Achilles' Tendon Experiences Reduced Depth and Volume After 3 Months of Recovery From 60 Days Bedrest.

Objectives: To examine the effect of 60-days of bedrest on morphologic changes in the Achilles' tendon using magnetic resonance imaging in 24 adults, and to explore the effects of artificial gravity (AG) by centrifugation intervention to counteract the effect of 60-days' bedrest on such changes.

Design: Randomized controlled trial evaluating the effect of 30 minutes AG application, either continuously daily, or intermittently 6×5 minute sessions daily.

Setting: Experimental bedrest facility.

Participants: Healthy participants (N = 24) aged 24-55 years.

Interventions: continuous AG (N = 8), intermittent AG (N = 8).

Main Outcome Measures: Achilles' tendon dimensions: depth, width, and cross-section area, volume at 2, 4, and 6 cm proximal to the tendon calcaneal insertion as baseline (baseline data collection), bedrest day-30 (HDT30) or 60 (HDT60), and during reambulation days 8, 90, and 450 (R8, R90, R450).

Results: Neither continuous nor intermittent AG interventions had any statistically significant effect on the Achilles' tendon dimensions. No changes in the Achilles' tendon were observed during bedrest. After 90-days of reambulation Achilles' tendons were thinner at 2 cm with reduced volume at 2-4 cm and 4-6 cm and reduced volume 2-4 cm, 4-6 cm and 2-6 cm after 450-days of reambulation compared with baseline. Compared with day 8 of reambulation, Achilles' tendons were thinner at 2, 4, and 6 cm from insertion and had decreased volume 2-4 cm, 4-6 cm and 2-6 cm after 450-days of reambulation.

Conclusions: This randomized controlled trial found no difference between control and AG interventions on Achilles' tendon dimensions during 60-days of bedrest. Following 90- and 450-days of reambulation after bedrest, participants had thinner and smaller Achilles' tendons, not prevented by AG. This study suggests that tendon changes can occur and persist after bedrest well into the reambulation phase and that clinicians should remain longitudinally vigilant for Achilles' injury.