"Case of the Month" – March 2017
Jasper Grimm, a male Newfoundland, routinely showed lameness in his pelvic limbs after exercise throughout his young life. At 6 months of age, he went to his veterinarian for bilateral stifle (knee) joint effusion and the start of femoral deformities making it difficult for Jasper Grimm to get up and walk normally. Shortly thereafter, in August 2016, his owner decided to have him evaluated by orthopedic surgeons at the UC Davis veterinary hospital.
His physical examination showed marked lameness in his pelvic limbs and an unwillingness to bear weight. He had severe muscle atrophy to both of his pelvic limbs, and he walked with both pelvic limbs rotated outward. Both of his stifles were swollen and painful during the examination.
Radiographs and a CT scan revealed that Jasper Grimm had lateral luxated patellas (dislocated kneecaps) in both hind legs. The diagnostic images showed severe angular limb deformities of his femurs; both his stifles and hips had some osteoarthritis. The femoral deformities and the lateral patella luxations were causing a crouched gait, and Jasper Grimm could not extend his stifle joints normally. Because his patellas were never in the groove, he had weakness and inability to walk on both limbs. He also had small articular cartilage defects.
The surgeons discussed Jasper Grimm’s case with his owner. They advised that it would be a lengthy process to help him achieve more comfort in his everyday life. In order to help Jasper Grimm bear more weight on his pelvic limbs, corrective surgeries (known as distal femoral osteotomies) were needed. The left leg had a more severe deformity compared to the right, and would be addressed first. If all went as planned, after two months of healing, the right leg could then be corrected. The goals of these surgeries were to make Jasper Grimm more comfortable and allow him to be able to walk like a normal dog again.
Jasper Grimm’s owner chose to proceed with the surgeries. Using images from the CT scan, the surgeons were able to perform 3D mapping of his legs and 3D print exact replicas of his bones to plan the safest and most effective surgery. This included shaping and fitting the plates to be used to stabilize his legs.
In late September 2016, he underwent the first of two procedures to correct his limb deformities. Dr. Amy Kapatkin, chief of the Orthopedic Surgery Service, and surgery resident Dr. Rebecca Hersh-Boyle executed the ostectomy plan (the cut of the distal femur to align it into a normal position), and stabilized it with both lateral and medial locking plates. The surgery was difficult due to scar tissue and muscle contracture from the limb deformity. The surgeons needed to perform an abrasion trochleoplasty (make a new groove for his patella). The articular cartilage was completely damaged in what used to be his patella groove so there was no attempt to salvage it. The patella tendon and muscle group pulled the patella lateral. A large lateral release of the patella tendon and muscle groups from the scar and then suturing the medial side kept the patella central in the groove. The patella was stable in the new groove after all these surgical steps.
For eight weeks following surgery, Jasper Grimm was under strict confinement except for bathroom breaks, which consisted of short, controlled leash walks using a sling to support his hips at all times. He also went to physical rehabilitation at a clinic near his home to help him regain range of motion of his stifle joint and help his muscle mass recover. He continued the assisted walking until the bone was completely healed.
In early January 2017, he recovered enough to move onto the same procedure on his right leg. The second surgery went well, and radiographs a month later showed the patella and bone plates in place. With the proper physical rehabilitation, Dr. Kapatkin expects his permanent condition to be a drastic improvement from the pain he experienced before the surgeries.
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