Chapter 21: Leg

The tibia is the only weight-bearing bone in the leg. The fibula is bound to the tibia by the interosseous membrane, which divides into a “Y” both proximally and distally. The proximal arm of the “Y” is composed of the anterosuperior tibiofibular ligament and the posterosuperior tibiofibular ligament. A similar division occurs distally with an anteroinferior and posteroinferior tibiofibular ligament. The upper portion of the fibula is of little importance and can be excised with little consequence. The lower portion cannot, because of its importance in forming the ankle mortise.

The muscles of the leg are enclosed in four fascial compartments: anterior, peroneal, deep posterior, and superficial posterior compartments. The anterior compartment includes the ankle and the foot dorsiflexors and the posterior compartments (superficial and deep) contain the plantar flexors. The peroneal compartment houses the foot evertors.

Tibial Shaft Fractures

Tibial shaft fractures are the most common long bone fractures in the body. Because of the superficial location in the leg, the tibia is also the most common bone involved in open fractures.

Because the tibia and fibula run parallel to each other and are tightly bound together by ligaments, a displaced fracture of one bone is frequently associated with a fracture of the other bone.

Tibial shaft fractures are classified on the basis of principles established by Nicoll.¹ Three factors determine the outcome of tibial shaft fractures.

1. Initial displacement

2. Comminution

3. Soft-tissue injury

Fractures are divided based on displacement into three groups: (1) <50% displacement, (2) >50% displacement, and (3) complete displacement or severely comminuted (Fig. 21–1). Tibial shaft fractures with <50% displacement have a 90% chance of union, whereas fractures with complete displacement have only a 70% chance of union.

The degree of associated soft-tissue injury is an often unrecognized factor affecting prognosis and treatment of the fracture.^2,3 Fractures associated with significant contusion of the overlying skin or muscles are associated with higher infection rates and poorer healing.

The average healing time for uncomplicated, nondisplaced fractures is 3 months. For displaced, open, or comminuted fractures, the average healing time is 4 to 6 months.

Mechanism of Injury

Multiple mechanisms may result in fractures of the tibia and fibula shafts. Direct trauma is a common cause of injury and usually results in associated soft-tissue injury. These fractures are frequently secondary to automobile collisions and typically result in transverse or comminuted fractures.

Indirect trauma associated with rotary and compressive forces, as from skiing or falling, usually results in a spiral or oblique fracture. Rotary forces occur when the leg and body rotate around a planted foot and are most likely to cause a spiral fracture. Bending forces may also result in a fracture that is oblique or transverse.⁴ A tibial plafond fracture is typically secondary to a fall from a height that drives the talus up into the tibia. These fractures are intra-articular and are covered in Chapter 22.

Examination

Tibial shaft fractures usually present with pain, swelling, and deformity. Although neurovascular damage is not commonly seen after these injuries, documentation of pulses as well as peroneal nerve function (dorsiflexion and plantar flexion of the toes) is imperative. The dorsalis pedis pulse should be palpated and compared with the uninjured extremity. Other findings consistent with compartment syndrome should be sought and the pertinent negative findings documented on the chart (see “Associated Injuries”).

Imaging

Anteroposterior and lateral views are generally adequate in defining the position of the fracture fragments (Figs. 21–2 to 21–4). When describing these fractures, it is important to assess the following:

1. Location: proximal, middle, or distal third

2. Type: transverse, oblique, spiral, or comminuted

3. Displacement: percentage of fracture surface contact

4. Angulation: valgus or varus of the distal fragment

Associated Injuries

Compartment syndrome is a frequently associated finding after a tibia fracture, and the clinical evaluation and documentation should reflect that the clinician considered this diagnosis. Tibia fractures are the most common cause of compartment syndrome, accounting for 36% of all cases. The incidence of compartment syndrome after tibial shaft fractures is 4.3%. It is three times more common in individuals younger than 35 years old.⁵

Evidence of a compartment syndrome is usually present within the first 24 to 48 hours following the injury. The muscle compartments should be palpated for tenderness or tenseness. Pain with passive stretch should be noted as well as the sensation between the first and second toes as an indicator of peroneal nerve function. If a compartment syndrome is suspected, emergent orthopedic consultation is recommended. The determination of compartment pressures, in addition to a thorough clinical examination, will determine the subsequent management plan.⁶

As mentioned earlier, neurovascular damage at the time of injury is uncommon, although severe injuries may present with incomplete or complete disruption of the neurovascular structures.⁷

Treatment

The emergency department (ED) management of tibial shaft fractures includes immobilization in a long-leg splint with the knee in 10 to 15 degrees of flexion and the ankle flexed at 90 degrees. The splint should extend from the mid-thigh to the metatarsal heads. An emergent reduction of a closed fracture is indicated when there is a limb-threatening vascular compromise.

