Ankle joint proprioception and passive mechanical properties of the calf muscles after an Achilles tendon rupture: a comparison with matched controls

Objective. To examine if ankle joint proprioception, passive stiffness, and torque relaxation responses of the involved and uninvolved limbs of persons with a previous history of an Achilles tendon rupture were different from matched controls. Design. Quasi-experimental mixed design. Background. The influence of an Achilles tendon rupture on the proprioceptive and kinetic performance of the involved and uninvolved ankle is not known. Methods. Twenty persons (mean age, 44.8 years) with a unilateral rupture and 20 matched controls (mean age, 44.2 years) volunteered. Proprioception was tested with a position-matching protocol from which absolute errors were quantified. A dynamometer was used to measure ankle joint angle and passive torque from which stiffness and torque relaxation were calculated. Results and conclusions. Proprioception absolute errors for the involved and uninvolved limbs of the experimental group were 27% and 31% greater respectively, than values for the control group. Torque relaxation values were greater in the involved limb versus the uninvolved limb or the control group (P = 0.003-0.04). In conclusion, participants with a previous history of an Achilles tendon rupture display proprioception deficits in both limbs and greater torque relaxation in the involved limb in comparison to matched controls.