The Effects of Fixation of the Ulna to the Radius in Young Foals

Abstract

The effects of radioulnar fixation were studied in 21 Quarter horse foals by applying a bone plate to the caudal aspect of the proximal part of the ulna, with screws engaging both the radius and the ulna. The plates were applied at 1 month of age in six foals (group I), 5 months of age in six foals (group II), and 7 months of age in three foals (group III). Six foals underwent sham operations at 1 month of age to serve as controls (group IV). Ulnar dysplasia and elbow subluxation developed in all treated foals. The magnitude of ulnar dysplasia was inversely related to the patient's age at fixation and was accompanied by degenerative joint disease and lameness in foals undergoing fixation at 1 and 5 months of age. Removal of the fixation appliances 16 weeks after implantation in three foals from each of groups I and II failed to reverse the degree of ulnar dysplasia. Although foals undergoing fixation at 7 months of age (group III) were not lame, radiographic evidence of subluxation and subtle degenerative changes in the articular cartilage of the treated elbow did develop. Recommendations for avoidance of radioulnar fixation were developed from these observations.

Ulnar osteotomy for treatment of cubital subluxation, following locking compression plate osteosynthesis of a radius fracture in a foal

“…1991). The decreased amount of dysplasia in foals undergoing fixation at 7 months of age supports the belief that fixation at age <7 months, as in our case, would probably produce significant dysplasia (Clem et al . 1988).…”

“…Furthermore, care was taken during surgery to avoid inserting the screws into the ulna. This would have fixed the ulna to the metaphysis or the diaphysis of the radius, which, with continuous growth occurring at this foal's proximal metaphyseal growth plate, would have resulted in subluxation of the ulna (Stover 1985; Clem et al . 1988).…”

“…Without any treatment the radio‐ulnar synostosis would have gradually increased the elbow subluxation and lead to malformation of the anconeal process with a high risk of concomitant radiographic evidence of degenerative joint disease (Clem et al . 1988).…”

“…Younger animals have greater potential to develop deformities and subsequent lameness. The magnitude of articular dysplasia resulting from radio‐ulnar fixation is inversely related to the foal's age at the time of fixation (Clem et al . 1988).…”

Surgical Repair of an Olecranon Fracture in a Horse

“…Fixation of the ulna to the radius during plating of olecranon fractures in mature horses has no untoward effects. However, radioulnar fixation in foals undergoing plating for repair of olecranon fractures has been responsible for different degrees of elbow displasia and humeroulnar subluxation (CLEM et al, 1988).…”