Purpose: The purpose of this work was to report mid-term results of a series of 162 total knee prostheses with an all-polyethylene plateau.

Material and methods: Between 1989 and 1995, 162 posterior stabilised cemented HLS2 total knee prostheses with an all-polyethylene plateau were implanted during first intention arthroplasties performed by the same surgeon. 142 prostheses were reviewed at more than one year, three patients died, and 17 were lost to follow-up (10%). Clinical results were assessed with the IKS criteria. Complete x-ray data included pangonograms. Mean follow-up was 4.5 years.

Results: Ninety-six percent of the patients were satisfied or very satisfied and 95% had no pain or mild pain. Mean flexion was 114°. The mean postoperative knee score was 81/100 and mean function score was 64/100. Radiographic findings showed the good position of the implants with mean AFT at 178.6°, mean AFm at 89.1° and mean ATm at 89°. There were eight failures (4.9%) requiring replacement of a component, two for frontal laxity, three for patellar fracture, one for infection, one for aseptic loosening, and one for an oversized tibial plateau. Two revision procedures were performed without implant replacement, one for pain (biopsy) and one for arthrolysis.

Discussion: These 162 prostheses with an all-polyethyl-ene plateau were retained among a consecutive series of 893 HLS prostheses. We compared the present results with those of the metal-backed prostheses implanted in this series and with data in the literature. We found a significant correlation between the presence of tibial lucent lines and postoperative alignment defects, explained by the type of tibial component, in these 162 all-polyethyl-ene plateau prostheses. These lucent lines did not progress with time and had no clinical consequence.

Conclusion: Clinial and radiological results with total knee prostheses with an all-polyethylene plateau, i.e. without metal backing, were very good in this series. We analysed our experience in comparison with the literature, focusing on the advantages and disadvantages of these two types of components.

Purpose: The purpose of this work was to analyse functional results in patients with objective patellar instability who underwent surgery between 1988 and 1999.

Material and methods: One hundred eighty knees, 140 patients, were included in this series. Minimum follow-up was two years, and the mean follow-up was five years (range 24 – 152 months). The IKDC 99 subjective knee chart was used for postoperative assessment. This chart has ten items for sports activities and functional status of the knee for everyday activities. Eighty-three percent of the patients (118 patients) responded to the questionnaire.

Results: Clinical assessment was available for 98 patients (63%) and phone interview data for 29 (20%). Subjectively, 111 (94.87%) patients were very satisfied, five (4.27%) were satisfied, and one was dissatisfied. We assessed results by pain level (37.6% mild or weather-related pain), residual oedema, sensation of blockage (15.8%), instability, daily activities (68% with difficulty in the kneeling position), sports activity and level.

Discussion: Certain authors (Insall) question the pertinence of operating objective patellar instability because of the risk of secondary femoropatellar degeneration. For us, surgical treatment is indicated when there has been at least one dislocation associated with morphological anomalies. We have not observed any cases of femoroatellar degeneration among our patients who were operated on more than ten years ago. The patients’ own subjective assessment shows that surgical treatment with medialisation and/or lowering of the tibial tuberosity has been effective with a very excellent rate of satisfaction. The quality of the results is directly related to correct treatment of the lesions (for patients without recurrent dislocation) and systematic analysis of the different factors contributing to patellar instability (trochlear dyplasia, patellar height, quadriceps dyplasia, length of the patellar tendon). Our rate of revision appears to be low but was directly related to the young age of this population and is close to or above the revision rates observed in series with follow-ups greater than two years.

Conclusion: Surgery for objective patellar instability gives good mid- and long-term results. The subjective IKDC score allows precise self-evaluation. We have not been able to find any correlation between subjective results and objective results.