Author: Sharlene A. Teefey, M.D.
Objectives: Upon the completion of this CME article, the reader will be able to:
1. Describe the ultrasound findings and etiologies for elbow disorders including lateral epicondylitis, olecranon bursitis, loose bodies, and rupture of the distal biceps or triceps tendon.
2.
3.
Compare and contrast the causes for and ultrasound findings in various disorders of the knee and lower extremity, including quadriceps tendon tear, patellar tendinosis/rupture, joint effusion, bursitis, gastrocnemius musculotendinous tear, and muscle hernia.
Discuss the ultrasound findings and etiologies for many ankle and foot disorders including, tibialis posterior tears/rupture, peroneus brevis tear, Achilles tendon tendinosis/tear/rupture, and Morton’s neuroma, plantar fasciitis, and plantar fibromatosis.
Introduction:
The field of musculoskeletal ultrasound is rapidly evolving and changing due to the introduction of high resolution linear array probes, tissue harmonic imaging, extended field of view imaging, power Doppler sonography, and the continuing emphasis on healthcare cost containment. Shoulder ultrasound is gaining widespread acceptance among orthopedic surgeons and radiologists alike; however, other joints such as the elbow, wrist and hand, hip, knee, and ankle, as well as, the muscles and fascia, bones, and soft tissues are also easily examined with ultrasound. This article will provide an overview of some of the more common pathologic conditions, which can be diagnosed with ultrasound (excluding the shoulder and hand and wrist which have been discussed in previous articles).
Ultrasound of the elbow
Ultrasound of the elbow is being performed with increasing frequency to evaluate for medial or lateral epicondylitis, olecranon bursitis, loose bodies, and rupture of the distal biceps or triceps tendon. Olecranon bursitis may be the result of repetitive trauma, gout, infection, or an inflammatory arthritis. The bursal fluid may be anechoic or complex. The

presence of complex fluid with internal echoes suggests purulent /crystalline material, or hemorrhage. Aspiration is necessary to further characterize the fluid and can easily be performed with ultrasound guidance. Wall thickening usually suggests chronic inflammation or infection.
Distal biceps tendon rupture, which occurs when the elbow is forcefully extended while flexed, can be diagnosed with sonography. On physical examination, a focal defect in the antecubital fossa, a palpable mass more proximally, and weakness in flexion and supination are evident. At sonography, the retracted end of the distal biceps tendon is often surrounded by fluid and hemorrhage and may demonstrate refractive shadowing (Figure 1).
A partial thickness tear can be more difficult to identify but appears as a hypoechoic defect in an otherwise intact tendon. Rupture of the distal triceps tendon is rare. The sonographic findings are similar to those seen with distal biceps tendon rupture.
Lateral epicondylitis is usually related to a sports activity that requires a repetitive motion and results in collagen degeneration and fibroblastic proliferation of the common extensor tendon. Usually, the origin of the extensor carpi radialis brevis is involved. At sonography, the common extensor tendon is enlarged and hypoechoic. If a partial tear is present, it will appear as a distinct anechoic defect in the tendon. Tendon calcification and bony spurs imply a chronic process.
Intra-articular loose bodies may be due to trauma or arthritis, and are easily visualized with ultrasound, in particular, when an effusion is present. Loose bodies appear as small, echogenic, shadowing foci within the joint.
Ultrasound of the knee/lower extremity
Although MRI will continue to play an important role when evaluating pathologic conditions of the knee, sonography has been shown to identify a wide range of intra and extra-articular pathologies, some of the more common include quadriceps tendon tear, patellar tendinosis/rupture, joint effusion, bursitis, gastrocnemius musculotendinous tear, and muscle hernia. Although rupture of the quadriceps tendon is uncommon, sonography has been shown to be sensitive and specific for evaluating quadriceps tendon rupture.
Quadriceps tendon ruptures may be traumatic or spontaneous (after knee arthroplasty) but have also been associated with a variety of diseases including autoimmune diseases, gout, rheumatoid arthritis, diabetes, and chronic renal failure. Patients usually present with limited

