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Filling the Gap: Growing Brody’s Bone

By: Carole Cloud Published: Aug 1, 2014

When Stuart Shapiro went to pick up his new puppy at an Amish farm in Harrisburg, he thought something wasn’t quite right. Brody had a slight limp. The farmer told Stu it wasn’t out of the ordinary, that puppies often tumble and twist as they go through their first few weeks, learning to walk and play with the rest of the litter. He would be fine. Young dog and soon-to-be owner bonded immediately and Stu took his new skinny, black puppy home, trusting all would be well.

X-rays of Brody’s right limb showing the short radius bone and the gap in the elbow joint (yellow arrow).Brody, who was underweight, but otherwise pretty healthy, moved from a bed of hay in a barn to urban life in the Rittenhouse Square section of Philadelphia. With a healthy diet and plenty of play time, Brody followed his new human everywhere, including the office. His was a happy canine life – except for a lingering problem with his right foreleg.

Brody continued to favor his front right leg, holding it up when he sat or stood still, as though he was in pain. Going up and down stairs wasn’t easy for him and, when he was tired, his limp became much more pronounced. Stu took him to a veterinarian, who initially thought Brody had dislocated his elbow. Treatments included anti-inflammatories and pain medications. But Brody’s condition worsened over the next several months and, in September, Stu decided to consult the orthopedic team at Penn Vet’s Ryan Hospital.

Stu and Brody met with Dr. Kimberly Agnello, assistant professor of small animal surgery, attending surgeon Dr. Adrienne Bentley, and resident Dr. Krista Cioffi. After careful examination and radiographs of Brody’s forelimbs, the diagnosis was immediately apparent. “We could see clearly from the x-rays that the radius on Brody’s right forearm was not making contact with the humerus as it should be,” said Dr. Agnello. Brody suffered from humero-radial or elbow incongruity, due to a foreshortened radius bone.

Intra-operative image of the external skeletal fixator device being placed on Brody’s limb to allow for distraction osteogenesis.Dr. Agnello explained that, in both dogs and children, the long bones in the legs and arms grow from an area at either end of these bones called the physis, or more commonly, the growth plate. These areas produce new bone tissue and determine the final length and shape of bones in adulthood. When growth plates close prematurely, which can either be hereditary or the result of a trauma, the bone is unable to achieve its normal length.

As a result of Brody’s incongruent elbow joint, he was bearing the majority of his weight through his ulna bone. The ulna is not equipped to handle full weight-bearing forces, and at less than one year of age, Brody had already developed osteoarthritis and pain in his elbow joint. To decrease Brody’s pain, improve his limb function, and prevent further injury, Drs. Agnello and Cioffi strongly recommended surgery.

Brody’s limb showing the placement of the external skeletal fixator and the post-operative x-ray showing the osteotomy (yellow arrow) in the radial bone.In Brody’s case, there were a few possible approaches to improve his bone deformity. One method would involve bone cuts and internal fixation using bone plates. However, this would have made his limb even shorter. A less traditional approach, a procedure called distraction osteogenesis, is a way to lengthen the limb that involves breaking the bone and applying an external fixation device around the limb.

Distraction osteogenesis in dogs was first described by the University of Pennsylvania School of Veterinary Medicine's Drs. David Nunamaker,  Charles Newton, and C.R. Dickinson in 1975 (Newton CD, Nunamaker DM, Dickinson CR: Surgical management of radial physeal growth disturbances in dogs. J Am Vet Med Assoc 167;1011, 1975).

By periodically adjusting the external device setting over the course of several weeks, the bone segments would gradually move apart from one another. This technique of moving the two segments of a bone slowly apart in a controlled manner allows for new bone to fill in the gap and make the bone longer. This surgical approach has been successfully used in children with abnormalities of their growth plates and in maxillofacial surgery.

Although distraction osteogenesis cases have been reported in canine patients, since it is a complicated technical procedure, it is not common in veterinary surgery. (Learn more by visiting the Orthopedics Case Study...)

Brody, one day after surgery with his limb bandaged.Stu swallowed hard, consulted with his family, and decided to go for the more experimental – and potentially more successful – of the options. Brody’s surgery was scheduled for October 14, the day before he turned one year old.

Brody’s surgery was performed using minimally invasive surgical techniques.  The first part of the surgery involved arthroscopy, where “key hole” incisions are made into the elbow joint and surgery is performed via a small camera and instruments. This was done to remove bone fragments and scar tissue that was filling the space where the radial bone was missing. Then an osteotomy (cut in the radial bone) was created and an external fixator device was placed on Brody’s limb using a c-arm or fluoroscopy. Fluoroscopy is a way of performing intra-operative x-rays to minimize surgical incisions and allow for precise placement of the external skeletal fixator.  And because it was close to Halloween, the antebrachium bandage was decorated accordingly. The distraction, or bone lengthening, was to start three days after surgery.

Stu and BrodyThe next challenge for Stu and his family was to keep Brody from jumping, running, playing with other dogs, or running up and down stairs for the next two months – quite an undertaking for a healthy dog who had just turned one. “We got home the day after surgery,” Stu said, “and I expected Brody to be in pain. But instead, he was jumping on the sofa.” Not the recommended course by far. Stu realized just how much he would need to keep an eye on Brody.

In addition to careful monitoring of Brody’s activities, Stu had to make sure his incision sites were kept clean to avoid risk of infection. And the hardest part of all was the regular lengthening, which involved turning screws on the external fixator. “It was very nerve-racking,” Stu said. “I was so afraid this would hurt him. All I wanted was for the benefits to outweigh the hardships for Brody. I wanted him to get better.”

Brody visits with Dr. Agnello and Dr. Cioffi for a check-up.After three long months, the device finally came off. The outcome? The final result was successful, both clinically and on x-rays. Today Brody is walking and running more comfortably and easily, and both x-rays and CT-scans revealed that the bone had lengthened the appropriate amount. Brody’s elbow is now congruent and the bone has healed. In other words, Brody hops and jumps and runs just like any regular young pup.

“After all that,” Stu said, “it paid off, just to see him the way he is now. He’s always been a happy dog, but now I also know he’s not in pain.”

Watch a video of Brody's latest check-up...