Objective: The aim of this study was to investigate the impact of preoperative patellofemoral osteoarthritis severity on the final patient-reported outcomes in patients with primary osteoarthritis who underwent total knee arthroplasty with patellar retention.
Methods: In this retrospective study, 167 patients (42 males, 125 females; mean age: 67.9 (range, 50-82) years), who underwent total knee arthroplasty with patellar retention due to primary osteoarthritis were included. The preoperative severity of patellofemoral osteoarthritis was classified according to the Iwano classification system. All the patients were then divided into two groups based on the severity of patellofemoral osteoarthritis: Group I, 73 patients (17 males, 56 females; mean age: 68.4 (range, 50-80) years) with mild osteoarthritis (stage 0-I) and group II, 94 patients (25 males, 69 females; mean age: 67.7 (range, 54-82) years) with moderate to severe osteoarthritis (stage II to IV). The mean follow-up was 42.8 (range, 24-59) months in group I and 41.7 (range, 24-63) months in group II. Clinical outcomes were assessed using the Oxford Knee Score, the New Knee Society Score-function score, and the Kujala score preoperatively and at the final follow-up. Also, the Forgotten Joint Score was performed at the final follow-up.
Results: The Oxford Knee Score improved from 22.5 (range, 18-26) preoperatively to 36.5 (range, 30-43) for Group I and from 21.9 (range, 16-25) preoperatively to 35.9 (range, 29-43) for Group II (P < 0.001). The Kujala score increased from 51.2 (range, 45- 65) preoperatively to 79.3 (range, 71-88) for Group I and from 50.3 (range, 42-60) preoperatively to 80.2 (range, 71-86) for Group II (P < 0.001). The New Knee Society Score-function score raised from 60.2 (range, 50-72) preoperatively to 82.2 (range, 72- 90) for Group I and from 59.5 (range, 48-69) preoperatively to 81.4 (range, 73-90) for Group II (P < 0.001). The Forgotten Joint Score was 69.9 (range, 63-76) in Group I and 70.2 (range, 62-77) in Group II (P = 0.49).
Conclusion: Evidence from this study has shown that the preoperative severity of patellofemoral osteoarthritis has no significant impact on the final patient-reported outcomes of patients with primary osteoarthritis after patellar retention total knee arthroplasty.
Level of evidence: Level III, Therapeutic Study.