The influence of the site of rupture and gap distance in acute Achilles tendon rupture treated with functional rehabilitation

To determine the influence of gap distance and its location on clinical and radiological outcomes in patients with acute rupture of Tendo-Achilles (TA) treated non-operatively with functional rehabilitation. Twenty-six patients with acute complete TA rupture underwent ultrasound (US) scanning within a week of their injury. The measurements taken included the distance of the rupture from the enthesis and the gap distance between the tendon edges in varying degrees of ankle and knee positions. All patients were managed non-operatively in functional weight-bearing orthoses. Nineteen patients were then followed up at a mean of 6.1 years (range 5.8–6.5) to assess their clinical and radiological outcomes. The outcomes included ultrasound assessment of tendon healing, Achilles Tendon Rupture Score (ATRS) and modified Leppilahti Score (mLS). In the initial ultrasound, the mean distance of the rupture from the enthesis was 52 mm (range: 40–76). The mean gap distance with the foot plantigrade was 11.4 mm, which reduced to 4.8 mm with the foot in equinus. At final follow up, no re-ruptures had occurred. The mean ATRS and mLS were 86 and 71 respectively. There was a significant correlation between the distance of the rupture from the enthesis with the MLS total score (p = 0.02), mLS Fatigue domain score (p = 0.03), and the ATRS domains of strength (p = 0.04) and fatigue (p = 0.02). There was no significant correlation between the measured gap distance with respect to the mLS, ATRS or individual ATRS domain scores. Also, there was no significant difference in ATRS and mLS outcomes when comparing tendons with respect to healed tissue appearance and fibre orientation on ultrasound. The initial gap distance had no relationship with any of the measured clinical outcomes at the final follow up. The distance of the gap from the enthesis, however, may carry a greater prognostic value following non-operative treatment of Achilles tendon injuries.