Abstract
Introduction
In 1976 the senior author presented to the Associations the results of patellectomy with satisfactory results in less than 50% of cases. In 1989 with the increasing success of TKR we started a prospective study of the Lubinus prosthesis for patellofemoral arthritis. After 4 years results were not satisfactory. The main causes of failure were mal-tracking and instability leading to polythene button wear, and arthritic disease progression. A new prosthesis was designed in 1996 to correct these problems.
Methods
We have prospectively recorded the results of a consecutive cohort of 537 Avon arthroplasties. The outcomes have been assessed with survivorship, pain, Oxford and WOMAC scores. We have identified 24 patients from our own series and from tertiary referrals who have persistent pain, due to technical error rather than arthritic disease progression.
Results
Survivorship for revision at 5 Years was 96% and overall there were 63 revisions. Results over 10 years show excellent and consistent improvement in both pain and function as judged by the median WOMAC score and are similar to patients with a TKR. The pain score improved from 45% (16) to 87% (7.5), the function score improved from 50% (21) to 80% (12.5). The Oxford score improved from 39.5% (19) to 69% (33). Symptomatic arthritic disease progression occurred in 12% of cases causing recurrent pain. Persistent non-arthritic pain was due to three main causes: minor misplacement of the femoral or patella components or over sizing, leading to retinacular impingement and over stuffing of the patellofemoral joint.
Conclusion
This prosthesis has shown consistently good results with few problems over 14 years. New instruments will increase the accuracy of insertion and attention to detail in the performance of the operation will prevent problems. Disease progression remains the main cause of failure and strict pre-operative criteria are essential.
