Purpose: Revision patellofemoral arthroplasty (PFA) is a relatively uncommon procedure, with no published reviews identified in the literature. Revision PFAs performed at our institution were reviewed to determine the reasons for PFA failure, the technical ease of revision and to document patient-reported outcomes after revision.

Methods: A prospective review of a cohort of 411 Avon PFA patients identified 31 subsequent revision knee procedures in 27 patients. Data was collected from the institution’s prospective data base, operative reports, X-rays and medical records. Post-operative knee scores (Oxford Knee Score, WOMAC Osteoarthritis Index, Bristol Knee Score) were available on 26 knees.

Results: The commonest reason for revision was progression of osteoarthritis (18 cases) followed by undetermined pain (7 cases). Patients with undetermined pain were found to be revised sooner than patients with disease progression (33 months vs 63 months) and also reported poorer outcome scores at 2 years post revision than the disease progression group.

Only two trochlea components were loose at the time of revision and one patella had a large amount of macroscopic wear. All other components were found to be well fixed with minimal wear at the time of revision. There were no difficulties in removing either component. No cases required augments or stemmed femoral components due to bone loss.

Patients undergoing revision surgery did report improvement in their post revision outcome scores compared with their pre-operative scores. The average Oxford Knee Score improved from 17 to 23, Bristol Knee Pain Scores improved from 11 to 20 and Bristol Knee Functional Scores improved from 15 to 16. These results are poorer than those recorded by the overall cohort of primary PFA.

Conclusion: PFA is easy to revise to a primary total knee. Results of revision knees are improved from pre-operative scores but not as good as expected.

Purpose: Trochlea dysplasia is a developmental condition characterized by an abnormally flat or dome shaped trochlea. This predisposes to recurrent patella instability. This study prospectively reviews the early results of patients undergoing a trochleoplasty procedure which corrects the dysplastic anatomical abnormality.

Patients and Methods: All patients were recruited from the senior author’s (JDJE) specialist knee clinic following the standard patellofemoral assessment. Patients were seen pre-operatively to collect epidemiological data, ensure completion of patient reported assessment forms and document clinical examination findings and investigations. Duration of instability and previous procedures performed for patella instability were recorded. Multiple patient-reported outcome measures were recorded. Outcome score assessments and clinical examinations were repeated post-operatively, along with a patient satisfaction questionnaire. All operations were carried out by the senior author with supplementary procedures based on pre-operative assessment.

Results: 22 patients had a minimum of 12 months follow-up. The average age was 21 years and the average duration of instability symptoms (pre-trochleoplasty) was 7 years. There were 16 females and 6 males. Mean follow up was 18 months. Patients reported improvement in outcome when the pre and post-operative scores were compared (mean scores of Oxford 34 to 41, WOMAC 23 to 15, Kujula 62 to 79, IKDC 62 to 81, and Lysholm 57 to 77). The patient satisfaction questionnaire revealed just one patient not satisfied with the procedure despite good patient reported outcome scores. The majority of patients perceived improvement due to the surgery and agreed they would recommend the procedure to others despite some residual symptoms. Recurrent instability after trochleoplasty was rare (one subluxation) and range of movement was uniformly excellent.

Conclusion: Early results of this trochleoplasty for patients with trochlea dysplasia and symptomatic recurrent patella instability are encouraging.

Trochlear dysplasia is a developmental condition characterised by an abnormally flat or dome-shaped trochlea and is an important contributory factor to patellofemoral instability and recurrent dislocation. We studied prospectively a series of 54 consecutive patients (59 knees) with patellofemoral instability secondary to trochlear dysplasia, who were treated by a trochleoplasty by a single surgeon between June 2002 and June 2007.

Pre- and post-operative scores were assessed by the patients and a satisfaction questionnaire was completed.

Of the 54 patients (59 knees) in the series, 39 (44 knees) were female and 15 (15 knees) were male. Their mean age at surgery was 21 years and 6 months (14 years 4 months to 33 years 11 months). In 40 patients (42 knees) the mean follow-up was for 24 months (12 to 58). One patient was unable to attend for follow-up. An analysis of the results of those patients followed up for at least 12 months showed a statistically significant improvement in outcome (p < 0.001 for all scores). Overall, 50 patients (92.6%) were satisfied with the outcome of their procedure.

The early results of trochleoplasty are encouraging in this challenging group of patients.

Chronic patellofemoral instability can be a disabling condition. Management of patients with this condition has improved owing to our increased knowledge of the functional anatomy of the patellofemoral joint. Accurate assessment of the underlying pathology in the unstable joint enables the formulation of appropriate treatment. The surgical technique employed in patients for whom non-operative management has failed should address the diagnosed abnormality. We have reviewed the literature on the stabilising features of the patellofemoral joint, the recommended investigations and the appropriate forms of treatment.