Early protected weight-bearing for acute ruptures of the Achilles tendon: do commonly used orthoses produce the required equinus?

P. Ellison, L.W. Mason, G. Williams, A. Molloy

Introduction: The dichotomy between surgical repair and conservative management of acute Achilles tendon ruptures has been eliminated through appropriate functional management. The orthoses used within functional management however, remains variable. Functional treatment works on the premise that the ankle/hindfoot is positioned in sufficient equinus to allow for early weight-bearing on a 'shortened' Achilles tendon. Our aim in this study was to test if 2 common walking orthoses achieved a satisfactory equinus position of the hindfoot.

Methods: 10 sequentially treated patients with 11 Achilles tendon injuries were assigned either a fixed angle walking boot with wedges (FAWW) or an adjustable external equinus corrected vacuum brace system (EEB). Weight bearing lateral radiographs were obtained in plaster and the orthosis, which were subsequently analysed using a Carestream PACS system. The Mann-Whitney test was used to compare means.

Results: Initial radiographs of all patients in cast immobilization showed a mean tibio-talar angle (TTA) of 55.67° (SD1.21) and a mean 1^st metatarsal-tibia angle (1MTA) of 73.83° (SD9.45). There were 6 Achilles tendons treated in the FAWW. Their measurements showed a mean TTA of 27.67°(SD7.71) and 1MTA 37.00 (5.22). 5 tendons were treated using an EEB; there was a statistically significant (p< .05) increase in both the TTA 47.6° (SD5.90) and 1MTA 53.67 (SD5.77) compared to the FAWW group.

Discussion: Plantar-flexion at the ankle was significantly greater in the EEB comparative to the FAWW, and very similar to the initial equinus cast. The use of wedges produced an equinus appearance through the midfoot, without producing equinus in the hindfoot as the heel pad rests on the top wedge. We express caution in the use of wedges for Achilles treatment as they do not shorten the Achilles tendon and may result in a lengthened tendon and reduced plantar-flexion power in the long-term.