Does torn discoid meniscus have effects on limb alignment and arthritic change in middle-aged patients?

BACKGROUND

The purpose of the present study was to evaluate the characteristics of the discoid lateral meniscus in patients more than forty years of age. We studied whether a torn discoid lateral meniscus that has no treatment until middle age would increase the tendency of the knee to develop a varus deformity and investigated the correlation between torn discoid lateral meniscus and osteoarthritis.

METHODS

We retrospectively reviewed the records for 164 knees in 158 patients who were more than forty years old and who underwent a knee arthroscopic procedure from 1992 to 2007. The mean age at the time of surgery was fifty-two years. Comparative evaluation of the clinical and radiographic differences between the eighty-four patients with torn discoid lateral meniscus (Group A) and the seventy-four patients with a torn normally shaped lateral meniscus (Group B) was carried out.

RESULTS

Preoperative standing anteroposterior radiographs, which were made for all patients, showed that varus deformity was more common in Group A than in Group B and that osteoarthritic changes in both the medial and lateral compartments were also more common in Group A. With regard to chondral injury, Outerbridge grade-3 or 4 involvement was identified in 46% of the knees in Group A and 18% of the knees in Group B.

CONCLUSIONS

In the present study of middle-aged patients, those with a torn discoid lateral meniscus had a higher prevalence of varus knee deformity and a higher prevalence of osteoarthritis. Knees with a discoid lateral meniscus that have diminished valgus alignment should be monitored carefully with long-term follow-up because a discoid lateral meniscus may increase the risk for progression to degenerative knee osteoarthritis.