Purpose of the study: Acetabular version is a most important parameter for repositioning the acetabular fragment during periacetabular osteotomy. Recently, a few studies have presented a significant number of dysplastic hips with acetabular retroversion. There have not however been any studies devoted specifically to the severity of bilateral acetabular retroversion. The purpose of this work was to determine the incidence of bilateral retroversion in patients undergoing periacetabular osteotomy for dysplasia in order to identify and validate a retroversion index which would be predictive of the degree of retroversion. This index could be added to congenital hip dysplasia classifications to include acetabular version.

Material and methods: The Lequesne lateral view of the hip was obtained in 174 patients (348 hips, 137 women and 37 men, mean age 30 years) undergoing periacetabular osteotomy for symptomatic dysplasia. One hundred ninety-five hips (56%) were operated on and 153 (44%) were considered normal or non-symptomatic and were not operated. The following parameters were noted for each hip: VCE, VCA, HTE, femoral head extrusion, index of acetabular depth, crossing-over, retroversion index. The retroversion index was checked on a bone model of the pelvis which was x-rayed in the neutral position then turned progressively. Statistical data were analyzed with SAS.

Results: Five percent of the operated hips presented neutral version, 53% anteversion and 42% retroversion. Twenty-four percent of the non-operated hips were normal, 22% presented pure retroversion and 54% were dysplastic. All of the measurements were significantly deviated towards dysplasia for operated hips, with the exception of the retroversion index and the VCA.

Discussion: These data validated the retroversion index and confirmed that one out of three dysplastic hips displays retroversion. In addition, it would appear that for dysplastic hips with retroversion, the degree of lateral coverage or the HTE angle determines whether surgery is needed or not and not the degree of retroversion. But as pure retroversion can be symptomatic in itself, and since the majority of these version or cover anomalies can be treated by periacetabular osteotomy, we propose a classification of hip dysplasia included acetabular version.

Conclusion: This classification is designed as an aid for the orthopedic surgeon for reorienting the acetabular fragment to obtain the optimal position.

Purpose of the study: The majority of acetabular bone defects observed during revision hip surgery can be treated with a hemispheric implant, associated or not with a bone graft. In many patients however, loss of bone stock is so great that a more complex system must be used with a sustaining ring, multilobulated implants, or massive allografts. All have their technical difficulties or problems with fixation. The purpose of this work was to evaluate a new technique for acetabular reconstruction using modular implants fashioned with a new biomaterial, porous tantalum, which had specific properties favoring osteointegration.

Material and methods: These modular implants were fashioned so as to enable reconstruction of the acetabular cavity in cases with complex loss of bone stock. The design allows simultaneous biological incorporation and mechanical support with a press-fit hemispheric cup. These implants were used for 16 hips (16 patients, 12 women and 4 men, mean age 63.6 years, age range 34–86 years). These patients were followed for 31.9 months on average (range 24–39 months). The acetabular defects were Paprosky 2A (n=1), 2B ‘n=3), 2C (n=1), 3A (n=5), 3B (n=6). On average, these patients had undergone 2.8 cup replacements (1–9) on the same hip.

Results: The mean Harris hip score improved from 39.31 (range 33–52) preoperatively to 75.18 (range 52–92) at last follow-up. Preoperatively, the center of rotation of the prosthetic hip was situated a a mean horizontal distance of 18.6 mm (range −3 to 46 mm) and a mean vertical distance of 27.6 mm (range −16 to 52 mm) from the ideal center of rotation according to Ranawat. Postoperatively, the prosthetic center of rotation was situated at a mean horizontal distance of 10.5 mm (range 1–25 mm) and a mean vertical distance of 7.4 mm (range −15 to 25 mm) front the ideal center of rotation. None of the implants presented loosening or migration at last follow-up.

Discussion: At short-term follow-up, this modular system for acetabular reconstruction has provided good results for acetabular reconstruction which can accept a hemispheric cup alone and which would have required use of other reconstruction methods such as structural allografts, sustaining rings or other.

Conclusion: A longer follow-up will be needed to determine whether these good clinical and radiological results persist with time.

Dysplasia epiphysealis hemimelica of the left proximal femur was diagnosed in an eight-month-old girl. At the age of 18 months, radiographs of the hip and MRI showed overgrowth and loss of containment of the femoral head. She underwent resection of the superior portion of the head and neck of the femur at the age of 2.5 years. Six months later further radiographs and an MR scan show that the mass has increased in size and that hip containment has been lost. Further plain radiographs have shown that the left knee, ankle and spine were involved.

To the authors’ knowledge, this is the first report of dysplasia epiphysealis hemimelica involving both the lower limb and the spine. A review of the literature is presented.

Purpose: Bone remodelling and osteolysis around total hip prostheses remains an ineluctable corollary of prosthetic loosening. Alendronate (biphosphonate) has proven its efficacy for the treatment of osteoporosis of the lumbar spine and the femoral neck. There has been some in vitro work pointing out its contribution to the inhibition of osteolysis induced by particles. One in vivo study has demonstrated its interest in prevention of osteolysis around non-cemented total hip arthroplasties. The purpose of our work was to study the efficacy of this drug in the prevention of periprosthetic osteolysis around cemented total hip arthroplasties using biphotonic absortiometry (DPX).

Material and methods: The series included 38 patients who underwent unilateral total hip arthroplasty for degenerative hip disease. After double blinded randomisation, 20 patients were given 10 mg Alendronate per day with 600 mg calcium and 18 patients were given a placebo with 600 mg calcium for two years. All patients were followed with standard x-rays and DPX of the operated hip. Examinations were performed on the fourth postoperative day and on the third, sixth, twelveth and twenty-fourth postoperative month. The analysis concerned the periprosthetic zones defined by Gruen.

Results: DPX demonstrated significant reduction in bone mineral density (BMD) in all patients included in the study. This reduction was the same for the two groups early in the study and reached a maximum at three months; a divergence was observed thereafter. For the placebo group, the loss reached a plateau up to the sixth month after which the BMD started to rise progressively remaining at 12.7% reduction at two years (p< 0.002). In the ALN group, there was no plateau, BMD increased directly to reach 6.9% bone loss at two years (p< 0.003).

Discussion:The use of Alendronate enabled a significant reduction of periprosthetic bone loss at two years post-op. Our results are the first to our knowledge demonstrating a beneficial effect in vivo of the use of Alen-dronate on bone behaviour around cemented total hip arthroplasties.

Conclusion: Taking into account the short follow-up in this series, and its small size, other studies are indispensable to confirm this beneficial effect in vivo. The action of Alendronate could facilitate revision surgery by preserving bone stock.