10-YEAR RESULTS OF A HYDROXYAPATITE COATED INSALL-BURNSTEIN II TOTAL KNEE REPLACEMENT

Abstract

We have prospectively followed 100 consecutive HA coated knee replacements performed from 1990–1992. The prostheses was a cruciate sacrificing IB II, with HA coating on the femoral and tibial components. The average age at surgery was 72.5 years [32–92]. The indications for surgery was predominantly osteoarthritis [93 cases]. 3 knees required cemented tibial components at surgery and were excluded from the series. All knees were mobilised full weight bearing postoperatively.

Patients were reviewed annually with radiographic and clinical evaluation [Hospital for Special Surgery Knee score]. There was no loss to follow-up and at most recent review 48 people [60 knees] were alive. Of these, 47 knees had a final radiographic examination; the remaining knees were assessed clinically but did not attend hospital.

Using revision or need for revision as the endpoint for failure, 6 knees have been revised giving a 10 year survival of 92% [CI 0.96–0.76]. 3 tibial and 2 femoral components underwent aseptic loosening. 1 revision was for infection and 1 for technical errors.

Using pain as the endpoint for survival, 5 surviving knees [9.3%] complained of moderate or severe pain at rest or during exercise and could be regarded as failures.

There is a very low incidence of radiolucent lines at the prostheses-bone interface with 11 radiolucent zones of < 1mm under the tibial component [knee society radiological evaluation]. 72% of cases demonstrated evidence of bone-prostheses bonding with ‘spot welds’ or buttress formation.

Overall the survival at ten years is comparable with cemented fixation. We believe the evidence of bone-prostheses bonding and absence of radiolucent lines indicates that the surviving knees will continue to function well.