Thursday, December 15, 2011

Charlie Brown and a Knee Injury

Photo by gurana

For those of you that do not recognize the visual allusion above, it is a simulacrum of a famous bit of Americana: Lucy pulling the football away from Charlie Brown. Once I became a doctor, I began to look at this a bit differently, and began wondering what kind of injuries Charlie Brown might sustain thanks to Lucy's wicked intentions. Ah, the loss of innocence....

In this case, a 17 year old female sustained a knee hyperextension injury one day ago, and heard a "pop". The orthopedic surgeon suspected an ACL tear, and referred the patient for an MRI scan.

A sagittal proton-density image reveals that the ACL (pink arrow) and posterior cruciate ligament (PCL, green arrow) are intact, and identifies a tear of the posterior capsule (red arrow).

In a normal patient, the posterior capsule (blue arrows) is easily seen:

A sagittal T2 fatsat image of our patient depicts the tear and the associated edema:

An axial intermediate image also identifies the tear:

In a normal patient, the posterior capsule green arrows) is easily seen:

Posterior capsular tears are associated with hyperextension injuries of the knee. Hyperextension of the knee can result when direct force is applied to the anterior tibia while the foot is planted or from an indirect force, such as a forceful kicking motion (Sanders et al., Radiographics 20, S135-S151, 2000). Hyperextension injuries can result in tears of the posterior capsule, ACL, PCL, anterior bone contusions, and injuries of the posterolateral corner. There may be associated meniscal tears as well. The pattern of injury correlates with the mechanism of injury (Hayes et al., Radiographics 20, S121-S134, 2000).

MRI signs of a tear of the posterior capsule include frank disruption and high signal intensity in or adjacent to the capsule on T2-weighted MR images. In the intercondylar area, however, normal openings for the vascular structures and nerves may be present, and these should not be confused with tears. (De Maeseneer et al., AJR 182, 955-962, 2004).

Posterior capsular tears are commonly associated with PCL injuries, but can occur without significant ligament damage, as in this case.

Vic David MD

Monday, November 14, 2011

Figure Skaters and Bursitis

 Photo by YN 08-09

Figure skaters soar and float above the ice, spinning and delighting us with their skill and acrobatics. Skaters spend hours on the ice, and subject their ankles and feet to great stress. When their skates do not fit perfectly, the soft tissues of the foot and ankle can become irritated.

In this case, a 25 year-old female figure skater presented to her orthopedic surgeon complaining of a painful mass over the medial malleolus of her tibia. The physical examination confirmed the presence of a mass along with extensive local soft tissue edema, and she was sent for an MRI for further evaluation.

An axial T2 fatsat image identifies an oval, mass (red arrows) immediately superficial to the medial malleolus (yellow arrow):


A coronal T2 fatsat image again identifies the mass (red arrows) and the medial malleolus (yellow arrow), and also depicts the extensive soft tissue edema (white arrows):

An axial postcontrast T1 fatsat image shows that the majority of the mass fails to enhance. There is thin, circumferential enhancement of the lesion:

Based on these images, a diagnosis of medial malleolar bursitis was made. Brown et al. (AJR 2005, 184:979-983) described the appearance of the medial malleolar fat in an asymptomatic population and described the MRI appearance of the medial malleolar bursa. They described ten patients with medial malleolar bursitis (six figure skaters and four ice hockey players). 

The medial malleolar bursa is an adventitial bursa. It develops as a consequence of abnormal, extended pressure over the medial malleolus of the tibia. An adventitial bursa is a reactive bursa that forms as a result of chronic soft tissue irritation. Unlike a true bursa, an adventitial bursa lacks a true epithelial lining.  In the foot and ankle, adventitial bursae are most common in the forefoot, typically occurring under the first and fifth metatarsophalangeal joints. They can also be found medial or dorsal to the first metatarsal head, and superficial to the medial malleolus, as in this case.

Medial malleolar bursitis is usually treated nonsurgically, with activity modification, anti-inflammatory medications, and topical treatment. If the patient's symptoms do not resolve over a prolonged period of time, surgical resection of inflamed bursa may be necessary.  This injury may be prevented by wearing properly fitted skates, using extra padding, and avoiding overtraining.

