Suspensory ligament branch injuries are common in equine athletes such as show jumpers, dressage horses, and racehorses. While their prognosis in sport horses is fair, in Thoroughbred racehorses it’s poor.
At the 2018 British Equine Veterinary Association Congress, held Sept. 12-15, in Birmingham, U.K., Ian Wright, MA, VetMB, DEO, Dipl. ECVS, HonFRCVS, hospital director of Newmarket Equine Hospital, in Suffolk, U.K., described how to treat these tears surgically to bring racehorses back to function.
The suspensory ligament, which runs down the back of the cannon bone, divides into two branches that attach to the sesamoid bones at the back of the fetlock. Injury to these branches of insertion causes significant wastage in Thoroughbreds, said Wright. Because suspensory ligament branch (SLB) tears heal by scar tissue, horses cannot recreate the structure post-injury. So Wright hypothesized that removing the affected tissue would help these horses heal.
To find out, he conducted a retrospective study of 29 Thoroughbred racehorses admitted to Newmarket Equine Hospital from 2007 to 2015 with SLB lesions that had been treated surgically. The horses’ average age was 2, and they primarily suffered single branch injuries to their forelimbs. Clinical signs included lameness, loss of definition and sensitivity to pressure at the affected area, palpable thickening, and heat. Ultrasound was key to diagnosing these injuries, said Wright.
Surgical exploration revealed that all horses had defects at the palmar/plantar (outside) margin of the SLB and evidence of adhesions and scar or granulation tissue, he said. Surgeons removed the disrupted SLB fibers and debrided the scar tissue until left with healthy margins. Postoperatively, horses received non-steroidal anti-inflammatories and remained bandaged for about 23 days. The team removed staples at around Day 13 after surgery. Horses received two to three weeks of rest, followed by six to eight weeks walking, before progressing to trotting, etc., explained Wright.
Of the 28 horses available for follow-up, he noted that:
- 66% returned to racing;
- Of those, it took six to 30 months (about 15 months, “not a quick return,” said Wright) until they made their first start back;
- Recovered horses made between one and 27 (mean nine) starts;
- Ten horses won and 14 placed; and
- Only one horse had a documented reinjury.
“Surgery appears to have a good prognosis and has proved superior to noninvasive management,” in his experience, said Wright. He added, however, that this treatment is very lesion-specific and not applicable to all suspensory branch injuries.