Open fractures may be gently cleaned and dressed (Fig. 21–5). Tetanus prophylaxis (when indicated) and parenteral antibiotics should be initiated. Emergency operative debridement with external or internal fixation is recommended.^8–10

Emergent orthopedic consultation is advised for patients with tibial shaft fractures because of the high incidence of compartment syndrome, which may evolve later. For this reason, patients with tibial shaft fractures and significant soft-tissue swelling should be hospitalized with elevation of the extremity and close observation for the development of a compartment syndrome.

Definitive treatment options include cast or brace immobilization, external fixation, and intramedullary nailing. Plating is occasionally used today, but the operation may cause additional soft-tissue injury. The degree of fracture displacement and comminution, mechanism of injury (high energy vs. low energy), and associated soft-tissue injury all play an important role in the surgeon’s selection of therapy.

Closed treatment with a long-leg non–weight-bearing cast is reserved for patients with nondisplaced fractures with minimal soft-tissue injury.³ A displaced fracture that undergoes closed reduction can also be treated closed as long as it is stable. Tibial shaft fractures managed nonoperatively must be monitored with frequent radiographs to ensure that the fracture does not displace during treatment. The cast can usually be removed within 6 to 8 weeks, after callus formation has occurred. Problems with cast immobilization include knee stiffness and difficulty ambulating following treatment.

When there is displacement, comminution, or instability, intramedullary nailing is the treatment of choice of most orthopedic surgeons.^3,10–13 The prevalence of nonunion and malunion is greatly decreased compared with the other methods of treatment. In addition, patients had less time off work with a more predictable and rapid return to full function.¹² In patients with severe open tibial shaft fractures, external fixation with delayed intramedullary nailing is preferred.^2,3

Complications

Shaft fractures of the tibia and fibula have several significant complications.

1. Nonunion or delayed union

2. Compartment syndrome

3. Chronic joint pain or stiffness

Fibular Shaft Fracture

Isolated fibular shaft fractures are uncommon injuries and are usually associated with a tibia fracture (Fig. 21–6). They are often due to direct trauma over the lateral aspect of the leg or after a gunshot wound (Fig. 21–7).⁴

Fibular shaft fractures present with pain that is exacerbated with walking and a discrete area of tenderness over the fracture site. Examination should include a thorough assessment of the ankle. One must exclude a Maisonneuve fracture in which deltoid ligament rupture or a medial malleolus fracture accompanies a proximal fibula fracture.

Fibular shaft fractures without associated fracture of the tibia are treated symptomatically, and usually heal without complications. Splinting the leg can be utilized for pain relief. Some patients have little pain and tolerate initial crutch walking without immobilization.

Tibial Stress Fracture

Stress fractures are common in the leg and are frequently misdiagnosed as contusions, strains, periostitis, exertional compartment syndrome, or nerve entrapment. The tibia is especially prone, accounting for almost one-half of cases.¹⁴ They occur in young athletes, dancers, or military recruits early in their training period. The most common location of a tibial stress fracture is the posteromedial cortex of the diaphysis. Anterior cortical stress fractures also occur and are more problematic because of decreased vascularity and the tension in this area.¹⁵

Clinical Presentation

The patient complains of an insidious onset of soreness or a dull ache in the leg, which is increased with activity. Eventually, if untreated, the ache becomes continuous even at rest and at night. There may be localized tenderness with some soft-tissue swelling over the fracture site, which is usually at the upper third of the leg.¹⁴

Imaging

Radiographs obtained early are negative, and the condition may be misdiagnosed. However, 2 weeks to 3 months later, a fine, transverse line with periosteal reactivity along one or both cortices will be present. Other diagnostic tests include bone scan and magnetic resonance imaging (MRI). Bone scan is very sensitive and reveals a focal area of uptake in all three phases.¹⁴ MRI is more specific than bone scan but is more expensive.¹⁵

Treatment

Tibial stress fractures are most often treated nonsurgically. Rest and orthotics are usually required. Nonsteroidal anti-inflammatory agents should be avoided because of their inhibitory effects on bone healing.¹⁶ Gradual resumption of activity over the next 1 to 2 months is required for healing to take place and the development of pain during that time necessitates a decrease in activity level.

