Objectives: To investigate the retro-patellar cartilage (RPC) morphology and the patterns of retropatellar cartilage wear as well as the patients’ kneeling ability to determine whether the kneeling ability is related to the area and pattern of wear in the cartilage.
Methods: 30 patients undergoing primary TKAs participated in this study. The patients were seen in the preoperative assessment clinics and consented to allow intraoperative photographing of their retro patellar cartilage. These photographs were used to determine the area and pattern of wear by using Image J software. The total area of the retropatellar cartilage and the area of wear was measured and used to calculate the percentage of RPC wear. The percentages of retro patellar cartilage wear for all the patients were linked with their kneeling ability before the surgery.
Results: 15 patients (cases numbered 1-15, termed group A) were able to kneel, and 15 patients (cases numbered 16-30, termed group B) were unable to kneel. The % of wears for all RPC images measured 3 times with a week interval and the average of the records in the 1st, 2nd, and 3rd week recorded for statistical analysis. Mean % of RPC wears in-group A was (15%), and in-group B was (36%). Intra-Rater and Inter-Rater Reliability statistically assessed by using Intraclass Correlation Coefficient. Patients who able to kneel (Group A) had normal RPC superior surfaces with no damages in comparison with patients who unable to kneel (Group B) who had damaged superior surfaces medially and laterally. All the RPC surfaces (Superior, Middle and Inferior) were damaged in Group B patients (Unable to kneel).
Conclusion: No direct association was found between the retropatellar cartilage damage and the kneeling ability. The most damaged areas were found in the middle and lower thirds of retropatellar cartilage.