Exertional Compartment Syndrome in an Equestrian
David K. Lisle, MD; James B. Tucker, MD
THE PHYSICIAN AND SPORTSMEDICINE - VOL 32 - NO. 2 - FEBRUARY 2004
In Brief: When evaluating lower-leg pain, the clinician must consider compartment syndrome resulting from exercise, even in the absence of trauma or if the exercise is seemingly benign. Equestrian sports would seem an unlikely source of acute compartment syndrome, but the examiner should consider unusual mechanisms of injury in any case. Although intracompartment tissue pressure measurements can help make the diagnosis, excessive pain is a more reliable early warning sign of acute compartment syndrome. A timely diagnosis and immediate surgical treatment may prevent serious long-term sequelae.
Acute compartment syndrome is an orthopedic emergency that requires immediate surgical intervention. Despite growing awareness of compartment syndrome, its diagnosis continues to be a challenge, because the presentation of patients who have increased intracompartmental pressure varies. Compartment syndrome is often associated with significant direct trauma to a limb, but it may also be induced by strenuous activity. To our knowledge, the following case of exertional compartment syndrome linked to horseback riding is the first of its kind.
A 50-year-old woman came to the emergency department with numbness on the dorsum of her right foot and burning pain along the lateral right leg. Earlier in the day, she attended a horseback riding class to learn the posting technique. Posting requires riding off the saddle (figure 1), and the patient recalled using her calf muscles extensively for the entire 2-hour lesson. The patient stated that she had not ridden for 10 years before the day of the class. She denied any trauma to the limb but stated that severe pain began within the first hour of riding. The pain worsened following the lesson and was not relieved by over-the-counter pain medication.
Physical exam. The patient's right leg was edematous over the lateral compartment and severely tender with passive range of motion. Although the patient was unable to dorsiflex or plantar flex her foot, she was able to move her toes, and a palpable dorsalis pedis pulse was noted. The neurologic exam was normal except for mild paresthesia on the dorsolateral aspect of the affected foot.
Initial diagnosis and treatment. The differential diagnosis included tibial or fibular stress fracture, peroneal tendinitis, periostitis (medial tibial stress syndrome), fascial hernia, peroneal muscle strain, peroneal muscle spasm, and occult leg trauma. The diagnosis of peroneal muscle spasm was made by the emergency department physician, and the patient was discharged with instructions to ice the leg. She was given oxycodone hydrochloride and told to return if the pain worsened or continued for more than 3 days.
Subsequent exam. The pain increased in her right leg, and she returned to the emergency department 2 days later. She reported numbness extending from the dorsum of her foot to the lateral leg. She continued to have difficulty moving her foot and was able to bear weight only with extreme discomfort. Physical examination of the right leg revealed a tense lateral compartment extending from the head of the fibula to the lateral malleolus. The patient was able to plantar flex the affected foot, but she was unable to dorsiflex or evert. The lateral leg lacked sensation to light touch, and posterior tibial and dorsalis pedis pulses were appreciated.
Final diagnosis. Lateral compartment syndrome was clinically diagnosed, and an orthopedic consultation was requested to confirm the diagnosis. A Stryker pressure system indicated that her lateral and anterior compartmental pressures were 115 mm Hg.
Treatment. The patient underwent an emergency fasciotomy of the lateral compartment and decompression of the peroneal nerve. Two days later, the patient returned to the operating room for debridement of necrotic tissue. The anterior tibialis muscle was spared, but the peroneus longus and brevis muscles were swollen, fibrotic, and discolored. The muscles that appeared necrotic were excised. The patient recovered well postoperatively and was given a foot drop brace. She was discharged 11 days after her initial emergency department presentation.
Seven months after surgery, complete sensation on the dorsum of the foot had returned. Although no eversion was possible, she was able to dorsiflex the foot completely and no longer required the foot drop brace.
Exertional Compartment Syndrome
Much attention has been given to the increased incidence of compartment syndrome following heavy exertion in sports such as soccer, long-distance running, and cycling.1 This case adds equestrian sports to that list. In posting, foot position that stresses the lateral compartment and prolonged periods of holding one's weight off the saddle are implicated in causing acute compartment syndrome.
