Fractures of the adult distal humerus compromise ~2% of all fractures. Approximately one-third of humeral fractures occur in this region. The intercondylar fracture pattern is the most common type. Low-energy distal humerus fractures result from simple falls in the middle-aged and elderly, either from a direct force or from transferred axial force from a fall onto an outstretched hand. The mechanism of injury in younger individuals is more likely from motor vehicle accidents or sports.
Structurally, the distal humerus has a triangular medial and lateral column and connecting arch distally. Each column has an epicondyle and a condyle. The distal part of the lateral column is the capitelluml; whereas, the distal part of the medial column is the medial epicondyle. The trochlea is the medial most aspect of the articular segment, which serves as a "tie arch" between the columns. The capitellum and trochlea are the articulating portions of the distal humerus and project anteriorly ~45 degrees. The trochlea has a valgus angle of 4-8 degrees and is externally rotated 3-8 degrees. The intramedullary canal terminates 2-3cm proximal to the olecranon fossa.
Fractures of the distal humerus can be classified descriptively as supracondylar (extension-type or flexion-type), intercondylar, transcondylar, condylar, capitellum, trochlea, medial epicondylar, lateral epicondylar, or fractures of the supracondylar process. Intercondylar and condylar fractures can be classified according to the Riseborough-Radin and Milch classification systems, respectively.
Patients present with pain and swelling, making landmarks difficult to appreciate. Range of motion may elicit pain, crepitus, and/or gross instability. A careful neurovascular examination is essential. Serial examinations may be necessary to rule out an impending compartment syndrome. Significant swelling within the cubital fossa may cause vascular impairment or a volar compartment syndrome leading to Volkmann ischemia.
Standard AP, lateral, and oblique x-rays of the elbow should be obtained. A vertical split may be seen on the AP view extending between the medial and lateral columns in an intercondylar fracture. Traction views or a CT may help decipher the fracture pattern for pre-operative planning. An anterior or posterior "fat pad sign" may be evident on the lateral view from hemarthrosis or effusion in more subtle fractures.
The goal of treatment is anatomic articular reduction and restoration of alignment. Non-displaced fractures may be treated with splints, casting, and early range of motion. Internal fixation may be necessary to achieve a stable articular reduction. The articular segment must also be stably fixed to the metaphysis and diaphysis. Regardless of treatment selected, early elbow range of motion is critical to avoid long-term stiffness.
- Volkmann ischemic contracture: neurovascular compromise resulting from an unrecognized compartment syndrome
- Stiffness: early range of motion may prevent or reduce its severity
- Post-traumatic arthritis: can result from the initial articular impact and also from an imperfect articular reduction
- Ulnar neuropathy: improper reduction of lateral condylar fractures can cause a tardy ulnar nerve palsy requiring a transposition. Abundant callus formation of medial fractures can also cause ulnar nerve symptoms. The ulnar nerve is also at risk during surgical exposure.
- Heterotopic ossification