Les vis et trajets de vis ont-ils une influence sur l’ostéolyse pour les cupules acétabulaires sans ciment avec polyéthylène hautement réticulé ? Étude cas-contrôle à 7-10 ans de recul

Abstract

BackgroundThe use of screws and the presence of screw holes may cause acetabular osteolysis and implant loosening in cementless total hip arthroplasty (THA) using conventional polyethylene. In contrast this issue is not fully understood using highly cross-linked polyethylene (HXLPE), particularly in large comparative study. Therefore, we performed a case-control study to assess the influence of screw usage and screw holes on: (1) implant fixation and osteolysis, and (2) polyethylene steady-state wear rate, using cases with HXLPE liners followed up for 7-10 years postoperatively. HypothesisThe screw usage and screw holes adversely affect the implant fixation and incidence of wear-related osteolysis in THA with HXLPE. Patients and methodsWe reviewed 209 primary cementless THAs performed with 26-mm cobalt-chromium heads on HXLPE liners. To compare the effects of the use of screws and the presence of screw holes, the following groups were established: (1) with-screw (n=140); (2) without-screw (n=69); (3) no-hole (n=27); and (4) group in which a cup with screw holes, but no screw was used (n=42). Two adjunct groups (no-hole cups excluded) were established to compare the differences in the two types of HXLPE: (5) remelted group (n=100) and (6) annealed group (n=82). Implant stability and osteolysis were evaluated by plain radiography and computed tomography. The wear rate from 1 year to the final evaluation was measured using plain X-rays and PolyWare Digital software. ResultsAll cups and stems achieved bony fixation. On CT-scan no acetabular osteolysis was found, but there were 3 cases with a small area of femoral osteolysis. The mean steady-state wear rate of each group was (1) 0.031±0.022, (2) 0.033±0.035, (3) 0.031±0.024, (4) 0.029±0.018, (5) 0.030±0.018, and (6) 0.034±0.023mm/year, respectively. A comparison of the effects of screw usage or screw holes found no significant between-group differences in the implant stability, prevalence of osteolysis (no acetabular osteolysis and 3/209 at femoral side (1.4 %) and steady-state wear rate. DiscussionThis study suggests that there are no adverse effects on the results of THA with HXLPE from the use of cups with screw holes and the use of screws for cup fixation.Level of evidence: Level III retrospective case-control study.