carpal hyperextension / arthrodesis
Arthrodesis (fusion of a joint)
Arthrodesis can be an effective procedure to restore acceptable function and alleviate pain when other medical or surgical treatments are not possible. A thorough knowledge of carpal anatomy and strict adherence to the principles of arthrodesis are essential to success. The most important factor in determining whether a partial carpal arthrodesis can be performed is the stability of the antebrachiocarpal joint. Multiple techniques, including plating, pinning, and external skeletal xation, have proven successful.
What is arthrodesis?
Arthrodesis means the surgical fusion of a joint. In other words, the bones forming the joint are permanently joined together so that there is no movement in this part of the limb. Arthrodesis is a salvage procedure that is generally only performed when there are no other options to save the function of the joint. Drs. Brown and Sherburne perform both complete and partial carpal arthrodesis joint fusion procedures routinely at the Animal Clinic of Billings and Animal Surgery Clinic.
What is a partial carpal arthrodesis?
The fusion of low motion joints in the carpal joints of your dog is referred to as partial carpal arthrodesis. These joints are low motion joints, that do not require articulation to allow reasonable gait and movement in your dog. When disease or injury occurs to these carpal joints that can not be repaired or resolved by other medical methods, surgical arthrodesis with the application of surgical plates and bony fusion of the joint surfaces can be achieved with a partial carpal arthrodesis on your dog. By fusing the joint, pain-free movement can be achieved for your dog. Treating injury or osteoarthritis of the low motion carpal joints is achieved in the carpal and carpometacarpal joints by encouraging bone growth and fusion to occur on the joint surfaces while stabilizing them with surgical plates. This procedure is performed under general anesthetic by your veterinarian.
What joints can be arthrodesed (fused)?
The shoulder, elbow, carpal (wrist), stifle (knee), hock (ankle) and digit (toe) joints can be arthrodesed. The main joint that cannot be fused is the hip joint. This is generally not a problem since the hip joint can be replaced with an artificial one. Elbow and knee replacements are also possible alternatives to arthrodesis of these joints.
Reasons for performing an arthrodesis
The principle indications for arthrodesis are:
- osteoarthritis that is causing chronic pain and cannot be managed medically
- joint instability that cannot be treated by other means
- fractures involving the joint surface that cannot be repaired
- infection involving the joint that fails to respond to antibiotics
- tumours in or around joints
- muscle/tendon rupture that cannot be managed directly
Pancarpal or Complete Carpal Arthrodesis Joint Fusions in Dogs
Fixation of surgical plates may be external or internal to the joint, depending on the type of damage or disease, and what method will be most effective. A variety of different size plates are available and the correct size needs to be selected in order for fixation to be successful. Radiographs taken prior to surgery will be used to plan the surgical procedure and address approach and appropriate plates to be used.
Prior to surgery you will be required to fast your dog so as not to cause complications with the administration of general anesthetic. Your dog will be sedated, given intravenous anesthetic and then intubated and anesthesia maintained by gas. The area to be incised on the forelimb dorsal to the carpal joints is shaved and antiseptically cleaned prior to incision. Surgical drapes are used to maintain a sterile surgical site. A dorsal incision is made distal to the antebrachium and extending to the distal metacarpi. Subcutaneous tissue is incised and blood vessels are moved aside. Muscles are manipulated aside to reach the intercarpal and carpometacarpal joints Joint capsules of the radiocarpal, middle carpal and carpometacarpal joints are severed and articular cartilage destroyed and removed with use of a surgical drill or other surgical instruments. Forage may be created by drilling holes in the subchondral bones to provide vascular access to the newly forming, fusing bone. Cancellous bone grafts taken from another part of the body, usually the humerus of the same leg, are inserted into the joint spaces. The forelimb is positioned into a normal standing angle prior to insertion of surgical plates. A curved compression plate is affixed with surgical screws to the radius, radial carpal bone, and metacarpal bones. Tissues are sutured and the leg is supported with a splint bandage. Your dog will be allowed to recover from anesthetic in the veterinary hospital. Your dog may be hospitalized for 24 to 48 hours if medical conditions warrant this or may be released the same day.
There are a number of important steps when fusing a joint:
- the surface of the joint (known as the articular cartilage) must be removed to enable bony fusion.
