Acetabular Revision with Hemispherical Porous Coated Prosthesis

Han, Chang Dong; Kang, Ki Won; Lee, Woo Suk

Abstract

PURPOSE: To report the results of acetabular revisions performed with the cementless, hemi-spherical porous coated component supported by viable host bone and minimal allobone graft for acetabular deficiencies.
MATERIALS AND METHODS
A retrospective study was completed for 22-revision acetabular components, using the cementless hemispherical porous coated prosthesis and minimal femoral head allograft. There was an average follow up of 48 months, with a range of 24 to 84 months. Radiographic measurements were performed in several aspects; cup-allograft contact, inclination, vertical and horizontal migration of acetabular cup, and acetabular zone by modified zone of DeLee and Charnley, in which location, size and progression or non-progression of radiolucent zone were recorded. The acetabular deficiencies were classified by the American Academy of Orthopaedic Surgeons Committee and were type I in 2 hips (9%), type II in 12 hips (55%), and type III in 8 hips (36%). Twenty acetabular cup cases of Harris-Galante II were used in this study, 1 case of Harris- Galante I, and 1 case of Duraloc. The average size of the cup was 57(44-66) mm.
RESULTS
The average cup-allograft contact was 72.5% in 19 cases and we could not differentiate the margin between the host bone and the allograft in 3 cases. There was no significant vertical or horizontal migration of acetabular cup. Radiolucent zones in follow-up radiographs were 8 cases in zone IA, 4 cases in zone IB, 4 cases in zone IIB, 9 cases in zone IIC, 8 cases in zone IIIA, and 7 cases in zone IIIB. One case showed 2 mm radiolucent area in zone IIC and another case showed 3 mm radiolucent area in zone IIB, but the radiolucencies were not progressive. The remaining cases showed less than 0.5 mm radiolucent area or no radiolucent zone. The average period of bony incorporation was 13.1 months.
CONCLUSIONS
We suppose that acetabular revision with the cementless hemispherical porous coated cup supported by viable host bone and minimal bone graft produces good results.