Sonography of the quadriceps muscle: Examination technique, normal anatomy, and traumatic lesions.
Lesions of the quadriceps muscle (QM) are frequently seen by sonographers, and in most cases they are the result of sports-related trauma. An accurate assessment of the severity of the lesion is essential, particularly when the patient is a professional athlete. In most cases, careful history-taking and a thorough physical examination are sufficient for making the diagnosis and indicating the most suitable imaging studies for each case.
Clinical assessment alone, however, may not be sufficient for distinguishing contusions from small, partial tears or for estimating the size of a tear. Therefore, at least in patients who are professional athletes, imaging studies are necessary to plan appropriate therapy that will allow prompt functional recovery.
Muscles cannot be visualized with conventional radiography, but it is used routinely in prepubertal patients because it can detect apophyseal detachments, which are the most frequent muscle lesion in this age group. Radiography is also useful when myositis ossificans is suspected. Magnetic resonance imaging, thanks to its excellent tissue contrast, allows simultaneous assessment of muscle, joint, and bone planes. It remains a second-line study due to its high cost and relatively low availability. It is also associated with various contraindications, the most important of which is the presence of a cardiac pacemaker.
Rectus femoris tear, sagital and transverse section.
Ultrasonography has a number of advantages, including widespread availability, absence of contraindications, and low cost. It can also be used for dynamic studies of the muscle during contraction and relaxation, and if doubts arise, scans can easily be obtained of the contralateral muscle for comparison purposes.
These qualities make it an excellent tool for follow-up of patients with QM lesions, when follow-up is necessary. This article reviews the anatomy of the QM, the technique used for standard ultrasound examination of this muscle, its normal appearance on ultrasound, and the sonographic characteristics of the most common traumatic lesions that affect it.
Anatomy of the proximal rectus femoris. RF = rectus femoris; black arrow = direct tendon and its insertion on the anteroinferior iliac spine; white arrow = indirect tendon and its insertion on the lateral.
Hematoma of the rectus femoris
The quadriceps muscle (QM) is located in the anterior compartment of the thigh . It is composed of 4 muscle bellies: the rectus femoris (RF), which lies in the anterior portion of the thigh; the Vastus medialis (VM) and Vastus lateralis (VL) on the inner and outer portions, respectively; and the Vastus intermedius (VI), which is located posteriorly. The Vastus muscles originate from the anterior, medial, and lateral aspects of the femur.
Rectus muscle tear.
The RF originates from the anterior inferior iliac spine (AIIS), and it has three proximal tendons: the straight or direct tendon, which arises from the AIIS; the indirect tendon that inserts into the superolateral rim of the acetabulum; and a small reflected tendon that inserts into the anterior capsule of the hip joint. The direct and indirect tendons continue in 2 aponeurotic laminae that extend to the lower third of the muscle. The direct tendon continues as the superficial lamina; the indirect tendon as the central sagital lamina .
Rupture rectus M distal part.
The 4 bellies of the QM converge distally to form the thick quadriceps tendon, which inserts into the superior pole of the patella. The tendon is composed of multiple laminae positioned one on top of the other. The superficial lamina is continuous with the muscle fibers of the RF.
Transverse section showing Rf= rectus femoris, and Vi = Vastus intermedius, VL=Vastus lateralis & VM= Vastus medialis.
The intermediate lamina receives the fibers of the VM and VL, and the deepest lamina receives the fibers of the VI. A fairly small portion of the fibers of the superficial lamina lies superficial to the patella and merge directly into the patellar tendon. The description supplied above corresponds to that provided by most anatomy textbooks, but recent studies based on anatomical dissections, have revealed considerable variability in the composition of the distal tendon .
The patients are examined in the dorsal decubitus position with the hip and knee in the neutral position .
Internal or external rotation of the lower limb is necessary for complete assessment of the lateral or medial aspect of the muscle.
The examination can be done with a moderate- to high-frequency transducer, depending on the thickness of the muscle.
A good overall evaluation of the QM can usually be achieved with a multi frequency (5–12-MHz) linear transducer. If there is substantial muscle hypertrophy, a 5-MHz transducer is preferable as it offers better visualization of the deep planes. A systematic approach will allow complete exploration of the QM and reveal even small lesions that can easily be missed.
A scans are made at the level of the RF tendon. As a rule, the examination begins at the proximal end of the muscle and proceeds distally.
The axial scans are done first because they provide more panoramic views. Areas of interest are then explored with longitudinal scans.
A fundamental landmark in examinations of the cranial portion of the RF is the anterior superior iliac spine, which can be readily identified by palpation. The transducer is placed over this structure on the axial plane and moved distally for 4–5 cm to visualize the AIIS, which is the insertion point for the direct tendon of the RF. The indirect tendon, which follows an oblique course, is examined with an oblique axial scan at the lateral aspect of the uppermost portion of the thigh.
