Saturday, March 29, 2008

Evaluation of Thumb RCL Tears

A while ago, I discussed a case of a tear of the ulnar collateral ligament (UCL) of the first MCP joint, an injury also known as Gamekeeper's thumb. The radial collateral ligament of the thumb can also be injured. Here is a case of a patient who sustained an injury to his thumb while doing karate.

Oblique coronal intermediate-weighted images, anterior to posterior. There is a frank tear of the RCL (red arrow). Note the UCL (green arrow), which contains subtle abnormal signal, representing a concurrent grade 1 sprain of the UCL.

(click on image to enlarge)
Injury of the RCL was discussed by Coyle (J. Hand Surg. 2003;28A:14-20). He noted that RCL tears are often missed, because functional grasp and pinch complaints are often minimal. There is no general agreement on appropriate treatment of these lesions, with some authors suggesting casting, and others surgical repair. Interestingly, a Stener-equivalent lesion can occur, with the abductor aponeurosis interposing itself between the torn RCL and the base of the proximal phalanx.

Vic David MD

Sunday, March 23, 2008

Standing on the Shoulders of Giants

No less a luminary than Isaac Newton said, "If I have seen further it is by standing on the shoulders of giants." Physicians, too, rely upon the work of our predecessors.

Henry Jaffe MD is considered by many to be the most distinguished bone pathologist of modern times. With Louis Lichtenstin MD, he established the nature of osteoid osteoma, osteoblastoma, giant cell tumor, eosinophilic granuloma, pigmented villonodular synovitis, chondroblastoma, nonossifying fibroma, chondromyxoid fibroma, and aneurysmal bone cyst. Describing any one of these entities would be a fine achievement, but he also developed a system for the evaluation and classification of bone lesions.

All of these diseases are seen by the musculoskeletal radiologist. Here are images from a 16 year-old boy, who presented with 2 months of leg pain. An X-ray showed dense cortical sclerosis:

Coronal STIR images show striking marrow edema in the mid right tibia:

Axial images were performed through the area of bone marrow edema:

(click on image to enlarge)
(A,B,C) MRI images reveal a 6 mm enhancing lesion (red arrow) in the peripheral medullary cavity of the tibia. There is extensive medullary sclerosis (yellow arrows) that is hypointense on all pulse sequences. There is thickening of the cortex (green arrow) of the adjacent tibia. (D) CT image at same level shows a lucent nidus (red arrow) with a central calcification.

The findings are diagnostic of an osteoid osteoma. The differential diagnosis for a lucent lesion surrounded by a rim of sclerosis is relatively brief: stress fracture, Brodie's abscess, intracortical hemangioma, and osteogenic sarcoma. The combination of MRI and CT will often strongly favor one diagnosis.

Osteoid osteoma was described by Jaffe in 1935. It's nice to remember the work of our predecessors now and then, as we work in the present, and seek to find truth in the future.

Vic David MD

Friday, March 14, 2008

Bagels and HAGLs

The origin of the venerable bagel is still an issue for debate.

Most food historians have come to the conclusion that the bagel is of Jewish origin, probably created in Poland, sometime in the 17th century. In medicine, we are familiar with the BHAGL, which stands for Bony Humeral Avulsion of the Glenohumeral Ligament.

(BTW, the word "humerus" is actually a misspelled borrowing of the Latin work "umerus", which means "shoulder". I wonder if anyone was sued for linguistic malpractice over this.)

The HAGL lesion is a Humeral Avulsion of the Glenohumeral Ligament, i.e. a BHAGL without the bone avulsion. A HAGL injury occurs in the setting of anterior shoulder dislocation. In 1942, the orthopedic surgeon Toufick Nicola first described capsular avulsion of the IGHL (inferior glenohumeral ligament) from the humerus in patients following shoulder dislocation, so this injury is a well-known entity.

Despite this, this lesion may be overlooked at arthroscopy, so the radiologist can help alert the surgeon to look specifically for this lesion. Twenty year-old weightlifter with a shoulder dislocation 4 weeks ago, images from an MR arthrogram:

(click on image to enlarge)
There is a HAGL lesion (red arrows), with extensive edema. Contrast does not extravasate freely into the axilla because this is a subacute injury, and some healing has occurred. For comparison, here is a normal shoulder, with arrow denoting normal IGHL:

(click on image to enlarge)
A sagittal image from the injured patient shows the torn, lax anterior band of the IGHL:

Bui-Mansfield et al. have recently described a classification scheme for humeral avulsion of the glenohumeral ligament (AJSM 2007, 35:1960-1966). They divide these injuries into:

1) Anterior HAGL (tear anterior band IGHL at humerus)
2) Anterior BHAGL (anterior HAGL with a bone avulsion from the humerus)
3) Floating AIGHL (tear anterior band IGHL at the humerus and at the glenoid)
4) Posterior HAGL (tear posterior band IGHL at humerus)
5) Posterior BHAGL (posterior HAGL with a bone avulsion from the humerus)
6) Floating BHAGL (tear posteiror band IGHL at the humerus and at the glenoid)

Just writing this is making me glance at the toaster and reach for the cream cheese....

