Purpose of the study: Revision acetabular surgery with bone stock deficiency is a difficult problem. The use of cementless component and bioactive ceramics seemed to be a promising alternative.

Since 1996, we have been filling bone defect at the time of revision with macroporous calcium phosphate ceramic. We reported our first experience between 1996 and 1999.

Material and methods: The procedure was carried out in 35 hip reconstructions ( 35 patients ) at a mean follow-up of 6 years ( range 5 to 7,4). The average age of the patients was 56 years( range 28 to 83).

2 patients died of a cause unrelated to the procedure and 2 patients were lost of follow-up. Bone defect were classified into type I ( 4 hips), type IIA ( 8 hips ), type IIB ( 5 hips), type IIC ( 9 hips), IIIA ( 4 hips ), type IV ( 5 hips ) according to Paprosky classification.

The functional status of the patients was evaluated according to the Merle d’Aubign ip rating.. The interfaces bioactive ceramics/bone base and bioactive ceramics/cementless component, as well as the homogeneity and the density of the graft were examined radiologically.

Results: Functionally, the Merle d’Aubigné hip rating improved, increasing from11,3 to 15,9. Failure of fixation of the acetabular component occurred in 11,4 % of the acetabular reconstructions ( 4 hips in 35 patients). One was diagnosed as loose on the basis of radiographic criteria alone and the other three hips had a loose acetabular component at reoperation. We observed no failed reconstruction when the acetabular component is in direct contact with host bone on 50 % or more of its surface area.

We saw no radiolucent lines or spaces at the interface between bioactive ceramics and the host bone. Morphological changes or a decreased in graft volume were not seen, except for the patient with the loose cup.

Discussion-Conclusion: The findings of the present study support the use of bioactive ceramics and cement-less acetabular component in the presence of loss bone in order to achieve the goals of a revision hip replacement, provided that at least 50 % support of the cup can be obtained with host-bone.

Purpose: Adding bone marrow cells to ceramic materials provides an osteoprogenic capacity favouring bony regrowth. Likewise, addition of platelets, which contain growth factors, might increase the rate of bone formation. The purpose of this work was to quantify in vitro the osteogenic potential obtained by adding platelet-rich plasma (PRP) to the bone marrow culture on ceramic materials.

Material and methods: PRP was obtained by centrifugation of blood and added to bone marrow cells harvested from the iliac crest and cultured on biphasic macroporous ceramic materials. Addition of PRP was repeated with platelet counts every two days. Differentiation of bone marrow cell into cells with osteogenic potential was evaluated by quantifying alkaline phosphatase activity after 15 days culture.

Results: Proliferation of mesenchymatous cells was clearly enhanced in cultures with PRP (+31%). Mean prevalence of phasphatase-alkaline-positive colonies was also improved after addition of PRP (+38%). Similarly, alkaline phosphatase activity was higher after addition of PRP (+31%).

Discussion: Adjunction of PRP to bone marrow cells cultured on ceramic materials stimulates proliferation of osteoblast-like cells. Increased cell proliferation and differentiation observed in vitro provides quantitative elements favouring the combination of platelets with bone grafts using bone substitutes.

Purpose: Fat or marrow embolism during or after bone and joint surgery is a serious complication. We wanted to determine the incidence and circumstances of peroperative embolism in patients undergoing lumbar spine surgery with and without instrumentation.

Material and methods: Sixty adult patients with degenerative lumbar spines underwent peroperative and early postoperative transoesophageal ultrasonography. The lumbar procedure involved instrumentation with insertion of pedicular screws in 40 patients.

Results: Moderate to severe signs of embolism (Pitto classification grade 2 or 3) were observed in 80% of the patients who underwent instrumentation procedures but in none of those who had not been instrumented (p < 0.001).

Discussion: Among the different procedures performed on the posterior lumbar spine, insertion of pedicular screws appears to be the leading cause of pulmonary embolism. The approach, laminectomy, discectomy, and bone abrasion do not appear to produce detectable embolism.

Conclusion: We consider that the observed embolic manifestations, also observed in intramedullar procedures, are potentially fatal after spinal surgery.

Purpose: Combining biomaterials with non-cemented cups is a new approach to acetabular construction in patients with bone stock loss after failure of conventional techniques. We evaluated our early results and attempted to ascertain limitations.

