Cadaveric assessment of osteoarthritic changes in the patello-femoral joint: evaluation of 203 knees.

PURPOSE: The purpose of this study was to determine the prevalence, type of lesion, and depth of osteoarthritic (OA) changes in the patello-femoral (PF) joint.
METHODS: Two hundred and three cadaveric knees were included in this study with median age of 84 years (54-97). Patella OA lesions were classified using Han's method: (Type 1) no or minimal lesion, (Type 2) medial facet lesion without involvement of the ridge, (Type 3) lateral facet lesion without involvement of the ridge, (Type 4) lesion involvement of the ridge, (Type 5) medial facet lesion with involvement of the ridge, (Type 6) lateral facet lesion with involvement of the ridge, (Type 7) global lesion. Femoral side OA lesions in the PF joint were classified using modified Chang's method: (Type 1) no or minimal lesion, (Type 2) medial facet lesion, (Type 3) centre of patella groove lesion, (Type 4) lateral facet lesion, (Type 5) global lesion. OA depth evaluation was performed following Outerbridge's classification.
RESULTS: OA lesions of the patella were observed as follows: (Type 1) 31%, (Type 2) 16%, (Type 3) 3%, (Type 4) 12%, (Type 5) 22%, (Type 6) 2%, (Type 7) 14%. Outerbridge's classification of over Grade 2 OA depth was observed in 75.9% of subjects. Femoral side OA lesions of the PF joint were observed as follows: (Type 1) 42%, (Type 2) 20%, (Type 3) 26%, (Type 4) 2%, (Type 5) 11%. Outerbridge's classification of over Grade 2 OA depth was observed in 58% of subjects.
CONCLUSION: Patella OA and femoral side OA in the PF joint occurred mainly on the medial side. Isolated OA in the lateral facet of the PF joint was exceedingly rare. Female subjects had a greater incidence of severe PF-OA than male subjects, and therefore, the physicians should pay attention when they treat the female subjects not to advance the PF-OA.