Anterior cortical tibial stress fractures are treated with casting or surgical fixation.¹⁵ If there is suspicion of an anterior cortical stress fracture, the patient should be splinted and given crutches while awaiting definitive testing and referral to an orthopedic surgeon.

Acute Compartment Syndrome

Compartment syndromes are among the most potentially devastating problems presenting to the ED. Volkmann ischemic contractures are the end result of muscle and nerve ischemia when the condition is not treated. Early diagnosis and the recognition of the early signs of this process are crucial to the emergency physician.

The leg is the most common location to develop a compartment syndrome, with the anterior compartment being most commonly involved. Other compartments in the leg include the superficial and deep posterior compartments and the peroneal (lateral) compartment (Fig. 21–8). The contents of each compartment are listed in Table 21–1.

Compartment syndromes of the leg can be caused by a number of conditions. A tibia fracture is the most common precipitant, but other conditions that may result in compartment syndrome include constrictive dressings or casts, crush injuries, and arterial injuries.¹⁷ Thus, an increase in compartmental pressure can be caused by (1) compression of the compartment (e.g., cast) or (2) volume increase within the compartment (e.g., hematoma). For an extensive list of the causes of compartment syndrome, refer to Chapter 4.

Clinical Presentation

Clinical evaluation begins with a high degree of suspicion. The earliest and most reliable sign of a compartment syndrome is severe pain, typically out of proportion to the apparent severity of the injury. The pain is not well localized, is progressive, and increases in intensity. In addition, palpation of the involved compartment will reveal that it is tense. Pain with passive stretch is an early sign but can be confused when there is a contusion. One must remember that paresis and paresthesias are not reliable and occur late, as do diminished pulses.

Because the anterior and deep posterior compartments of the leg are most commonly involved, a detailed description of those two presentations is outlined subsequently.¹⁸

Anterior Compartment Syndrome

This syndrome is characterized by anterior tibia pain, weakness of dorsiflexion of the ankle and the toes, and variable degree of sensory loss over the distribution of the deep peroneal nerve (web space between the first and second toes).

The emergency physician must not wait for the development of foot drop or paresthesias, as these are late findings. With the onset of severe pain over the anterior compartment, there is loss of function so that it becomes almost impossible to contract the muscles within the compartment. Passive stretching of the muscles causes significant pain. The skin over the compartment becomes erythematous and shiny and is warm and tender to palpation with what is described as a “woody” feeling.

Anterior compartment syndrome may be misdiagnosed as muscle spasms, shin splints, or contusions. However, if the examiner is aware that the previously mentioned conditions can result in a compartment syndrome, he or she will not miss the diagnosis.

Deep Posterior Compartment Syndrome

The deep posterior compartment encloses the flexor digitorum longus, the tibialis posterior, and the flexor hallucis longus as well as the posterior tibial artery and nerve. The transverse crucial septum forms the posterior wall of the compartment, whereas the interosseous membrane forms the anterior wall.

The clinical picture of this syndrome is usually complicated by the involvement of other surrounding compartments. However, there is increased pain on passive extension of the toes and weakness of flexion as well as hypesthesia over the distribution of the posterior tibial nerve along the sole. The patient also has tenseness and tenderness along the medial distal part of the leg. All of these signs may become evident within 2 hours to as long as 6 days from the injury.

Treatment

If one suspects this diagnosis, the compartment pressures must be measured in the ED. Compartment pressure can be quickly and easily measured using a commercially available battery-powered monitor (Stryker STIC monitor). A description of this technique is available in Chapter 4.

