The Richards Series 2 total hip prosthesis: a 13-year study and radiographic evaluation

Abstract

This retrospective long-term study analyzes the clinical function, failures, and radiographic status of 131 Richards Series 2 prostheses in total hip arthroplasties (THAs) performed during 1981 and 1982. After a minimum follow-up period of 11 years, the results were evaluated. Sixty two (54%) patients with 71 THAs were available for follow-up; 44 (38%) patients with 49 THAs had died. Three patients with three THAs were lost to follow-up, and seven patients with eight THAs were unable to participate in the examination due to causes not related to their present hip status. Ten patients underwent revision THA during the observation period. The median hip functional index (HFI) was 8.6 preoperatively and 15.8 at follow-up. Hip functional index correlated to radiographic signs of loosening. With revision as endpoint, the Kaplan-Meier survivorship for all 131 hips was 93% after 10 years and 91% after 12 years. The radiographic examination at follow-up revealed 5 (8%) definite loose cups and 12 (19%) definite loose stems. Including the number of aseptic loosened cups and stems confirmed at revision, aseptic loosening was found in 6% of all cups and 13% of all stems. This radiographic evaluation confirmed that lack of containment of the cup and varus position of the stem were factors influencing the long-term stability of the prostheses, whereas etiology, type of arthritis, and ectopic ossification did not. A fixation and stability score that was modified for cemented prostheses was developed and was of value in detecting the prostheses at risk. The long-term results of the Richards Series 2 THA are acceptable and comparable with other long-term studies on conventional prosthetic designs. Ten percent to 20% revision THAs due to aseptic loosening can be expected. In addition, patients younger than age 60 at surgery and especially men were found to belong to a high-risk group with regard to revision THA. These patients must be evaluated carefully so that revision THA can be performed before the bone bed is destroyed.