Chapter 19: Thigh

The thigh is the largest anatomical portion of any extremity, and is comprised of powerful muscle groups that encase the femoral shaft. The femur is the heaviest and longest bone in the body. It has an excellent blood supply derived from the profunda femoris artery, and its periosteum receives extensive collateral circulation. As a result, the femur is well protected from devascularization and has good healing potential.

The musculature of the thigh is divided into three compartments by intermuscular septa that attach to the linea aspera, a ridge that runs down the posterior aspect of the femur (Fig. 19–1). The anterior compartment contains hip flexors and knee extensors, including the four quadriceps muscles (the rectus femoris, vastus medialis, vastus lateralis, and vastus intermedius). The posterior compartment is occupied by the hamstrings, which include the long and short heads of the biceps femoris as well as the semimembranosus and semitendinosus muscles medially. The medial compartment consists of the adductor muscle group, which includes the adductor longus, brevis, and magnus, as well as the gracilis.

Femoral Shaft Fractures

The femoral shaft extends from an area 5 cm distal to the lesser trochanter to a point 8 cm proximal to the adductor tubercle.

Femoral shaft fractures are classified into three types.

1. Spiral, transverse, or oblique shaft fractures

2. Comminuted femoral shaft fractures

3. Open femoral shaft fractures

Distinguishing between a spiral, transverse, or oblique fracture does not alter either the treatment or prognosis.

Comminuted fractures are further classified by Winquist based on the size of the fracture fragment and the degree of comminution (Fig. 19–2).¹ Grade I fractures have minimal or no comminution, and fracture fragments are small (≤25% of the width of the femoral shaft). Grade II fractures possess a fracture fragment of 25% to 50%, whereas grade III fractures are associated with a large butterfly fragment (>50% of the width of the femoral shaft). Grade IV fractures possess circumferential comminution over an entire segment of bone with complete loss of abutment of the cortices.

Atypical femur fractures result from brittle bone failure rather than significant trauma. These fractures are characterized by a transverse morphology and lack of comminution.^2,3 Atypical femur fractures occur from an area distal to the lesser trochanter to just proximal to the supracondylar flare of the distal femoral metaphysis. Several recent studies have tried to show an increased risk of atypical femur fractures with the use of bisphosphonates although such a definitive association remains unclear.^2,3 Nevertheless, these fractures are thought to comprise only 1.1% of all femoral fractures.⁴

Mechanism of Injury

In 75% of cases, femoral shaft fractures are secondary to a high-energy force.⁵ The mechanism can be a direct blow or an indirect force transmitted through the flexed knee. Automobile collisions are the most common cause, but gunshot wounds represent an increasing proportion of these fractures.⁶ Fracture of the femur following a low-energy mechanism may suggest a pathologic fracture in adults or nonaccidental trauma in pediatrics.

In children, fracture of the femur is the most common musculoskeletal injury requiring hospitalization.⁷ Falls and motor vehicle accidents account for approximately three-fourths of these injuries, however it is estimated that approximately 15% of femoral fractures in children younger than 2 years are due to nonaccidental trauma.⁷ The strongest predictors suggesting a nonaccidental, as opposed to an accidental mechanism, include a child who has not yet obtained the ability to walk, age younger than 18 months, history or mechanism inconsistent with injury pattern, and physical and/or radiographic evidence of prior trauma.^7–9 Although spiral fractures have been classically associated with nonaccidental trauma, transverse fractures are in fact the most common type of fracture in both accidental and nonaccidental injuries.¹⁰

Examination

The patient will present with severe pain in the involved extremity and will usually have visible deformities (Fig. 19–3). The extremity may be internally rotated, shortened and there may be crepitation with movement. The thigh will be swollen and tense secondary to hemorrhage and formation of a hematoma. Neurologic examination should be performed to assess the function of the sciatic nerve. Arterial injuries are rare, but they must be excluded on the initial examination. Arterial injuries associated with a femoral shaft fracture may be suspected in the presence of an expanding hematoma, diminishing or absent distal pulses, or worsening neurologic signs. Neurovascular examination should be repeated frequently, especially after splinting or other manipulation of the involved extremity.

