Medial Meniscus Extrusion After 30-Minute Running in Individuals Who Underwent Meniscus Surgery or ACL Reconstruction...

Medial meniscus extrusion is a contributor to developing knee joint complications; however, the relative degree of medial meniscus extrusion and its response to running in individuals with a history of knee joint surgery remain unclear. We evaluated whether medial meniscus extrusion in individuals who underwent meniscus surgery or ACL reconstruction and in healthy individuals differs before and after 30 minutes of treadmill running.

Case-control study.

A total of 63 participants (21 with meniscus surgery: 30.0 y, 172.5 cm, 74.4 kg; 21 with ACL reconstruction: 27.0 y, 172.5 cm, 74.4 kg; 21 healthy controls: 24.9 y, 171.3 cm, 68.7 kg) were studied. Ultrasonographic images of medial meniscus extrusion in the supine and standing positions were obtained using a 12-MHz linear probe before and after 30 minutes of treadmill running at a self-selected moderate intensity. The running speed, heart rate, and step count among groups were compared. Data were analyzed using analysis of variance and Tukey-adjusted post hoc tests (P < .05). Cohen's effect sizes (d) and mean differences, and 95% CIs were also calculated.

There was a significant group by time interaction for medial meniscus extrusion in the supine (F2,60 = 8.00, P = .0008) and standing (F2,60 = 3.42, P = .04) positions. Specifically, individuals who underwent meniscus surgery showed a 13% increase in medial meniscus extrusion after running (P = .01; d = 0.57; Δ0.24 mm; 95% CI, 0.11-0.58). However, Tukey-adjusted pairwise comparisons did not identify any statistical differences (P > .16 for all tests). There was a nonsignificant group effect in running speed (F2,60 = 1.16, P = .32), heart rate (F2,60 = 0.70, P = .50), and step count (F2,60 = 1.92, P = .16) during 30-minute treadmill running.

When subjected to cyclic mechanical loading from 30 minutes of running, knees with prior meniscus surgery could experience greater extrusion of medial meniscus (<13%) following running, whereas ACL-reconstructed and healthy knees do not show comparable changes.