Vic David MD

Saturday, October 15, 2011

High Heels and Morton's Neuromas

Photo by Amy the Nurse

Through many centuries, high-heeled shoes have been linked to increasing female attractiveness. (For an interesting overview of high-heel footwear, go here). The chronic use of high-heeled footwear comes at the cost of increased foot problems, including toe deformities, bunions, and Morton’s neuromas.

In the following case, a 45 year-old female presented to her podiatrist with metatarsalgia (pain involving the forefoot), and was referred for an MRI scan of the foot. A coronal T1 image reveals mass lesions in the second intermetarsal space (red arrow) and the third intermetatarsal space (blue arrow):

The location and signal features of the lesions are compatible with Morton’s neuromas.

On a coronal T2 fatsat image, the neuromas have different signal features, with the larger second intermetatarsal space lesion (red arrow) primarily hypointense, while the smaller third intermetatarsal space lesion is difficult to see, illustrating the variable appearance of Morton’s neuromas on T2 fatsat images:

 An axial T1 image confirms the presence of both neuromas:

A sagittal intermediate image better depicts the fusiform morphology of the neuroma in the second intermetarsal space:

There is a great deal of information about Morton’s neuromas that can be easily found on the internet. Here, we concentrate on imaging of this condition.

What is the best position for MR imaging of Morton’s neuromas?

Weishaupt et al. (Radiology 226: 849-856, 2003) examined this question by scanning 18 patients with 20 Morton’s neuromas in the prone (plantar flexion of the foot), supine (dorsiflexion of the foot), and upright weight-bearing positions. They concluded that:

--> Morton’s neuromas show position-dependent changes in shape in the prone, supine, or weight-bearing body positions.

--> Morton’s neuromas are best visualized in the prone position.

Thus, imaging of the forefoot should be done in the prone position, whenever possible.

What is the clinical significance of a Morton’s neuroma that is detected incidentally, while imaging the forefoot for another reason?>

Bencardino et al. (AJR 175: 649-653, 2000) retrospectively reviewed 85 consecutive foot MR examinations. The patients were subdivided into symptomatic or asymptomatic groups, with regard to Morton’s neuromas. Surgical confirmation was available in eight of 25 symptomatic patients. They diagnosed Morton’s neuromas in 33% of patients with no clinical evidence of this condition. Slightly larger lesions were observed in the symptomatic group of patients; however, significant overlap was noted between the two groups. They found that asymptomatic Morton’s neuromas can be found in a significant number of patients.

Thus, when a Morton’s neuroma is detected on MR imaging, one must correlate the imaging observations with clinical symptoms.

How good is MRI for the diagnosis of recurrent Morton’s neuromas?

Espinosa et al. (Radiology 255: 850-856, 2010) examined this issue in a study where they studied 58 consecutive patients who had undergone resection of a painful Morton’s neuroma. Pre- and postoperative MR imaging, and clinical follow-up for a minimum of 2 years after surgery were available. They concluded:

--> Morton’s neuroma–like abnormalities are commonly encountered on MR images after Morton’s neuroma resection. 

--> Although these abnormalities are larger in patients with symptoms, there is a high degree of size overlap; thus, they do not allow differentiation between symptomatic and asymptomatic patients.

Thus, MR imaging is of limited utility in the assessment of recurrent Morton’s neuromas.

Is intravenous contrast (gadolinium) needed for the diagnosis of Morton’s neuromas?

There is conflicting data in the literature on this topic. In 1993, Terk et al. (Radiology 189: 239-241, 1993) published an article which advocated the use of gadolinium in the assessment of Morton’s neuromas. Subsequently, Zanetti et al. (AJR 168, 529-532, 1997) and Williams et al. (Clin Radiol 52: 46-49, 1997) questioned the utility of enhanced T1-weighted fat-suppressed sequences in the assessment of this condition.

In general, intravenous contrast (gadolinium) is not needed for the routine evaluation of Morton’s neuromas.

Vic David MD

Sunday, September 18, 2011

Expectations, Perceptions, and a Shoulder Fracture

Our expectations can certainly influence our perceptions. For example, in the figure below, the image "13" is perceived readily as a number when it is surrounded by other numbers (lower line). In the upper line, it is surrounded by letters, and it is perceived differently, recognized more slowly and less readily by the brain.

