Does the measure of Achilles Tendon Resting Angle correlate with outcome after functional bracing and rehabilitation for Achilles rupture?

C Plant, J Skidmore, A Pritchard, V Dhukaram

Background: Acute Achilles tendon ruptures can be a devastating injury with a prolonged recovery period (1). Following the UKSTAR trial, Achilles tendon ruptures are predominately treated with a functional rehabilitation bracing program (2). The aim of treatment is to avoid lengthening of the tendon, and hence the resultant loss of function. The Achilles tendon resting angle (ARTA) provides a simple assessment of tendon length that can be performed in the clinical setting (3). This study assesses the Achilles tendon resting angle over a 52-week period and the correlation with functional outcome.

Methods: A total of 182 consecutive patients with an acute Achilles tendon rupture were treated with a 10-week functional rehabilitation regime. The relative Achilles tendon resting angle was recorded as the difference between the limbs at the time of injury, then once treatment commenced at 4-, 11-, 26- and 52-weeks post injury. Patients with a previous Achilles rupture of the contralateral leg were excluded. The functional outcome was assessed using the Achilles tendon rupture score at 26- and 52-weeks post injury.

Results: The relative Achilles tendon resting angle improved by 5 degrees with functional bracing and plateaued after 11 weeks post injury. The functional outcome continued to improve to 52 weeks post injury with a mean ARTS of 77.9 (15.1). No correlation was detected between the ARTA and ARTS at either 26- or 52- weeks. Only one patient sustained a re-rupture.

Conclusion: Functional bracing reduces the extent of tendon lengthening and improves the functional outcomes of patients up to a year post-injury. The relative ARTA as part of clinical assessment however, fails to provide an indication of the long-term functional outcome of these patients.