Key Points
The growth plates are much softer than other regions of the bones, therefore are more prone to injury
Since most of the longitudinal growth of bones occurs up to eight months of age, growth plate injuries that occur after this point are not as devastating
A portion of the damaged growth plate may remain functional (open) and thus the bone and limb becomes twisted
Surgery is generally done as soon as possible after this type of injury occurs
Initial visit- downloadable forms/information for clients:
History sheet - Client initial consultation history
Growth plate injury client education handout
Discharge instructions for postop care - dog
Discharge instructions for postop care - cat
2-week recheck visit - downloadable forms/information for clients:
History form - 2 week postop (Telemedicine evaluation)
Postop care instructions 2-week recheck - dog
8-week recheck visit - downloadable forms/information for clients:
History form 8-week recheck (in hospital)
Postop care instructions 8 week recheck - dog
Other important pages on our website that discuss growth plate fractures:
- Angular limb deformity
- Elbow fractures
- Distal femoral fractures
Anatomy
Dogs and cats under one year of age have growth plates, which are located near the ends of the bones of the limbs. Growth plates are responsible for growth of the bones. The growth plates are much softer than other regions of the bones, therefore are more prone to injury and fracturing. Growth plates normally fuse or close down as the pet matures. Most of the pet’s growth occurs during four to eight months of age. After eight months of age, little longitudinal growth of bones occurs. Usually by one year of age the growth plates are closed and are not visible on x-rays. An exception is the growth plate of the head of the femur bone can remain open for up to 2 years.
Growth plate injury
Since most of the longitudinal growth of bones occurs up to eight months of age, growth plate injuries that occur after this point are not as devastating. The growth plate is a weak link in the bone construct, therefore it is more susceptible to injury. A Salter-Harris classification of growth plate fracture has been described in humans and seems to relate to prognosis. Type 1 has the best prognosis and type 5 having the worst. In pets the Salter-Harris classification also may relate to the final prognosis, but the age at which the fracture occurs tends to be a significant factor. The diagrams below show the different type of fractures (the blue line represents the soft growth plate tissue, the red line represents the fracture line, and the speckled red line is a crushed growth plate).
Common locations of the various Salter-Harris growth plate fractures in dogs and cats
Type 1 – hip joint (slipped femoral capitis), knee (distal femur)
Type 2 – knee (distal femur)
Type 3 – elbow (distal humerus)
Type 4 – elbow (distal humerus)
Type 5 – carpus (distal ulna or the distal radius less commonly), this results in an angular limb deformity
Results of growth plate fracture
Growth plate becomes nonfunctional in many cases and the final length of the bone may be shorter than normal. If the final length of the bone is not 20 to 25% shorter than the normal bone, the pet likely will not have a noticeable gait abnormally when walking or running, since dogs and cats walk in a semi-crouched position (versus man walks with the legs straighter). A portion of the growth plate may remain functional (open) and thus the bone and limb becomes twisted. In the front limb where the bones are paired (radius and ulna) the limb may become twisted in three planes at the wrist (carpus)
Preparation for surgery
The pet should be fasted prior to surgery, as instructed by the surgical team. Water is usually permitted up to the time of admission to the hospital. The surgical team should be informed of any medications that your pet is currently receiving. Just prior to surgery, your pet will receive a sedative, have an intravenous catheter placed for the administration of intravenous fluids and intravenous medications, be induced under general anesthesia with medication(s), and have a breathing tube (endotracheal tube) placed to allow delivery of oxygen and gaseous anesthesia. The surgical site will be clipped and cleansed with an anti-septic solution in preparation for surgery. While under general anesthesia, the pet’s breathing will be assisted with a ventilator and vital parameters such as heart rate, respiratory rate, core body temperature, blood pressure, oxygenation of the blood (pulse oximetry), exhaled carbon dioxide (capnography), and heart rhythm (EKG) will be monitored to ensure the pet’s well being. Pain will be controlled both during and after surgery with analgesics (pain-controlling medication). Please note that each surgical and anesthesia team may elect to chose a different, but effective analgesia protocol.
Surgery
Timing of surgery is dependent on the type of injury and location occurs. For example if a complete growth plate closure of the ulna occurs, ulnar ostectomy should be done as soon as possible in order to allow the radius bone to grow straight. If a partial closure of a growth plate has occurred in the radius or distal tibia, we generally follow these cases with monthly radiographs and once the twisting of the bone has stopped, then corrective surgery is performed; if done too early, the continued abnormal growth of the bone will continue to twist the limb. Your pet's surgeon will determine what needs to be done. For type Salter-Harris type 1, 2, 3 and 4 growth plate fractures, surgery is done within a few days of the injury.
Generally pins are used to repair these types of fractures if a type 1 or 2 fracture occurs. Type 3 and 4 may need a screw and pin placed. If the joint surface has been directly violated as in a type 3 or 4 fracture the joint should only be immobilized with a bandage or splint/cast for a very short period of time. Prolonged splinting of a limb that has had a repaired joint fracture could lead to permanent stiffness of the joint. The elbow and knee seem to be the most common regions to have problems if immobilized for too long (get scar tissue and joint becomes very stiff).
Aftercare
After surgery, you can continue to give your pet a prescribed pain reliever to minimize discomfort. It’s also extremely important to limit your pet’s activity and exercise level during this post-operative period. Rehabilitation exercises can be done at your home or if you choose, by professionally trained therapists at an animal rehabilitation center. Rehabilitation therapy should be continued until your dog is bearing weight well on the operated limb (typically 2 – 4 weeks after surgery). Detailed instructions will be given to you after the surgery. The surgeon will monitor the healing process with two follow-up exams. The first is scheduled at two weeks after the surgery and the second is at five to eight weeks after the surgery; during the second visit the repaired bone will be x-rayed. By 8 weeks after surgery, most dogs and cats are fully weight-bearing on the operated limb, although exercise should be limited during the first three months after the procedure. If your pet had an extensive surgery such as an angular limb deformity correction, the recovery period may be a bit longer than a typical fracture.
Complications
Complications after surgery may include anesthetic death, shortened limb length, functional gait abnormality, twisted limb/paw, infection, arthritis of affected joints, and failure of the bone to heal.