Exertional compartment syndrome develops when increased pressure within the limited confines of a myofascial compartment compromises the circulation and function of the enclosed tissues. During exercise, a 20% increase in the compartment volume may occur when muscle fibers swell and intracompartmental blood volume increases.2 The anterior compartment is affected in 40% to 60% of patients, and the deep posterior compartment is the second most common site at 20% to 40%. Both the anterior and lateral compartments are affected in 12% of patients, and pure lateral compartment syndrome occurs in only 3% to 10%.1,3,4
Diagnosis. The hallmark presentation for compartment syndrome is pain out of proportion to physical exam findings.5-7 Excessive pain, usually described as constant and poorly localized over the affected compartment, is one of the earliest signs. Other signs are pain with passive movement and sensory deficits or paresthesias in the distribution of the cutaneous nerve that passes through the involved compartment. Later signs, such as motor deficits and the absence of a dorsalis pedis pulse, may indicate well-established ischemia and possible permanent damage. The five "Ps" (pain, paresthesia, pallor, paralysis, and pulselessness) are all possible presentations, and if all five are seen, irreversible damage has most likely occurred. Pallor and pulselessness are both nonspecific signs of compartment syndrome and should not be used as the solitary diagnostic feature.8
When compartment syndrome is suspected, the objective measurement of intracompartmental tissue pressure may be used to help confirm the diagnosis; however, an accurate diagnosis may be made based solely on physical exam findings and clinical suspicion. The level of tissue pressure that requires fasciotomy remains controversial. Generalities about measurements should be avoided, because hypotensive and hypertensive individuals will have markedly differing cutoff pressures. Matsen et al5 suggest that fasciotomy be done at pressures greater than 45 mm Hg. Whitesides et al8 recommend fasciotomy when pressures are within 30 mm Hg of the patient's diastolic blood pressure.
Two important factors should be kept in mind when evaluating compartment pressure readings. First, the compartment pressure does not directly correlate with the severity of muscle and nerve ischemia. Second, the ability of muscle to withstand ischemia varies between patients.6 Therefore, compartment pressure measurement should be viewed as only one tool for the clinician. Although high compartment pressure is diagnostic, a low measurement should not rule out compartment syndrome when clinical evaluation is highly suggestive. The primary care or emergency physician should obtain an orthopedic consultation whenever compartment syndrome is suspected.
Treatment. Prompt surgical decompression is the only accepted treatment for compartment syndrome. The sooner treatment is initiated, the lower the incidence of residual deficits. The goal for the surgeon is to save the affected limb. The quality of decompression should not be compromised by aesthetics, such as the number or length of incisions. Adequate decompression can be performed using either one- or two-incision fasciotomies. Both techniques can successfully decompress all four compartments, but the double-incision technique allows for an easier decompression of the deep posterior compartment.6
Awareness of Elevated Pressure
Our literature search found no other reported cases of exertional compartment syndrome in the lateral compartment following horseback riding. Our patient presented with classic signs and symptoms of acute compartment syndrome, but the diagnosis was delayed by an absence of clinical suspicion in the emergency department. With no history of trauma and with an apparently harmless preceding activity (ie, horseback riding), the patient's presentation seemed unusual, and the diagnosis of compartment syndrome was not considered.
Although isolated peroneal compartment syndrome is truly rare, our literature review noted one case of an otherwise healthy 28-year-old male baseball player who experienced minimal trauma to the lateral leg.9 After prompt diagnosis and magnetic resonance imaging that did not delay treatment, the patient underwent emergency fasciotomy and had no permanent postoperative sequelae. Earlier diagnosis and treatment would have limited the severity of, or perhaps prevented, muscle necrosis and disability in the patient in our case report.
Our case emphasizes the need for a heightened suspicion of compartment syndrome in patients at risk, including those engaged in any type of strenuous exercise. The patient's own assessment of exertion level in an activity should alert the examiner to ask more questions about unfamiliar sports or activities. Compartment syndrome should be included in the differential diagnosis for all patients who have lower-leg pain that is out of proportion to physical exam findings, regardless of trauma history. An increased awareness of compartment syndrome and all of its different mechanisms will lead to earlier recognition and fewer delayed diagnoses.
Exertional compartment syndrome in the lateral compartment following horseback riding is rare. Patients who have a history of heavy exertion are at increased risk of compartment syndrome, but this is far more common in the anterior compartment. Our patient's unusual circumstances did not raise suspicion and delayed the correct diagnosis.
This case emphasizes that trauma to the lower leg is not required for the diagnosis of compartment syndrome. Heavy exercise, even as seemingly benign as horseback riding, can lead to a dangerous increase in intracompartmental pressure. By increasing the index of suspicion for compartment syndrome in patients who have unlikely histories but suggestive clinical presentations, permanent damage from compartment syndrome can be avoided.
Dr Lisle is a third-year resident, and Dr Tucker is the director of St Joseph's Hospital Family Medicine Residency in Syracuse, New York. Dr Tucker is also a professor of family medicine at State University of New York Upstate Medical University in Syracuse. Address correspondence to James B. Tucker, MD, St Joseph's Hospital, Dept of Medical Education, 301 Prospect Ave, Syracuse, NY 13203; e-mail to [email protected].
Disclosure information: Drs Lisle and Tucker disclose no significant relationships with any manufacturer of any commercial product mentioned in this article. No drug is mentioned in this article for an unlabeled use.