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Question

Difficulty: MediumPhysical Examination Findings

A 58-year-old man presents to the urgent care clinic complaining of left elbow pain and swelling that began 3 days ago. He works as a carpet installer and reports frequently leaning on his elbows during his work shifts. He denies any recent falls, skin abrasions, tick bites, or fevers. Vital signs are temperature 37.1°C (98.8°F), blood pressure 128/82 mmHg, heart rate 76/min, and respiratory rate 14/min. On physical examination, there is a discrete, fluctuant, 4-cm swelling over the posterior aspect of the left elbow with mild overlying erythema. The patient has full, painless passive range of motion of the elbow joint. Active range of motion is completely intact but elicits mild discomfort at the posterior elbow during maximum flexion. Palpation of the medial and lateral epicondyles reveals no tenderness. Which of the following is the most likely diagnosis based on these physical examination findings?

  1. Olecranon bursitisAnswer
  2. B
    Septic arthritis of the elbow
  3. C
    Lateral epicondylitis
  4. D
    Triceps tendon rupture
  5. E
    Cellulitis of the elbow

Answer

Olecranon bursitis
The correct diagnosis is olecranon bursitis. The hallmark physical examination finding that differentiates peri-articular conditions (such as bursitis or tendinopathy) from true intra-articular pathology (such as septic arthritis or gout) is the preservation of painless passive range of motion. In this patient, the joint capsule itself is completely unaffected, allowing the examiner to passively move the elbow without stretching inflamed synovial tissue. The localized, fluctuant swelling over the posterior elbow in a patient with a history of occupational pressure points clearly to isolated inflammation of the olecranon bursa.

Step-by-Step Solution

1
Analyze the patient's demographics, occupational history, and vital signs.
The patient is a carpet installer with chronic pressure on the elbows and no systemic signs of infection (afebrile).
Occupational history often reveals the mechanism of chronic microtrauma leading to musculoskeletal complaints.
2
Evaluate the specific physical examination findings of the affected joint.
There is a focal, fluctuant posterior swelling. Crucially, passive range of motion is full and painless, while active range of motion causes only mild discomfort.
Comparing passive versus active range of motion is the key clinical step to differentiate intra-articular from peri-articular pathology.
3
Synthesize the findings to formulate the most likely diagnosis.
The painless passive range of motion rules out intra-articular infection or inflammation. The focal, fluctuant mass corresponds to the anatomical location of the olecranon bursa.
Intra-articular processes (like septic arthritis) cause pain with any capsular movement, whereas peri-articular processes (like bursitis) allow for painless passive movement of the joint itself.

Key Concept

Differentiating articular from peri-articular pathology using physical examination relies heavily on passive range of motion; peri-articular disease (such as bursitis) typically preserves painless passive range of motion, whereas intra-articular disease restricts both active and passive motion due to severe pain.
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Topics

Physical Examination Findings

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