In a prospective randomised trial 76 knees with isolated degenerative changes in the medial femoral condyle of grades 3 or 4 were treated by either arthroscopic debridement (40) or washout (36).

All knees were followed up for at least one year and 58 for five years. The mean follow-up time was 4.5 years in the debridement group and 4.3 years in the washout group.

At one year 32 of the debridement group and five of the washout group were painfree and at five years 19 of a total of 32 survivors in the debridement group and three of the 26 in the washout group were also free from pain. The mean improvement in a modified Lysholm score was 28 for the debridement group at one year and 21 at five years. In the washout group it was only 5 at one year and 4 at five years.

For knees with lesions of the medial femoral condyle of grades 3 or 4, arthroscopic debridement appears to be the treatment of choice with over half the patients free from pain after five years.