ROLE OF ABRADED IMPLANT EXCHANGE IN REVISION OF UNCEMENTED KNEE ARTHROPLASTY

Abstract

Purpose: To study the effect of retaining an abraded femoral component on the outcome of primary revision of uncemented total knee prosthesis.

Method: 66 revision procedures for failed uncemented porous coated anatomic (PCA) total knee replacement were performed in 60 patients. At review, four patients had died while two were lost to follow up, therefore 60 knees in 54 patients were included in this prospective study. The principal indications for primary revision were polyethylene wear and loosening of the tibial base plate. 14 patients had a well fixed femoral component and hence were retained while 46 patients had both the components revised. All patients were prospectively assessed prior to surgery, at three months, six months and yearly thereafter. Review comprised clinical and radiological assessment. The mean follow up was 8.4 yrs (7–12 yrs)

Summary of results: The mean pre-operative Hospital for Special Surgery knee score after the first revision improved at a follow up of 8.4yr (7–12yr) giving 39 (65%) excellent, 17 (28.4%) good and four (6.6%) poor results. 13 out of 60 knees needed a further revision. Six of these second revisions which had only the tibial component changed failed very early (mean of 2.1 yr) when compared to the rest (6.8yr), probably due to wear between the abraded retained femoral component and polyethylene insert. The estimated odds ratio (relative risk) of second revision in patients with retained femoral component compared to those with revision of both the components was 4.17 (95% C.I. 1.07 – 15.4).

Conclusion: We recommend exchange of all the components at the time of revision of PCA knee prostheses. Significance: To our knowledge, this is the only study involving such a large number of PCA revisions and looking into the effect of retaining the femoral component compared to changing both the components on the outcome of revision.