Introduction: During femoral impaction bone grafting high forces and hoop strains may be generated with subsequent risk of fracture. Vibration is commonly used in civil engineering applications to increase aggregate compressive and shear strengths. We hypothesized that the use of vibration during impaction bone grafting, reduces the maximum hoop strains, and hence risk of fracture, and improves particle interlocking, producing a stronger aggregate.

Method: A series of femoral impaction bone graftings on physiological composite femurs, using morsellised graft from fresh frozen human femoral heads were performed. The standard Exeter impaction technique was used in the control group and vibration assisted compaction used in the study group. Total force imparted, hoop strains and subsidence rate were measured.

Results: Significantly more allograft was used in the vibration group than in the control group (73.1g, 79.5g, p=0.01). Higher mean peak loads were produced during proximal compaction in the control group (3.28kN) than in the vibration group (1.71kN, p=0.005). Higher mean peak and mid proximal hoop strains were generated in the control group (13.2%, 5.6%) compared to the vibration group (4.2%, 2.7% p=0.009, p=0.006). The mean total axial subsidence after 50,000 cycles was significantly less in the control group (2.47mm, SD 0.55) compared to the vibration group (1.79mm, SD 0.30, p=0.03).

Discussion: The use of vibration leads to reduced peak loads and hoop strains in the femur during graft compaction which may reduce the risk of femoral fracture. Additionally the resulting graft is better able to resist subsidence thus conferring improved mechanical stability. A safer, more flexible method to compact bone graft could lead to the more widespread use of IBG in revision hip surgery.

Introduction and Aim: One of the suggested advantages of hip resurfacing arthroplasty is that it offers the possibility of a straightforward revision. As the femoral canal is not violated during the resurfacing procedure, it is postulated that the outcome of revision surgery should be equivalent to that of a primary hip arthroplasty. The purpose of this study was to investigate whether revision was as straightforward and as successful as has been suggested.

Method: 14 patients underwent revision surgery due to the failure of the femoral component of their Birmingham hip resurfacing. The femoral component was revised to a cemented Zimmer CPT stem, with a large modular metal head (MMT). The acetabular component was found to be well fixed and was left in situ. Radiographs were studied to review any change in offset or leg length. These patients were matched with a group who had undergone a hybrid total hip arthroplasty as a primary procedure, using the same bearing.

The Oxford and Harris Hip scores were used to measure outcome.

Results: In the revision group, there were 10 males and 4 females. The mean age was 56 (48–68). The mean time to revision was 11.6 months. The reasons for revisions were:

9 femoral neck fractures, 4 femoral neck resorption and 1 femoral component migration.

Post revision Oxford score =18 (12–25), HHS=92 (85.5–97.4).

Post primary Oxford score =18 (12–40), HHS=94.2 (86–97.4).

Comparison of the post-op radiographs demonstrated that offset was improved following revision. Leg length did not change significantly.

The mean follow-up was 2 years and there were no significant complications.

Discussion: Our results show that revision of the failed femoral component gives excellent results. The outcome was not significantly different to the primary THA group. Femoral offset was improved in total hip replacement compared to resurfacing.

Aim: To assess the mid term clinical and radiographic results of the ABG II uncemented hip arthroplasty.

Methods: All patients treated consecutively with the ABG hip (n=42) as a primary total arthroplasty were identified and contacted. The response rate was 89% (n=38). Responders were assessed by means of the Merle D’Aubigne1 (MDA) scoring system and radiographs taken. Radiographic assessment was carried out by two independent assessors who were blinded to the clinical outcomes. An overall assessment of loosening was made based on seven radiographic signs.

Results: The mean age of patients was 61 years (range: 44–73). Average MDA score at present day follow up was 17.6 (maximum 18) and did not decline with time post surgery. There was no evidence of radiographic loosening in any hips. There was one revision for a peri-prosthetic fracture sustained 10 days post op. Survivor-ship (all cases) was 100% for cup and 97.37% for stem at 7 years. There was no evidence of early cup loosening.

Discussion A recent study has shown unacceptably high rates of cup failure secondary to premature wear and osteolysis2 but this has not been evident in this series. Although this study did show cup eccentricity in 4 patients (representative of liner wear) there was no clinical nor radiographic evidence of cup loosening, osteolysis or failure.

Conclusion In the medium term we have shown excellent clinical outcomes with no evidence of early loosening of the ABG II hip prosthesis