Fracture, Coronoid

By admin On Nov 30, 2023

Ovid: 5-Minute Sports Medicine Consult, The

Fracture, Coronoid

David A. Stone

Delmas J. Bolin

Basics

The coronoid process:
- An important stabilizer of the elbow to varus stress and posterior ulnar displacement.
- Part of the sigmoid notch, the portion of the proximal ulna that articulates with the humerus.
- Has several important soft tissue insertions:
  - The brachialis muscle inserts anteriorly, distal to the capsule; the anterior joint capsule inserts very close to the tip of the coronoid; the anterior bundle of the medial collateral ligament and the lateral collateral ligament complex insert at the base of the coronoid.
When the coronoid is fractured at the base, the ligament insertion sites are often preserved because failure occurs through bone, not the ligament insertions. Smaller fractures are likely to be associated with ligament injury.
Usual mechanism of injury is elbow dislocation as a result of a fall on an outstretched hand.

Description

Coronoid fractures are classified based on anatomic location of the fracture; subclassification according to the associated soft tissue injuries and fractures to determine treatment (1,2):

Type 1: Fracture of the tip of the coronoid:
- Tip subtype 1 fractures involve <2 mm of coronoid and may be isolated or associated with a fracture dislocation.
- Tip subtype 2 fractures involve >2 mm and generally is associated with “terrible triad” injuries (ie, elbow dislocation, radial head fracture, and coronoid fractures).
Type 2: Fracture of the anteromedial facet:
- Anteromedial subtype 1 fractures extend from just medial to the tip of the coronoid to the anterior half of the sublime tubercle (the insertion of the medial band of the medial collateral ligament).
- Anteromedial subtype 2 fractures extend to the tip of the coronoid.
- Anteromedial subtype 3 fractures extend to the anteromedial rim and the entire sublime tubercle but do not always extend to the tip of the coronoid.
Type 3: Fracture of the basal aspect of the coronoid involving >50% of the coronoid:
- Basal subtype 1 fractures involve the basal coronoid alone.
- Basal subtype 2 fractures are associated with fractures of the olecranon.

Epidemiology

Uncommon, rarely occurring as an isolated injury
In elbow dislocations, 2–15% of cases have coronoid process fractures.

Risk Factors

Displacement of large coronoid process fracture fragments has been associated with recurrent dislocation.
No known significant risk factors to date

Commonly Associated Conditions

Elbow instability
Radial head fracture
Olecranon fracture
Loss of range of motion
Degenerative joint disease (posttraumatic arthritis)
Ulnar, median, radial, and anterior interosseous nerve injury
Brachial artery injury
Heterotopic ossification

Diagnosis

History

Common mechanism is fall on outstretched hand.
Most patients with coronoid fractures present with elbow dislocations.
Direct impact is a less common cause.

Physical Exam

Diffuse edema within and around the elbow joint
Tenderness is usually multifocal. Look for radial head tenderness as well as olecranon tenderness.
Range of motion (ROM) is limited, and crepitus on ROM should be noted.
Anteroposterior instability may be present.
Neurovascular examination is paramount, especially if there is elbow deformity.
If elbow is dislocated, perform neurologic and vascular examinations before reduction. Repeat neurovascular examination after elbow dislocation is reduced, and assess for elbow instability.
Palpate radial head and olecranon to look for accompanying fractures.

Diagnostic Tests & Interpretation

Imaging

Standard elbow x-ray series (anteroposterior, lateral, and 1 or both obliques) should be requested at the time of evaluation.
- Evaluate for comminuted fractures, where reduction may not be advisable.
- Repeat plain radiographs after elbow relocation.
If radial head tenderness is present, radial head view should be added to x-ray series.
Advanced imaging: Small coronoid fractures can be difficult to distinguish from radial head fractures, and both CT scanning and MRI should be considered if radiographs are not definitive.

Differential Diagnosis

Elbow subluxation
Posterior lateral rotatory instability
Acute ulnar collateral ligament sprain
Radial head fracture
Hyperextension injuries to joint capsule

P.185

Treatment

Acute treatment (1,3)[B]:
- Elbow dislocations with coronoid fractures should be evaluated for instability and splinted in position of stability.
- Tip subtype 1 fractures do not involve the insertion of the anterior capsule and can be treated with immobilization for 1–2 wks.
- Tip subtype 2 fractures almost always involve the anterior capsule insertion and are often seen in terrible triad injuries. They should be referred to orthopedics; they often will require suture fixation because the fragments are too small to be secured with screws.
- Anteromedial subtype fractures are associated with incongruent articulation of the ulnohumeral joint and may lead to posttraumatic degenerative joint disease. These fractures require surgical stabilization.
- Basal coronoid fractures generally have less soft tissue disruption than tip or anteromedial fractures but require stabilization to prevent recurrent instability and traumatic degenerative joint disease.
Special considerations:
- Posttraumatic degenerative joint disease correlates with patient age.
- Ulnar nerve injuries occur from handling of nerve and do not always resolve.
- Subluxation or repeat dislocation usually requires repeat surgery.
- Contractures and heterotopic ossification are common after treatment.
Rehabilitation:
- Early mobilization with active and active assistive ROM should begin as soon as comfort allows, generally after 1 wk.
- A hinged brace to protect the elbow from varus and valgus stress generally is prescribed for the 1st month, and blocking of the terminal 30 degrees of extension during early rehabilitation is common.
- Prophylaxis for heterotopic ossification is not routine (eg, indomethacin or Naprosyn).
- Resistive exercises generally are delayed for 6 wks.
- Serial radiographs are commonly obtained to confirm maintenance of concentric reduction.

Surgery/Other Procedures

Surgery to repair soft tissue injuries associated with coronoid fractures is being performed increasingly.

Ongoing Care

Prognosis

Joint stiffness and limited ROM are common with prolonged immobilization.
Presence of posttraumatic arthritis correlates with patient age.
Pain is a common complaint in at least half of all patients after treatment.

Codes

ICD9

813.02 Fracture of coronoid process of ulna, closed
813.12 Fracture of coronoid process of ulna, open

Clinical Pearls

Coronoid fractures can be managed conservatively with meticulous diagnosis.
Athletes with associated soft tissue injuries or instabilities should be referred early for orthopedic evaluation.
Athletes return to play when fractures are healed and when they have restored painless ROM with normal strength and flexibility.
Recovery can be prolonged, and careful follow-up is important.
Patients with type 1 tip fractures generally can return to play within 6–8 wks.
Patients with injuries requiring surgery frequently require longer rehabilitation time prior to return to play.
Lockout elbow bracing should be considered because it can help to stabilize the elbow and can be an important adjuvant to healing and rehabilitation.