Dislocation and subluxation of the total hip replacement.

In 502 total hip replacements, it was noted that 7 (1%) dislocated postoperatively in the first 6 weeks. This was usually related to improper positioning of the implant or to improper positioning of the implant or to unusual positioning of the patient postoperatively. There was no difference noted between the type of implant and the incidence of dislocations. Twenty-eight subluxations (5.5%) occurred. There was no statistical correlation with the percentage of nonunions and the type of prosthesis; however, 22 of the 28 subluxations were in Charnley prostheses. Ninety-three per cent of the subluxations were secondary to hyperflexing activities.