Surgical treatment of carpal flexural deformity in 72 horses

Carpal flexural deformities (CFD) are frequently encountered in the horse, with both congenital and acquired forms described. The success of surgical correction of CFD, both in terms of the ability to achieve a straight palmar carpal angle and the impact on future athletic performance, requires further investigation.

To report the surgical management and outcome of treatment of flexural deformity of the carpus in 72 horses up to 12 months of age.

Information was obtained from the medical records of horses surgically treated for CFD and through follow-up contact with owners. At the time of examination each case was graded on the severity of the flexural deformity as grade 1, 2, or 3, in order of ascending severity. Surgical treatment consisted of tenotomy of the ulnaris lateralis and flexor carpi ulnaris muscles. Re-assessment of the palmar carpal angle was made in the immediate postoperative period and again from at least 8 months after surgery via telephone contact with owners and/or breeders. A successful outcome was defined as achievement of a straight palmar carpal angle. Long term outcome was assessed in terms of fullfilment of intended use for horses reaching 3 years of age at the time of the study.

A total of 135 surgical procedures were performed on 72 horses. A successful outcome was recorded in 111 limbs (82%). Excluding cases lost to follow-up, surgical correction was more successful in restoring a straight palmar carpal angle in grade 1 limbs (25/25, 100%) compared to grade 2 limbs (78/87, 89%) and grade 3 limbs (8/14, 57%). For those horses that had reached 3 years of age, 26 of 36 Thoroughbreds started in a race (72%) and 12 of 14 non-Thoroughbreds fulfilled their intended use (86%).

Tenotomy of the ulnaris lateralis and flexor carpi ulnaris tendons for treatment of grade 1 and 2 CFD's has an excellent prognosis for restoration of a straight palmar carpal angle and for intended athletic pursuit of the horse. In cases of grade 3 CFD, the prognosis following surgery is guarded, especially in neonates. Horses treated in this study were up to 12 months of age, indicating that this deformity may not always be self-limiting as previously thought, and treatment may be required for successful resolution of flexural deformity of the carpus in older animals. The results of this study will help veterinarians to make recommendations regarding the surgical treatment of CFDs.