Compartment Syndrome of the Lower Leg

Original Editors - Geoffrey De Vos

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Introduction

Acute compartment syndrome (ACS) of the lower leg is a time-sensitive orthopedic emergency that relies heavily on precise clinical findings.

• Lower leg ACS is a condition in which increased pressure within a muscle compartment surrounded by a closed fascial space leads to a decline in tissue perfusion and compromises motor and sensory function.
• In addition to muscle, key structures within the fascial compartment that are affected by increased compartment pressures include nerves and vasculature.

Late findings of ACS can lead to limb amputation, contractures, paralysis, multiorgan failure, and death. Hallmark symptoms of ACS include the 6 P’s: pain, poikilothermia, pallor, paresthesia, pulselessness, and paralysis. The definitive treatment of ACS is timely fasciotomy.

Image 1: Compartment Syndrome Picture

Etiology

Any condition that results in an increase of pressure in a compartment can lead to the development of acute (ACS) or chronic exertional compartment syndrome (CECS).

ACS occurs after:

• Fracture of the tibial diaphysis
• Soft-tissue injury
• Intensive muscle use
• Everyday extreme exercise activities
• Arterial injury
• Drug overdose
• Burns

One of the main causes of CECS is repetitive and strenuous exercise. During strenuous exercise, there can be up to a 20% increase in muscle volume and weight due to increased blood flow and oedema, so pressure increases. If this pressure elevates to 30 mmHg or more, small vessels in the tissue become compressed, which leads to reduced nutrient blood flow, ischemia and pain.^[ The anterior compartment is affected more frequently than the lateral, deep and superficial posterior compartments.

Male patients are ten times more impacted by ACS than females, possibly due to males having larger muscle mass within a fixed compartment. Younger patients (≤ 35 years of age) are also at a greater risk to ACS due to having tighter fascia and larger muscle mass and as they are prone to injuries or accidents

Clinically Relevant Anatomy

There are four compartments in the lower leg and these include the anterior, lateral, superficial posterior and deep posterior compartments.

Each compartment contains specific nerves, arteries and veins, muscles, and bony structures that with injury contribute to the unique clinical presentations in ACS.

Knowledge about the most important structures within these compartments is critical to efficiently assess and diagnose physiologic changes in ACS that contribute to pathologic development

Characteristics/Clinical Presentation

Patients with compartment syndrome of the lower leg suffer from long term impairment such as reduced muscular strength, reduced range of motion and pain. The most common symptoms by a compartment syndrome are:

• Feeling of tightness
• Swelling
• Pain (on active flexion knee and particularly passive stretching of the muscles)
• Paresthesia

Pain and swelling are the leading symptoms in this condition and it appears and aggravates during physical activities such as running and other sports like basketball and football. The pain is usually located over the involved compartments and may radiate to the ankle or foot. Burning, cramping, or aching pain and tightness develop while exercising. In extreme cases (or with inappropriate treatment) it is possible that the lower leg, ankle and foot can be paralysed.

Pain:
Pain is classically the first sign of the development of ACS, is ischaemic in nature and is described as being out of proportion to the clinical situation. The sensitivity of pain in the diagnosis of ACS is only 19 % with a specificity of 97 %, which can result in a high proportion of false-negative or missed cases, but a low proportion of false-positive cases and if present the condition is recognised relatively early.

Pain is often felt with passive stretching of the affected muscle group. For example, if ACS is suspected in the deep posterior compartment of the leg and the foot is dorsiflexed, increased pain will be evident.

Neurological symptoms and signs:
Paraesthesia and hypoesthesia may occur in the territory of the nerves traversing the affected compartment and are usually the first signs of nerve ischaemia, although sensory abnormality may be the result of concomitant nerve injury. Ulmer reported a sensitivity of 13 % and specificity of 98 % for the clinical finding of paraesthesia in ACS, a false-negative rate that precludes this symptom from being a useful diagnostic tool.

Paralysis of muscles contained in the affected compartments is recognised as being a late sign and has equally low sensitivity as others in predicting the presence of ACS, probably because of the difficulty in interpreting the underlying cause of the weakness, which could be inhibition by pain, direct injury to muscle, or associated nerve injury.

Swelling:
Swelling in the compartment affected can be a sign of ACS, although the degree of swelling is difficult to assess accurately, making this sign very subjective. The compartment may be obscured by casts, dressing, or other muscle groups, for example in the case of the deep posterior compartment.

Diagnostic Procedures

Diagnosis of ACS is based largely on physical examination and six cardinal clinical manifestations described as the six P's.

• The six P's include: (1) Pain, (2) Poikilothermia, (3) Paresthesia, (4) Paralysis, (5) Pulselessness, and (6) Pallor. The earliest indicator of developing ACS is severe pain. Pulselessness, paresthesia, and complete paralysis are found in the late stage of ACS.
• Additionally, serial measurement of ICP is critical in confirming and determine progression of ACS.
• Other diagnostic considerations including the use of ancillary testing such as laboratory testing or imaging.

