Patellofemoral osteoarthritis is generally considered a contraindication for unicondylar knee arthroplasty. Therefore, even with an intact lateral compartment, bicondylar surface replacement is preferred when patellofemoral osteoarthritis is present, despite comparatively worse functional results. In the present study, the influence of patellofemoral osteoarthritis on the outcome of the Oxford III unicondylar implant was investigated.
The HSS and the patella score according to Turba were used to retrospectively evaluate the outcome of 44 Oxford III unicondylar implants at an average follow-up of 35 months. The degree of patellofemoral osteoarthritis was radiographically graded according to the Sperner score.
The HSS score improved to an average of 92.3 points (68-99; p<0.001 vs preoperative score). With the patella score, only good and very good results were observed. At follow-up examination almost 70% of the knees showed patellofemoral osteoarthritis of degree III-IV. No correlation was found between the functional scores and the degree of patellofemoral osteoarthritis.
Radiographic patellofemoral osteoarthritis seems to have no influence on the functional outcome of the Oxford III unicondylar knee arthroplasty. Therefore, unicondylar surface replacement is indicated even with radiographic evidence of patellofemoral osteoarthritis, provided that it is clinically asymptomatic.