Avulsion fracture of the medial epicondyle apophysis, usually extra-articular; fragment may incarcerate in the joint or be associated with elbow dislocation.
Represents ~10–20% of pediatric elbow fractures, often in boys 9–14 years, frequently linked to sports with valgus stress (throwing, gymnastics).
Relevant anatomy
Medial epicondyle:
Secondary ossification center: appears ~5–7 years, fuses ~15–18 years.
Origin of common flexor–pronator mass (pronator teres, FCR, PL, FDS, FCU).
Medial collateral ligament (ulnar collateral ligament – UCL) inserts partly on the epicondyle; fracture = functional UCL injury.
Ulnar nerve courses posterior to medial epicondyle → risk of neurapraxia or entrapment.
Epidemiology & risk factors
10–20% of pediatric elbow injuries; up to 30–55% associated with elbow dislocation (classically posterolateral).
~75% occur in males; peak age 11–13 years.
Mechanisms:
FOOSH (fall onto an outstretched hand) with valgus load.
Avulsion by flexor–pronator mass/UCL during throwing.
Elbow dislocation with medial epicondyle incarcerated in the joint.
Mechanism & pathophysiology
Valgus stress → tensile failure of medial epicondyle apophysis before UCL failure.
With dislocation: fragment may be avulsed and trapped intra-articularly; may obstruct reduction or remain incarcerated after reduction.
Chronic valgus overload in overhead athletes → apophysitis (“Little League elbow”) with risk of eventual avulsion.
Clinical presentation
Medial elbow pain, swelling, tenderness over medial epicondyle.
Possible deformity if associated dislocation.
Examination priorities
Assess elbow stability to valgus stress (in extension and 30° flexion).
Document ulnar nerve: intrinsic hand strength, sensation in ulnar digits.
Assess ROM and mechanical block (suggesting incarcerated fragment).
In throwing athletes: pain with valgus stress, decreased performance, “pop” at time of injury.
Imaging
Standard AP and true lateral elbow radiographs.
Oblique views and comparison films may help when ossification center nebulous.
Displacement measurement is difficult (fragment lies posteromedial, often displaced anteromedially); use consistent method (distance between cortical edges on AP/oblique).
CT or 3D CT rarely required; may help pre-op planning in incarcerated or markedly displaced fractures.
Ultrasound or MRI can be useful in equivocal cases or suspected associated UCL injury, but are not routinely required.
Classification (pragmatic)
By displacement / stability
Nondisplaced or <2–5 mm displaced.
Moderately displaced (~5–15 mm).
Grossly displaced (>15 mm) or fragment incarcerated in joint.
By associated lesions
Isolated fracture.
Associated elbow dislocation (reduced vs irreducible / incarcerated).
Associated ulnar nerve dysfunction.
No single universally accepted formal classification; clinical decision-making is based more on displacement, elbow stability, and associated injuries.
Treatment principles – general
Goals: restore medial column stability (UCL/flexor–pronator origin), prevent chronic valgus instability, pain, and nonunion.
Historically, majority treated nonoperatively; more recent trends show increasing surgical fixation, especially in active patients with displacement.
Nonoperative management
Indications (common across guidelines)
Nondisplaced or minimally displaced fractures (typically <5 mm; many authors accept up to 5 mm, some up to 10 mm in low-demand patients).
Stable elbow to valgus stress; no incarcerated fragment in the joint.
No mechanical block; no open injury.
Low-demand or non-overhead-athlete patient.
Method
Long-arm cast with elbow ~90° flexion, forearm neutral or slight pronation.
Duration 3–4 weeks, then progressive ROM.
Outcomes
High rate of fibrous or bony union with good function and low pain scores, even when radiographic nonunion persists.
Asymptomatic nonunion is common and usually benign; symptomatic nonunion or valgus instability may require delayed fixation.
Operative management
Clear indications (widely accepted)
Fragment incarceration within the elbow joint.
Elbow dislocation that cannot be reduced or remains unstable due to fragment.
Open fracture.
Ulnar nerve entrapment or progressive neuropathy.
Gross valgus instability.
Relative indications / gray zone
Displacement 5–15 mm: decision based on age, limb dominance, sport (overhead/throwing/gymnast), and surgeon preference.
High-demand overhead athletes: many authors favor fixation even for 5–7 mm displacement to optimize valgus stability.
Evidence summary on displacement thresholds
Systematic reviews show:
Operative fixation → higher union rates but no clear superiority in pain or functional scores vs nonoperative treatment overall.
Recent meta-analyses and large cohort data (including JAMA Network Open 2025) suggest cast immobilization can provide functional outcomes comparable to surgery in many displaced fractures, with fewer complications and reoperations, but with more radiographic nonunion.
Clinical practice remains heterogeneous; counseling should reflect this uncertainty.
Surgical technique (overview)
Approach: medial elbow incision; protect ulnar nerve (identify and decompress if needed).
Remove incarcerated fragment from joint if present; irrigate and inspect articular surface.
Reduce fragment anatomically to distal humerus; temporarily fix with K-wires.
Definitive fixation:
Smooth or partially threaded K-wires (often 1–2, crossed).
Cannulated screw (with or without washer) in older children/adolescents with sufficient fragment size.
Confirm reduction and stability fluoroscopically; assess valgus stability intra-operatively.
Post-op: short immobilization (1–3 weeks) followed by early ROM.
Complications
Common
Radiographic nonunion or fibrous union (more frequent after nonoperative treatment; often asymptomatic).
Mild loss of elbow motion (usually extension).
Valgus instability
Results from inadequate restoration of UCL origin.
Can present with pain in throwing, positive valgus stress test, late ulnar neuropathy.
Ulnar nerve dysfunction
Neurapraxia at presentation, iatrogenic injury, or delayed neuropathy due to valgus laxity or hardware irritation.
Symptomatic nonunion / malunion
Medial elbow pain, instability, or deformity → may require late ORIF ± bone graft.
Less common; risk increased after extensive dissection and prolonged immobilization.
Outcomes
Overall, both nonoperative and operative treatments yield high rates of return to activities and satisfactory patient-reported outcomes when indications are appropriately selected.
Key controversies / practical decision points
Optimal displacement threshold for surgery (2 mm vs 5 mm vs 10 mm) – no consensus; decision should integrate:
Objective displacement.
Stability, dominance, sport demands, and imaging evidence of incarceration or articular involvement.
Role of routine fixation in overhead athletes with modest displacement:
Some advocate early ORIF to restore UCL origin and prevent valgus instability; others report excellent outcomes with casting and gradual return.
References
Kamath AF, Baldwin K, Horneff J, Hosalkar HS. Operative versus non-operative management of pediatric medial epicondyle fractures: a systematic review. J Child Orthop. 2009;3(5):345-357. doi:10.1007/s11832-009-0192-7
Rehm A, Thahir A, Ngu A. Pediatric Medial Epicondyle Fracture Management: A Systematic Review. J Pediatr Orthop. 2021;41(2):e202-e203. doi:10.1097/BPO.0000000000001692
Grahn P, Helenius I, Hämäläinen T, et al. Casting vs Surgical Treatment of Children With Medial Epicondyle Fractures: A Randomized Clinical Trial. JAMA Netw Open. 2025;8(5):e258479. Published 2025 May 1. doi:10.1001/jamanetworkopen.2025.8479