Imaging

Routine anteroposterior and lateral views are usually adequate in demonstrating the fracture (Figs. 19–4 and 19–5). Pelvis and knee views should be included as there is a significant incidence of associated injury. In the patient with multiple associated injuries requiring aggressive resuscitation, radiographs of the femur may be of lower priority. In addition, stress fractures of the femoral shaft may not be visualized on these routine views, and up to half of associated femoral neck fractures may be missed by plain films.¹¹

Associated Injuries

The high-energy force needed to generate a femoral shaft fracture often results in additional injuries. A careful and systematic evaluation should be done on patients with femur fractures to evaluate for potential multiple injuries. Ipsilateral femoral neck fractures are associated with up to 9% of femoral shaft fractures, but may be missed in up to 30% to 50% of cases.^11,12

In pediatric patients where femoral shaft fractures are more common, polytrauma is present in approximately 20% of cases. The majority of associated injuries includes other fractures, abdominal injuries and closed head injuries.¹³

The femoral shaft has a rich blood supply. In adults, fractures are associated with an average blood loss of 1 to 1.5 L.⁶ In children, however, isolated femoral fractures are rarely associated with significant blood loss.¹⁴ Particularly in children, bleeding into the thigh from a closed femoral shaft fracture is not typically enough to cause hypotension. In these cases, another source of bleeding should be sought.¹⁵

Associated sciatic nerve injuries are rarely encountered with these fractures secondary to the protective surrounding musculature. The incidence of sciatic or peroneal nerve injury in the setting of a femoral shaft fracture is 2% after a blunt mechanism and increases to 9% after a gunshot wound.⁶

Treatment

The emergency management of this injury begins in the prehospital setting. The extremity should be immobilized in a traction splint or a pneumatic anti-shock garment. Hare or Sager traction splints provide immobilization, distract the fracture, and reduce the potential space for bleeding. The Sager traction splint is illustrated in Chapter 1. In the presence of a sciatic nerve injury, a splint should be placed without traction to avoid further injury to the nerve. Traction splints should not be used in grossly contaminated open fractures.

Pain medications should be provided early and emergent referral and admission are indicated. One must remember to treat the patient for the associated blood loss and consider the high likelihood of concomitant injuries as outlined earlier.

Intramedullary nailing is the preferred method for definitive treatment of femoral shaft fractures in adult patients (Fig. 19–6).^16–18 Advantages of intramedullary nailing include early patient mobilization, minimally invasive operative technique, and low complication rate.¹⁶ This technique can be employed in virtually any fracture along the length of the femoral shaft, including periprosthetic fractures and severely comminuted fractures.¹⁸ Retrograde nailing is usually reserved for the treatment of femoral shaft fractures with ipsilateral femoral neck or intertrochanteric fractures, patients with bilateral femur fractures, and the morbidly obese.^17,19,20

The management of open fractures is outlined in Chapter 1. Open fractures of the femoral shaft require emergent operative debridement. Grade I and II open fractures can be treated with immediate closed femoral nailing, with infection as low as 2%.²¹ External fixation is useful for patients with severe grade IIIB and IIIC open fractures.

Management of pediatric femoral shaft fractures is variable, and debate continues as to which fixation methods are most appropriate in different situations. Spica casting is still favored in children under the age of 6, whereas children aged 6 to12 are commonly managed with flexible intramedullary nails. Locked intramedullary nails are reserved for children older than 10 years. Plating is commonly used in comminuted fractures and external fixation is favored in situations involving extensive soft-tissue injury of the thigh.^22,23

Timing of fracture fixation in all patients with multiple injuries remains controversial and an area of continued interest.^16,24

Complications

Femoral shaft fractures are often complicated by a variety of other systemic injuries as a result of their association with high-energy forces. Both the severity of the fracture itself and the degree of polytrauma are closely associated with mortality.²⁵ Unilateral fractures associated with head and abdominal injuries have mortality rates as high as 45% and 52%, respectively.²⁵ Thigh compartment syndrome is a rare complication of femoral shaft fracture.