knee extension. Sonographic findings for a full thickness tear include complete disruption of the tendon fibers and a gap filled with hemorrhage and fluid (Figure 2). Gentle distal traction on the patella is useful to confirm the presence of a complete tear. If a partial tear is present, a focal hypoechoic defect will be identified.
Patellar tendinosis is an overuse injury that occurs in athletes, and is caused by repetitive use of the extensor mechanism of the knee. The tendon undergoes mucoid degeneration and fibroblastic proliferation. Patients usually present with anterior knee pain/tenderness at the patellar-tendon junction. Sonographic findings include hypoechoic, proximal focal thickening of the tendon, hyperemia on color or power Doppler, and calcification; the latter suggests chronic change.
Joint effusions are easily detected with sonography. Effusions may be due to inflammatory arthritis, osteoarthritis, trauma, infection, crystalline arthropathy, or tumor.
Intra-articular fluid can easily be visualized with sonography by examining the suprapatellar bursa, however, fluid should also be searched for medial and lateral to the patella. The fluid may be anechoic, complex, or contain loose bodies. The presence of debris, a thick synovium, or septae suggests hemorrhage, infection, or an inflammatory arthritis.
Ultrasound has also been shown to be useful for evaluating the many bursae that surround the knee. While often due to repetitive trauma, bursitis may also occur due to infection, inflammatory arthritis, or dialysis-related amyloid arthropathy. At sonography, acute traumatic bursitis appears as an enlarged fluid-filled bursa with a normal wall thickness.
The presence of internal echoes, a thick synovium, or septae suggests hemorrhage, infection, or inflammation, and is often a chronic process.
The most common bursa of the knee is the Baker cyst, which becomes distended when joint fluid is extruded into the gastrocnemius-semimembranosus bursa. Baker cysts are most commonly associated with an inflammatory arthritis, osteoarthritis, a joint effusion, or a meniscal tear. At sonography, a distinct fluid collection, often containing loose bodies, will be visualized at the level of the medial aspect of the popliteal fossa (Figure 3A) (Figure
3B). The cyst neck can occasionally be visualized between the medial head of the gastrocnemius muscle and semimembranosus tendon. The presence of internal echoes, a thick synovium, and septae suggests hemorrhage, infection, or an inflammatory arthritis.
Although patients usually present with a painless mass in the popliteal fossa, the presence of pain suggests either an underlying abnormality of the knee joint or rupture of the cyst. At

sonography, the inferior margin of the cyst has a tapered appearance when ruptured and complex fluid can be seen dissecting into the calf.
A gastrocnemius musculotendinous tear is a fairly common injury due to asymmetric contraction of the gastrocnemius muscle and simultaneous knee extension. It occurs in middle-aged men who play sports such as tennis and is thought to occur due to degeneration of the musculotendinous junction. At sonography, the distal medial head of the gastrocnemius is torn and hemorrhage can be seen dissecting along the aponeurosis between the gastrocnemius and soleus muscles.
Finally, muscle hernias can occasionally occur, most commonly in the lower third of the anterior leg. Patients complain of focal pain over the herniation, perhaps due to ischemia of the muscle. Hernias are often due to trauma, prior surgery, or chronic compartment syndrome. The fascial defect and associated muscle herniation can easily be seen with ultrasound.
Ultrasound of the ankle/foot
A number of authors have recently reported using ultrasound to evaluate ankle and foot pain. Some of the more common pathologic conditions include tibialis posterior tears/rupture, peroneus brevis tear, Achilles tendon tendinosis/tear/rupture, and Morton’s neuroma, plantar fasciitis, and plantar fibromatosis. Tibialis posterior tendon tears seem to occur in sedentary, middle-aged or elderly women and have been associated with inflammatory arthritis, obesity, autoimmune diseases, diabetes, gout and steroid use. Tears are thought to occur as a result of repetitive microtrauma and can progress to complete rupture. Patients with tears usually present with pain and tenderness along the course of the tendon. If rupture occurs and it is untreated, it will eventually cause pes planus, hindfoot valgus, and forefoot abduction. At sonography, a spectrum of findings, depending on the stage of tendon dysfunction, will be seen. An enlarged hypoechoic tendon with preservation of the normal fibrillar echotexture is indicative of tendinitis. If a partial tear is present, a distinct longitudinal hypoechoic defect will be observed, usually in the infra-malleolar portion of the tendon (Figure 4A) (Figure 4B) (Figure 4C). When ruptured, the tendon fibers will be completely disrupted. This usually occurs at the insertion. Associated findings include tendon sheath fluid, tenosynovitis, and tendinitis as evidenced by increased color
Doppler.