The normal compartment pressure is <10 mm Hg.¹⁹ Pressures >20 mm Hg should prompt admission and surgical consultation. A pressure of 30 to 40 mm Hg is generally considered grounds for an emergent fasciotomy in the operating room.²⁰

The fasciotomy is accomplished by making a longitudinal skin incision over the compartment. The underlying fascia is split along the length of the compartment allowing the contained muscle to expand. Fasciotomy performed early, that is, <12 hours after the onset of symptoms, results in the return to normal function in 68% of patients, whereas only 8% of those with fasciotomies done after 12 hours had completely normal function. A complication rate of 54% is seen with delayed fasciotomy, compared to only 4.5% with early fasciotomy.²¹ Traditionally, when all four compartments are involved in the syndrome, double incision fasciotomy or fibulectomy has been advocated.²² However, more recently, it has been proposed that a single incision fasciotomy for the four compartments is also a safe alternative.²³

Chronic Exertional Compartment Syndrome

Chronic exertional compartment syndrome (CECS) occurs after exercise when intramuscular pressure increases.²⁴ Swelling after strenuous activity results in up to a 20% increase in muscle volume.²⁵ The majority of cases occur after chronic overuse in an athlete, although acute cases have been described.²⁶ CECS is missed in 14% of cases after repeated consultations because of minimal findings on physical examination, and in some studies, misdiagnosis is much higher.²⁷ CECS most commonly occurs in the lower leg.

Clinical Presentation

The clinical history of CECS of the lower leg is typically that of an athlete who describes recurrent pain in the area of the affected compartment during activity. The pain is usually depicted as an ache or tightness and can be localized over the involved compartment. The pain may not develop until 24 to 48 hours after the precipitating event.²⁵ After a period of rest, the pain characteristically subsides, only to recur again with the onset of the same exercise. In some patients, paresthesias may develop over an involved nerve. The condition is bilateral in over 80% of patients. The majority of cases involve the anterior or posterior compartments.^24,28–33

Examination

The patient has a scarcity of definitive findings on examination.^30,34 In some cases, a sense of soft-tissue fullness, swelling, and thickening is present. Sensory loss on the plantar aspect of the foot is associated with CECS of the deep posterior compartment, whereas paresthesias on the dorsum of the foot may be present with anterior compartment involvement.¹⁵

Diagnosis

When this syndrome is suspected on clinical grounds, a bone scan should be ordered to rule out a stress fracture or periostitis (shin splints).³² MRI may reveal an increase in signal intensity between the resting and postexercise scans. The definitive diagnosis is established by intracompartmental pressure measurements, which reveal a preexercise compartment pressure of >15 mm Hg or a postexercise compartment pressure of >30 mm Hg 1 minute after exercise or >20 mm Hg 5 minutes after exercise.^15,25

Treatment

This condition is not as urgent as an acute compartment syndrome. The patient should be referred for compartment pressure measurements. Various treatment modalities such as physical therapy, orthotics, rest, and alternate activity have minimal or no effect.^35,36 Once the diagnosis of CECS is established, fasciotomy of the involved compartment is recommended.^15,25,37,38 Fasciotomy in CECS leads to sustained relief of leg pain and improved patient satisfaction.³⁹

Shin Splints

The term “shin splints” refers to the syndrome of pain in the leg from running and should exclude stress fractures, fascial hernias, or ischemic disorders.^15,40 This condition is also referred to as soleus syndrome and medial tibial stress syndrome (MTSS). MTSS is currently the preferred terminology. Hyperpronation of the foot, overuse, a sudden increase in exercise intensity, or a change in training surface may precipitate MTSS. The end result is a muscle-induced traction periostitis on the posteromedial border of the tibia.^15,40

Clinical Presentation

MTSS usually occurs early in the training period of athletes when running on hard surfaces. The pain of MTSS is a dull ache. The most common site of pain is the posteromedial surface of the distal two-thirds of the leg.

Examination

On examination, the hindfoot is in a valgus position and the forefoot may be hyperpronated. Palpable tenderness is elicited over the posteromedial border of the distal tibia. Percussion over this area of the tibia will cause pain, whereas passive or active ranges of motion of the ankle are not painful.

Diagnosis

Diagnosis is most frequently made by bone scan, which reveals diffuse, linear uptake. However, both plain films and bone scan may be normal. MRI will help differentiate MTSS from stress fractures.⁴¹

Treatment

Many forms of treatment for shin splints have been advocated, but generally, the pain does not subside until the patient stops running. The basic treatment is rest, ice, and analgesics. Nonsteroidal anti-inflammatory agents should be avoided if there is suspicion of a stress fracture.¹⁶

Muscle Injury

Contusion

Contusions are extremely common in the lower extremity because direct blows are frequent in this area. Four types of contusions are seen: (1) anterior leg producing severe pain caused by increased anterior compartment pressure; (2) subcutaneous portion of the tibia, which, because of the superficial location of the tibia, often results in a traumatic periostitis; (3) posterior compartment, which is less common and not nearly as painful as contusions of the anterior compartment; and (4) lateral, where the peroneal nerve winds around the proximal fibula. Contusions laterally over the proximal fibula may produce a painful neuritis or even transient paralysis of the peroneal nerve with a secondary foot drop.

