Prosthetic dislocation in customized total hip replacement: a clinical and radiographic review

The incidence of dislocation reported in the literature varies between studies. Some (Hamblen 1984) quote a rate of between 0.5 and 3%, while others (McCollum & Gray 1990) quote 3 to 5%. A more recent text (Miller 1992) states that dislocation occurs in I to 4% of primary total hip replacements. The Belfast Custom X-press hip system comprises a modular, customized, cemented, titanium stem, together with cobalt chrome or ceramic heads, and is used in conjunction with a cemented Charnley-type socket. Since 1992, over 1500 prostheses have been implanted and documented (Wallace et al 1992, Engela et al 1993, O'Brien et al 1994, Nixon et al 1994, Beverland 1994, James et al 1995). A total of 1023 Custom X-press total hip replacements were reviewed radiographically. The dislocations in this group were compared to a subset (chosen at random from the custom hip database) of 347 arthroplasties who did not dislocate. Several factors were found to influence dislocation: femoral head size was the most important factor in our series. The smaller femoral head size (22.225 mm) was significantly more likely to dislocate, P<0.01. In only one case in the dislocated group could malalignment of the components be seen as the definitive cause of dislocation. The problem of sislocation following hip replacement remains a complex, multifactorial problem. There is evidence from the nursing and medical literature that increasing experience and careful technique, coupled with comprehensive patient education, will minimize this complication of total hip replacement.