Material and methods: Between January 1, 1996 and December 31, 2000, we changed 229 cups. The reconstruction combined biomaterials with a non-cemented cup for 48 patients (mean age 57 years, age range 29–84). Mean retrospective follow-up was 37 months (7–67) with two patients lost to follow-up early.

Two types of cups coated with hydroxyapatite were used depending on the acetabular potential for retaining the implant: 26 ATLAS press-fit cups (four screwed) and 22 Cerafit cups with Surfix anchor screws. Bony defects were filled with grains of macroporous calcium phosphate ceramic, alone or in combination with an autol-ogous bone graft (five patients) and/or an iliac bone marrow graft (24 patients). The Harris and modified PMA clinical scores were used for assessment. According to the Antonio classification, preoperative bone loss was grade II in 18, grade III in 27, grade IV in 3. We attempted to determine the percent of bone support under the cup before reconstruction. The centre of the prosthesis rotation and the interfaces with the biomate-rials were checked regularly.

Results: At short-term, this technique provided a clear functional improvement (Harris improved from 53.7 to 81.3 points). The bone-biomaterial interface did not show any lucent lines and tended to become homogeneous (31 cases). Seven patients (15.2%) developed millimetric lucent lines around stable implants. We had nine failures (19.6%) and performed four surgical revisions (8.7%) for major inclination of the cup in three and recurrent dislocation in one. There were also five patients with an asymptomatic implant migration. Excepting one case, the cup inclinations occurred when the bony support was less than 50% of the acetabulum while only one migration was noted with less than 50% bony support (p=0.02).

Discussion: At short-term this technique, which is easy to perform and less costly and safer than allografting, provides similar results. We observed a continuous construct between the receiver bone and the macroporous biomaterial in all cases. Mechanically, the cup was stable when the bony support was healthy and involved more than 50% of the acetabulum. Other reconstruction strategies should be considered in other cases.

Purpose: Indications for anterior release associated with posterior release for stiff idiopathic scoliosis in adults has varied from institution to institution. The traction view is taken as a useful tool to determine whether anterior release is necessary. The purpose of this study was to validate this hypothesis in a homogeneous group of patients with specifically defined idiopathic scoliosis and to determine predictive value of the traction view. Based on this prediction, we then compared postoperative frontal correction in patients with and without anterior release, performed thoracoscopically.

Material and methods: All patients had idiopathic thoracic scoliosis with a Cobb angle greater than 60° and less than 35% reduction on the standard traction view. Cotrel-Dubousset instrumentation was used for release/posterior fusion procedures. A posterior approach was used alone in group 1 patients (n = 46). Group 2 patients (n = 10) underwent thoracoscopic first intention anterior release/fusion.

Results: The postoperative Cobb angle was strongly correlated with the preoperative angle on the traction view (r = 0.86, p < 0.001). The traction view predicted the postoperative Cobb angle actually achieved rather than the degree of correction of the Cobb angle. The severity of the curvature, 81.5° and 83.3° in groups 1 and 2 respectively, and reducibility on the traction view, 61.6° and 62.1° in groups 1 and 2 respectively, were not different. Likewise the postoperative angles were not significantly different between the two groups (47.4° and 45.4° respectively).

Discussion: The traction views were found to predict reduction of the thoracic curvature even for stiff scoliosis but with a wide error. The two groups were comparable since there was no difference in the mean degree of reducibility under traction. Consequently, anterior release did not appear to improve the postoperative correction in the frontal plane.

Conclusion: The traction view does not appear to be sufficiently discriminating to determine the usefulness of anterior release associated with posterior release for the treatment of stiff idiopathic thoracic scoliosis.

We performed biopsies during reoperation for minor complications in two active young patients 9 and 19 months after massive bone allograft implantation for bone tumour. The grafts were dead and resorption-apposition activity, when present, was predominantly in subperiosteal areas. Inflammatory infiltration was very seldom found.

Features considered as ‘microfractures’ or ‘microcracks’ were noted in the cortical ring together with the formation of woven bone, in areas with remodelling. Such cracks are likely to be of mechanical origin and do not inevitably lead to complications.