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year follow-up, and the remaining 13 patients had follow-up between four and 5.5 years.Hydroxyapatite (HA) block. The block (manufactured by Sumitomo Osaka cement Co. Ltd. atthe time of surgery, now Olympus Terumo Biomaterial Co. Ltd.) consisted of HA solid materialwith porous sections on two aspects, 1 mm depth each, which aimed to provide rigid fixation tohost bone by osteoconduction on the bony interface and to prevent cracking of the block bymetal screws at the time of installation on the other side. (Fig. 1) Blocks were available in foursizes (length, width, height): 3 x 1 x 1.5, 3 x 1.5 x 1.5, 4 x 1 x 1.5, or 4 x 1.5 x 1.5 cm, each, andeach block had three or four holes for fixation, depending upon the size of the block.Operative technique. All operations were performed with the patient in the lateral decubitusposition and using a posterolateral approach without osteotomy of the greater trochanter. TheHA block was used to manage the lateral acetabular roof defect located proximally at the rim ofthe acetabulum. Before fixation, the acetabular roof was trimmed to accommodate therectangular shape of the HA block (Fig. 2) and then a suitable size of the HA block was placedand fixed by metal screws (Fig. 3). The coverage ratio of the socket by the graft was defined aswidth of morsellized bone plus HA block to the socket (Fig. 2). An all-polyethylene socket(manufactured by Japanese Medical Materials (JMM) Co. Ltd.) was cemented in place with useof an impaction autogenous graft or allograft of morsellized bone. All but three stems (cases#4, 10, and 13) were cemented. Highly porous HA granules (size: 0.1-0.6 mm in diameter)were mixed in to increase the volume of morsellized bone in the cases #9-14 (Table 1). Thebrand of used cement was Simplex-P for the cases #2 and 3 and Endurance (CMW) for theother cases.　All of the cases were operated by the same surgeon (M.M.) assisted by hiscolleagues.The coverage ratio was 50% or more in all of the cases (Table 1). Eleven sockets were insertedand fixed within the true (original) acetabulum, and three, all classified as Crowe Group IV,were located more proximally as the distance from the lower border of the socket to the teardrop was between one and 2.5 cm in each of those cases. We were compelled to place thesocket more proximally in those three cases of severe dysplasia, because it was not possible toelongate the affected extremity sufficiently (4cm or more). HHHPost-operative regimen. On the third post-operative day the patients began a rehabilitationprogrammed by clinical path under the supervision of a physiotherapist. The use of crutches forambulation was begun on the 10 th to 14 th post-operative day, with progressive weight-bearingas tolerated. Time to full weight bearing was 3 to 4 weeks postoperatively.ResultsNo acetabular components had definite radiographic evidence of loosening, and no acetabularcomponents were revised. Both the HA block and the bone graft used in acetabularreconstruction in THA functioned well, even in the one initial case with 16-year follow-up. Inthat one initial case, the HA block and the socket remained rigidly fixed, although the autograftwas partially resorbed. (Table 1, Fig. 4) Only mild polyethylene wear and minor osteolysiswere noted on the latest radiograph of the initial patient. For the 13 other cases, all socketswere also rigidly fixed with full incorporation of both the HA block and the autograft orallograft (Table 1, Fig. 5), and there was no radiographic evidence of resorption of the impactedbone graft in any of the 13 cases with four to 5.5 year follow-up. Radiolucent zones betweenthe HA block and the acetabular roof diminished over time, and stable fixation of the block wasmaintained in all cases. Clinically, the mean Japanese Orthopaedic Association (JOA) score forthe hips improved from 37 points preoperatively to 90 points postoperatively. (Table 1)DiscussionThere have been several reports on the use of bulk femoral head autograft for acetabularreconstruction in acetabular bone deficiency due to developmental dysplasia of the hip.Spangehl et al. 6　 reported that the method of reconstruction with the bulk autograft formoderate anterolateral acetabular bone deficiency provided reliable uncemented socket fixationin a study with 5- to 12-year follow-up. Shinar and Harris reported that 21 of the 27 acetabularfile:///E|/ISTA2010-Abstracts.htm[12/7/2011 3:15:47 PM]