Abstract
Purpose of the study:
Recent literature raised concern on the adverse effects, incidence of pseudo tumours and raised blood and urine Chromium and Cobalt levels in patients with a metal on metal articulation. The purpose of this study was to follow up a cohort of patients that received a metal on metal total hip replacement with minimum follow up of ten years and to compare the results with the literature.
Methods:
All the available patients that underwent metal on metal total hip replacements during 1999 to 2000 with a minimum follow up of 10 years were clinically examined and evaluated with the Harris Hip Score; X-rays; Full Blood Count; CRP; LFT; U, K & E; blood and urine Chromium and Cobalt levels and Ultrasonic examination of the hip. The ultrasound was done by an independent experienced ultrasonographist in each case to exclude pseudo tumours or fluid collections. The patients were clinically examined to try and find any adverse effects of the metal on metal articulation.
Results:
We found one patient that had a revision of the femoral component for a peri-prosthetic fracture retaining the metal on metal articulation that subsequently developed loosening and a pseudo tumour. The remaining patients had excellent Harris Hip Scores and their implants showed no osteolysis or radiological signs of loosening.
Conclusion:
Despite the recent concern we obtained good results after ten year follow up with metal on metal prosthesis. However we do recommend careful selection of patients, detailed attention to surgical technique and close follow up when considering metal on metal articulation. Patients should be counselled about the possibility of tissue reaction to the bearing surface and possible future revision surgery.
