A condylar humerus fracture refers to a break in the distal, joint-forming part of the humerus, near the elbow. These fractures are always accompanied by varying degrees of injury to surrounding soft tissues and can compromise locomotor function.

Classification and Types

Condylar humerus fractures are a subset of distal humeral fractures. They are specifically classified as complete articular fractures, meaning the joint surface is fractured and entirely detached from the diaphysis (shaft) of the bone. Humeral T- or Y-fractures are representative examples of this type. Partial articular fractures involving only part of the joint surface, such as unicondylar fractures (e.g., lateral or medial condyle fractures), are also common.

Specifically, distal humeral fractures are categorized as follows:

Distal Partial Articular (Type 1-3-B):
Lateral condyle sagittal fracture (B1).
Medial condyle sagittal fracture (B2).
Frontal unicondylar fracture (B3).
Distal Complete Articular (Type 1-3-C):
Simple, metaphyseal simple or wedge fracture (C1).
Simple, metaphyseal multifragmentary fracture (C2).
Multifragmentary fracture (C3).

Etiology and Predisposition

Humeral fractures account for 34% of forelimb fractures and 10% of all fractures in dogs, with the majority occurring in the middle and distal thirds of the bone. Condylar fractures (Type 1-3 B) are more common in dogs than supracondylar fractures, which are more common in cats.

The causes are generally categorized as:

Minor trauma (e.g., short fall) in young dogs.
Major trauma (e.g., vehicular accident, high fall) for diaphyseal and/or condylar fractures.
Fractures secondary to Incomplete Ossification of the Humeral Condyle (IOHC).
IOHC is the failure of fusion between the medial and lateral aspects of the humeral condyle.
Normally, ossification of this region is complete by 8 to 12 weeks of age.
In adult dogs with IOHC, a fibrous band remains, creating a structural weak point.
This condition is often seen bilaterally and is most common in spaniel breeds.
T-Y fractures (Type 1-3-C) in mature animals usually result from torsional stress and are particularly common in spaniel breeds due to their propensity for IOHC.

Clinical Presentation and Diagnosis

Animals with humeral fractures often present carrying the affected leg with the elbow dropped and the paw resting on its dorsal surface, which can mimic nerve injury. Correctly identifying the neurological status of the limb is crucial, and a withdrawal response to toe pinch and skin pricks can help determine if a concurrent nerve injury is present. Neurologic impairment is fortunately uncommon and usually temporary.

Diagnosis involves:

Palpation: The width of the condyles can be compared to the opposite side; it is increased with a condylar fracture.
Radiography: Essential for accurate diagnosis and treatment planning. At least two views at right angles are required. Prereduction radiographs of distal partial articular fractures typically show the fractured lateral portion dislocated proximally and rotated laterally and cranially, while the fractured medial epicondyle is usually rotated medially and caudally. Subluxation is present in the elbow joint.
Computed Tomography (CT): A reformatted dorsal CT scan can clearly show the hypoattenuating defect (fibrous band) between the medial and lateral aspects of the condyle in cases of incomplete ossification.

Surgical Approaches and Reduction

Accurate reduction of articular elbow fractures is imperative to prevent degenerative joint disease and elbow stiffness.

Surgical approaches for distal humeral fractures include:

Medial incision.
Lateral incision.
Often, both medial and lateral incisions are used.
For multiple or complex (Type C2 or C3) distal fractures, the transolecranon (caudal) approach by osteotomy of the olecranon tuber usually provides the best visualization and working area. This approach offers good exposure of the caudal surface of the distal humerus, including the condyle, trochlea, and anconeal process.
For simpler three-piece T-Y fractures, a combined lateral and medial approach can be used.

During open reduction of condylar fractures:

The fractured condyles are reduced and temporarily held by vulsellum or pointed reduction forceps.
Perfect anatomical reduction of the articular cartilages along the fracture lines is essential to prevent impingement of the anconeal process, limited range of movement, and abnormal wear.
For longer-standing condyle fractures (over 3-4 days old), an olecranon osteotomy (caudal approach) may be needed to simplify reduction due to increased soft tissue swelling and fragment adherence.

Fixation Techniques

The objective of fixation is rigid uninterrupted stabilization that can withstand considerable abuse during healing.

Specific techniques include:

Lag Screws:
Essential for most Type B (partial articular) and Type C (complete articular) intraarticular fractures in adult animals.
Fully threaded cortical screws are preferred over partially threaded cancellous screws because the dog's condylar bone is dense enough, and fully threaded screws are less prone to breakage in heavily stressed fractures like the lateral aspect of the humeral condyle.
Screws can be inserted diagonally from the opposite metaphyseal cortex into the fractured condyle, or from the articular surface for smaller fragments [587, 588f].
For T-Y fractures, a transverse hole is drilled through the condyles, and a cancellous or cortical screw is inserted with a lag effect to compress the fracture site, effectively converting it into a supracondylar fracture [134, 363, 365f].
All implants must be countersunk below the articular surface to prevent trauma to the opposing acetabular cartilage.
Intramedullary (IM) Pins and Kirschner Wires (K-wires):
Steinmann pins can be driven distally into the medial condyle for firm anchorage. Careful placement is needed to avoid breaking into the elbow joint.
An additional K-wire can be driven from the lateral epicondyle across the fracture to anchor in the medial cortex for Type A1 distal extraarticular fractures [113, 115f].
IM pins are not an option when the medial condyle is fragmented.
For toy breeds weighing less than 4 kg, two or more small pins or K-wires in a diverging pattern may be substituted for a transcondylar screw, but this is not recommended for larger breeds.
Additional K-wire in the epicondylar crest or a second screw in the metaphysis is necessary to prevent rotation and primary screw failure, especially if the metaphyseal fracture line is unfavorable for load sharing.
Bone Plates:
Generally preferred for comminuted distal metaphyseal/epiphyseal fractures of the humerus.
For supracondylar fractures, a caudomedial plate can be used, possibly supplemented with a lateral crest plate. The medial surface is flatter and easier to contour a plate to. Distal screws must be angled cranially to avoid the supratrochlear foramen.
Bone plate fixation has the highest percentage of successful results in T-Y fractures, especially Type C2 and C3.
For Type C2 (wedge) fractures, a bone plate applied caudally along the medial epicondylar crest and shaft is applicable.
Double-plate fixation is the safest method for Type C3 (multifragmentary) fractures. A medial plate is applied, and a second lateral plate is added in either neutralization or buttress fashion.
External Skeletal Fixators (ESF):
Unilateral type I single-bar or double-bar fixators are used for shaft fractures.
A distal fixation pin can be inserted across the condyles in a transcondylar position, as part of an ESF.
For complex Type A3 fractures, a strong buttress effect is needed, which can be supplied by double plating or a combination external skeletal fixator (hybrid type I-II) [120, 121f].

Postoperative Care and Prognosis

Elbow joint motion must be maintained postoperatively, so no external splintage is employed.
Passive Range of Motion (ROM) exercises are started as soon as tolerated.
Exercise is limited during the healing period.
IM pins are usually removed after clinical union. Other implants are left in place unless migration or soft tissue irritation occurs.
The prognosis for good to excellent function is high for distal partial articular fractures (89% for lateral condylar, 87% for medial condylar).

However, the prognosis is less optimistic for Type C (complete articular) fractures, with only 52% attaining good to excellent results in one study. Inadequate fixation is the most frequent cause of failure for T-Y fractures.