Assessment

Acute compartment syndrome

• On assessment, the primary finding is swelling of the affected extremity
• The inability to actively move flexors and extensors of the foot is an important indicator
• Signs such as progression of pain
• Pain with passive stretching of the affected muscles
• Often a disturbance sensation in the web space between the first and second toes is found as a consequence of compression or ischemia of the deep peroneal nerve. This nerve is found in the anterior compartment. Reduced sensation represents a late sign of ACS
• Absence of arterial pulse is more often a sign of arterial injury than a late sign of ACS
  

Chronic exertional compartment syndrome

• Pain starts within first 30 minutes of exercise and can radiate to ankle/foot
• Pain ceases when activity is stopped
• Daily activities usually not provocative
• On assessment, the primary finding is swelling of the affected extremity
• The inability to actively move flexors and extensors of the foot is an important indicator
• Signs such as progression of pain
• Recording of intra-compartmental tissue pressures (needle and manometer, wick catheter, slit catheter)

Outcome Measures

The most important determinant of a poor outcome from acute compartment syndrome after injury is delay in diagnosis. The complications are usually disabling and include infection, contracture and amputation. One of the main causes of delay may be insufficient awareness of the condition. While it is acknowledged that children, because of difficulty in assessment, and hypotensive patients are at risk, most adults who develop acute compartment syndrome are not hypotensive. Awareness of the risk of the syndrome may reduce delay in diagnosis. Continuous monitoring of compartment pressure may allow the diagnosis to be made earlier and complications to be minimised. Early diagnosis and treatment are important in order to avoid long-term disability after acute compartment syndrome.

Treatment

The gold standard treatment is fasciotomy, but most of the reports on its effectiveness are in short follow-up periods. It is recommended that all four compartments (anterior, lateral, deep posterior and superficial posterior) should be decompressed by one lateral incision or anterolateral and posteromedial incisions.

• Post operative care: Focuses on the following: (1) completion of frequent neurovascular examinations to ensure both adequate release of the affected compartment and that no new damages were incurred during the operative procedure, (2) tissues, if left open, are pink and viable, (3) use of negative pressure devices to facilitate sealing of wound and removal of wound exudate, and last (4) control of swelling
• Nonoperative treatmentWhenever safe and possible, simple treatment measure in ACS include loosening ace wraps, compression dressings, splints and uni- or bivalving casts.6 Elevation of extremity no higher than the level of the heart facilitates venous drainage, reduces edema and maximize tissue perfusion.6 Further, avoidance of knee flexion and foot dorsiflexion will facilitate uncompromised circulation throughout a limb and limit increases in ICP in the deep posterior compartment respectivelyTreatment should begin with rest, ice, activity modification and if appropriate, nonsteroidal anti-inflammatory drugs.

Physical Therapy Management

The only nonoperative treatment that is certain to alleviate the pain of CECS is the cessation of causative activities. Normal physical activities should be modified, pain allowing. Cycling may be substituted for running in patients who wish to maintain their cardiorespiratory fitness, as it is associated with a lower risk of compartment pressure elevation. Massage therapy may provide some benefit to patients with mild symptoms or to those who decline surgical intervention. Overall, however, nonoperative treatment has been generally unsuccessful and symptoms will not disappear without treatment. As alluded to, untreated compartment syndrome can cause ischemia of the muscles and nerves and can eventually lead to irreversible damage like tissue death, muscle necrosis and permanent neurological deficit within the compartment.

Physical Therapy in CECS

Conservative therapy has been attempted for CECS, but it is generally unsuccessful. Symptoms typically recur once the patient returns to exercise. Discontinuing participation in sports is an option, but it is a choice that most athletes refuse.

Conservative therapy

Conservative treatment of CECS mainly involves a decrease in activity or load to the affected compartment. Aquatic exercises, such as running in water, can maintain/improve mobility and strength without unnecessarily loading the affected compartment. Massage and stretching exercises also have been shown to be effective. Massage therapy can also help by patients with mild symptoms or people who have declined surgical intervention, enabling them to engage in more exercise without pain. Nonoperative therapy is aimed at obtaining or preserving joint mobility.

Pre-surgical therapy

Pre-surgical therapy in CECS includes reduction of activity, with encouragement of cross-training and muscle stretching before initiating exercise. This approach may also be helpful for primary prevention of CECS, although only limited research is available. Other preoperative measures are rest, shoe modification, and the use of nonsteroidal anti-inflammatory medications (NSAIDs) to reduce inflammation. It is recommended to avoid casting, splinting, or compression of the affected limb.

Post-surgical therapy

Post-surgical therapy for CECS includes assisted weight bearing with some variation, depending on surgical technique. Early mobilisation is recommended as soon as possible to minimise scarring, which can lead to adhesions and a recurrence of the syndrome.

Activity can be upgraded to stationary cycling and swimming after healing of the surgical wounds. Isokinetic muscle strengthening exercises can begin at 3-4 weeks. Running is integrated into the activity program at 3-6 weeks. Full activity is introduced at approximately 6-12 weeks, with a focus on speed and agility. The following are recommendations for a full recovery and to avoid recurrence;

• Wearing more appropriate footwear to the terrain
• Choosing more appropriate surfaces and terrain for exercise
• Pacing your activities
• Avoiding certain activities altogether
• Mastering strategies for recovery and maintenance of good health (e.g, appropriate rest between sessions)
• Modifying the workplace to lower the risk of injury

Postoperative physical therapy is essential for a successful recovery. depending on the nature of the procedure, expected timelines for healing and progress made during rehabilitation. Treatment incorporates strategies to restore range of motion, mobility, strength and function.

Conclusion

1. Acute Compartment Syndrome (ACS) of the lower leg is a time sensitive limb threatening surgical emergency.
2. Late findings of ACS can lead to limb amputation, contractures, paralysis, multi-organ failure and death.
3. Diagnosis is based on clinical suspicion, assessment of the six P's (pain, poikilothermia, pallor, paresthesia, pulselessness and paralysis) and intracompartmental pressure (ICP).
4. ICP measurement above 30mmHg is considered critical and treatment with emergent surgical decompression should be considered.
5. The gold standard of acute compartment treatment is full fasciotomy.