Extended Fixation for Paprosky Type III Acetabular Defects in Revision Total Hip Arthroplasty with a Minimum Follow-Up of 2 Years.

Objective: Revision of total hip arthroplasty for patients with severe acetabular bone defects is challenging. This study aims to report the minimum 2 years outcome of the iliac extended fixation technique in patients with Paprosky type III acetabular defects.

Methods: Fifty-seven revision total hip arthroplasty patients were retrospectively reviewed who underwent reconstruction with the concept of iliac extended fixation from 2014 to 2017 in our hospital. We proposed a new concept of "iliac extended fixation" in revision total hip arthroplasty as fixation extending superiorly 2 cm beyond the original acetabular rim with porous metal augments, which was further classified into intracavitary and extracavitary fixation. Patients were assessed using the Harris Hip Score and the Western Ontario and McMaster Universities Osteoarthritis Index Score. Radiographs and patient-reported satisfaction were assessed.

Results: At an average follow-up of 63 months (range 25-88 months), the postoperative Harris Hip Score and Western Ontario and McMaster Universities Osteoarthritis Index scores were significantly improved at the last follow-up (p < 0.001). The center of rotation was significantly improved (p < 0.05). Fifty-three (93.0%) patients were satisfied with the outcome. The extracavitary iliac extended fixation group had higher rate of osteointegration in zone 1A (the superior lateral zone) than the intracavitary iliac extended fixation group (82.3% vs 55.0%, p = 0.015), and significantly more horizontal screws fixation (5.1 ± 24.7° vs 42.3 ± 36.8°, p < 0.001).

Conclusion: Intracavitary and extracavitary iliac extended fixation with porous metal augments and cementless cups are effective in reconstructing severe superior acetabular bone defects. The difference in screw direction might reflect the different biomechanics of augment fixation.