Background: Insertional deep digital flexor tendon (DDFT) lesions with concurrent injury to the flexor surface of the distal phalanx are uncommon and there is limited information regarding prognosis. Objectives: To provide descriptive data on horses with insertional DDFT injuries and determine whether there is any association between magnetic resonance imaging (MRI) findings, and outcome. Study Design: Retrospective case series. Methods: Horses with lameness localised to the foot that underwent MRI between January 2015 and April 2019 were included. Injury of the DDFT, presence of short tau inversion recovery (STIR) hyperintensity at the flexor surface of the distal phalanx and concurrent lesions were recorded. Follow-up information was obtained by telephone questionnaire. Results: Thirty-two horses fulfilled the inclusion criteria. Thirty-one limbs had DDFT insertional lesions on MRI with three limbs showing hyperintense STIR signal of the flexor surface of the distal phalanx without a tendon lesion. Seventeen DDFT lesions were graded as mild and 14 as severe. Thirteen limbs showed hyperintense STIR signal within the tendon and 15 limbs showed hyperintense STIR signal within the flexor surface of the distal phalanx at the insertion of the DDFT and/or the distal sesamoidean impar ligament (DSIL). Eight horses returned to previous athletic function, 8 returned to a lower level of athletic activity, 4 were retired, 9 were subjected to euthanasia and 3 were lost to follow-up. No significant association was found between DDFT lesion severity, hyperintense STIR signal within the DDFT, hyperintense STIR signal at the flexor surface of the distal phalanx and outcome post-injury. Main Limitations: Small sample size and reliance on clients to provide accurate follow-up information. Conclusions: Insertional DDF tendinopathy carries a guarded prognosis for return to previous athletic function. The presence of hyperintense STIR signal at the flexor surface of the distal phalanx did not appear to influence the prognosis.
• This study provides further descriptive data, highlighting the role of MRI in the diagnosis of DDFT insertional injuries.
• Concurrent signal of the flexor surface of the distal phalanx is not well described in the current literature and to the authors’ knowledge, this is the first study reporting outcomes for DDFT injuries with and without hyperintense STIR signal of the flexor surface of the distal phalanx at the insertion of the DDFT and/or the DSIL.
- Deep digital flexor tendon
- Magnetic resonance imaging