A hematoma may form at the site of the contusion, and if this occurs in the anterior compartment, the patient may present as a surgical emergency requiring fasciotomy to prevent ischemia and subsequent muscle necrosis.

The treatment of these injuries is contingent on the extent of damage and the structures involved. If there is a fresh, palpable hematoma, one may aspirate it by using an aseptic technique followed by a pressure bandage and cold compresses for the next 12 hours. If the contusion is limited to diffuse muscle involvement, the initial treatment should include ice packs and rest of the extremity with elevation for the first 48 hours.

In contusions involving the peroneal nerve, the patient will have local swelling and pain. The patient will complain of paresthesias, with pain shooting to the lateral side of the leg and extending into the foot. Tingling and numbness will remain after the pain is gone. Patients with severe contusions to the common peroneal nerve will have the initial symptoms followed by a pressure sensation over the nerve and functional loss. Sensory hypesthesia and weakness of the dorsiflexors are present. This period of functional loss is followed by a period when nerve function returns, initially sensation, followed by motor function. The return of nerve function may be complete or partial.

The treatment for a nerve contusion is initially nonspecific with ice packs followed in 48 hours by heat applications. If paresis is noted, the muscles must be protected by supporting the ankle and foot in a brace. The foot is held in a neutral position. In patients in whom the contusion is followed by a quiescent period and then rapid paralysis, surgical exploration is justified. When paralysis is immediate, a more conservative approach is usually taken. Referral is indicated in all patients with nerve involvement.

Strains

Muscle strains are common in the calf due to chronic overuse or forcible contraction. The treatment is symptomatic with a period of rest, local heat, and gradual return to activity. Athletes should be cautioned that early return to activity before complete healing may entail a risk for further and more severe injury of the muscle. Nonsteroidal anti-inflammatory agents are of some benefit early during treatment for pain control and functional improvement; however, long-term use of these agents beyond 2 to 3 days is detrimental to the repair process.

A common question relates to the usefulness of stretching to prevent muscle strains. Clinical studies have demonstrated that stretching appears to be beneficial, but forces in excess of 70% of the muscle’s contractile force make the muscle more likely to be injured. Thus, when using stretching before running or other activities, one should use minimal force. Viscoelasticity is known to be temperature-dependent and warm-up is considered to protect against muscle strain.

Rupture

Gastrocnemius and Soleus

Rupture of the gastrocnemius or soleus can occur anywhere from the attachment on the femur to their attachment on the calcaneus, which is the most common site of rupture (along the musculotendinous junction). For more information regarding Achilles tendon rupture, the reader is referred to Chapter 22.

The patient notes pain and swelling with diffuse tenderness over the calf. Both active contraction and passive stretching cause pain along the muscle. The muscle may bunch up on any attempt at contraction. Surgical repair is indicated for complete ruptures. In patients with partial ruptures, an equinus cast is used until healing is complete. To detect a complete rupture, the physician should place the patient in a prone position with the feet hanging over the end of the table. Squeeze the upper calf and look for spontaneously occurring plantar flexion. If this does not occur, suspect a complete rupture.

Plantaris

This is a pencil-sized muscle that originates at the lateral condyle of the femur and passes beneath the soleus to attach on the Achilles tendon. In patients with plantaris rupture, pain is noted deep in the calf, which may be disabling. The patient may complain of a sudden sharp snap in the posterior part of the leg followed by a dull deep ache. Repair is not needed here; only symptomatic treatment is indicated.

Fascial Hernia

Fascial hernias are uncommon. The usual site is at the attachment of the anterior fascia along the anterior border of the tibia. The patient complains of an ache here that may initially be diagnosed as a contusion or periostitis. Later, a well-localized mass appears lateral to the tibial crest, which may be tender. The mass bulges when the muscle is flexed and the examiner may feel a defect on palpation. These patients usually are asymptomatic; however, if symptoms are noted, surgical repair is indicated.