Greater heel-rise endurance is related to better gait biomechanics in patients surgically treated for chronic Achilles tendon rupture.

PURPOSE: To determine the relationships among calf muscle function, tendon length and gait biomechanics in patients surgically treated for chronic Achilles tendon rupture. METHODS: Twenty-one patients with chronic Achilles tendon rupture (mean age 62 ± 13 years) were evaluated by heel-rise endurance test, Achilles Tendon Resting Angle (ATRA), ultrasound measurement of tendon length and three-dimensional gait analysis. A bivariate two-sided correlation test was performed on all variables in all patients. RESULTS: Better performance across all parameters of the heel-rise endurance test correlated with faster walking speed (r = 0.52-0.55), greater peak ankle power (r = 0.56-0.64), shorter stance phase (r = -0.52 to -0.76) and less peak ankle dorsiflexion angle (r = -0.49 to -0.64) during gait. Greater ATRA correlated with longer stance time (r = 0.47), greater peak ankle dorsiflexion angle (r = 0.48), less heel-rise repetitions (r = -0.52) and less heel-rise total work LSI (r = -0.44 to -0.59). CONCLUSION: Greater calf muscle endurance, especially heel-rise total work, is moderately correlated (r = 0.49-0.76) to better ankle biomechanics during gait in patients surgically treated for CATR. The heel-rise endurance test may be a clinical proxy for power development in the ankle joint during gait. LEVEL OF EVIDENCE: IV.