Differential Diagnosis for Elbow Locking

The patient's complaint of intermittent elbow locking over the past year can be attributed to various causes. Here's a categorized differential diagnosis:

• Single most likely diagnosis
  • Olecranon Bursitis: This condition, also known as "student's elbow," involves inflammation of the bursa at the back of the elbow, which can cause locking or catching sensations due to fluid accumulation or bursal thickening.
• Other Likely diagnoses
  • Loose Body in the Elbow: A loose fragment of bone or cartilage within the elbow joint can cause mechanical locking or catching, especially if the fragment interferes with joint movement.
  • Elbow Osteoarthritis: Wear and tear of the elbow joint can lead to the formation of osteophytes (bone spurs) or loose bodies, which may cause intermittent locking.
  • Medial or Lateral Epicondylitis: Although more commonly associated with pain, severe cases of golfer's or tennis elbow might lead to mechanical symptoms like locking due to tendon inflammation or tears affecting the joint's stability.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed)
  • Septic Arthritis: An infected elbow joint can present with a variety of symptoms, including locking, due to the accumulation of pus or inflammatory debris within the joint space. Prompt diagnosis and treatment are crucial to prevent joint destruction.
  • Tumor (e.g., Osteochondroma, Synovial Chondromatosis): Although rare, tumors within the elbow can cause mechanical symptoms, including locking. Early detection is vital for effective management and to prevent potential malignancy.
• Rare diagnoses
  • Elbow Ganglion Cyst: A ganglion cyst near the elbow joint can, in rare instances, cause mechanical symptoms by compressing nearby structures or by its presence within the joint.
  • Synovial Chondromatosis: A condition characterized by the growth of cartilage in the synovium of the joint, which can break off and form loose bodies, leading to locking or catching sensations.
  • Congenital or Acquired Elbow Deformity: Certain deformities, either present from birth or resulting from trauma, can lead to abnormal joint mechanics and symptoms like locking.

Each diagnosis has a unique set of clinical features and diagnostic approaches. A thorough history, physical examination, and appropriate imaging studies (e.g., X-rays, MRI) are essential for determining the underlying cause of the patient's symptoms.