Reconstruction of massive acetabular bone defects in primary and revision THA is challenging for reconstructive joint surgeons. The use of porous metal augments is one of the options. The advantages of porous metal augments are easy to use, modularity and lack of resorption. We investigated the radiological results of porous metal augments used for massive acetabular bone defects in primary and revision THA. Forty-one hips in forty patients had porous metal augments between 2011 and 2016. Thirty of the procedures were revision arthroplasties and 11 were primary procedures (Crowe type III in 5 hips, Crowe type IV in 3, septic hip sequalae in 2 and RA in one). Four of the revisions were second-stage reimplantation after infection. The Paprosky classification for revision was 2B in 4 hips, 2C in one, 3A in 3 and 3B in 22. Regenerex augments were used in 39 hips and trabecular metal augments were used in 2. Thirty-six cups were cemented and 5 cups were uncemented. Mean follow-up was 37.6 months (range, 1–82). Radiographic findings of osteointegration between host bone and the porous metal augments were assessed. The presence or absence of radiolucent lines between cement or cup/host bone and augment/host bone interface was noted. Two revisions were performed due to infection, one month and 66 months after operation. The other implants were stable without any complications. Osteointegration between host bone and the porous metal augments were recognized in 36 hips. Radiolucent lines between cement/host bone interface, less than 1 mm in width, were visualized in 2 hips. Porous metal augments are convenient and our short-term results showed excellent radiological results for massive acetabular bone defects in primary and revision THA.
We have reviewed 103 of 126 Chiari osteotomies carried out in our department between 1956 and 1987. The cases were graded radiologically, using the Japanese Orthopaedic Association (JOA) system, into a pre/early osteoarthritis (OA) group and an advanced OA group. In the pre/early group there were 86 hips. The mean follow-up was for 17.1 years (4 to 37). Preoperatively, 51 hips had an average JOA clinical score of 78.6 ± 8.4 points and the final mean JOA clinical score was 89.4 ± 12.5 points. Advanced degenerative change developed in 33.7% and one hip required a total replacement arthroplasty (TRA). Chiari osteotomy alone, without accompanying intertrochanteric osteotomy, was performed on 62 hips. For these the median survival time was 26.0 ± 2.5 years, using as the endpoint progression to advanced OA. Differences in survivorship curves related significantly to the severity of the preoperative OA, the shape of the femoral head and the level of osteotomy. In the advanced OA group, we followed up 17 hips for a mean of 16.2 years (1 to 27). Before operation, the mean JOA clinical score in 13 hips was 63.2 ± 7.9 points and the final score 84.0 ± 12.0 points. TRA was eventually carried out on four hips. Our findings suggest that the Chiari osteotomy remains radiologically effective for about 25 years. The procedure is best suited to subluxated hips with round or flat femoral heads and early or no degenerative change. Intra-articular osteotomy can lead to osteonecrosis, and should be avoided. In hips with advanced OA, the Chiari procedure creates an acetabulum which facilitates later TRA, and may delay the need for this procedure in younger patients.
