Introduction: The Oxford Unicompartmental Knee Hemiarthroplasty has been used in the Nelson region by three surgeons for over 10 years. This prosthesis has had favourable reports from the designers, with a 98% surviving 10-years or more. Other series have reported less successful results.

Aim: To evaluate the performance of this prosthesis in a provincial area.

Methods: Using the established audit system all patients were retrieved and their notes were reviewed. The patients were reviewed as outpatients according to the Oxford 12-item knee score and basic data were collected. Standardised radiographs were taken. Patients living out of the area were interviewed by telephone.

Sixty-three prostheses were implanted in 54 patients. Follow-up was from 55 to 144 months. Eighteen patients had died. Eight prostheses had been revised between four to 82months after the initial surgery. Of the patients who were reviewed, the average Oxford Knee score was 20. Two patients were not satisfied with the prosthesis.

Conclusions: These results are comparable with other non-designer series for the Oxford Knee. Patients who had successful replacements scored well and were very happy with their surgery, but there was a significant failure rate that must be taken into account when selecting patients for this prosthesis.

Introduction: To evaluate the medium-term outcome of patients undergoing revision knee arthroplasty with structural allograft for uncontained defects.

Methods: We followed prospectively 50 patients undergoing 52 revision knee replacements with 66 structural grafts in three institutions. An independent investigator reviewed twenty-nine knees in 27 patients after a mean of 96.9 months.

Results: Twelve knees were re-revised at a mean of 70.7 months. Two of these patients retained their allografts. Eleven patients died with their structural allograft and implants intact and were not awaiting revision at a mean of 93 months.

Failure was defined as an increase of less than 20 points in the modified HSS knee score at the time of the review or the need for an additional operation related to the allograft. Thirteen knees were deemed to be failures giving a 75% success rate. Graft resorption occurred in five patients resulting in implant loosening. Four failed due to infection and non-union between the host bone and allograft was present in two. One patient with both knees grafted failed to gain a 20-point improvement. Survival analysis showed a 72% survival at 10 years. Clinically, the modified HSS score improved from a mean of 32.5 pre-operatively to 75.6 at the time of the review. Radiographic analysis of the surviving grafts showed no severe resorption, one moderate and two mild cases of resorption. Evaluation for loosening revealed one patient with a loose tibial component, while three patients had non-progressive tibial radiolucent lines. All four patients were asymptomatic.

Conclusions: Our results demonstrated encouraging medium-term survival of allografts utilised for revision knee replacement in a group of difficult patients with massive bone loss.

Aim: The current trend in fixation of acetabular components is towards press-fit, no-hole components to reduce the wear debris production and its access to the bone prosthesis interface. The purpose of this study is to review the outcome of no holes or holes with or without adjuvant screw fixation in a porous expanded rim modular acetabular component of the same design with a minimum of two year follow up.

Method: This was a retrospective review of the charts and radiographs of 204 consecutive Osteonics PSL acetabular components inserted by the same surgeon. Radiographic analysis included assessments of radiolucencies in the three zones of Charnley & DeLee, as well as assessments of migration and wear using the technique of Livermore. Osteolytic cysts were recorded and any progression noted.

Results: The underlying diagnosis was similar in all groups with osteoarthritis comprising 57%. In the screw group one component has been revised for loosening secondary to impingement. Three had significant osteolysis, all of which have been revised. There was no significant difference for the 28 mm heads between the groups for radiolucencies or migration. The 22 mm heads had a higher rate of linear wear. Complications included seven dislocations, two with grade three heterotopic ossification and one late haematogenous infection.

Conclusion: Comparing acetabular components with and without screws and no-hole components there was no significant difference in radiolucencies, wear and migration. Osteolytic cysts occurred only in cups with holes and screws. Because of these findings the surgeon continues to use the no-hole cup wherever possible in primary and revision arthroplasty. Longer follow up will be required to confirm that this decreased osteolysis persists over time in the no-hole group.