Case of the Month:
“Hera”
Hera is a super cute 10 month old Maltese puppy. This ball of fluff and energy presented to North Mecklenburg Animal hospital in April for a complaint of limping on her front right leg. She was playing with a Jack Russell puppy friend over the weekend. The limp was most notable after getting up from lying down. On presentation she had no visible limp, but was painful on full extension of her right elbow. Hera was suspected to have some soft tissue damage, most likely from playing with her friend and was given a few days of “carprofen”, a doggie anti-inflammatory pain medication, with the instructions to return for X-rays if she did not improve.
Hera returned with her owners in one week’s time. She had initially improved slightly but was still favoring her front right leg. On exam she was still very painful with extension of her right elbow. It was also noted that she was holding her right paw at an unusual angle pointing away from her body. Her owners mentioned that they noticed this at home as well and had associated her stance with her “attitude.” In addition Hera had a few stubborn baby teeth that had not yet fallen out.
Hera was sedated, those pesky baby teeth were easily removed, and X-rays were taken of both of her elbows. An X-ray of her left elbow and lower arm were taken for comparison with her painful right elbow. X-rays showed the two bones in her right forearm, the radius and ulna, were growing unequally.
Growth deformities in the forelimb, sometimes called asynchronous growth of the radius and ulna, occur because of how the bones are paired together via ligaments and muscles. Bones grow via growth plates at both ends of the bone. The most distal growth plate, or the one closest to Hera’s paw, on her ulna bone (the skinny bone ) is cone shaped and very susceptible to damage. This growth plate is responsible for the majority of the growth of the ulnar bone. Injury to this growth plate caused the growth of Hera’s ulna to stop growing before her radius. Since the ulna and radius are paired together Hera’s shortened ulna caused her growing radius to bend or bow, this also deformed her paw to point outwardly. The bowing of this bone put pressure on Hera’s elbow. The elbow joint is generally a very congruent joint, or one that fits together just so. Any change in the congruency of this joint can be quite painful and is termed elbow dysplasia.
The treatment for Hera was surgery. The goal of surgery is to allow normal growth of the uninjured growth plates in the forearm and allow the radius to take a more natural and straightened position. Hera went to surgery in early May. An ulnar ostectomy was performed ( or removal of a small piece of her ulnar bone). A 1 cm chunk of Hera’s distal ulna was removed and replaced with a fat graft taken from her side (see photo). The fat was placed to prevent the bone from trying to heal back together. The ulna has no weight bearing function in the forelimb therefore removing part of this bone does not affect the limb. Separating the shortened ulna allowed Hera’s radius to straighten and her elbow to fit back together again.
One week after surgery Hera returned to have her sutures removed. Her owners were excited to report that she was no longer limping and was 100% better. She was cleared to begin normal activity again, just in time for her first birthday! Today Hera is doing wonderful and still cute as a button!
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