What is the differential diagnosis for a 45-year-old female with right elbow pain, localized to the antecubital area and directly on the elbow, without a history of injury?

Differential Diagnosis for Right Elbow Pain in a 45-Year-Old Female

The most likely diagnosis is lateral epicondylitis (tennis elbow), given the patient's age, absence of trauma, and tenderness over the lateral epicondyle and antecubital area, though medial epicondylitis, biceps tendinopathy, cubital tunnel syndrome, and occult fracture must be systematically excluded. 1, 2, 3

Primary Differential Diagnoses by Anatomic Location

Lateral-Sided Pathology

• Lateral epicondylitis is the most common cause of lateral elbow pain in patients over 40 years old, affecting 75% on the dominant side, characterized by degenerative tendinopathy of the extensor carpi radialis brevis tendon with pain at the lateral epicondyle and pain with resisted wrist extension 2, 3, 4
• Radial tunnel syndrome should be considered if lateral epicondylitis treatment fails, as posterior interosseous nerve entrapment can mimic lateral epicondylitis but presents with pain 3-4 cm distal to the lateral epicondyle 3, 4
• Radiocapitellar arthritis or osteochondral lesions of the capitellum can cause lateral pain and should be excluded with imaging 1, 3

Anterior/Antecubital Pathology

• Biceps tendinopathy commonly causes anterior elbow pain and is associated with repeated elbow flexion with forearm supination and pronation, presenting with tenderness in the antecubital fossa 4
• Occult radial head fracture must be excluded despite no reported trauma, as patients can have pain out of proportion to examination, significantly limited range of motion, abnormal joint end feels, and exquisite pain with palpation 5
• Anterior capsular strain or synovitis can cause diffuse antecubital tenderness 1

Medial-Sided Pathology

• Medial epicondylitis affects the flexor-pronator mass origin and presents with medial-sided pain, though pain can radiate to the antecubital area 1, 6
• Cubital tunnel syndrome (ulnar neuropathy) causes medial elbow pain with paresthesias in the ulnar nerve distribution and should be considered if neurologic symptoms are present 3, 6

Other Considerations

• Intra-articular bodies or loose bodies can cause mechanical symptoms like locking or catching 1, 3
• Olecranon bursitis typically presents with posterior elbow swelling but can cause diffuse elbow pain 4
• Night pain or pain at rest suggests inflammatory or neoplastic processes requiring urgent evaluation 3

Diagnostic Workup Algorithm

Step 1: Initial Imaging

Obtain plain radiographs of the elbow immediately as the most appropriate initial imaging study to exclude fractures, intra-articular bodies, heterotopic ossification, osteochondral lesions, soft tissue calcification, and osteoarthritis. 1, 2, 3

• Look specifically for avulsion fractures at tendon attachment sites and joint effusions indicating occult fractures 2
• Obtain comparison views of the contralateral elbow to assess for asymmetry 1, 3

Step 2: If Radiographs Are Normal or Nonspecific

• Reserve ultrasound or MRI without contrast for cases where radiographs are normal but significant tendon, ligament, or muscle injury is suspected 1, 2
• Ultrasound has 81% sensitivity and 91% specificity for detecting full-thickness tendon tears and can evaluate biceps tendon, common extensor origin, and collateral ligaments dynamically 1
• MRI is preferred for chronic elbow pain and provides comprehensive soft tissue evaluation 1, 4

Step 3: If Neurologic Symptoms Present

• Obtain electromyography (EMG) and nerve conduction studies when neurologic symptoms suggest posterior interosseous nerve syndrome, radial tunnel syndrome, or cubital tunnel syndrome 3, 7

Clinical Examination Pearls

Key Physical Examination Findings

• Lateral epicondylitis: Tenderness at lateral epicondyle, pain with resisted wrist extension and radial deviation 2, 3, 4
• Biceps tendinopathy: Tenderness in antecubital fossa, pain with resisted elbow flexion and forearm supination 4
• Occult fracture: Pain severity out of proportion to examination, significantly limited ROM, abnormal joint end feels, exquisite pain with tuning fork bony palpation, positive elbow extension test 5
• Mechanical symptoms (locking, catching) suggest intra-articular pathology requiring advanced imaging 1, 3

Common Pitfalls to Avoid

• Do not assume absence of trauma excludes fracture: Occult radial head fractures can occur with minimal trauma and may be missed on initial radiographs, requiring repeat imaging in 10-14 days or CT if clinical suspicion remains high 1, 5
• Do not rely solely on lateral epicondylitis diagnosis: If treatment for lateral epicondylitis fails after 6-12 weeks, reconsider the diagnosis and evaluate for radial tunnel syndrome, nerve entrapment, or intra-articular pathology 3, 4
• Do not overlook referred pain: Cervical radiculopathy can refer pain to the elbow and should be considered if examination findings are inconsistent 7
• Do not miss septic olecranon bursitis: If any swelling is present posteriorly, aspirate and analyze bursal fluid to differentiate septic from aseptic bursitis 4