Purpose of the study: We conducted a prospective randomized study to compare use of macroporous biphasic calcium phosphate ceramic and bone autografts for filling medial open wedge osteotomies of the proximal tibia.

Material and methods: This phase III pragmatic clinical trial was designed for direct patient benefit. Randomization was performed in the operating room after completing the osteotomy. Twenty-six men and 14 women, mean age 51 years (range 19–75 years) were included. A biomaterial implant was used for 22 patients and an autograft for 18. Mean correction was 10 mm (range 6–15). One patient was excluded from the analysis, no patient was lost to follow-up. All patients were reviewed at minimum two years follow-up.

Results: At three months, knees were less painful with less subjective functional impact after filling with an autograft (pain VAS 3.1 versus 2.1 and function VAS 3.4 versus 2.5). These results were more balanced at six months (pain 1.6 versus 1.8 and function 1.8 versus 2.1) and remained stable at one and two years. The IKS knee scores were symmetrical at one at two years for both groups (IKS1 93 versus 86 and IKS2 90 versus 90). Bone healing was achieved within the usual delay. Axial alignment was stable at two years in both groups. There were eleven complications (28%), nine requiring revision: infected hematoma (n=1), intraoperative vascular injury without serious consequences (n=1), loss of correction (n=2), nonunion after filling with biomaterial (n=1), iliac abscess after filling with autograft (n=2) and painful calcification of the iliac region requiring resection (n=1).

Discussion: We observed three factors which can favor mechanical failure after filling with a ceramic material: intraoperative rupture of the lateral hinge, obesity, and excessively early unprepared weight bearing.

Conclusion: Although the difference did not reach significance, the risk of mechanical complications appears greater with macroporous en bloc ceramic filling. This material is less tolerant to comorbid conditions (obesity) and requires very precise technique as well as careful observance of postoperative care (no early weight bearing). Nevertheless, this method does have the advantage of avoiding painful sequelae and complications related to harvesting the iliac graft.

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: 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.