Does decreased meniscal thickness affect surgical outcomes after medial meniscectomy?

There have been no clinical studies regarding the effect of decreased meniscal thickness on outcomes after meniscectomy.

To examine the postoperative outcomes of partial meniscectomy with or without horizontal resection compared with the outcomes of subtotal meniscectomy and to evaluate the influence of decreased thickness of the medial meniscus on outcomes after partial meniscectomy.

Cohort study; Level of evidence, 3.

A total of 312 patients who underwent medial meniscectomy were retrospectively reviewed. Patients were divided into 3 groups: group A (n = 84) included patients with partial meniscectomy with vertical resection, group B (n = 140) consisted of those with partial meniscectomy with horizontal resection, and group C (n = 88) included those with subtotal meniscectomy. Clinical function was evaluated by use of the Lysholm knee scoring scale, International Knee Documentation Committee (IKDC) subjective knee evaluation form, and Tapper and Hoover grading system. Radiologic evaluation was performed with the IKDC radiographic assessment scale as well as with measurements of the medial compartment height at the tibiofemoral joint. Preoperative values and postoperative values measured 5 years after operation were assessed.

Functional outcomes in group C were inferior to those in groups A and B according to the Lysholm knee score (mean ± SD for group A = 96.1 ± 4.7, group B = 94.9 ± 5.2, group C = 84.8 ± 11.4; P < .001), IKDC subjective score (group A = 92.1 ± 6.5, group B = 91.3 ± 8.8, group C = 81 ± 11.4; P < .001), and Tapper and Hoover grading system (P = .003). There was no significant difference in scores between groups A and B. With regard to radiologic evaluation, the IKDC radiographic grade for group C was worse than the grades for groups A and B (P < .001); there was no significant difference between groups A and B. However, the postoperative joint space on the affected side was higher for group A (4.7 ± 0.6 mm) than for groups B (4.3 ± 0.5 mm; P < .001) and C (3.7 ± 0.8 mm; P < .001). The joint space was higher in group B than in group C (P < .001).

Despite joint space narrowing, decreases in meniscal thickness after partial meniscectomy for horizontal tear had no additional adverse effect on 5-year functional and radiographic outcomes compared with conventional partial meniscectomy preserving whole meniscal thickness. In treating horizontal tears of the meniscus, partial meniscectomy with complete resection of the unstable leaf was an effective method in a 5-year follow-up study.