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Difficulty: MediumOrthopedic Surgery

A 6868-year-old man is evaluated in the surgical ward for a fever on postoperative day 55 following an uncomplicated right total knee arthroplasty. His temperature is 38.4∘C38.4^\circ\text{C} (101.1∘F101.1^\circ\text{F}), pulse is 98/min98/\text{min}, respirations are 16/min16/\text{min}, and blood pressure is 135/85 mmHg135/85\text{ mmHg}. The patient reports a new, deep aching pain in his right calf that is distinct from his surgical site pain. He has a medical history of hypertension and type 22 diabetes mellitus. Current medications include prophylactic subcutaneous enoxaparin, lisinopril, and metformin. Physical examination reveals a clean and dry surgical incision with mild, expected postoperative swelling around the knee, but no erythema, fluctuance, or purulent drainage. There is moderate, asymmetric swelling and tenderness in the right posterior calf. Passive dorsiflexion of the right foot elicits pain in the calf. Lungs are clear to auscultation bilaterally. A Foley catheter was removed on postoperative day 11, and he has been voiding without dysuria. Which of the following is the most appropriate next step in management?

  1. A
    Chest radiograph
  2. B
    Serum D-dimer assay
  3. C
    Urinalysis and urine culture
  4. Venous duplex ultrasonography of the lower extremityAnswer
  5. E
    Ultrasound-guided aspiration of the right knee

Answer

The correct answer is venous duplex ultrasonography of the lower extremity.
The most appropriate next step in management is a venous duplex ultrasonography of the lower extremity. This patient's clinical presentation is highly suspicious for a deep vein thrombosis (DVT), which classically presents on postoperative days 4 to 6 (the 'Walking' phase of the 5 Ws of postoperative fever). Following major orthopedic procedures such as total knee arthroplasty, patients are at a significantly elevated risk for venous thromboembolism despite prophylactic anticoagulation. Unilateral calf pain, asymmetric swelling, and pain with passive dorsiflexion (Homan sign) strongly suggest a DVT. Venous duplex ultrasonography is the diagnostic test of choice because it is non-invasive, highly sensitive, and highly specific for proximal lower extremity DVTs.

Step-by-Step Solution

1
Analyze the patient's vital signs and postoperative timeline.
The patient has a new fever on postoperative day 5 following a major orthopedic surgery.
Establishing the timeline helps narrow down the differential diagnosis using the '5 Ws' of postoperative fever.
2
Evaluate the localized physical examination findings.
There is unilateral right calf swelling and tenderness with a clean surgical site and clear lungs.
Localizing signs strongly point toward deep vein thrombosis (DVT) rather than pneumonia, a urinary tract infection, or a surgical site infection.
3
Determine the optimal diagnostic test for the suspected condition.
Venous duplex ultrasonography of the lower extremity is selected.
Ultrasound is the standard, non-invasive, first-line imaging modality required to confirm a suspected DVT before initiating therapeutic anticoagulation.

Key Concept

Postoperative deep vein thrombosis (DVT) frequently presents with low-grade fever and localized calf swelling 4 to 6 days after major orthopedic surgery. Venous duplex ultrasonography is the most appropriate initial diagnostic test.
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Topics

Orthopedic Surgery

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