Expectations influence perception over and over in our lives, and this phenomenon extends to radiology. The clinical setting creates a certain set of expectations in the mind of the radiologist. This situation cuts both ways, enhancing the ability of the radiologist to detect subtle findings (when he is explicitly looking for them), but also detracting from his ability to see these same subtle findings (when the expectation is that they will not be present).

In this case, an 80 year old grandmother tripped over her grandchild's toy and hit a wall 8 weeks ago. She had arthritis in both shoulders, and went to her orthopedic surgeon, since her right shoulder was hurting more than usual. X-rays were negative, and she was sent for an MRI for further evaluation.

A coronal T2 fatsat image reveals an unexpected, easily missed fracture of the spine of the scapula:

An axial gradient echo weighted image of the patient confirms the scapular spine fracture:

Fractures of the scapula are typically associated with major trauma, such as high-speed motor vehicle accidents or other crashes. 

In the absence of such trauma, one typically does not think of a scapular fracture as a cause of shoulder pain, but this was indeed the case in this example.

The scapula is also called the "shoulder blade" and helps stabilize the upper extremity against the chest. Here is a posterior view of the chest, showing the scapula:

Scapula, anterior view:

Scapula, posterior view:

The scapula is a flat, triangular bone that lies over the posterior surface of the rib cage. At its upper lateral corner is a cuplike depression called the glenoid fossa (red arrows) which forms the socket for the head of the humerus. The posterior surface of the scapula is divided by a nearly horizontal ridge of bone, the scapular spine (blue arrows). The spine extends laterally to form the acromion (black arrows) which overhangs the glenoid fossa. The anterior surface of the scapula, just medial to the glenoid fossa, has a beaklike projection called the coracoid process (green arrows) that acts as an attachment for muscles and ligaments. (chionline)

Most scapular fractures can be treated nonoperatively. In general, the results are satisfactory with conservative treatment. A sling support for 3-4 weeks and early rehabilitation is the key to successful non operative treatment. Treatment emphasizes symptom relief and early motion to prevent long-term stiffness. After motion is restored in the first four to 6 weeks, therapy is directed at rehabilitating the rotator cuff and strengthening parascapular musculature. (

This case illustrates that although scapular fractures are traditionally associated with high-energy trauma, they can also occur in elderly osteoporotic patients with a history of a minor trauma.

Vic David MD

Wednesday, August 17, 2011

Mixed Martial Arts and a Chest Injury

Photo by Michael Connell

The pectoralis muscle is a popular muscle for men and boys to develop. Women are drawn to "chiseled pecs", which is more than enough motivation for men to work on enlarging them.

Weightlifters are particularly prone to injuries of this muscle, and pectoralis tears are seen most often in young, athletic males. Patients with a ruptured pectoralis major present in the acute aftermath of the injury, with pain, extensive swelling, and ecchymosis of the anterior chest wall, axilla, and medial aspect of the affected arm. Injured patients frequently report a "pop" at the time of the injury.

Connell et al. (Radiology 210:785-791, 1999) described the proper technique used to image the pectoralis major. In 2000, Lee et al. (AJR 174:1371-1375) performed a beautiful cadaveric study, and described some salient features of the pectoralis major on MRI:

---> the pectoralis major tendon crosses anterior to the biceps tendon to become a thin, triangular-shaped structure at its insertion at the lateral lip of the intertubercular groove

---> one reliable landmark for the superior margin of the pectoralis insertion is the quadrilateral space, best seen in the axial plane. The superior edge of the pectoralis major insertion typically is identified at the level of, or within 1-1.5 cm inferior to the quadrilateral space (range, 0-1.2 cm).

---> another reliable landmark is the origin of the lateral head of the triceps muscle. The superior edge of the pectoralis major insertion is reliably identified on the anterior aspect of the humerus, approximately 5-10 mm superior to the level at which the lateral head of the triceps is first identified.

Here is an example of axial images through the normal pectoralis major tendon, superior to inferior, illustrating these principles:

(click on image to enlarge)

Green arrow = normal pectoralis major tendon. Orange arrow = latissimus dorsi tendon. Note the proximal aspect of the lateral head of the triceps muscle (pink arrow) and vessels within the quadrilateral space (blue arrow).

In this case, a 25 year old male injured his chest during a take down of an opponent during mixed martial arts training. He presented for his MRI approximately 1 week after his injury.

