Needless to say, such a therapeutic option was perceived with dismay by most of the young patients, who understandably felt that it was now that they needed a new hip, and they had no wish to wait for 10 or 15 years. In 2001 we evaluated all our patients who had received a total hip replacement [5]; in essence, we reviewed 4567 consecutive patients with AS and carried out an analysis on the 156 recipients (3.4%) of total hip replacements. Among these individuals, 309 hips had been replaced. Of these 309 hips, 255 were primary replacements, and 54 were revisions, and 64% of the total number of patients had bilateral replacements. Evaluation of: Vander Cruyssen B, Muñoz-Gomariz E, Font P et al.: Hip Involvement in ankylosing spondylitis, epidemiology and risk factors associated with hip replacement surgery. Rheumatology (Oxford) 49(1), 73–81 (2009). Destructive hip disease is highly prevalent in ankylosing spondylitis, especially for those with young age of onset. Suffering is significantly high and functional outcome is inevitably poor. Early total hip replacement keeps people at work and relieves suffering, but, regrettably, is often delayed by orthopedic surgeons who feel the patient is too young. We now know that total hip replacements survive well in spondlytic patients and benefit family members and society gain by such management.