Grading system of articular cartilage degeneration in osteoarthritis of the knee.

Degenerative findings observed in the articular cartilage of the knee during high tibial osteotomy with arthrotomy, unicompartmental arthroplasty, or total replacement were classified into 9 grades: Grade 0--normal, Grade I--yellow discoloration, Grade II--softening and unevenness, Grade III--fasciculation and attrition, Grade IV-a--erosion, Grade IV-b--ulcer down to subchondral bone, Grade IV-c--eburnation of subchondral bone, Grade V-a--bone destruction in an area less than 5 mm in depth, and Grade V-b--bone destruction in an area 5 mm or more. This series included 63 osteoarthritic knees with varus deformity in 56 Japanese patients (forty nine women and seven men) with an average age of 66.8 years (range: 49-83 years). One knee was Grade II, three were Grade III, ten Grade IV-a, eighteen Grade IV-b, twenty seven Grade IV-c, and four Grade V-b. There was a tendency toward positive correlation between the grade of articular cartilage degeneration and the radiographic grade seen in a standing radiograph.