(A) Axial intermediate image identifies an avulsion of the pectoralis major tendon at its insertion. Note the torn, retracted tendon (red arrows) and the biceps tendon (green arrow) which is displaced anteriorly. MRI clearly identifies the end the torn tendon (yellow arrow). (B) Axial T2 fatsat image better shows the edema associated with the injury.

Compare this appearance with a normal pectoralis tendon:

An oblique coronal T2 fatsat image of our patient shows marked fluid and edema (red arrows) at the myotendinous junction, the pectoralis major muscle (yellow asterisks), and the cephalic vein in the deltopectoral groove (green arrow):

The MRI scan precisely depicted the nature of the injury and allowed appropriate presurgical planning. The patient was operated on three days later, and the tear was repaired successfully.

When ordering an MRI to assess a possible pectoralis tear, it is generally best to order a “MRI of the chest”. If one requests an “MRI shoulder” the MRI technologist may inadvertently use a standard shoulder imaging protocol, which is very different than the protocol used to assess the pectoralis major. The standard shoulder protocol will not answer the clinical question.

In general, early surgical repair is associated with a better outcome for the athlete, with earlier return to full strength and range of motion. Immediate diagnosis avoids surgical delay, which has the advantage of avoiding adhesions, muscle retraction, and atrophy, which can occur as early as 6 weeks after the initial injury (Lee et al. AJR 174:1371-1375).

In the past, tears that have reached the chronic stage have been considered irreparable injuries. More recently, even chronic tears are addressed surgically, and still have a good outcome (Aarimaa et al., Am J Sports Med 32:1256-1262, 2004).

Vic David MD

Friday, July 15, 2011

Stairs and a Tendon Tear

Photo by Susan NYC

Steep stairs are a danger for the very young and very old, who must gingerly pick their way down stairs, to avoid a fall. Inevitably, despite all due care, some individuals will slip and injure themselves.

In this case, a 66 year old man fell going down steep stairs, and presented to his orthopedic surgeon with knee pain and loss of extensor strength.

A sagittal T2 fatsat image depicts a high grade partial tear of the quadriceps tendon. The distal edge (red arrow) of the tendon is well seen, as is the large hematoma (green arrow). The patella (pink arrow) is positioned more inferiorly than normal, and the patellar tendon (white arrow) is lax, suggesting that this is functionally a complete tear. The deep layer of the quadriceps tendon, composed of the vastus intermedius (yellow arrow), remains intact.

An axial image better depicts the size of the hematoma (green arrows) and again identifies the intact vastus intermedius component (yellow arrow) of the quadriceps tendon:

The quadriceps femoris (Latin for "four-headed muscle of the femur"), is a group of four muscles in the anterior thigh:

- rectus femoris
- vastus medialis
- vastus lateralis
- vastus intermedius

These four muscles originate from the pelvis and femur, and form the quadriceps tendon, which inserts on the superior aspect of the patella.

Photo by robswatski

On this frontal view, we can see the rectus femoris (white arrow), vastus medialis (yellow arrow), and vastus lateralis (green arrow). The vastus intermedius is deep to the rectus femoris, and is not seen.

The quadriceps tendon has 3 distinct layers:

- superficial layer, formed by the rectus femoris
- intermediate layer, formed by the vastus lateralis and vastus medialis
- deep layer, formed by the vastus intermedius [you can remember that the deep layer is the vastus intermedius by "intermediate is inside"]

The quadriceps tendon rarely ruptures in the young and healthy; rather, this is a disease of the old, with ruptures most common in the 6th & 7th decade of life. There is a strong male preponderance, with male victims outnumbering females 8:1. Quadriceps ruptures are associated with cortisone injections, diabetes, chronic renal failure, hyperthyroidism, and gout.

Most injuries are treated surgically, optimally within a few days of the injury.

Vic David MD

Wednesday, June 15, 2011

A Forearm Lump

Patients vary in their approach to lumps they find in their body. Some will seek medical attention immediately, while others will wait for the mass to enlarge or cause symptoms before going to see a physician.