General complication rates related to the repair of femoral shaft fractures are less than 5%.¹⁶ The most common complications are intraoperative fractures of the femoral neck and postoperative infection requiring surgical revision, each with a rate of 1.4%. Other potential but uncommon complications include delayed union, nonunion, malrotation, and hardware failure.¹⁶

Thigh Compartment Syndrome

Compartment syndrome of the thigh is a rare clinical entity. It occurs less frequently than compartment syndrome of the calf due to the thigh’s ability to accommodate larger volumes of fluid. Of the three compartments within the thigh—anterior, posterior, and medial—the anterior compartment is most commonly affected (Fig. 19–1).^26,27

Mechanism of Injury

Blunt trauma accounts for approximately 90% of cases of acute thigh compartment syndrome, with motor vehicle collisions being the most common traumatic mechanism.²⁸ However, many causes of thigh compartment syndrome have been identified, including femoral shaft fractures, muscle contusion or rupture, revascularization injury, external limb compression, and even anticoagulant-induced bleeding into the thigh.^27–32 In all cases, the underlying pathophysiologic mechanism is similar to that of other compartment syndromes, in which increased pressure within the limited compartmental space exceeds perfusion pressure, leading to circulatory compromise.

Examination

Like other compartment syndromes, the patient will present with severe pain that is exacerbated by passive stretch of the muscles within the involved compartment. The compartment is often swollen, tense, and exquisitely tender to palpation. Late findings may include sensorimotor deficits distal to the thigh. Anesthesia or paresthesia may be an early indication of nerve ischemia, whereas muscle paralysis is often a late sign indicating irreversible muscle and nerve damage.³⁰

Similar mechanisms of injury and clinical symptoms make compartment syndrome of the thigh often difficult to distinguish from severe contusion. Therefore, the diagnosis is often made both clinically and with the aid of intracompartmental pressure measurements.²⁸

Imaging

Although CT, MRI, and ultrasound have been studied for the diagnosis of compartment syndrome, their use is currently limited and may delay definitive management.³⁰

Associated Injuries

The high-energy trauma often involved in thigh compartment syndrome will result in many soft tissue and musculoskeletal injuries. Femur fractures are associated with up to 44% of cases of thigh compartment syndrome, interestingly with almost one quarter of these being open fractures. Severe complications, including neurologic deficits, infection, and renal failure are very common. Mortality rates as high as 47% have been reported, most often due to polytrauma and infection.²⁸

Treatment

The definitive treatment for thigh compartment syndrome is emergent surgical fasciotomy. The primary cause of poor outcomes from compartment syndrome is a delay of treatment.³⁰ The generally accepted indication is a difference between diastolic pressure and the measured compartment pressure of less than 30 mm Hg, although this is of continued debate.^28,30 Successful outcomes with conservative management involving bed rest, frequent compartment pressure measurements, cooling, and serial clinical examinations have been described in the absence of fracture.^30,33 Nevertheless, early fasciotomy is important to prevent complications of delayed diagnosis, and early surgical consult should be obtained in any patient suspected of having thigh compartment syndrome regardless of compartmental pressures.

