MCP Joint Follow-up

The answer was #1! Notice how ruddy the volar plate, extensor tendon appeared. For learning, I will start with the normal.

Here is the MCP joint. Pink is the volar plate. The orange is the extensor tendon (pollicus). Blue is the tendon sheath. Note the distinct borders.

Find the bad MCP

Answer tomorrow.
 

Knee (Anterior and Lateral)

Knee:

I had chance to do some self scanning on my own knee. For background, I'm without any major knee pathology or complaint. I am pain free. I anticipate a friend with PFPS vs. lateral ligamtenous strain next week and I'm trying to work on my normal findings anticipating pathology in hers.

Again, like the elbow, I used the ESSR guidelines. These are by no means comprehensive, but they are simple, straightforward, and an excellent framework for a brief bedside evaluation. I performed peri-patellar anterior, lateral, and medial knee exam. I did not perform posterior knee.

I'll walk you through the highlights.

Here was the starting point. Knee flexed to 20-30 degrees, probe placed over suprapatellar quadriceps tendon. You'l note femur as the hypoechogenic structure at the bottom. Directly above is the Vastus Intermedius. Directly above this is a very bright (hyperechogenic) structure representing the quadriceps tendon (from the rectus femoris located superior). Flanking the tendon on both sides is the Vastus Lateralis and Vastus Medialis.





I switched to long view of the quadriceps tendon as it approaches the patella. You'll note a cavity beneath the quad tendon, but above the femur. This is the suprapatellar synovial recess.



Here quadriceps hits patella.


Below I hightlighted the structures worth spotting. Orange represents quadriceps tendon, blue is synovial suprapatellar recess, yellow is prefemoral fat pad.

Next I moved to the Femoral Trochlea. I'm a sucker for wavy bones (like humerus) and the cartilage overlying. Note that this one is unique in that the knee is put into full flexion. You'll note the overlying quadriceps tendon assuming the V shape overlying the trochlea.

Infrapatellar scan for the patellar tendon (notable distinct structure in superior portion of screen). Beneath this lies Hoffman's Fat pad. I didn't find this to particularly satisfying view of the fat pad.


Part two coming shortly with LCL / MCL.

Sternoclavicular Joint

Today in clinic a gentleman came in with anterior chest pain. After the big MI / PE / Pneumo rule out, it appeared to be musculoskeletal. He had a history of fall with trauma to anterior chest 5 months ago.

He had very reproducible pain at sternoclavicular joint. I rarely think to ultrasound this, but it is as scannable as any AC joint.

Jacobsen does a nice piece on anterior / posterior dislocation and joint infection. He doesn't do much on routine osteolysis @ the SC joint. He does do a piece on osteolysis @ AC joint, which is a decent approximation of appearance on scan.

I thought I'd draw the simple anatomy.
I wish I could post the Jacobsen "AC Osteolysis" picture to give you a sense of what this gentlemen with SC joint pathology looked like. They were uncannily similar: Ligamentous swelling, erosion around sterum and clavicle tips, hypoechogenecity between bone tips. Rather than get sued for copyright infringement, I thought I'd draw out the image.

Anterior Elbow Case

I did some self scanning today, I had access to a medium-to-high res scanner today and wanted to test some elbow. Anterior elbow is pretty fascinating and high yield if you're interested. There are a lot of great structures within close proximity worth identifying. Also, the anatomy is pretty tricky to understand from a textbook. A good scan, however, makes the relationships very vivid.

As a resource, I used ESSR's Anterior Elbow guide. I found it to be the perfect level of detail. Jacobsen is my gold standard, but is unwieldy when bedside.

First off ,what can you see here:

• Brachialis tendon 
• Coronoid recess
• Articular cartilage of distal humeral
• Brachialis muscle
• Anterior fat pad
• Humeral capitellum
• Humeral trochlea
• Posterior Interosseous nerve (radial)
• Cutaneous sensory branch (radial nerve) 
• Median Nerve
• Brachial Artery
• Brachioradialis muscle
• Radial head / neck
• Superficial / Deep head of the supinator muscle

I took some screen shots of the highlights:

Anterior distal humerus epiphysis

I love the distinguished wave of this bony structure. Note the well defined hyaline cartilage overlying the bone. Finally, above this, is the brachialis muscle (with septum / tendon?) down middle. Remember, many muscles have septums. Many also have tendons that start in the belly of the muscle. I think this is tendon. You'll also note brachial artery (large circular hypechoic structure). Median nerve is to the right, though tougher to identify. 

I wanted to trace the brachialis muscle down to its insertion at the coronoid process of the ulna (pinky side for simple thinkers like me). I failed. The muscle belly seemingly disappeared into a mess of pronator teres. I'll try again later.

Radial Nerve Split into posterior interosseus + cutaneous sensory branch

I'm proud of this one. It takes a keen eye and good understanding of the anatomy. The radial head is exceedingly easy to find early on: it's the only nerve spiraling around the tricepital area. It's decent sized as well. As we track down the radial (thumb / lateral) side, we hit a branch point around the head of the radius. See Page 4 for a fantastic diagram 

Here the radial nerve splits into posterior interosseus nerve and cutaneous sensory branch of the radial nerve. This is the first tip off: you will see a split. It's fairly subtle. The next big clue is what I've captured below: the posterior interosseus nerve going through the supinator muscle (Arcade of Frohse).

Below you can see the hypoechoic radial head. Overlying this is a muscle circumferentially surrounding the head with a very bright body bisecting the muscle. This is the radial nerve bisecting the supinator muscle.

Yellow = posterior interosseus nerve
Orange = supinator
Blue = Radius

Later Thigh Injury

I  played basketball 3 days ago and received a knee to my lateral left thigh. It is tender to palpating over roughly a quarter size area. The pain feels superficial. There is no ecchymosis or swelling. No palpable deformity. Pain is exacerbated with hip deep flexion or knee hyper extension.

I put ultrasound to it.

I suspect this is the Vastus Lateralis muscle, though this may be Tensor Fasciae Latae.

Initial scan in short axis:

I was pretty surprised. I expected a deep hematoma or fluid collection. Instead, initial scan only revealed a "nubin" as seen circled with red. Normally I would think this was incidental, but it correlated directly to pain source. On better angling, (second photo) you can see the "nubin" prominently protrude downward from fascial plane into muscle. Whether this is an anatomical disruption, imaging overread, or actual injury, I'm not certain. 

I moved to long axis next.

Here I see more definitive evidence of muscle injury. The top and bottom photo have some definite disruption. The only problem is the tubular shape: these could certainly be vascular structures (particularly in the middle photo, which respects fascial planes). I forgot to Doppler, which would have solved my question. That being said, fibrillar disruption are irregular and were not seen throughout the remainder of the Vastus Lateralis exam, suggestive of muscle fiber disruption injury. Note the hypoechoic structure underlying muscle body is the Femur.

Two Head Biceps

Anatomy Lesson today. This will preempt some shoulder MSK ultrasound anatomy.  A few key take aways I want to demonstrated before tomorrow:

• Biceps Brachii has two heads: long and short. Short head is Superficial. Long head is Deep.
• Long head (Biceps) goes under the Subscapularis Tendon on its way to the head of the Humerus. The short head runs over the Subscapularis muscle on it's way tot he coracoid process (Scapula)