A 50 year-old female presented to a hand surgeon with a slowly enlarging forearm mass:

The surgeon referred the patient for an MRI scan, to further characterize the mass. Coronal and sagittal T1-weighted images identify an encapsulated, fat-containing mass (red arrows) along the dorsal aspect of the forearm, with a few, thin internal septations (blue arrows):

An axial T1 image better depicts the relationship of the mass to the radius (R) and ulna (U):

An axial T2 fatsat image confirms that the lesion is composed of fat, and also better defines the deep extension of the lesion to the level of the interosseous membrane and anterior interosseous neurovascular bundle (green arrow):

An axial T1 fatsat image obtained after the administration of gadolinium shows that the lesion does not enhance:

Thus, the forearm mass is well-encapsulated, contains only a few-thin septations, has no nodular areas, and fails to enhance after the administration of gadolinium. The diagnosis of a simple lipoma was made, and important anatomic relationships were described in the radiology report, for preoperative planning. The lesion was excised, and was confirmed to be a simple lipoma.

MRI is often used to characterize soft tissue masses. The initial questions are usually:

- is the mass benign or malignant?

- what are the anatomic boundaries of the mass, and what is its relationship to critical structures such as major nerves and arteries?

- can a specific tissue diagnosis be provided?

A simple, but useful approach is to put the mass into one of three categories, which MRI can do with a high degree of reliability:

--> ganglion cyst

--> lipoma or other fat-containing mass

--> does not fit criteria for ganglion cyst or fat-containing mass, and needs further analysis

When a discrete, homogeneous fat-containing mass is encountered, a simple lipoma can be diagnosed with certainty. When an inhomogeneous fat-containing mass is found, further analysis is required. Gaskin and Helms examined 126 fat-containing masses, to better understand how to differentiate simple lipomas from well-differentiated liposarcomas (AJR 162:733-739, 2004) and concluded:

--> MRI is 100% specific for a simple lipoma, when the lesion has a characteristic appearance

--> infiltrating intramuscular lipomas also have a characteristic appearance, and can be diagnosed with confidence

They also noted that when a fat containing mass is heterogeneous (thickened or nodular septa, significant nonadipose tissue, prominent foci of high T2 signal, and prominent areas of enhancement), the lesion may be benign or malignant. In their series, 10/16 (63%) of the lesions suspicious for malignancy were benign lipoma variants, such as chondroid lipoma, osteolipoma, hibernoma, angiolipoma, lipoleiomyoma, and necrotic lipoma.

Thus, about two-thirds of soft tissue masses that contain fat and are suspicious for malignancy will actually turn out to be benign in nature. Nonetheless, it is important for the radiologist to alert the clinician and pathologist to the possibility of a liposarcoma, so that the patient can be managed appropriately.

A common question that is asked is, "Does the MRI need to be done with intravenous contrast?". When a simple lipoma or a typical ganglion cyst is found, there is usually no need to administer intravenous contrast for further characterization. Unfortunately, one does not know the nature of the mass before doing the MRI, so it is often best if the clinician orders the examination with intravenous contrast, "at the discretion of the radiologist".

Vic David MD

Sunday, May 15, 2011

Rock Climbers and Pulleys

Photo by groundzero

"There are only 3 real sports: bull-fighting, car racing and mountain climbing. All the others are mere games."— Ernest Hemingway

Critical to mountain and rock climbing are extraordinarily strong fingers, which can find small cracks in the rock, and propel the ardent climber skyward. Flexion of the fingers is generated by the flexor digitorum profundus and flexor digitorum superficialis (sublimus) tendons, which attach to the distal phalanx and middle phalanx, respectively. These tendons are held close to the underlying bone by five annular or "A" pulleys, that prevent bowstringing during flexion:

Figure courtesy of Nicros

Of the five annular pulleys, the A2 pulley is the most commonly injured. Injuries can vary from partial tears to complete tears. Rock climbers are particularly prone to pulley injuries, due to the tremendous load placed on the pulleys when the climber grips tightly, and levers himself upward. The traditional rock climbing grip ("crimp position"), which involves hyperflexion of the proximal interphalangeal (PIP) joint and hyperextension of the distal interphalangeal, puts high stress on these pulley structures. Tears can develop over time, or be acute in nature.

Pulley tears can be imaged using MRI or ultrasound. On ultrasound, a partially torn pulley is thickened and hypoechoic (Martinoli et al., Skel Rad 29, 387-291, 2000). On both ultrasound and MRI, complete pulley tears will manifest with an increased distance between the flexor tendon and the underlying bone, since the pulley is no longer holding the flexor tendon in place, with this sign accentuated during finger flexion. High resolution imaging will easily identify the normal A2 and A4 pulleys, allowing direct detection of pulley injuries.

