A 32-year-old man sustains a midshaft fracture of his left tibia during a motor vehicle accident. The fracture was surgically fixed and stabilized in a plaster cast soon after the patient arrived in the emergency department. Continuous morphine by patient-controlled anesthesia pump was provided for analgesic effect. Sixteen hours after the surgery, the patient complains of significant pain in his left calf. He appears very uncomfortable, is sweating and shifting restlessly in bed, and pleads for better analgesia. He has no other medical problems. His last tetanus toxoid booster shot was 2 years ago. Which of the following is most likely to be present on physical examination?

Question

A 32-year-old man sustains a midshaft fracture of his left tibia during a motor vehicle accident.  The fracture was surgically fixed and stabilized in a plaster cast soon after the patient arrived in the emergency department.  Continuous morphine by patient-controlled anesthesia pump was provided for analgesic effect.  Sixteen hours after the surgery, the patient complains of significant pain in his left calf.  He appears very uncomfortable, is sweating and shifting restlessly in bed, and pleads for better analgesia.  He has no other medical problems.  His last tetanus toxoid booster shot was 2 years ago.  Which of the following is most likely to be present on physical examination?

Quizplus · Accepted Answer

Explanation: This patient presents after surgical repair of a traumatic left tibial fracture with acute onset of muscle pain in the left calf worrisome for acute compartment syndrome. Common etiologies include traumatic long bone fractures, trauma without fracture (e.g., crush injuries, thermal burns, and vascular injury in extremities), and nontraumatic causes (e.g., prolonged limb compression, animal venom exposure, and nephrotic syndrome). Human muscle is divided into compartments linked by strong fascial planes that are not flexible. Each of the above etiologies can cause either a decrease in compartment size or an increase in compartment pressure that does not allow adequate tissue expansion for an increase in fluid in the injured area. The rise in the intracompartmental pressure causes decreased venous outflow, increased venous pressure, decreased arteriovenous pressure gradient, and decreased perfusion to the tissues. The end result is tissue edema and increased interstitial pressure. In the later stages, arterial blood flow also decreases, further worsening compartment pressure and edema (Choice A). Early symptoms for compartment syndrome include pain out of proportion to the injury, persistent deep pain, and paresthesias. Early physical signs of acute compartment syndrome include tightness of the area, muscle weakness, and pain with passive stretching of the muscles. Patients left untreated can have symptoms progress to paralysis, muscle contracture, sensory deficits, infection, and skin ulceration and tissue necrosis, possibly requiring amputation of the limb (Choice D). Compartment pressures should be measured, and pressures >20-30 mm Hg typically require fasciotomy as definitive therapy to relieve high compartment pressure. This patient should be evaluated emergently for compartment pressures and treated with fasciotomy if greatly elevated. (Choice B) Loss of deep tendon reflexes can be seen in association with acute compartment syndrome but is typically a later finding. (Choice E) Subcutaneous crepitation is a sign of air in the tissues, with possible tissue edema, and can be seen in trauma or gas gangrene but is not typically seen in acute compartment syndrome. Educational objective: Compartment syndrome should be suspected in patients with trauma who have early physical signs of extremity tightness, weakness, pain with passive muscle motion, and pain out of proportion to the injury (the most sensitive and early sign). Treatment involves measuring compartment pressures and fasciotomy. References: Acute compartment syndrome in lower extremity musculoskeletal trauma (http://www.ncbi.nlm.nih.gov/pubmed/16272268)

A 32-Year-Old Man Sustains a Midshaft Fracture of His Left