Increased polyethylene wear after cementless ABG I total hip arthroplasty.

Introduction: The cementless, hydroxyapatite-coated Anatomique Benoist Giraud-I (ABG-I) hip endoprosthesis represented a modern implant in the 1990s. The aim of the current retrospective study was to evaluate the clinical and radiological results of this prosthesis. In addition, an analysis of the complications and retrieved implants was conducted.

Materials/methods: The medium-term results (follow-up 5.23 years) of 193 hip joints are presented. Of 158 total cohorts, 81.9% was able to undergo follow-up performed with standardized clinical and radiological investigations. Physical characteristics of the patients and the underlying disease prompting the need for total hip arthroplasty, as well as a clinical score (Merle d'Aubigné) were recorded. At the time of follow-up, a radiologic examination of all patients with a standardized evaluation was performed. In addition, the migration of the acetabular cup and femoral head as well as polyethylene wear could be determined digitally in 118 cases (61.1%) using one-picture Roentgen analysis.

Results: Clinical results, as measured with a Merle d'Aubigné Score increase from 8.4 to 16.2, were very good. Radiographs demonstrated successful osseous integration of the anatomically molded shaft. Within the period of the investigation, no revision procedures of the femoral shaft were necessary. However, the rate of polyethylene abrasion of 0.23 mm/year was markedly high. 13.9% of hips (n = 27) required acetabular cup revision due to wear. This calculates to a prosthesis 7-year survival probability of 63%. Intraoperative findings during the revision cases showed extensive periacetabular osteolysis with foreign body granulation tissue. Analysis of data from the total patient cohort versus data from cases requiring revision showed a significantly increased frequency of high polyethylene wear in young active patients as well as in cases where an unfavorable acetabular cup to femoral head relation existed in correspondence with polyethylene thickness. There is evidence, however, that suggests that multifactorial causes for the increased wear are significant in regards to the principal material and technical features of the prosthesis.

Conclusion: On the basis of these results, it is strongly recommended that all patients treated with an ABG-I hip endoprosthesis should receive close clinical and most importantly close radiologic follow-up.