Only 0.8% of arthroplasties registered on the National Joint Registry in 2006 are patello-femoral. The Leicester patello-femoral replacement (Corin) has been in use for over 10 years with satisfactory initial results. The indication for use is isolated patello-femoral osteoarthritis with the theoretical benefits of bone preservation, maintenance of normal knee mechanics and easy revision. The implant was only available in one size and the femoral component was uncemented.

We reviewed 49 patients managed with this prosthesis with a median follow up of 10 years (range 4-16). The mean age of the patients at time of surgery was 64. 62 arthroplasties were performed.51 were in females and 11 in males giving a 5:1 ratio. Thirteen patients had bilateral procedures. Thirty-nine revisions (62.9%) were performed for progressive tibio-femoral arthritis or prosthetic failure. Mean time to revision was 5 years 3 months. The knees were revised to total knee replacements without the need for stems, wedges or constraint. The unrevised knees had a mean survivorship of 8 years 6 months with a range of 4-14 years. The mean Oxford score for these surviving implants was 22.5.

Results of other implants from the literature included the Avon prosthesis with 80% satisfaction rate at 5 years and the Lubinus with 45% satisfaction rate at 7.5 years. The Leicester device showed a pattern of progressive failure with up to 40% revision at 5 years. However those with surviving implants were reasonably happy as shown by the Oxford scores.

We concluded that patello-femoral replacement has a role though this is not as well defined as TKR or even UKR. We posed the question as to whether these results were due to poor patient selection or design failings of the Leicester prosthesis. This prosthesis has been successful at reducing pain and improving function and may have been more successful with more sizes of implant, better instrumentation and more rigid patient selection.