Peroneus brevis tears are less common. Patients complain of lateral retro-malleolar pain and swelling. Disruption of the superior peroneal retinaculum due to trauma or a shallow fibular groove are two predisposing factors that lead to repetitive peroneal subluxation causing a tear or “split” of the retro-malleolar peroneus brevis. On sonography, the tendon assumes a boomerang or “C” shape.
Achilles tendinosis/tear/rupture is frequently associated with sports related activities but may also occur in patients with inflammatory arthritis, autoimmune diseases, diabetes, and gout. An enlarged, hypoechoic tendon with an intact fibrillar echotexture is suggestive of tendinosis, whereas a distinct hypoechoic, longitudinal defect suggests an intra-tendon partial tear. It can be difficult to distinguish between tendinosis and a partial tear at sonography. Increased color Doppler flow is often an associated finding. Rupture usually occurs at a zone of relative avascularity located 2 to 6 cm proximal to the tendon’s insertion on the calcaneus. Patients usually present with sudden, severe calf pain, swelling, and a palpable defect in the tendon. At sonography, diastasis of the torn tendon ends is evident
(Figure 5). If acute, a hemorrhage will frequently fill the gap between the torn tendon ends.
The gap should be quantified with the ankle in dorsiflexion and plantar flexion, which will help the surgeon to decide whether surgery or conservative treatment is indicated.
Morton neuroma occurs in middle-aged women and is thought to be due to repetitive trauma to the neurovascular structures that are trapped by the intermetatarsal ligament and then compressed between the metatarsal heads during ambulation.
Histologically, Morton neuroma represents perineural fibrosis of the plantar digital nerve at the level of the metatarsal head. Most patients present with burning plantar pain and parasthesias, which radiate from the level of the metatarsal heads to the toes. The pain is frequently exacerbated with walking and relieved by rest. At sonography, a Morton neuroma will appear as a well-defined, hypoechoic lesion with slight through transmission. It most commonly occurs in the interspace at or slightly proximal to the metatarsal heads, especially the 2-3 or 3-4 interspaces. Those that can be detected with ultrasound are usually at least 5 mm in diameter. Visualization of the digital nerve entering and exiting the lesion strengthens the diagnosis but is very difficult to identify. An associated fluid filled bursa may also be seen at this level and should not be confused with the neuroma.
Plantar fasciitis is associated with repetitive trauma (running, dancing, tennis), inflammatory arthritis, autoimmune diseases, and gout. Patients present with heel pain on

awaking that increases with walking but decreases with increased activity and they have tenderness at the insertion of the fascia on the calcaneus. On sonography, the plantar fascia is thickened (  4 mm) and hypoechoic (Figure 6). Another entity of the plantar fascia, plantar fibromatosis, can also be diagnosed with ultrasound. It is a benign, but aggressive neoplasm that involves the mid to distal aspect of the fascia. Patients usually notice painless, palpable nodules. On sonography, the nodules are hypoechoic and intimately related to the plantar fascia but do not invade into the deeper foot muscles.
Figures:
1 Longitudinal image of the anterior aspect of the right elbow shows a distal biceps tendon rupture. Fluid surrounds the retracted tendon, which also demonstrates refractive shadowing. (The left side of the image is proximal).
2 Longitudinal image (extended field of view) of a rupture of the right quadriceps tendon. Fluid surrounds the more inferior aspect of the tendon, which remains attached to the patella. (The left side of the image is proximal).
3A Longitudinal image of the right popliteal fossa shows a Baker’s cyst filled with complex fluid. The inferior aspect of the cyst is pointed suggesting rupture. (The left side of the image is proximal).
3B Transverse image of the right popliteal fossa shows the neck of the Baker’s cyst, which is between the medial head of the gastrocnemius muscle belly and semimembranosus tendon. (GC = medial head of gastrocnemius muscle belly, SM
= semimembranosus tendon).
4A Transverse image shows a tibialis posterior partial thickness tear. Note the enlarged tendon and the hypoechoic defect within the tendon.
4B Longitudinal image also shows the tibialis posterior defect. Note the lack of normal fibrillar echotexture in this region.
4C Longitudinal image shows increased color Doppler flow within the tibialis posterior
5 tendon in the region of the defect. (The left side of the image is proximal).
Longitudinal image (extended field of view) shows an Achilles tendon rupture (below the two cursors). The gap is filled with hemorrhage and fluid. (The left side of the image is proximal).

6 image is proximal).
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4.
The longitudinal image labeled “L” shows a hypoechoic thickened plantar fascia measuring > 4 mm consistent with plantar fasciitis. The normal right (R) plantar fascia, which measures  4 mm, is shown for comparison. (The left side of the
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About the Author
Sharlene A. Teefey, M.D. is currently a Professor of Radiology at the Mallinckrodt
Institute of Radiology at Washington University School of Medicine in St. Louis Missouri.
She is a member of numerous societies and organizations including the American College of
Radiology, the Society of Radiologists in Ultrasound, and the American Institute of
Ultrasound in Medicine.
She is a reviewer of manuscripts for Radiology, the American Journal of Roentgenology, and
Radiographics. She has more than 50 publications in peer review medical journals and has been a speaker at numerous institutions and conferences across the country.
2.
Examination:
1. The presence of wall thickening seen on ultrasound in olecranon bursitis usually suggests
A.
B.
C.
D. chronic inflammation. acute trauma. a nearby tendon rupture. hemorrhage.
E. the initial onset of gout.
Distal biceps tendon rupture occurs when the elbow is
A. forcefully flexed further while already flexed.
B. forcefully flexed while extended.
C. at rest and then is suddenly pulled.
D. forcefully extended while flexed.
E. traumatically hit from the side.
3. A partial thickness distal biceps tendon tear can be more difficult to identify but
A. is identified by the presence of tendon calcifications.
B. appears as a hypoechoic defect in an otherwise intact tendon.
C. is identified by the presence of bony spurs.
D. is identified by tendon sheath thickening.
E. appears as a hyperechoic defect in an otherwise intact tendon
4. The origin of which of the following muscles is usually involved in lateral epicondylitis?
A. extensor pollicis brevis
B. flexor carpi ulnaris
C. extensor pollicis longus
D. extensor carpi radialis longus

