The effects of fixation of the ulna to the radius in young foals.

The study reveals the negative impact of fixating the ulna to the radius in young foals causes elbow subluxation, ulnar dysplasia, lameness, and joint disease, with severity related to the age at the time of fixation.

Investigation Methodology

• The study involved 21 Quarter horse foals whose ages ranged from 1 month to 7 months.
• A bone plate was applied to the caudal aspect of the proximal part of the foals’ ulna, using screws to engage both the radius and the ulna. This process is known as radioulnar fixation.
• The foals were split into different groups depending on their age at the time of operation: Group I consisted of six foals operated on at 1 month, Group II consisting of six foals operated on at 5 months, and Group III consisting of three foals operated on at 7 months. A control group (Group IV) of six foals underwent sham operations at 1 month.

Observations and Findings

• All treated foals developed elbow subluxation and ulnar dysplasia as a result of the procedure.
• The seriousness of ulnar dysplasia was inversely related to the patient’s age at the time of fixation. That means the younger the foal was at the time of the operation, the more severe the dysplasia was.
• Lameness and degenerative joint disease also developed in foals who underwent fixation at 1 and 5 months of age.
• Removing the fixation appliances 16 weeks after being implanted in foals from group I and II did not reverse the ulnar dysplasia.
• Foals from group III (who underwent fixation at 7 months) exhibited no lameness but did show signs of elbow subluxation and subtle degenerative changes in the articular cartilage of the treated elbow in radiographic examinations.

Recommendations

• Based on the observations, it was strongly recommended to avoid radioulnar fixation in foals due to the associated complications such as dysplasia, lameness, elbow subluxation, and degeneration of joint.