Distal Humerus Physeal Separation - Pediatric - Pediatrics

Introduction
Overview a distal humerus physeal separation is a traumatic fracture usually seen in children under the age of three and is often a birth fracture related to delivery. the fracture pattern should raise suspicion of child abuse. treatment is usually operative closed reduction and pinning. it is also referred to as a transphyseal distal humerus fracture Epidemiology demographics typically seen in children under the age of 3 although variations can be seen in older children (see below) Mechanism vaginal delivery (birth fracture) from force of labor or obstetric maneuvers shoulder dystocia and traumatic delivery are at higher risk cesarean section from excessive traction nonaccidental trauma rotational force / twisting fall on outstretched hand with elbow extended Pathoanatomy physis is biomechanically the weakest location in distal humerus Associated conditions abuse or battered child syndrome (up to 50%) Prognosis often missed diagnosis as very difficult to diagnose up to 50% missed by radiologist in patients with early recognition and prompt treatment, outcomes are very good
Classification
Salter-Harris classification older children (>3y) have Salter-Harris II injuries metaphyseal fragment attached to distal fragment younger children (<3y) have Salter-Harris I injuries pure physeal injury rare cases have intra-articular extension (Salter-Harris III or IV) can be difficult to differentiate from a lateral condyle fracture Displacement of the distal fragment most commonly posteromedial rarely can be anterior
Presentation
History birthing process (see above) fall from height (bed, chair, down stairs) typically onto extended elbow another child jumps/falls on a child's elbow nonaccidental trauma unwitnessed injuries inconsistent explanations history of multiple injuries, burns, bites, bruising skin lesions are most common findings in nonaccidental trauma Physical exam inspection pseudoparalysis / diminished spontaneous movement swelling or ecchymosis neurovascular rarely neurovascular compromise
Imaging
Radiographs recommended views AP and lateral centered on the elbow "baby gram" (radiograph of entire extremity) or forearm/arm radiographs can lead to missed diagnosis stress radiographs may be helpful to clarify the diagnosis skeletal survey if child abuse suspected findings posteromedial displacement of the radial and ulnar shafts relative to the distal humerus may be the only finding in infants forearm not aligned with humeral shaft soft tissue swelling, joint effusion (posterior fat pad) anterior fat pad may be absent if capitellar ossification center is present, it will be aligned with radius shaft, making diagnosis definitive Ultrasound indications uncertain diagnosis advantage no need for sedation disadvantage need experiences technician findings static exam detect separation of epiphysis from metaphysis by noting lack of cartilage at distal humeral metaphysis dynamic exam detect instability of epiphysis relative to metaphysis MRI not routinely used disadvantage requires sedation in young children Elbow arthrography indications uncertain diagnosis often combined with CRPP in OR findings visualization of entire distal articular surface and proximal radius technique posterolateral approach or direct posterior approach direct posterior into olecranon fossa recommended in young children to prevent iatrogenic damage to the articular cartilage when posterolateral portal is used inject equal parts saline:contrast bring elbow through range of motion if pinning is needed, arthrogram aids visualization of pin starting points on capitellum aids assessment of quality of reduction by seeing anterior humeral line intersecting capitellum advantage if performed under anesthesia in OR, can perform reduction and stabilization simultaneously if needed
Differential Diagnosis
Elbow dislocation almost never happens in <3 yrs because distal humerus physis is weaker than bone-ligament interface, predisposing to physeal fracture rather than ligament disruption/dislocation typically distal fragment is displaced posterolaterally with elbow dislocations Other fractures often misdiagnosed (or delayed diagnosis up to 1 week) as supracondylar, condyle, epicondyle fractures
Treatment
Nonoperative posterior long arm splint then long arm casting x 2-3 weeks indications limited role because most fractures are displaced nondisplaced fractures late presenting fractures treat nonoperatively initially deformity will persist/develop, requiring osteotomy in future Operative closed reduction and pinning indications displaced fractures (most) pinning is necessary to ensure adequate reduction, which may be lost with casting alone once the swelling subsides technique combined with elbow arthrogram to determine direction of initial displacement and adequate reduction
Technique
Closed Reduction and Pinning approach general anesthesia use elbow arthrogram to determine direction of displacement reduction maneuver gentle traction (very little force required) distal fragment may sometimes be grasped between index finger and thumb and reduced to humeral shaft correction of translation/malrotation elbow flexion acceptable parameters (similar to supracondylar humerus fractures) no cubitus varus anterior humeral line should bisect capitellum no malrotation pinning 2 or 3 x 0.062inch K wires these larger pins help prevent loss of reduction from lateral side, retrograde fashion divergent engage both cortices good spread at fracture site then perform live fluoroscopy through range of motion and slight varus/valgus stress to ensure no loss of reduction immobilization bend / cut pins splint the arm postoperative care admit overnight to observe for compartment syndrome (may not be necessary in all cases) see 1 week postoperatively with radiographs to ensure no loss of reduction see 3 weeks postoperatively with radiographs and remove pins in office allow full active ROM at that time physical therapy is rarely needed typically follow patients for 2-4 years after injury to ensure there is no growth arrest, deformity, or osteonecrosis (see below)
Complications
Cubitus varus up to 70% have this complication more common than with supracondylar fractures cause AVN of medial condyle malunion (common because of missed diagnosis, or loss of reduction) growth arrest treatment lateral closing wedge osteotomy Medial or lateral condyle AVN may lead to fishtail deformity seen in all distal humerus fractures Loss of motion usually no functional limitation Growth disturbance progressive cubitus varus joint irregularities angular deformity limb-length discrepancy treatment observe initially, undertake surgery when > 5 years old larger extremity child more cooperative can address all deformities in one surgery.