5.
6.
E. extensor carpi radialis brevis
Regarding intra-articular loose bodies, all of the following are true EXCEPT
A. They may be caused by trauma.
B. They appear as small, echogenic, shadowing foci within the joint.
C. They are easily visualized, especially when an effusion is present.
D. They may be caused by arthritis.
E. They appear as anechoic shadows within the joint
Quadriceps tendon ruptures may be traumatic or spontaneous but have also been associated with a variety of diseases including all of the following EXCEPT
A. autoimmune diseases
B. diabetes
C. hyperthyroidism
D. gout
E. chronic renal failure.
7. For quadriceps tendon tears, gentle ______ traction on the patella is useful to confirm the presence of a complete tear.
A. distal
B. proximal
C. medial
D. lateral
E. mediolateral
8. For patellar tendinosis, the finding of calcification suggests
A. the presence of a tendon rupture.
B. chronic change.
C. that the cause is gout
D. an acute reaction.
E. a hormonal abnormality.
9. Regarding joint effusions of the knee, all of the following are true EXCEPT
A. They are easily detected with sonography.
B. They may be due to inflammatory arthritis, osteoarthritis, trauma, infection, crystalline arthropathy, or tumor.
C. Intra-articular fluid can easily be visualized with sonography by examining the infra-patellar bursa
D. The fluid may be anechoic, complex, or contain loose bodies.
E. The presence of debris, a thick synovium, or septae suggests hemorrhage, infection, or an inflammatory arthritis.
10. Bursitis of the knee can be caused by all of the following EXCEPT
A. repetitive trauma
B. infection
C. inflammatory arthritis
D. quadriceps tendon rupture
E. dialysis-related amyloid arthropathy

11. The most common bursa of the knee is the ______, which becomes distended when joint fluid is extruded into the gastrocnemius-semimembranosus bursa.
A. Baker cyst
B. Morton’s cyst
C. Popliteal bursa
D. Anterior patellar bursa
E. Posterior patellar bursa
12. At sonography with a Baker cyst, the inferior margin of the cyst has a _______ appearance when ruptured and complex fluid can be seen dissecting into the calf.
A.
B. half moon rounded
C. tapered
D. boomerang or “C”
E. bulbous
13. At sonography for a gastrocnemius musculotendinous tear, the distal medial head of the gastrocnemius is torn and hemorrhage can be seen dissecting along the aponeurosis between the gastrocnemius and _______ muscles.
A. peroneus longus
B. peroneus brevis
C. flexor digitorum longus
D. soleus
E. anterior tibial
14. Muscle hernias can occasionally occur in an extremity, most commonly in the
A. upper third of the anterior arm
B. lower third of the posterior arm
C. upper third of the anterior leg
D. upper third of the posterior leg
E. lower third of the anterior leg
15. Tibialis posterior tendon tears seem to occur in
A. sedentary, middle-aged or elderly women
B. athletic women
C. children
D. athletic men
E. sedentary, middle-aged or elderly men
16. Peroneus brevis tears are not common, but on sonography, the tendon assumes a
________ shape.
A. bulbous
B. tapered
C. rounded
D. boomerang or “C”
E. rectangular

17. Achilles tendon rupture usually occurs at a zone of relative avascularity located
_______ to the tendon’s insertion on the calcaneus.
A. 1 to 3 cm distal
B. 2 to 6 cm distal
C. 6 to 9 cm distal
D. 1 to 3 cm proximal
E. 2 to 6 cm proximal
18. For acute Achilles tendon rupture, at sonography, diastasis of the torn tendon ends is evident, and the gap should be quantified with the ankle in _______, which will help the surgeon to decide whether surgery or conservative treatment is indicated.
A.
B.
C. valgus flexion only varus flexion only both dorsiflexion and plantar flexion
D. plantar flexion only
E. dorsiflexion only
19. Morton neuromas that can be detected with ultrasound are usually at least _____ mm in diameter.
A. 1
B. 5
C. 8
D. 10
E. 15
20. On sonography with plantar fasciitis, the plantar fascia is thickened at ______ mm and hypoechoic.
A.  1
B.  4
C.  7
D.  9
E.  11