Section: Veterinary Care In-depth
Diagnosis
History. Your veterinarian will ask you many questions regarding the development and progression of the problem. Your pet's age is important to know, as well as any history of trauma. If other veterinarians have done any X-rays, then you should bring these results to your veterinarian's attention. If you have tried any treatments for this problem, it's helpful to tell your veterinarian about them and whether or not they had any effect.
Physical exam. Your veterinarian will perform a complete physical exam and will watch your pet walking and trotting to identify any abnormalities in the gait. The exam will also include palpation of every part of every leg, checking for broken bones, ligament injuries, pain, swelling, mobility of the joints and symmetry between the right and left legs; listening to your pet's heart and lungs; temperature; and palpating the abdomen to be sure there are no other problems.
Blood and urine tests. If your pet will be undergoing anesthesia and surgery, blood and urine tests are run to be sure that your pet is not anemic and there is no underlying liver or kidney problems that might make anesthesia risky.
Radiographs (X-rays). When the injury first occurs, the damage to the growing cells is not evident on X-rays. As time goes by and the leg grows abnormally, asymmetry is evident between the affected and unaffected leg. X-rays are always taken of both the right and left legs to compare normal with abnormal and to help plan the surgery. X-rays are also taken after surgery to assess the outcome of the procedure. More X-rays are taken as the bones heal in the following months to be sure everything is progressing well.
Treatment
The abnormality must be diagnosed as early as possible in order to have the best chance for success. Angular limb deformities require surgical correction, and the type of surgery depends on the patient's age and the type of deformity. Often, more than one surgical procedure is necessary to correct the abnormality.
Generally, the damaged portion of the physis is removed, or the bone is cut near the damaged area to relieve the "tethering" effect it has on its paired bone.
In mature animals that are no longer growing, the curvature of the limb is either corrected at the time of surgery by cutting the bone and repositioning it straight. In patients that are young enough and have significant growth potential, the bone can be cut and allowed to straighten out as it grows.
The joint incongruity can be adjusted directly during surgery or allowed to adjust itself as the patient grows after surgery.
The cut ends of the bone can be fixed in position using either a bone plate and screws, pins or an external fixators, which is a device that has pins penetrating the bones and skin and are connected by bars on the outside of the skin. A bandage, splint or cast may also be added to provide support and/or decrease swelling.
If there is a large discrepancy in length between the affected leg and the opposite leg, then a bone lengthening procedure called distraction osteogenesis can be used. This entails application of an external fixator, which may encircle the leg with metal rings and bars. The bone ends are gradually spread apart over a period of weeks to months by having the owner turn a knob or nut on the apparatus a couple times each day. Bone fills in over the fibrous tissue that is spread apart during the distraction process and significant gains in length can be achieved.