Quadriceps Contusion

Quadriceps contusions, after muscle strains, are the second most common type of quadriceps injury in athletics, comprising approximately 14% of all thigh injuries in high school sports and 19% of all muscle injuries in professional soccer.^34,35

Mechanism of Injury

The usual mechanism of injury is a direct blow to the quadriceps muscles, often from an opponent’s knee or sporting equipment.³⁴ This compresses the underlying muscle and soft tissues against the femur causing myofiber and capillary rupture, forming a hematoma.³⁶

Examination

The patient will often report a traumatic mechanism and complain of localized pain. The ability to play following injury, as well as the time interval between injury and presentation, are important indicators of injury severity and prognosis.³⁵ Physical examination will reveal tenderness to palpation, swelling, and often ecchymosis at the site of injury (Fig. 19–7). If signs such as pulselessness, paresthesia, or paralysis suggestive of compartment syndrome are found, early surgical consultation should be considered and intracompartmental pressures obtained.

A clinically and prognostically useful classification system grades quadriceps contusions as mild, moderate, and severe.³⁷ In a mild contusion, the patient has localized tenderness, no alteration of gait, and knee motion without pain up to at least 90 degrees of flexion. In a moderate contusion, the patient displays swelling and a tender muscle mass. Knee motion is restricted to <90 degrees and the patient walks with an antalgic gait. The patient is unable to climb stairs or arise from a chair without considerable discomfort. In patients with severe contusions, the thigh is markedly tender, swollen, and indurated. Knee motion is severely limited (<45 degrees), and there is either a severe limp or the patient is unable to ambulate. Average disability times are progressively longer with increased severity: 13 days for mild, 19 days for moderate, and 21 days for severe.³⁸

Imaging

The diagnosis of quadriceps contusions is usually a clinical one. However, imaging may be useful in distinguishing contusions from avulsions and strains, especially when the presentation is subacute. Ultrasound and MRI are sensitive indicators of soft-tissue injury; however, the availability of ultrasound in the emergency department makes it particularly useful in this circumstance. Hematoma on ultrasound will appear as interruption in the normal architecture of the muscle with localized hypoechogenicity.^36,39

Treatment

Treatment of thigh contusions is often approached in a staged manner from the time of injury. The immediate goal is to control propagation of the hematoma by immobilizing the knee of the contused thigh in 120 degrees of flexion for 24 hours.³⁴ This can be done either by an elastic wrap or adjustable brace and should be done as soon as possible after the injury occurs. Ice and compression should also be employed during this time and the patient should ambulate with crutches. In one study involving naval athletes who received immobilization within 10 minutes of injury followed by range-of-motion stretching as described below, the average time from injury to return of unrestricted full athletic activity without disability was 3.5 days.⁴⁰

After the brace is removed, the patient should engage in active pain-free range-of-motion stretching of the involved thigh. Once the patient is able to attain 120 degrees of pain-free motion in the ipsilateral knee, functional rehabilitation should begin and the use of crutches may be discontinued. In athletes, the use of a thigh pad to prevent recurrent injury to the site of the contusion should be encouraged.⁴⁰

The effect of nonsteroidal anti-inflammatory drugs (NSAIDs) on muscle injuries is thought to be paradoxical, with early use leading to improvement but sustained use leading to impairment in functional capacity and histology.⁴¹ NSAID use in the first 3 days appears to have no detrimental effect.⁴² Corticosteroids are not an effective adjunctive therapy for thigh contusions.³⁴

Complications

Myositis ossificans occurs as a complication in up to 17% of muscle contusions.³⁴ It should be suspected if symptoms worsen 2 to 3 weeks after the initial injury. Risk factors for development of myositis ossificans include associated knee effusion, severe injury, and delay in treatment.³⁸ Compartment syndrome is also a potential complication especially in contusions with large hematoma formation.⁴³

Muscle Strains and Rupture

Adductor Strains

Mechanism of Injury

Adductor muscle strains are the most common groin injury in athletes.⁴⁴ The sports with highest prevalence of this injury include ice hockey and soccer, where strong eccentric contraction of the adductor muscle group is required.⁴⁵ This injury is usually caused by forced abduction of the thigh. Decreased adductor strength and range of motion are both risk factors for the development of adductor strains.⁴⁴

Examination

The patient complains of pain that is localized to the groin region. With incomplete rupture, the pain is made worse by passive abduction of the thigh and is accentuated by active adduction against resistance. Ecchymosis may be present (Fig. 19–8). If complete rupture has occurred, the examiner will often see bunching of the muscle along the medial aspect of the thigh near the groin.

