Hinged circular fixator construct for correction of congenital metatarsal deformity in a foal.

This study discusses the use of a hinged circular fixator to correct a bone deformity in the hindlimb of an American Quarter Horse colt. Despite complications during the treatment, the surgical intervention successfully led to resolution of the colt’s lameness and a partial rectification of the deformity.

Background of the Study

• The study focuses on a five-week-old American Quarter Horse colt, presented due to an identified deformity and lameness in its left hindlimb.
• Upon examination using radiographs, the cause was detected as a varus deformity with recurvatum, identified in the mid-diaphysis of the third metatarsal bone.
• Such a condition had been causing significant discomfort to the horse, interfering with its normal mobility and necessitating the intervention of a surgical procedure.

Surgical Intervention

• The surgical procedure involved a method called osteotomy, which essentially means cutting of the bone to rectify the deformity.
• This was to be carried out at the centre of rotation of angulation within the mid-diaphysis of the third metatarsal bone.
• A four-ring hinged circular external fixator construct was applied, post-surgery, to aid the healing of the bone.
• The osteotomy site was distracted over a period of 11 days for optimal positional correction of the deformity.
• Despite the operative procedure, a series of complications arose during the course of treatment, including a broken fixation pin, infection at the surgical site, and temporary laxity of the support tendons and ligaments of the opposite metatarsophalangeal joint.

Post-Surgery Results and Insights

• The fixator was removed 152 days after the initial surgery when the bone formation was deemed sufficient to support the limb without the construct.
• The result was a successful correction of the deformity and resolution of the lameness, with the horse being able to walk more comfortably post-surgery.
• Using a hinged circular construct was found to be effective for partial rectification of the deformity and the consequential lengthening of the limb.
• However, such surgical interventions may come with complications, which call for careful monitoring and post operative care, to ensure the overall well-being of the foal post-surgery.