Loosening of the acetabular component of a total hip prosthesis with the concomitant loss of acetabular bone stock has become an important problem. Several techniques have been devised to compensate for the acetabular bone defect. These include
the
use
of additional bone cement and the use of autograft or allograft in conjunction with bipolar endoprosthesis or micropore or hydroxyapatite coated acetabular cup or acetabular reinforcement ring.
At Seoul National University Hospital, allograft without cement or acetabular ring has been used to fill the defect of acetabulum in hip revision arthroplasty since November, 1988. Initially bipolar endoprosthesis was used as an implant, but
later
hemispherical porous coated or hydroxyapatite coated cup with screw fixation were used.
Total thirty eight hips (bipolar endoprosthesis 12 cases, THRA 26 cases) were followed more than one year. In these cases, the amount of migration of cup, which was measured by using the teardrop as a base, and the Harris score were analyzed.
@ES The results are summerized as follws
@EN 1. In bipolar hemiarthroplasty of total 12 cases, the average duration of follow-up was 2 year. The Harris score was improved from 58.1 preoperatively to 67.9 postoperatively. during the follow-up, cup migrations were developed in 8 cases
(67%)
and
cup migrations were progressed over 6 months in 7 cases (58%) and (67%) and cup migrations were progressed over 6 months in 7 cases (58%) and they were considered to be the candidates for revision and the remains were considered satisfactory.
2. In total hip replacement arthroplasty of total 26 cases, the averag duration of follow-up was 1 year 3 months. The Harris score was improved from 58.9 preoperatively to 74.6 postoperatively. During the follow-cup migration were developed in 10
cases
(38%) and the migration were progressed in 5 cases (19%) and 2 cases of them were revised because of loosening the other 16 cases were considered satisfactory.
3. The cases were analized according to the of the deficiencies of the acetabulum. When bipolar hemiarthroplasty was done at the acetabulum with superolateral bone stock, in the three of eight cases progressive migration was occured. And without
superolateral bone stock, progressive cup migrations were noticed in the all of four cases. But, when cementless THRA was done at the acetabulum with imtact superolateral bone stock, there were no cases cup failure and when THRA was done at the
acetabulum without superolateral bone stock, in the five of eight cases of cup failure were occured.
So, in cup revision arthroplasty for acetabular bone defect, THRA with screw fixations is more reliable method than that of bipolar cup. When superior and/or lateral segmental defect in acetabulum is present, neither revision with bipolar nor
THRA
show
better result. In that cases, the reinforcement procedure is mandatory.
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