Imaging

Imaging is not necessary unless the diagnosis is in question. Ultrasound may be used to diagnose adductor muscle or tendon tears but not strains. MRI can be used to confirm a muscle strain or tear, and has prognostic value but is generally not needed for the diagnosis. Pelvis radiographs should be obtained if there is concern for avulsion injury at the origin of the adductor longus.

Treatment

Adductor strains should be treated with relative rest, ice, and short-term use of NSAIDs followed by physical therapy. A return to sports is allowed once the patient has regained at least 70% of their former adductor strength and pain-free full range of motion. This process can take approximately 4 to 8 weeks.

Chronic adductor strains may require up to 6 months of physical therapy. Failure to respond to prolonged physical therapy may be an indication for surgical referral for tenotomy.⁴⁴

Complete rupture of the tendinous insertion of the adductor warrants surgical referral for repair.

Hamstring Strain

Mechanism of Injury

Hamstring strains are common in runners, water skiers, hurdlers and in other sports that involve jumping and kicking such as soccer. The mechanism is usually sudden, forceful flexion at the hip with extension at the knee. Prior hamstring injury is a risk factor for hamstring strain. Other potential risk factors include patient age, lack of hamstring flexibility, and increased peak quadriceps torque.⁴⁶

Examination

The patient will present with acute onset of posterior thigh pain. There will be pain with weight bearing and an antalgic, stiff-legged gait that usually inhibits athletic activity.

Examination should be performed with the patient in the prone position with the knee flexed. There is usually swelling in the posterior thigh with tenderness to palpation. Severe injuries may be accompanied by ecchymosis in the posterior thigh. The examination should include thorough palpation of the entire muscle belly searching for a defect that represents a tear. Complete tears of the hamstring musculature are rare.⁴⁷

Knee flexion should also be tested. If there is less than 30% strength compared to the contralateral uninjured limb and significant posterior thigh or knee ecchymosis, consider an MRI to evaluate for possible proximal hamstring rupture.⁴⁶

Imaging

Usually the diagnosis of a mild strain is clinical and no imaging is necessary. Plain films are useful in more severe injuries to identify whether avulsion has occurred, as the avulsed segment of bone may be visible. In the case of suspected rupture or avulsion, MRI is an important tool that may affect surgical decision-making.⁴⁶ Some studies have shown that the size of the strain’s appearance on MRI may correlate to time lost from sporting activity.^47,48

Treatment

The acute treatment for hamstring strains includes rest and rehabilitation, ice, compression, and elevation usually for 3 to 7 days. The goal of this treatment is to limit the initial inflammatory response, control hemorrhage and edema, and improve pain.⁴⁶ NSAIDs are also used during this time. Gradual mobilization as tolerated is made over a period of 2 to 6 weeks depending upon injury severity, and crutches may be used initially until pain-free ambulation is possible.

The risk of hamstring strain recurrence is high, with athletes shown to have 20 times the risk of recurrence in the first 3 weeks back in play compared to their noninjured peers. A progressive agility and trunk stabilization program may reduce the reinjury rate. Stretching has not been definitely shown to improve recurrence rates. To avoid reinjury, the patient should be advised to avoid early return to sports until they are appropriately rehabilitated.⁴⁷

