Background: Acetabular implant revision with large bone defects, can be challenging. One of the reconstruction options is a “jumbo cup” (outer diameter ≥62mm in women and ≥66mm in men). We hypothesized that cementless jumbo cups is a reliable technique to reconstruct hip joint with satisfying radiological and clinical outcomes.
Material and Methods: Fifty-two consecutive acetabular revisions arthroplasty where a cementless jumbo cup was used were assessed. Clinical outcomes were assessed by Harris Hip Score (HHS), WOMAC index and SF-12. Hip centre was assessed on anteroposterior (AP) view according to Pierchon’s criteria. The reconstructed hip center was considered as satisfying when its location was located from −10 to + 10 mm proximally (y axis) and/or medially (x axis) in comparison with ideal theoretical hip center location. Cup migration and modification of abduction angle were considered as significant when there were respectively ≥5mm and to ≥5° in comparison with the immediate postoperative AP view.
Results: Mean component size was 67.6 mm (min 62, max 81). According to Paprosky classification, there were 5 cases of type 1, 11 type 2A, 12 type 2B, 11 type 2C, 11 type 3A and 2 type 3B. Cancelous bone chips allograft were used in 34 cases and bulk bone allograft in 14. Immediate postoperative AP view showed a mean abduction cup angle of 41.3° (26–53), a satisfying hip centre positioning in 78% on x axis and in 70 % on y axis. In the remaining cases, we noted an improved implant positioning. For the patients with intact contra-lateral hip (n=29), we noted, in comparison with normal side, a mean lateralisation of the hip center of 3 mm (−10 – +16) and a mean ascension of 7 mm (−10 – +33) associated with an average limb length discrepancy of – 4 mm (−19 – +9). At the last follow up [radiological data: 79 months (24–236) and clinical data: 88 months (27–241)], 6 patients were died and 3 were lost of follow up. The mean HHS was 82% (15–100), WOMAC 86% (27–100), SF-12 46 (14–61) and 53 (15–63). Bone graft integration was completed in all but 3 cases. Significant cup migration (≥5mm) occurred in only one case. The complications were: dislocation in 5 cases (4 revisions with constrained liner), infection in 4 cases (2 treated conservatively and 2 revised in 2 times procedure) and Brooker’s type III or IV ectopic ossifications in 11 cases. No case required revision for aseptic loosening.
Discussion: Jumbo cups appear as a reliable procedure to manage bone loss in acetabular revision. The complication rate is comparable with other reconstruction procedures (massive allograft, reinforcement rings, high hip center…). Cementless fixation and satisfying hip center restoration promote respectively the bone integration and allow an optimal biomechanical joint functioning. These are the main conditions for high long term survival rate.