In this case, a 36 avid rock climber complained of a painful ring finger, with pain maximal at the base of the finger. He began to notice the pain after a day of climbing, six weeks before seeking medical attention. Physical examination revealed swelling at the base of finger, but no bowstringing of the tendons. The patient was referred for an MRI to assess the A2 pulley, and to exclude a flexor tendon sheath ganglion cyst.

An axial intermediate image reveals diffuse thickening of the A2 pulley of the ring finger (red arrow). The pulley remains continuous, without focal discontinuity. The normal middle finger A2 pulley (green arrow) is also seen.

Here is the corresponding axial T2 fatsat image:

A coronal intermediate image depicts the abnormally thickened A2 pulley:

Sagittal images of the ring finger were also performed:

(A) Gradient echo and (B) T2 fatsat images show the abnormally thickened A2 pulley, along with local soft tissue edema. In normal patients, the A2 pulley cannot be seen on sagittal images, since it is a diaphanous structure tightly applied to the underlying flexor tendons.

MRI yields the diagnosis of a partial, interstitial tear of the A2 pulley with reactive local soft tissue inflammation, and allows proper treatment.

Treatment of partial pulley tears is usually conservative, although complete annular pulley ruptures may be addressed surgically. Rock climbers are tough individuals, and some of them will attempt to "climb through" partial pulley tears, but rest is the recommended approach.

Vic David MD

Friday, April 15, 2011

Torn Tendon with Two Heads

Photo by toksuede

Football (or soccer) is a venerable game that existed for several hundred years. The original balls were made out of animal bladders, which were cleaned, inflated, and kicked around. Not surprisingly, injuries related to the kicking motion have also existed for hundreds of years. The kicking motion can place a high degree of stress on muscles and tendons that originate in the pelvis, such as the rectus femoris muscle.

The rectus femoris muscle has two distinct origins. The direct (straight) head arises from the anterior–inferior iliac spine (AIIS), while the indirect (reflected) head originates from the superior acetabular ridge and hip capsule. The indirect (reflected) head is the primary head. The two heads unite, and form the rectus femoris muscle, shown in red below:

A frontal view of the pelvis depicts the origin of the direct head (red) from the AIIS, and the origin of the indirect head (blue) from the superior acetabular ridge:

Remember that the indirect head in inferior (both words begin with "i"). An oblique view of the pelvis better depicts the relationship of the two origins to the acetabulum:

The two heads of the rectus femoris tendon are well depicted on the following oblique axial image, which depicts the origin of the direct head (red) from the AIIS, and the origin of the indirect head (blue) from the superior acetabular ridge:

In the following case, a 14 year old boy experienced sharp pain while kicking a soccer ball. A coronal STIR image shows an avulsion of the direct head of the rectus femoris (red arrow) from the AIIS:

Axial images show the avulsed bone fragment (red arrow) and the attached tendon, as well as the intact indirect head (yellow arrow) of the rectus femoris:
Consecutive sagittal images show the avulsed bone fragment (red arrow), direct arm of the rectus femoris (green arrow) and indirect arm of the rectus femoris (yellow arrow):

Rectus femoris tears typically affect the direct head, but one can also involvement of the indirect head, alone or in concert with direct head tears. With direct head tears, one often sees a flake of bone on conventional radiographs, corresponding to an avulsion fragment. MRI can help confirm the diagnosis.

Avulsion of the anterior superior iliac spine can simulate this injury if the fragment is retracted inferior to the level of the anterior inferior iliac spine (Stevens et al. Radiographics 19:655-672, 1999). Rectus femoris tears can lead to a soft tissue mass, and a chronic rectus femoris tear can mimic a tumor (Temple et al, AJSM 26:544-548, 1998).

Injuries of the rectus femoris typically respond well to conservative therapy. Avulsions of both the anterior superior and anterior inferior iliac spines tend to be less symptomatic and disabling than avulsions of the ischial tuberosity, and recovery typically occurs over a few weeks (Combs JA, Physician Sports Med 22:41-49, 1994). Fortunately, rectus femoris tears usually respond well to conservative therapy, and heal over several weeks.

Vic David MD