The injured limb presents lower values in foot structure measurements 6 years after an achilles tendon rupture

Abstract

Background. It is not known if foot structure may change after an Achilles tendon rupture and if a possible change may have an impact on lower limb function. The primary aim of the study was to explore the difference in foot structure between injured and healthy limb and between two treatment groups, at mean 6 years after an Achilles tendon rupture. A secondary aim was to explore if the differences in foot structure correlated with functional and clinical outcome. Methods. Ninety patients (15 women) with the mean (SD) age of 49 (9) years were evaluated. They had all been randomized to be treated with (n = 45) or without (n = 45) surgery. Foot structure was evaluated with Navicular Drop (Ndrop) and Drift (Ndrift), Longitudinal Arch Angle (LAA) and standing Dorsiflexion with knee straight and bent (DFstraight) and (DFbent). Calf muscle performance was evaluated with Single-leg standing heel-rise test and tendon length with ultrasound. For Patient-reported outcome measurements, Achilles tendon Total Rupture Score (ATRS) and Physical Activity Scale (PAS) were used. Both limbs were evaluated and the limb symmetry index (LSI (%) = injured/healthy × 100) was calculated. Results. In all patients, the injured limb demonstrated lower values (injured/healthy) in Ndrift (6.0/6.7 mm, p = 0.034), Ndrop (6.6/7.4 mm, p = 0.32) and DFbent (44/46°, p < 0.001). In the group treated with surgery, there was significant difference between limbs in DFbent (44/46°, p = 0.002). In the non-surgically treated group, the injured limb demonstrated significantly lower values in Ndrift (6.0/7.4 mm, p = 0.005), Ndrop (6.9/8.2 mm, p = 0.005) and DFbent (44/46°, p = 0.008). There was no difference between treatment groups in LSI-values. Conclusions. An Achilles tendon rupture seems to have an impact on foot structure long time after the injury. There is a need to clarify if the injury influences both feet and if there is a difference between treatment groups.