Fractures of the humerus are relatively common in the dog and cat with approximately half of all humeral fractures occurring in the distal portion of the bone.
Distal humeral condylar fractures are far more common in dogs than in cats. The rarity of condylar fractures in cats may be partially explained by their straighter condyles and relatively wider and thicker epicondylar crests.
Lateral condylar fractures are common and may occur from either minor or severe trauma in dogs and cats of all ages.
The high incidence of condylar fractures resulting from minor trauma in immature animals may be explained by the relative weakness of the fusion zones of the principle centers of ossification of the developing distal humerus.
Substantial number of condylar fractures, however, occur in adult animals. One study found an increased risk for male Cocker Spaniels over two years of age fracturing their humeral condyle with only minor loading forces.The findings of this study suggest that certain breeds of dogs may be predisposed to distal humeral condylar fractures after sustaining minor trauma equal to or only slightly greater than the loading forces generated by normal activity.
Fractures of the lateral humeral condyle (capitulum) occur as abnormal compressive forces are directed upward through the radius. The condyle shears off the intercondylar area through the supratrochlear foramen and the lateral supracondylar ridge.
Several factors are associated with the higher incidence of lateral versus medial condylar fractures. The capitulum is the major weight-bearing surface because of its articulation with the radial head. As forces are directed through the radius, they are transmitted directly to the capitulum.
Fractures of the medial condyle (trochlea) are less common because of its less frequent weight bearing position. In addition, the shape of the distal humerus is such that the capitulum sits off the midline of the central axis of the body, predisposing itself in injury. Finally, the lateral supracondylar ridge is smaller and biomechanically weaker than its medial counterpart.
Treatment of lateral condylar fractures should be directed at complete restoration of joint anatomy and function. Because these fractures are intra-articular, perfect reduction with inter-fragmentary compression is required for optimal postoperative function.
Closed methods of reduction and external fixation cannot usually reduce the fracture fragments perfectly and prolonged immobilization of the joint, which is necessary for fracture healing may lead to joint stiffness.
Open reduction and internal fixation are indicated for optimal alignment and stabilization of lateral condylar fractures and an early return to function. An early return to function will help alleviate elbow stiffness and degenerative joint disease.
While several surgical approaches may be used to expose lateral condylar fractures, excellent exposure with minimal soft tissue dissection is achieved via a lateral or craniolateral approach to the elbow.
The most common method employed for repair of lateral condylar fractures is a trans-condylar lag screw with or without an additional cross-pin for increased rotational stability.
Pre-operative tests depend in part on the age and general health of the animal.
Radiographs (x-rays) of thorax is done to diagnose the underlying injury prior to surgery.
Often a complete blood count, PT/PTT, serum biochemical test, a urinalysis, and possibly an EKG will be performed prior to surgery.
Type of Anesthesia:
General anesthesia is needed to induce unconsciousness, complete control of pain, and muscle relaxation.
In the usual case, the pet will receive a pre-anesthetic sedative-analgesic drug to help him relax, a brief intravenous anesthetic to allow placement of a breathing tube in the windpipe, and subsequently inhalation (gas) anesthesia in oxygen during the actual surgery
Once the fracture site is adequately exposed, fibrin, clots, blood, and interposed soft tissue should be removed to allow perfect anatomic reduction of the articular surface.
With the fracture reduced, a transcondylar hole is drilled beginning at a point juts cranial and ventral to the palpable lateral epicondylar crest. The drill hole is tapped, the later condylar fragment is over-drilled to create a gliding hole, and transcondylar lag screw is placed.
In order to ensure central placement of the lag screw through the condyle, an alternate technique may be employed. The lateral condylar fragment is outwardly rotated and the gliding hole is drilled from the intercondylar fracture surface out through the lateral site of the condyle.
The fracture is then reduced, the medial condyle is appropriately drilled, and tapped and a lag screw is placed. An anti-rotational Kirshner wire is then driven from the lateral condyle and seated into the medial cortex of the distal humeral shaft.
The elbow joint should be put through a full range of motion to assess stability and to check for crepitus.
The procedure takes about 1 to 1-1/2 hours to perform in most cases, including the needed time for preparation and anesthesia.
Risks and Complications:
The overall risk of this surgery is low. The major risks are those of general anesthesia, bleeding (hemorrhage), postoperative infection, and wound breakdown (dehiscence) over the incision.
Overall complication rate is low, but serious complications can result in anesthetic death or the need for additional surgery.
I prefer to place the limb in a soft padding bandage to help control swelling during the immediate post-operative healing period for 5-7 days.
The owners are advised to restrict the animal’s exercise for the first 6-8 weeks after surgery, while employing gentle, passive physiotherapy to help prevent elbow stiffness.
When early surgical intervention, accurate anatomic reduction and rigid internal fixation are employed a good to excellent result should be expected.
The typical stay following surgery is 1-2 days but will vary depending on the overall health of the pet and the underlying reason for the surgery.