- a bone graft should be placed into the spaces between the bones to promote fusion. This may be an autograft (from the patient), an allograft (from a donor) or a combination of both.
- the bones forming the joint to be arthrodesed must be rigidly stabilized to maximize the possibility of bony fusion. This is most commonly achieved with one or two plates that are secured to the bones under the skin. Occasionally an external skeletal fixator (a metal framework) is employed, where the bones are stabilised with pins that penetrate the skin and are attached to bars on the outside of the limb.
- exercise must be restricted until there is radiographic (X-ray) evidence that the bones have fused. This often takes eight to 12 weeks.
Risks and complications
The majority of arthrodesis operations are uneventful and are not associated with complications, however, these are major procedures and thus the following complications are possible:
- loosening or breakage of implants (plates, screws, pins) may occur if the joint fails to fuse in sufficient time. Implant failure can result in joint instability and necessitate further surgery.
- wound problems, such as breakdown and infection, are primarily associated with arthrodesis of the carpal (wrist) and hock (ankle) joints. Wound management within the first few weeks of surgery is of vital importance to minimise this risk. Dressings are often applied to the limb to minimise swelling and prevent the patient interfering with the wound.
- fracture of bones adjacent to the fused joint may occur due to the abnormal forces that result following arthrodesis surgery.
How good is limb function following arthrodesis surgery?
Limb function after arthrodesis surgery is primarily dependent on which joint is fused. It is good following carpal (wrist) and hock (ankle) arthrodesis and fair following shoulder arthrodesis. Fusion of the elbow or stifle (knee) joint significantly compromises limb function. Dogs and cats generally have to swing the limb outwardly (circumduct) when walking in order to prevent the toes dragging on the ground.
Carpal arthrodesis joint fusion relieves pain and discomfort in the affected limb and allows adequate movement and functioning for your dog to resume normal activities such as running, jumping and playing. Overactivity should be discouraged during recovery for best results. If plates are not adequately sized, or articular cartilage is not adequately removed, failure of the fusion can occur and instability results.
Is Arthrodesis surgery safe?
In those patients where arthrodesis is indicated, the vast majority benefit from surgery. Fusion of a joint is undoubtedly a major undertaking, but these procedures are commonly performed at the Animal Clinic of Billings and Animal Surgery Clinic. We will be pleased to give as much help and support as possible if you decide to give your dog or cat the opportunity of arthrodesis surgery.
Carpal Arthrodesis Joint Fusion Recovery in Dogs
A bandage with splint or cast is usually placed for three to four weeks to provide stabilization and protect joint and incision. The bandage will need to be maintained as directed by your veterinarian. Bandages are usually changed weekly, and the surgical incision should be checked more frequently to ensure infection or wound dehiscence has not occurred. Bandaging should stay clean and dry. You will need to check for cast and bandage sores and to ensure circulation is adequate. Sutures will be removed in 10 to 14 days by your veterinarian. Analgesics will be prescribed post-surgery and antibiotics and anti inflammatories if deemed necessary. Activity should be restricted to limited walks on a leash. Arthrodesis will be confirmed by follow-up radiograph at four, eight, and twelve weeks or as deemed appropriate after surgery by your veterinarian. An e-collar may be used to prevent your dog interfering with the bandage or surgical wound. Partial weight bearing on the limb usually resumes in one to two weeks, with full weight bearing at two to four months.
Dog Carpal Arthrodesis Joint Fusion Procedure Considerations
Arthrodesis procedures can be prone to complications such as septicemia in the joints, or failure of plates. Proper treatment with antibiotics, careful surgical procedures, and careful fitting and customization of surgical plates can prevent these complications from occurring. Other limbs and joints need to compensate until healing occurs, and this puts added strain on them. If disease or disorder is present in other limbs this will create issues and arthrodesis of joints may not be appropriate. Plates may need to be removed after healing occurs if complications occur such as cold sensitivity, infection, irritation, or strain from plate placement.
Carpal Arthrodesis Prevention in Dogs
Carpal injuries from hyperextensions during activity or accidents such as falls or motor vehicle accidents are common in dogs. Ensuring your dog’s environment is safe from hazards and that they are not left unsupervised or loose outside will greatly reduce the likelihood they will be involved in household accidents, motor vehicle accidents, or fights with other animals, resulting in injury to the carpal joints.