eMedicine Specialties > Sports Medicine > Lower Limb

Quadriceps Injury

Author: Thomas M DeBerardino, MD, Associate Professor of Orthopaedic Surgery, University of Connecticut Health Center
Coauthor(s): Leslie Milne, MD, Assistant Clinical Instructor, Department of Emergency Medicine, Harvard University School of Medicine
Contributor Information and Disclosures

Updated: Jan 19, 2010

Introduction

Background

Several types of quadriceps injuries can occur, the most common being the quadriceps contusion, which is painful and disabling. The usual cause of the quadriceps contusion is a direct blow to the anterior thigh from an object or another person (eg, helmet, knee). Very rarely, this injury can be severe enough to progress to an acute compartment syndrome.

Because the quadriceps is in contact with the femur throughout its length, it is susceptible to compression forces. The rectus femoris is the most commonly injured portion of the muscle because of its anterior location. Minimally, impact causes cellular edema of the muscle, but complete capillary disruption with localized hemorrhage leading to a tense anterior compartment can occur. The muscle is more resistant to injury if it is struck while in a contracted nonfatigued state. Other quadriceps injuries range from simple strains to more complex and disabling muscle ruptures.

Frequency

United States

Although quadriceps strains are common, minimal information about the frequency with respect to specific sports is available. As for quadriceps contusions, the most detailed frequency data came from the US Military Academy at West Point,¹ and the distribution per year was reported as follows: rugby 4.7%, karate and judo 2.3%, football 1.6%, and all other sports fewer than 1%. Quadriceps muscle hernias are believed to be more common in soccer, basketball, and rugby.

The incidence of jumper's knee at the quadriceps insertion onto the patella is less common than patellar tendinitis. One study reported that of all tendinopathies affecting the extensor mechanism, the frequency of patellar tendinitis at its insertion was 65%, quadriceps tendinitis was 25%, and patellar tendinitis at its insertion into the tibial tuberosity was 10%.

Rupture of the quadriceps tendon is more common in both older patients and younger athletes. Several studies show that the mean age of patients with quadriceps rupture is about 65 years. However, in athletes, the mean age cited ranges from 15 to 30 years. Sports associated with quadriceps rupture are high jump, basketball, and weight lifting. Rupture is also not uncommon in patients with renal failure.

Functional Anatomy

The quadriceps femoris acts as a hip flexor and knee extender. The quadriceps femoris is composed of the following:

• Rectus femoris
• Vastus lateralis
• Vastus medialis
• Vastus interomedialis

Origins/insertions of quadriceps components include the following:

• Rectus femoris - Ilium/tibial tuberosity
• Vastus lateralis - Femur/tibial tuberosity
• Vastus medialis - Femur/tibial tuberosity
• Vastus interomedialis - Femur/tibial tuberosity

The 3 thigh compartments are as follows:

• Anterior - Quadriceps muscles, femoral nerve and artery
• Posterior - Hamstring muscles, sciatic nerve
• Medial - Adductor muscles, cutaneous branch of obturator nerve

Sport-Specific Biomechanics

The function of the quadriceps is primarily that of tibial (knee) extension. One electromyography (EMG) study showed that the maximum extension moment and maximum quadriceps EMG activity were early in the kicking action, as the initial flexion changes to extension. This moment occurs before the foot makes contact with the ball. The peak activity of the hamstring occurs after the quadriceps peak, shortly before the ball is struck. The largest extension moment in this study was 260 Nm; this corresponds to a calculated tensile force in the patellar tendon of 7 times body weight.

The mechanical properties of the quadriceps have been studied. The central aspect of 10-mm wide sections of the quadriceps was subjected to tensile loading and compared to a similar patellar tendon section. The ultimate load to failure of the unconditioned patellar tendon was higher (53.4 N/mm²) than the unconditioned quadriceps tendon (33.6 N/mm²). Strain at failure was also higher for the preconditioned patellar tendon (14.4%) than for the quadriceps tendon (11.2%).

Microscopic sections of human quadriceps tendon as it inserts into the patella show no crimping and no cement line. This is unlike other tendon insertion sites. The interdigitation between collagen fibers and the distinction between tendon and bone was least distinct along the anterior third of the patella.

A discussion of the biomechanics of specific injuries is as follows:

• Strains, overuse, and rupture: The most common sites of injury correlate to the muscle tendon junctions both proximally and distally and to the muscle belly itself. Muscle strains are usually due to repetitive functional overload. Not surprisingly, quadriceps strains most commonly affect athletes who subject their knees to high levels of repeated loading of the extensor mechanism. The overuse trauma may range from microscopic failure of soft tissue with its associated inflammation or gross rupture. Gross rupture may be partial or complete. A large sudden load may cause the entire insertion to be compromised, leading to complete rupture. Repetitive loading, particularly eccentric loads, causes microfailure, usually at the muscle tendon junction. This microfailure can result in partial tears.
• Contusion: Direct trauma to the quadriceps may cause muscle fiber and connective tissue rupture and formation of a hematoma. Trauma to the quadriceps causes muscle fiber rupture, disruption of connective tissue, and hematoma formation. Inflammatory cells and macrophages enter the site of injury and begin clearing necrotic muscle cells. This process occurs over 2-3 days. Then, muscle cells attempt to regenerate at the same time scar tissue is being formed. A severe thigh contusion can lead to a compartment syndrome.
• Muscle hernia: The cause of this is not clear. It is usually associated with a sudden forceful kick, but it may be associated with a weakened or previously injured quadriceps fascia.