Vic David MD

Tuesday, March 11, 2008

Sharks and the Soleus Muscle

In life, sometimes you don't get what you expect. The Shark Shield is an electronic device designed to be attached to a surfboard, to repel sharks. During testing, instead of repelling sharks, it attracted a 12-foot great white shark, which promptly inhaled it as a nice snack. Not what the designers expected. Oh well, back to the drawing board....

In radiology, too, sometimes you encounter something besides what you expect.

A common clinical scenario is calf pain after a tennis injury. This is most often due to a tear of the medial head of the gastrocnemius muscle, or a tear of the plantaris muscle. Clinicians are sometimes concerned about an Achilles tear as well. When I hear this history, I usually look for these things. In this case, however, I saw something a little different:

Coronal STIR images reveal edema in the mid- and distal third of the right calf (red arrows). The left calf (yellow arrows) is normal.

Axial images depict a partial tear of the soleus muscle (red arrows). The soleus muscle of the left calf (yellow arrows) is normal:

Thus, when you there is a history of calf pain after trauma, consider that any of the components of the Achilles myotendinous unit (triceps surae) can tear. Thus, examine the medial and lateral heads of the gastrocnemius, and the soleus. Tears of the plantaris tendon should also be looked for (Helms et al., Radiology 1995, 195:201-203).

Saturday, March 8, 2008

Bubbly Lesion in the Hand

"Bubbly lesions of the bone."

Hearing that phrase will put me in the Wayback machine, and instantly transport me back a few years, to residency, and FEGNOMASHIC. Positively Proustian, the experience. Bubbly lesions and madeleines, there is a connection there somewhere....

One sees bubbly lesions of the bone on MRI episodically, alas, usually without the conventional radiograph, which has often been done elsewhere. Here is a young adult male, with a bubbly lesion of the ring finger metacarpal:

(click on image to enlarge)

Note that the lesion signal is isointense to hyaline cartilage of all pulse sequences. There is rind-like peripheral enhancement. This appearance is suggestive of an enchondroma, but tissue is necessary for a definitive diagnosis. This is a biopsy-proven enchondroma.

Maffucci's syndrome is a nonhereditary enchondromatoses, first described by Angelo Maffuci:

Angelo Mafucci
(courtesy R. Ciranni)
Virchows Arch 2006; 449:495-497

Here is the illustration from his original paper in 1881, describing his eponymous syndrome in the distal femur:

(courtesy R. Ciranni)
Virchows Arch 2006; 449:495-497

Maffucci was an Italian pathologist who not only described multiple enchondromatosis, but also made important contributions to the understanding of tuberculosis and anthrax. After a long and illustrious career, he succumbed to malaria in 1903.

Ollier described another enchondromatosis 19 years after Maffuci's original description. Both Maffuci and Ollier syndromes are characterized by multiple enchondromas. Patients with Maffucci's syndrome also have multiple hemangiomas and, less commonly, multiple lymphangiomas.

Monday, March 3, 2008

Famous Duos and the UCL

Chances are that you have no idea who Frank Jobe MD is, but I am willing to bet that most of you have heard about the operation he pioneered, the Tommy John operation. As I tell my kids, life is not fair- the doctor who came up with the operation is far less familiar to people than the first patient, the baseball pitcher Tommy John:

The Tommy John operation reconstructs the ulnar collateral ligament (UCL) of the elbow. It is a tremendously successful procedure, one of the few that is said to result in a functional result that is as good as the native ligament.
MRI is an excellent way to evaluate the UCL.

Direct coronal images of a
baseball pitcher with medial elbow pain. There is a tear of the anterior band of the UCL:

(click on image to enlarge)
Coronal oblique images depict that the tear has occurred at the sublime tubercle of the ulna:

Lewis and Clark. Watson and Crick. Ben and Jerry. These are all famous duos that have changed history. OK, maybe it's going a little far to say that Ben and Jerry changed history, but try some Cherry Garcia ice cream first, and you may feel differently. None of these individuals would have reached their level of success without their partners.

When it comes to MR imaging, the radiologist also needs a partner. That partner is the MRI technologist, who has a simply huge impact on the quality of the images that are obtained. I am lucky enough to work with some fabulous technologists, who go far beyond the level of positioning the patient and pushing some buttons. They understand that MRI is an interactive examination, and that practitioners of the art (and it is very much an art at its best level) perform the sequences necessary to answer the clinical question.

Some people try to "cross-train" x-ray or CT technologists to do MRI, and then wonder why the pictures do not look very good. Well, that is like asking a pianist to play the violin- yeah, they are both musical instruments, but I don't want to be in the room when the piano player is stroking the bow, unless I have a pair of earplugs.

This case is a good example of how a great MRI tech can make a real difference. The technologist recognized that there was a UCL tear on the standard sequences, and then set up the twenty degree coronal oblique scan (Cotton et al., Radiology 1997; 204:806-812) to view the ligament optimally. This obliquity produced the perfect picture, the one you look at and say, "Oh, that's obvious". It takes experience and desire to produce that picture, and not every technologist is able to do it. Those that can should be considered artists.

Vic David MD