Structure and function of the Achilles tendon and plantarflexors after non-surgical management of Achilles tendon rupture: A cross-sectional study

Abstract

Background Achilles tendon rupture (ATR) impacts the structure and function of the tendon and triceps surae. We aimed to describe recovery at different time points after injury using ultrasound imaging, strength testing and patient reported outcomes.

Methods Cross-sectional study design, collecting data from 15 different non-surgically managed participants at six independent rehabilitation time points (week 0, 8, 10, 16, 26, 52 post ATR). Outcomes included ultrasound tissue characterisation (UTC), isometric plantarflexor strength, Achilles tendon rupture score (ATRS), Euroqol 5-dimension, hospital anxiety and depression scale and Tampa Scale for Kinesiophobia. UTC echo type percentage is reported as aligned fibrillar structure (AFS) and disorganised fibrillar structure (DFS).

Findings Participants mean (SD) age was 48 years (15.8), 91 % male, body mass index 29kg/m2 (4.3) and 54 % was white British. Primary mechanism of injury was sport (71 %). Ruptured tendon cross-sectional area (CSA) was 303.55 mm² (90.43) at 10 weeks and 218.18 mm² (61.82) at 52 weeks post ATR. For the ruptured tendon, later assessment time points were associated with decreased AFS but had no association with DFS. Isometric plantarflexor strength on the ruptured limb at 52 weeks was 61.3 kg (20.8) or 0.7x bodyweight (BW). Non-ruptured plantarflexor strength was 93.3 kg (29.5) or 1.1x BW. Leg symmetry index at 52 weeks was 67 %. ATRS at 52 weeks was 75.1 (16.5).

Conclusion Substantial tendon remodelling may occur during the initial 52 weeks post ATR, CSA was 28 % lower from 10 weeks to 52 weeks. At 52 weeks there was persistence of fibrillar disorganisation, isometric plantarflexor weakness and reduced function.