Aims: To test the outcome of acetabular revisons with impacted morsellized bone grafts and a cemented cup at a minimum follow-up of 15 years. Methods: Between 1979–1986 62 acetabular revisions (58 patients) were performed with impacted bone grafts and a cemented cup. Two cases (2 hips) were lost to FU. The average age at operation was 59.1 years. The indication was aseptic in 56 and septic loosening in 4 hips. Defects were AAOS-classiþed as ñcavitaryñ in 37 and ñcombinedñ 23 cases. Femoral-head allografts were used. Acetabular re-revisions were determined, the HHS obtained and radiographs analyzed. Results: Nineteen cases (20 hips) died within þfteen years after the operation, none had a re-revision. Eleven acetabular re-revisions were performed: 2 septic loosenings (3 and 6 years p.o.), 7 aseptic loosenings (6, 9, 11, 12, 13, 14, 14 year p.o.) and two for cup wear (12 and 17 yrs p.o.). The average HHS at follow-up was 86 (50–100). There were no additional radiographic failures. Using Kaplan-Meier analysis the survival with endpoint revision for any reason was 79% at 15 years and 71% at 20 years; for aseptic loosening of the cup 84% at 15 years and 84% at 20 years. Conclusions: This technique is attractive to reconstruct acetabular bone stock loss.

Aims: The effects of bone graft washing and bone graft particle size on initial cup stability in an acetabular model were studied. Methods: From fresh human femoral heads large (8–12 mm) and small (2–4) grafts were produced. Four different groups were tested; large washed, large unwashed, small washed and small unwashed. An AAOS type 3 combined defect was reconstructed in a synthetic acetabular model using a metal mesh and screws. Bone grafts were impacted in a standardized way using a hammer and metal impactors. Cement was pressurized and a PE cup was inserted. Cups were dynamically loaded with 1500 N and 3000 N for 15 minutes using an MTS-device, RSA was used to calculate 3-D cup migrations. Next a lever-out test of the cup was done in a displacement (16¡/minute) controlled test. After testing CT scans of the cups were made to quantify cement layer roughness, as a measurement of cement penetration. Results: Cups reconstructed with large washed bone grafts migrated signiþcantly less during mechanical compression and withstood signiþcantly higher lever-out moments. Washing improved cup stability for both small and large grafts, however only signiþcantly for the larger bone grafts. A signiþcantly higher cement penetration depth was found for all large bone grafts, washing did not inßuence cement penetration depth. Discussion: For acetabular revisions with bone impaction grafting we recommend to use large washed bone grafts.

Introduction: Even in extensive osteonecrosis of the femoral head, a head-preserving method is preferable in younger patients. This study presents the results of bone impaction grafting for osteonecrosis of the femoral head.

Materials and Methods: After a core biopsy and removal of the osteonecrotic area, impacted morsellized bone allografts were used to fill the femoral head to regain sphericity, and to prevent collapse. This prospective, single-surgeon study included 28 consecutive hips in 27 patients with extensive osteonecrotic lesions (ARCO classification Stage 2 (11 hips), Stage 3 (14 hips), and Stage 4 (three hips). Fourteen hips had preoperative collapse. The mean age of the patients was 33 years (range, 15–55 years).

Results: At a mean follow-up of 42 months (range, 24–119 months), eight hips (29%) had been converted to a total hip arthroplasty. Of the 20 reconstructions that were in situ, 18 were clinically successful (90%) and 70% were radiologically successful. Patients who were younger than 30 years at surgery had a significantly better radiologic outcome, even when compared to heads with higher stages of osteonecrosis. Patients with preoperative collapse or a continuous use of corticosteroids had disappointing results.

Discussion: This method is attractive as a salvage procedure for osteonecrosis of the femoral head. It is relatively simple and quick to perform, and it does not intervene with an eventual future hip arthroplasty.

Introduction: Between 1985 and 1995 an uncemented Osteonics hip prosthesis with bipolar Universal Head was the implant of choice in young patients with osteonecrosis of the femoral head and with posttraumatic secondary osteoarthritis of the hip.

Materials and Methods: 30 bipolar hemiarthroplasties were performed in 24 patients with an average age of 34 years. Twenty-six hips had osteonecrosis of the femoral head and 4 hips had secondary osteoarthritis. All prostheses were Osteonics Omnifit collarless stems with an UHR universal head. 11 were non-HA-coated prostheses (NG) and 19 proximal HA-coated prostheses (HA). The mean duration of follow-up was 10.4 years.

Results: Clinically, at final follow-up, the Harris Hip Score increased from a preoperative average of 41 points to 76 points (NG 70 and HA 80 points). Thigh or groin pain was present in 16 of 30 hips (NG 3/11 and HA 10/19). Radiographically, a subsidence of 5 mm or more was the major problem in the non-coated prostheses, 11 of 30 hips (NG 10/11, HA 1/19), but osteolysis was mainly seen in the HA-coated group, 20 of 30 hips (HA 17/19, NG 3/11). Total proximal migration of 5 mm or more of the bipolar head was found in 18 prostheses (NG 5/11 and HA 13/19). The revision rate for aseptic loosening was 8 of the 30 hips (NG 3/11 and HA 5/19). During the revisions, major destruction of the polyethylene (PE) inserts were found.

Discussion: The revision rate of the Osteonics Omnifit Prosthesis with bipolar UHR is too high to use this implant in young patients with ON. Bone destruction due to third body wear is probably the main cause. Extensive proximal femoral bone loss is seen predominately in the HA group. The loosening rate in the HA-coated group showed no difference with the non-coated group although the reason for this is different.

It has been generally accepted that dynamic mechanical load is important for normal bone physiology, remodeling and fracture healing. Impacted morsellized grafts can be seen as healing of many small fractured bone parts, involving bone remodelling, apposition and formation of new bone. Therefore load may be stimulative for the incorporation of this type of graft.

In a pilot study we observed a positive effect of load on the density of incorporated bone after 12 weeks. Based on these results we hypothesised that physiological loading has a stimulatory effect on the early stage of bone graft incorporation. To test this idea we implanted fresh frozen allograft bone chips in 12 goats and loaded these grafts with the newly developed subcutaneous pressure implant ( Lamerigts et al., Biomaterials2000; 21: 741–7). The goats were divided in two groups: non-loaded and loaded. The loaded group was subjected to a loading regime of 3 MPa for 5 days/week (1 Hz, one hour/day). After 5 weeks the bone mineral density was measured with quantitative CT scanning, followed by routine histology and histomorphometry.

Bone mineral density was not affected by load. Histology revealed microscopic evidence of normal bone graft incorporation as seen in previous studies. The amount of active incorporating bone was higher under load (p< 0.05).

The formation of a new bony structure was not affected by load in this early stage of bone graft incorporation. However, load resulted in a more active graft incorporation after 5 weeks. The difference between the loaded and non-loaded group might be partially obscured by a low level of physiological loading in the non-loaded group induced by the daily activity of the animals.