Reconstruction of Paprosky type IIIB acetabular bone defects using a cup-on-cup technique: A surgical technique and case series.

BACKGROUND: Paprosky type IIIB acetabular bone defects are very difficult to reconstruct. For severe defects, we developed our own cup-on-cup technique. We defined the tantalum metal (TM) revision shell with the peripheral titanium ring removed as a TM-cup augment and the cementless hemispherical acetabulum component combined with a TM-cup augment as the cup-on-cup technique. AIM: To report the short-term results of patients with type IIIB acetabular bone defects reconstructed using the cup-on-cup technique.
METHODS: We retrospectively reviewed six patients (six hips) with a mean age of 59 years who underwent acetabular reconstruction using our cup-on-cup technique between January 2015 and January 2017. All acetabular bone defects were classified as type IIIB without pelvic discontinuity using the system of Paprosky. All patients were followed both clinically and radiographically for a mean duration of 42 mo.
RESULTS: The mean Harris hip score improved from 32.4 pre-operatively to 80.7 at the last follow-up. The mean vertical position of the hip rotation centre changed from 60.9 mm pre-operatively to 31.7 mm post-operatively, and the mean horizontal position changed from 33.6 mm pre-operatively to 38.9 mm post-operatively. Greater trochanteric migration after extended trochanteric osteotomy occurred in one of six hips at 3 mo. There was no evidence of component migration at the last follow-up.
CONCLUSION: The short-term results suggest that our cup-on-cup technique could be considered an effective management option for Paprosky type IIIB acetabular bone defects without pelvic discontinuity. ©The Author(s) 2020. Published by Baishideng Publishing Group Inc. All rights reserved.