Definition

Muscle contusions and strains account for 90% of contact sport–related injuries [1,2]. Quadriceps muscle contusions result from blunt trauma to the anterior thigh and are encountered most commonly in contact sports such as football, soccer, basketball, and wrestling. Injury is caused by a direct hit from a helmet, shoulder pad, elbow, or knee or being struck by a puck while playing hockey [3]. The acute trauma damages muscle tissue, causing hemorrhage and subsequent inflammation. A contracted muscle will absorb more force and this will result in a less severe injury [4]. At 12 to 24 hours after the injury, quadriceps contusions are graded mild, moderate, or severe. A mild contusion has more than 90 degrees of knee flexion with normal gait; moderate, between 45 and 90 degrees of knee flexion with antalgic gait; and severe, less than 45 degrees of knee flexion with severely antalgic gait [4,5].

Symptoms

Quadriceps contusions may not be immediately evident after the contact injury. Pain, swelling, and decreased range of motion of the knee, particularly flexion, are seen within 24 hours. Symptoms may worsen with active muscle contraction and with passive stretch. Loss of knee range of motion can be the result of muscle and articular edema as well as of physiologic inhibition of the quadriceps muscle group and “splinting” due to pain. After injury, the quadriceps muscle group often becomes stiff, and the patient may have difficulty bearing weight on the affected extremity, resulting in an antalgic gait. Hemorrhage and resultant hematoma are described as either intermuscular (between the muscles) or intramuscular (within a muscle).

Physical Examination

Visual inspection of quadriceps contusion shows a variable amount of swelling and discoloration over the anterior thigh due to hematoma formation and intramuscular bleeding. Pain of varying intensity is present on palpation of the quadriceps muscle group. A firm palpable mass may be noted in the anterior thigh and is usually due to hematoma formation; if the hematoma formation is large, a knee effusion may also be present. Bone incongruity and tenderness may indicate fracture of the femur, patella, or tibial plateau. Check for the presence of distal pulses and capillary refill and assess range of motion of adjacent joints to be sure that the injury is localized to the anterior thigh.

Evaluation of range of motion reveals decreased knee flexion, especially past 90 degrees; knee extension will be less painful than flexion [6]. Extension lag or complete lack of extension is noted in partial or complete quadriceps rupture. With quadriceps tendon rupture, a palpable defect may be present. However, quadriceps rupture is a relatively rare injury more common in patients older than 50 years, and it is typically associated with underlying metabolic or inflammatory disease [7]. Muscle stretch reflexes of the patellar tendon may be inhibited, and serial measurements of thigh circumferences should be made during the initial 24- to 72-hour postinjury period to assess for possible compartment syndrome. Paresthesias, loss of pulses, distal pallor, intense pain, and decreased temperature should alert the clinician to consider this diagnosis (see Chapter 67). Sensory testing should include the femoral and saphenous nerve distribution of the distal leg.

An intermuscular hematoma with septal or fascial sheath hemorrhage may be more likely to disperse and to result in distal ecchymosis. If the contusion is in the distal third of the quadriceps, discoloration and swelling will often track into the knee region because of gravity. An intramuscular hematoma may resolve more slowly and may be associated with myositis ossificans and scar contracture.

Functional Limitations

Initially, gait will be antalgic and weight bearing difficult on the involved extremity. Rehabilitation typically occurs in three phases. In the first phase (first 24 hours), pain usually limits activity, and the patient may require crutches [8]. During a period of days to weeks, climbing stairs, running, and “kicking” activities will be limited secondary to knee stiffness and pain associated with terminal knee flexion and extension. Most patients recover uneventfully.

Diagnostic Studies

Plain radiographs are initially obtained in moderate to severe quadriceps contusions to rule out a coexisting fracture. Magnetic resonance imaging is the diagnostic imaging study of choice and allows visualization of the involved quadriceps muscles. Resolution of the injury, as detected by magnetic resonance imaging, lags behind functional recovery [9]. Ultrasonography may be helpful if tendon injury is suspected [10