Radial and Ulnar Fractures in Cats
The radius and ulna are the two bones that comprise the forearm. Fractures (breaks) of these bones are frequently encountered in veterinary medicine. Because of the conformation of the forearm, both bones, the radius and ulna, usually fracture at the same time.
In cats, these fractures are usually the result of trauma, but can be caused by disease of the bone itself. These fractures can occur in an immature bone (one that has not finished growing), or in a mature one, can be “open” or “closed” and can be “simple” or “comminuted.” They can also involve either the carpus (wrist) or elbow joints.
Depending on the nature of the fracture and the age of the animal, different methods of repair may be indicated for each situation. Radius and ulna fractures can have serious complications if not repaired, or if the repair fails, and can result in developmental abnormalities of the leg if the animal is immature when the injury occurred.
What to Watch For
Diagnosis of Fractures of the Radius and Ulna in Cats
A thorough physical examination is important to determine if fractures are present and to determine if there are other injuries. No laboratory tests are required to make the diagnosis, but your veterinarian may recommend the following:
Treatment of Fractures of the Radius and Ulna in Cats
Emergency care for concurrent problems caused by the trauma is the most important part of treatment. After stabilization, additional treatment may include:
Home Care and Prevention
Bring the animal to the veterinarian as soon as possible after any trauma for immediate attention. Try to prevent your pet from walking or moving too much. Prompt veterinary treatment is recommended. Do not attempt to place a splint or bandage on the leg unless there is profuse bleeding.
After surgical repair of the fracture, the animal must be kept restricted from activity for several weeks and the skin incision should be monitored while healing. A recheck with your veterinarian will occur in several weeks to evaluate how the bones are healing (with new radiographs), to monitor the animal’s progress, and to make sure it is safe to increase the animal’s activity level.
Many traumatic events are true accidents and thus unavoidable. Small cats should be limited from jumping from heights. If these cats are allowed on the furniture, ramps or stairs may allow these cats to get up and down without risk of injury. Avoid the chance for motor vehicle trauma by not allowing your cat to roam.
In-depth Information on Radial and Ulnar Fractures in Cats
Radius and ulna fractures are common and motor vehicle trauma is the most frequent cause. These injured animals tend to be young, non-neutered males who roam away from home and get hit by a car. Animals of both sexes and of any age are susceptible to this type of trauma if not kept restrained. Small cats (e.g. Italian greyhound) tend to be especially susceptible to these types of fractures with relatively minor trauma, like jumping off a bed
Animals can develop non-traumatic fractures of the radius or ulna when certain disease conditions exist. These fractures, also known as “pathologic fractures,”can occur if the animal is malnourished, has a systemic illness such as kidney disease, has an endocrine disorder such as hyperparathyroidism, has a bone infection (osteomyelitis) or has cancer of the bone.
Immature bones have growth plates (physes) that are still “open” and growing. These regions of the young bone are susceptible to damage caused by the trauma that can result in premature “closure.” Due to the interrelationship between the two bones of the forearm during growth, premature closure of one growth plate before maturity can cause abnormal curvature of the bones and joint incongruities. This can result in future pain and lameness. The most common type of premature growth plate closure occurs in the distal physis of the ulna (the end of the bone near the wrist). This causes forward bowing of the forearm with lateral (outward) deviation of the carpus. Abnormalities can also occur in the elbow secondary to this type of growth plate injury.
Depending on the location and amount of energy of each particular trauma, fractures can occur in various portions of the bone. Most fractures involve the proximal, midportion or distal diaphysis (shaft) of the bones. Sometimes fracture of the ulna can occur in combination with a luxation (dislocation) of the radius at the elbow instead of a fracture of that bone. Uncommonly, joint fractures occur involving the surfaces of the elbow joint or wrist.
Fractures of the diaphysis of the radius and ulna can be classified as “open” or “closed” depending on whether the skin surface has been damaged during the injury. Open fractures have a greater chance of getting infected and may have more complications than closed fractures.
As with all fractures, fractures of the radius and ulna can also be classified as “simple” if each bone breaks into two pieces or “comminuted” if there are multiple pieces.
Each case of antebrachial fracture needs to be evaluated in its entirety (age of animal, severity of the fracture, experience of the surgeon and financial concerns of the owner) to determine the most appropriate and best form of treatment.
Inappropriate case management, inadequate surgical stabilization or poor aftercare can lead to complications, such as non-unions (fractures that will not heal), malunions (fractures that heal in an abnormal direction or orientation), osteomyelitis (bone infection), arthritis or a non-functional leg.
A thorough physical examination is very important to make sure your pet is not showing signs of hypovolemic shock secondary to the trauma or blood loss. It is also important to make certain that there are no other injuries present. Additional tests may include:
Emergency care for concurrent problems is paramount. Shock is a frequent result of major trauma and must be treated quickly. Treatment for shock involves intravenous fluid administration to maintain blood pressure and adequate oxygen delivery to the body. Injury to the lungs and chest cavity are also commonly seen after major trauma and may require supplemental oxygenation or removal of free air (pneumothorax) from around the lungs. Once stabilized, additional treatment may include:
Follow-up Care for Cats with Radial and Ulnar Fractures
If surgery is not required or not pursued, and a cast or splint is used to immobilize the leg instead, the animal must be strictly confined to allow the arm to heal and prevent excessive pain. Because the bone fragments are not as well stabilized when this course of treatment is followed (compared with surgical fixation), excessive motion or activity can prevent the fracture from healing at all or cause it to heal improperly.
After discharge from the hospital, the animal must be restricted from activity to allow the fracture time to heal properly. Activity must be restricted for several weeks after surgery; the duration will vary depending on the severity of the injury and any concurrent injuries the animal may have. Restricted activity means that the animal should be kept confined to a carrier, crate, or small room whenever he cannot be supervised. Playing and rough-housing should be avoided, even if he appears to be feeling well. The use of stairs should be limited.
Animals whose fracture was repaired with an external fixation device will have pins exiting the skin. The “pin tracts” should be monitored daily for excessive swelling or discharge. Some discharge is normal and any crusty build-up that occurs at these sites can be gently cleaned with warm water.
Analgesics (pain medications) or anti-inflammatories should be given as directed by the veterinarian. Analgesics, such as butorphanol (Torbugesic®) can cause sedation, and anti-inflammatories, such as aspirin or carprofen (Rimadyl®), can cause an upset stomach. Your veterinarian should be informed if any adverse side effects occur.
The skin incision needs to be monitored daily for signs of excessive swelling or discharge. These can indicate problems with the incision or infection. If at any point prior to the recheck radiographs being taken the animal stops using the leg again after some improvement following surgery, there could be a problem.
Several weeks after surgery, the arm will need to be radiographed again to make sure the bone is healing properly. If the healing has occurred as expected, the external fixator, if present, will be removed and the animal’s activity level will be allowed to increase slowly back up to normal over the next few weeks.
In general, any other implants that were used in the repair will be left in place unless they cause the animal a problem at some point in the future. Potential problems can include migration (movement) or infection of the implant.
In younger animals, it’s very important that the arm be monitored closely for signs of abnormal growth. Injuries to the growth plates cannot be completely determined at the time of the injury or surgery. Signs such as curving or bending of the leg or worsening lameness can occur very quickly after the injury and early intervention by the veterinarian may be able to prevent future problems.