Management of Types III and IV Acetabular Deficiencies with the Longitudinal Oblong Revision Cup

Thirty-five longitudinal oblong revision (LOR) cups were used to reconstruct 29 type III and 6 type IV acetabular defects. Intraoperatively, we considered that cup contact was complete when we achieved a continuous contact between the cup periphery and the acetabular rim. When there were areas with a lack of contact, we considered that the contact was partial or incomplete. All patients were followed up for 4 to 8 years (mean = 6.3 years). At the latest follow-up, 30 cups were stable (85.8%) and 5 had migrated (14.2%). We found a significant relation between incomplete cup contact with the acetabular rim and subsequent failure (P = .042). The abduction angle was significantly increased in the group of unstable cups (P = .032) because of the migration of the acetabular component that became more vertical. Pain, limp, use of walking aids, functional level, and limb-length discrepancy significantly improved postoperatively (P < .0001). The Harris hip score improved from a mean preoperative score of 37 points to that of 79 points (P < .01). This implant showed satisfactory stability at early to midterm follow-up.