Long-term outcomes of muscle volume and Achilles tendon length after Achilles tendon ruptures

Purpose The best treatment for Achilles tendon (AT) ruptures remains controversial. Long-term follow-up with radiological and clinical measurements is needed. Methods In this retrospective multicentre cohort study, patients ( n = 52) were assessed at a mean of 91 months follow-up after unilateral AT rupture treated by open, percutaneous or conservative (non-surgical) treatment. Demographic parameters, time off work, maximum calf circumference and clinical scores (ATRS, Hannover, AOFAS) were evaluated. Muscle volume and cross-sectional area of the calf and AT length were measured on MR images and were compared between groups and to each patient’s healthy contralateral leg. Results Reduced muscle volume was found across all groups with a higher muscle volume in the conservative (729.9 ± 130.3 cm 3 ) compared to the percutaneous group (675.9 ± 207.4 cm 3 , p = 0.04). AT length was longer in the affected leg (198.4 ± 24.1 vs. 180.6 ± 25.0 mm, p < 0.0001) without difference in subgroup analysis. Clinically measured ankle dorsiflexion showed poor correlation with AT length ( R 2 = 0.07, p = 0.008). Muscle volume strongly correlated with the cross-sectional area ( R 2 = 0.6, p