( Do both sides for comparison when you find heamtoma or tear).
The tendon is then examined with oblique coronal scans. The medial and distal portions of the RF are examined with axial scans, advancing the transducer distally.
The anterior and central aponeuroses are clearly visualized: the latter is shaped like a comma, the former is visualized as a thickening of the muscle fascia. The examination continues with exploration of the Vastus muscles, which are scanned axially and then longitudinally.
Information obtained during the static examination can be supplemented with a dynamic examination performed during isometric muscle contraction.
This approach is sometimes more suitable for detecting small partial tears. When the muscle plane has been fully explored, the distal tendon is scanned. During this phase, the knee is flexed approximately 30° to straighten the tendon.
(tear at the edge of the muscle).
This eliminates anisotropy artifacts, which result in hypoechoic areas in the distal portion of the tendon that may be mistaken for focal tendinopathy or even partial ruptures. The tendon is examined first with sagital scans and then in the axial plane.
Ultrasonography allows excellent visualization of the proximal tendons of the RF. The straight tendon is cylindrical with smooth borders. Some degree of thickening at the level of the cranial insertion is normal. The internal structure is homogeneously hyperechoic. On axial scans, the tendon is visualized as a more or less oval-shaped structure located medial to the indirect tendon. The latter tendon, owing to its oblique course, is often associated with substantial posterior shadowing that can be mistaken for intratendinous calcification.
Sagital images allow complete exploration of the direct tendon from its insertion into the AIIS to the myoaponeurotic junction. Moving the transducer laterally reveals the indirect tendon, a hypoechoic band that descends toward the upper rim of the acetabulum. It is visualized best on oblique axial images.
Axial scans of the RF muscle reveal its characteristic internal architecture, which is related to the presence of the vertical aponeuroses . The latter is represented by a mildly curved, comma-shaped hyperechoic structure, which is normally quite distinct from the muscle tissue and extends as far as the lower third of the muscle.
In the sagital plane, it appears much more difficult to assess owing to its orientation and thickness. The internal fibers of the Vastus muscles are not arranged in any particular manner. They are characterized by the presence of short connective-tissue septa. The fascia that surrounds each of the Vastus muscles is clearly visualized as a thin hyperechoic layer. Their presence allows one to distinguish the VI from the VM and RF. Distinguishing the VL from the VI is more difficult because these two muscles merge laterally.
On longitudinal scans the quadriceps tendon appears to be composed of 3 or 4 hyperechoic tendinous laminae separated by thin hypoechoic bands, which represent lax connective tissue. The distal insertion of this tendon into the superior pole of the patella can be well visualized only when the knee is flexed.
Muscle lesions are frequently associated with sports-related or occupational trauma.. In some sports, like soccer. Muscle lesions can be divided into 3 main etiopathogenetic groups: lesions caused by direct trauma (contusions); those caused by indirect trauma (sprains), which usually occur during eccentric contraction; and rare lesions caused by cuts (lacerations).
Contusions are classified as mild, moderate, or severe, depending on the limitation of joint movement they cause.
Sprains, too, are divided into 3 classes according to the number of muscle fibers involved: first-degree sprains, which involve a few of the fibers within a muscle fascia; second-degree sprains, in which the surface of the damaged fascia represents less than ¾ of the total section of the muscle; and third-degree sprains, in which the surface of the rupture amounts to more than ¾ of the total section and may extend to the entire muscle belly (complete rupture).
Clinically speaking, sprains have three typical characteristics: 1) sharp pain associated with a technical movement, 2) the injured area can be located with precision by the patient and verified by careful palpation; 3) impaired mobility that varies with the severity of the lesion.
lesions may mimic hip pain or a lesion of the tensor fascia lata. The athlete reports the sensation that something in the hip was displaced during the trauma and complains of pain in the region of the tensor fascia lata. Together with the long head of the biceps femoris, the RF is the muscle most frequently involved in recurrent indirect trauma, i.e., a new lesion involving the same area of the muscle (or at least the same muscle) that occurs within 6 months of the initial injury. The typical clinical manifestations of the recurrent lesions are similar to those of the primary lesion.
Prompt diagnosis (within a few days of the muscle trauma) is essential to ensure timely and complete healing and to reduce the likelihood of recurrence. For this reason, imaging studies are important. Together with the clinical findings, they help the physician identify the lesion, and they can be repeated as needed to monitor the progress of healing .
Thank you for reading.
Steve Ramsey, PhD. Calgary – Alberta .