Thigh Muscle Rupture

The rectus femoris, adductors, and hamstrings can rupture anywhere from their origin to their insertion. The patient is often misdiagnosed as having a contusion, and often there is a delay in diagnosis. Surgery is more complicated and less effective on chronic ruptures, stressing the importance of timely diagnosis. The telltale signs and symptoms develop with time, and may not be present in the acute setting. This emphasizes the need for appropriate instructions to follow-up if the mechanism suggests tendon rupture. Recommend close follow-up to patients if they develop a large ecchymosis, a muscle bulge, or they have weakness with knee flexion. Rupture can occur when a tendon is suddenly eccentrically loaded. For example, hamstring ruptures usually result from sudden flexion at the hip with knee extension. These injuries are more common in water skiers, and can also occur if a patient slips on an icy surface with their leg outstretched. Educate patients to look for the development of a large ecchymosis, or a mass (suggesting the tendon/muscle is retracted) and weakness.⁴⁶

Examination

The examination should include inspection for ecchymosis or deformity, palpation of bone attachment site, assessment for the presence of an intact tendon bundle, or appreciation of a palpable defect detected during strength testing.

Imaging

For suspected proximal thigh tendon rupture, consider a plain AP radiograph of the pelvis to evaluate for fracture or avulsion fractures. If normal, patients may still have a partial or complete tendon rupture. Consider using ultrasound in the acute and subacute setting to assess for local hematoma, muscle tear, tendon bundle attachment, or complete rupture (Fig. 19–9).

Treatment

A minimum of 6 weeks is needed for healing when partial rupture involving the muscles of the thigh occurs. Activity is permitted to the tolerance of pain; however, no sports or vigorous activity is allowed. Ambulation with crutches and a gradual return to activity is advised. Patients with complete ruptures should be made nonweight bearing, and referred. Surgical treatment is indicated for total or near-total hamstring muscle rupture. It is also considered in cases of bony avulsion of the ischial tuberosity when the avulsed fragment is displaced >2 cm. Surgical outcomes are superior when performed in the acute phase (less than 4 weeks from injury).^46,48,49

Fascial Hernia

The muscles of the thigh are invested in fascial sheaths. The fascial sheaths along the anterior and lateral aspect of the thigh are thinner just anterior to the iliotibial band. The patient may present to the ED with a complaint of a small palpable mass that appears when the quadriceps is contracted and disappears when the muscle is relaxed. Treatment is usually not necessary; however, if the symptoms warrant, surgical repair may be indicated.

Myositis Ossificans Traumatica

Myositis ossificans traumatica is a common condition in which a non-neoplastic ectopic calcium deposit is found in soft tissue at a site of prior trauma and hematoma. Myositis ossificans occurs as a complication after muscle contusion injuries in 9% to 17% of cases.^35,50 This condition is commonly seen in the anterior thigh muscles after a moderate or severe contusion. The patient is usually a young athlete playing a contact sport.⁵¹ In most cases of myositis ossificans, the involvement is limited to the middle third of the thigh; however, in some it extends into the proximal third. Cases of myositis ossificans in the adductor muscles have also been reported. Myositis ossificans can also be congenital, occur after surgery, present as a complication of paraplegia or prolonged immobilization, or can be seen in the setting of serious disease such as clotting factor deficiencies. It can also be mistaken for osteosarcoma.⁵⁰

Examination

Myositis ossificans is usually diagnosed 2 to 4 weeks after injury to the thigh. Palpation may reveal a firm and tender mass in the soft tissue. The patient may have limited range of motion due to pain or mass effect.

Imaging

The radiograph usually shows evidence of irregularly shaped heterotopic bone within 2 to 4 weeks after an injury (Fig. 19–10). Three forms of myositis ossificans have been described: (1) a type with a stalked connection to the adjacent femur, (2) a periosteal type with continuity between the heterotopic bone and the adjacent femur, and (3) a broadbase type with a portion of the ectopic bone projecting into the quadriceps muscle.³⁷

Treatment

The emergency physician should be aware of the preventive measures to avoid the development of myositis ossificans. The patient with a quadriceps contusion should be cautioned against early active use of the quadriceps and forceful passive flexion of the knee. Once present, myositis ossificans is usually not severely disabling, although some patients may require surgical excision due to pain once the bone has matured. Once the diagnosis is established, appropriate referral and follow-up are indicated.