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.

The overwhelming majority of distal humeral fractures involve the elbow joint and are classified according to their anatomic location. Lateral condylar fractures are common and may occur from either minor or severe trauma in dogs and cats of all ages. Because of the close proximity of the thoracic cavity, additional injuries such as pneumothorax, hemothorax, pulmonary contusion, traumatic myocarditis, diaphragmatic hernia, and thoracic wall trauma can occur concurrently with humeral fractures. These potential injuries should be identified and treated appropriately prior to repair of the humeral fracture.

The severity of the trauma sustained has been shown to influence the resulting fracture type. While severe trauma has been shown to result in simple lateral condylar fractures and the associated injuries previously mentioned, the majority of lateral condylar fractures result from minor trauma. 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 principal centers of ossification of the developing distal humerus. A 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 the normal activity. 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.

What are humeral condylar fractures?

The humeral condyle is the name given to the end of the bone (called the humerus) at the top of the front leg (the forelimb). Together with the radius and ulna (the two bones of the antebrachium or forearm) the humeral condyle makes up the elbow joint. Fractures of the humeral condyle are amongst the most common type of broken bone seen in dogs. They also occur in cats but are much less common in this species.

Two types of fractures are seen. In young dogs that jump down from a height it is not uncommon for the force travelling up the limb when the animal lands to cause a fracture of the condyle. In some other dogs, there is an inherent weakness of the condyle, known as a humeral condylar fissure, and this weakness can cause a fracture during normal exercise. This type of fracture is more common in spaniel breeds, such as the Springer Spaniel. Fractures often involve one side of the condyle with the outside (lateral) aspect being more frequently involved than the inside (medial) aspect; however, in some dogs both sides of the condyle can fracture in a ‘Y’ or ‘T’ shaped configuration.

How are humeral condylar fractures diagnosed?

Radiographs (X-rays) of the elbow enable the diagnosis of humeral condylar fractures. In some cases it is important to obtain a number of views of the joint since the fracture may be minimally displaced. Occasionally more advanced imaging of both elbow joints, such as a CT scan, can provide additional useful information such as a fissure in the humeral condyle of the other limb.

How are humeral condylar fractures treated?

Surgery is the best treatment for almost all humeral condylar fractures. The operation involves repositioning the bone fragments back into the correct place and stabilising them using screws, pins and bone plates. Fracture repair can be challenging due to the involvement of the joint (with the need to accurately reconstruct this component of the fracture to minimize the subsequent development of osteoarthritis), the small size of the fragments and the possibility of an underlying weakness in the bone that can affect fracture healing. However, with appropriate surgical technique, most dogs are very comfortable after their operation and can start to walk and bear weight on the limb within a day or so.

What aftercare is needed?

Most dogs can go home the day after surgery with only a light dressing on the limb. Walks on the lead can be started immediately, but unrestricted exercise off the lead, such as running or jumping must be avoided. As with most fractures, painkillers are usually given for a week or so.

Physiotherapy and hydrotherapy are often recommended. Dogs that have undergone the surgery need to be taken to their local vets for a check-up after one week and then after two weeks for removal of skin stitches. We would normally plan to see dogs back for reassessment after about six weeks, when follow up X-rays may be taken.

What are the risks and possible complications?

Although surgery is very successful in the majority of dogs, there are potential risks and complications. These can include infection, poor bone healing and implant breakage. In the long term, some degree of osteoarthritis is almost inevitable, although in many dogs this does not cause any major problems.

In dogs with an underlying humeral condylar fissure, or weakness in the condyle, the weak point may never fully heal and screw breakage can be seen in the long term. Treatment of screw breakage may necessitate another operation.

All aspects of your pet’s care, including the risk of complications, will be discussed in detail during your initial consultation with the orthopaedic surgeon, before any treatment is started.

What is the outlook for my dog?

Surgery for fractures of the outside (lateral aspect) of the humeral condyle is relatively routine and the outlook is generally good, although some degree of osteoarthritis of the joint is often seen. It should be borne in mind that, although the surgery is relatively straightforward, there is no margin for error and problems can be seen, especially in the hands of inexperienced surgeons.

Overview

  • 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:

  • 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.

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.

After Care:

  • 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.

Prognosis:

  • When early surgical intervention, accurate anatomic reduction and rigid internal fixation are employed a good to excellent result should be expected.

Hospitalization:

  • 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.