Clinical

History

• Quadriceps contusion
  • The mechanism is usually a blow to the anterior thigh with an object (eg, bat) or contact with another athlete (eg, knee, head) or gear (eg, helmet).
  • A severe trauma and large contusion can lead to a compartment syndrome. This diagnosis should be considered in patients with crush injuries, in patients with fractures resulting from high-energy trauma, in patients on anticoagulants, in patients with bleeding disorders, and in patients with multiple traumas.
  • A compartment syndrome of the thigh is very rare compared to compartment syndromes of the lower leg. The thigh compartments are much larger, allowing for tissue expansion, and the forces are distributed over a greater area. Unless rapid bleeding has occurred, these patients generally present with a gradual increase in their symptoms. The blood vessels injured usually are the deep perforating branches of the vastus intermedius (because of the direct attachment of that muscle to the femur).
  • Untreated, a compartment syndrome may lead to muscle necrosis, fibrosis, scarring, and limb contractures. Nerve injury may result either from the direct blow or from compression within the compartment.
  • Symptoms include painful anterior thigh, painful weightbearing, and unwillingness to flex the knee because of thigh pain.
• Quadriceps tendon sprain
  • Blazina first described peripatellar tendinitis affecting the quadriceps tendon or the patellar tendon and termed this jumper's knee in 1973. He noted that it commonly occurred in jumping athletes.
  • The mechanism is sudden stretching or repeated eccentric contraction of the muscle causing pain and dysfunction immediately or 1-3 days later.
  • Symptoms include pain with ambulation and knee flexion and inability to extend the knee if the quadriceps is ruptured.
• Quadriceps muscle partial tear
  • The mechanism is kicking or sprinting.
  • Incomplete intrasubstance tears of the rectus femoris tendon occur at the deep portion of the indirect head and the muscle there. The location, while along the distal part of the rectus femoris, is more proximal than the quadriceps strain at the patellar insertion.
• Quadriceps tendon rupture: Many authors have concluded that the tendon usually ruptures in an area of tendinosis. In patients with bilateral injuries or injuries associated with trivial trauma and no history of previous strain, consideration should be given to the associated use of anabolic steroids or the diagnoses of renal disease and metabolic bone disease (hyperparathyroidism).
• Special cases: This category includes ruptures after surgery. The surgeries that may be associated with this complication include lateral release, total knee replacement, or anterior cruciate ligament or posterior cruciate ligament reconstruction. Rupture of the quadriceps tendon after surgery may be associated with the procedure to harvest the graft used to reconstruct the cruciate ligaments or aggressive release of soft tissues in the case of lateral release and total knee replacement.

Physical

• Quadriceps contusion
  • Normal medial and posterior thigh
  • Tensely edematous and tender anterior thigh
  • Limited knee flexion
    • Mild - Greater than 90°
    • Moderate - From 45-90°
    • Severe - Less than 45°
  • For ruptures (complete and partial): Extensor lag indicates partial and complete tears; no extension indicates complete tear.
  • Gait abnormalities
    • Mild - Normal
    • Moderate - Antalgic
    • Severe - Severe limp
  • Knee effusion: Effusion may or may not be present.
  • Exquisite anterior thigh tenderness with knee flexion
  • Increased circumference of affected thigh
  • Straight-leg raise: Patients are able to perform this unless the extensor mechanism is disrupted.
  • Normal sensation in distal extremity: If sensation is compromised, consider compartment syndrome. The anterior compartment contains the femoral nerve, and testing of the lateral, intermediate, and medial cutaneous nerves should be performed if compartment syndrome is suspected.
  • Pain: Disproportionately high level of pain for examination triggers suspicion of compartment syndrome.
• Muscle strain: Tenderness is elicited by direct palpation of the quadriceps at the patellar insertion, or the patient reports pain when testing for resisted extension.
• Quadriceps muscle hernia: A soft mobile mass, which may be tender, is palpated anteriorly with contraction of the quadriceps. A fascial defect may be appreciated.
• Muscle partial tear: Thigh asymmetry with a nontender or mildly tender muscle mass at the distal aspect of the rectus femoris is a common finding.
• Quadriceps tendon rupture
  • Inability to straight-leg raise (extensor mechanism disrupted)
  • Muscular defect in distal anterior thigh with mass in proximal thigh

Causes

• Quadriceps contusion or compartment syndrome - Direct blow to anterior aspect of thigh
• Quadriceps strain or rupture - Acute stretch or repeated eccentric muscle contractions with immediate or delayed (1-3 d) presentation of pain, stiffness, and decreased function

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