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Introduction

A capitellar fracture is a rare type of elbow injury involving the capitellum, which is a rounded bony prominence on the distal end of the humerus (upper arm bone). The capitellum articulates with the radial head of the forearm, allowing smooth movement and stability at the elbow joint. Fractures of the capitellum account for less than 1% of all elbow fractures, but they are clinically important because they can severely disrupt elbow function, range of motion, and long-term joint stability if not managed properly. Due to their intra-articular nature, these fractures often demand precise diagnosis and specialized treatment to restore joint congruity and prevent complications such as stiffness, instability, or post-traumatic arthritis.

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Anatomy of the Capitellum

The capitellum is located on the lateral side of the distal humerus. It is a spherical structure covered with articular cartilage and forms the humeroradial articulation by articulating with the radial head.
Key anatomical points include:

  • Location: Lateral part of the distal humerus.
  • Function: Helps in flexion, extension, pronation, and supination movements of the elbow.
  • Articular coverage: Almost completely covered with cartilage, which makes fracture healing more complex.
  • Blood supply: Provided by branches of the radial recurrent and radial collateral arteries. Damage during trauma may compromise healing.

Because the capitellum is intra-articular, fractures in this region are directly exposed to joint fluid, which can delay healing and increase the risk of degenerative changes.

Causes and Mechanism of Injury

Capitellar fractures are usually caused by trauma and are commonly associated with other elbow injuries. The mechanisms include:

1. Fall on an outstretched hand (FOOSH):

  • The most common mechanism.
  • A sudden axial load is transmitted through the radial head to the capitellum.

2. Direct trauma to the elbow:

  • Less common, but possible in high-energy injuries such as sports accidents or road traffic accidents.

3. Shearing force:

  • The fracture is typically the result of a shear force applied to the capitellum by the radial head when the elbow is partially flexed.

4. Sports injuries:

  • Gymnastics, football, or activities involving a fall or sudden impact can contribute.

5. High-energy trauma in younger patients and low-energy trauma in elderly:

  • In young adults, these fractures are often related to road traffic accidents.
  • In elderly, osteoporosis contributes, making fractures occur even with minor falls.

Clinical Features

Patients with a capitellar fracture usually present with the following symptoms:

  • Pain: Sudden onset of severe pain in the elbow, worsened by movement.
  • Swelling: Rapid swelling due to hemarthrosis (bleeding into the joint).
  • Limited motion: Difficulty in flexion, extension, and rotation of the forearm.
  • Mechanical block: The displaced fragment may block elbow motion.
  • Tenderness: Localized tenderness over the lateral aspect of the distal humerus.
  • Deformity: In displaced fractures, the contour of the elbow may appear abnormal.
  • Associated injuries: Radial head fractures, trochlear fractures, and ligament injuries may accompany capitellar fractures.

Diagnosis

1. Clinical Examination

A careful history of the mechanism of injury, along with localized tenderness, swelling, and restricted range of motion, raises suspicion.

2. Imaging Studies

X-rays:

  • Standard anteroposterior (AP) and lateral views are necessary.
  • Lateral view often shows the fracture better, as the capitellum is superimposed in the AP view.
  • Look for the “double arc sign” (representing fracture of both capitellum and trochlea).

CT Scan:

  • Provides detailed visualization of fracture pattern and fragment size.
  • Essential for preoperative planning, especially in comminuted or complex fractures.

MRI:

  • Rarely required, but may be useful in detecting osteochondral injuries or associated soft tissue injuries.

Management

The treatment of capitellar fractures depends on fracture type, displacement, and patient factors (age, bone quality, activity level).

1. Non-Operative Management

  • Indicated only for non-displaced fractures.
  • Immobilization with a posterior splint or cast for 2–3 weeks.
  • Early mobilization is encouraged to prevent stiffness.
  • Rarely used because most capitellar fractures are displaced.

2. Operative Management

Surgery is the preferred treatment for displaced fractures.

A. Open Reduction and Internal Fixation (ORIF)

  • Most commonly used method.
  • Small screws (headless compression screws or Herbert screws) are used to fix the fragment.
  • Aim is anatomical reduction and stable fixation to allow early mobilization.

B. Fragment Excision

  • Indicated in small, non-reconstructable osteochondral fragments.
  • Not preferred in large fragments due to risk of instability.

C. Arthroscopic-assisted fixation

  • Minimally invasive approach in select cases.
  • Allows direct visualization of articular reduction.

D. Total Elbow Arthroplasty

  • Considered in elderly patients with severe comminution or osteoporotic bone where fixation is not feasible.

Prognosis

The overall outcome depends on:

  • Accuracy of reduction.
  • Stability of fixation.
  • Early initiation of mobilization.

Most patients regain good function with timely and appropriate treatment. However, complications like stiffness and arthritis may limit long-term results, especially in complex or comminuted fractures.

Conclusion

Capitellar fractures, though uncommon, are serious injuries involving the articular surface of the distal humerus. They often occur due to falls or direct trauma and require careful diagnosis through clinical examination and imaging. While non-operative treatment is rarely suitable, surgical fixation using screws is the gold standard for displaced fractures. Early mobilization and physiotherapy are critical to achieving optimal recovery. With proper management, most patients achieve satisfactory function, though the risk of long-term stiffness and arthritis remains, highlighting the importance of precise treatment and diligent follow-up care.

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