Review Question - QID 218562

This child has sustained a distal humerus physeal separation, which has a strong association with non-accidental trauma. Therefore, a skeletal survey must be performed to evaluate for additional bony injury.

Distal humerus physeal separations are relatively uncommon, but occur primarily in children <3 years old because of the lesser biomechanical strength of the physis at this age compared to ligaments and ossified bone. A fall on an outstretched arm or non-accidental trauma (NAT) are common mechanisms for injury. If NAT is suspected, child protective services should be contacted and a full work-up should be performed including a skeletal survey. With regards to the injury itself, there is usually posteromedial displacement of the distal segment, which can help differentiate it from an elbow dislocation which usually dislocates posterolaterally. Additionally, the capitellar ossification center remains well aligned with the proximal radius, indicating that the injury is through the distal humerus physis and not the elbow joint or proximal forearm.

Hariharan et al. examined transphyseal humerus separations in a multi-center study reviewing 25 years of data. They noted it to be relatively uncommon, occurring in 79 patients over the study course, with the most common mechanisms being accidental trauma and non-accidental trauma. Most patients were successfully treated with an arthrogram and lateral pinning, with a complication rate of 14%.

Leaman et al. looked at identifying factors for non-accidental trauma in children <2 years old, noting that fractures are the 2nd most common presentation of child abuse behind bruising/burns. They noted that 32% of fractures in children <1 year old and 5% in children 1-2 years old were considered NAT. Factors they noted to be associated with NAT included age <1 year age, multiple fractures, metaphyseal corner fractures, transverse diaphyseal fractures, and fractures in Medicaid patients.

Beckmann et al. published a case report on the imaging of a distal humerus physeal separation, noting that without diligence, these injuries can be mistaken for elbow dislocations. They discuss that radiographs and ultrasound can be useful diagnostic tools, depending on patient factors such as age and size. Once diagnosed, an arthrogram is a useful imaging tool intra-operatively to help with visualizing the reduction during pinning, as the distal humeral articular surface is mostly cartilaginous at this point.

Figures A & B are AP and lateral elbow radiographs that demonstrate a distal humerus physeal separation. Careful attention should be paid to the relationship between the capitellar ossification center and the proximal radius which are still congruent in these radiographs.

Incorrect Answers:
Answer 1: Elbow dislocations more commonly occur posterolaterally, while distal humerus physeal separations are more likely to occur posteromedially.
Answer 3: Nonoperative management is a treatment option, but in displaced fractures, as seen in Figures A & B, the patient would be at high risk for residual deformity and malunion.
Answer 4: Lateral epicondyle fractures occur in children most commonly between ages 6 and 8 and usually require surgical intervention. Distal humerus physeal separations are more common in children <3 years old.
Answer 5: Medial epicondyle fractures are at risk of having an incarcerated fragment remaining in the elbow joint, which would require urgent attention.