Abstract
Introduction:
Distal femoral replacement is recognised as the optimum treatment for malignant distal femoral tumours. Aseptic loosening is known to be a major cause for failure in these implants. Studies have indicated that the HA coated collar promotes osteointegration and bony in growth. This study compares long term aseptic loosening in implants with HA coated collars to those without in the immature skeleton.
Objectives:
To assess the effect of HA coated collars on aseptic loosening in extendable distal femoral replacement prosthesis in the immature skeleton.
Methods:
All paediatric patients undergoing distal femoral replacement with extendable prosthesis were retrospectively reviewed between 1980–2003. A total of 32 patients were reviewed. 24 patients underwent distal femoral replacement with extendable prostheses without a HA coated collar. This cohort was compared to 18 patients who were treated with an extendable prosthesis with a HA coated collar between 2001–03. Average follow up in patients without a collar was 10.1 yrs (6–18) and 8.1 yrs in those with a collar (4–11). All patients with identified infection were excluded. Radiographs taken at last follow-up were analysed for loosening.
Results:
Thirty-one patients were treated for primary osteosarcoma and one for a histiocytoma. Average age at operation was 13 yrs for both groups (non-collared 6–17, collared 4–11). Three of 24 patients in the non-collared cohort underwent revision compared to 1 of 18 in the collared group. The cause of revision in the collared group was infection. One patient in each cohort died within 5 years of surgery. Mean loosening score at last follow up for the non-collared group was 11.2 compared to 2.5 for the collared group with a p value of <0.05 (Mann Whitney-U).
Conclusions:
Aseptic loosening is a major cause of failure for distal femoral replacement prosthesis. HA coated collars have been shown to promote osteointegration. Little comparable data exists between collared and non-collared extendable prosthesis in the immature skeleton. Our data demonstrates that HA coated collars significantly reduce long term loosening in the immature skeleton.
