UMEM Educational Pearls - By Brian Corwell

Radiologic evaluation of the elbow (Part 2)

Helpful clues in the evaluation of elbow trauma:

• The Anterior humeral line and the Radiocapitellar line
  • The anterior humeral line: On a true lateral film, this line is drawn along the anterior aspect of the humeral shaft on the lateral radiograph This line passes through the middle one third of the capitellum in bones that are not injured. It is very useful for detecting subtle fractures.
    • http://www.radiologyassistant.nl/images/thmb_4214e859138b1anthumlinebest.jpg
  • Fractures (i.e. supracondylar) usually result in displacement of the capitellum posteriorly.
  • Thus, the anterior humeral line passes through the anterior one third or entirely anterior to the capitellum.
    • http://www.imageinterpretation.co.uk/images/elbow/RAISED FAT PADS, SUPRACONDYLAR graphic.jpg
• The Radiocapitellar line: Since the radius articulates with the capitellum, a line is drawn through the middle of the radius shaft and extended proximally through the joint should bisect the capitellum on all views (AP & lateral).
  • http://img.medscape.com/pi/emed/ckb/radiology/336139-415822-5412.jpg
  • http://nypemergency.org/images/v2c18n.jpg
  • Improper alignment indicates a radial head dislocation (which may be very subtle)
    • http://nypemergency.org/images/mont.jpg
    • http://www.radiologyassistant.nl/images/49304bf192d7e12.jpg

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Helpful clues in the evaluation of elbow trauma

Fat pads:  The fat pad sign can be seen with any joint effusion (infection, inflammation) but in the setting of trauma, effusions are indicative of fractures about the elbow (even if no fracture line can be identified).

There are two fat pads within the elbow. Normally, on a true  lateral radiograph only the anterior fat pad is seen as a small triangular radiolucent shadow anterior to the distal humeral diaphysis. The posterior fat pad is ordinarily not visualized on a lateral radiograph because it is tucked away within  the olecranon fossa. 

Normal lateral view: http://nypemergency.org/images/ElbowNormal.jpg

With fractures, the joint becomes distended with blood.  The anterior fat pad becomes displaced superiorly and outward from the humerus giving the so called "sail sign."  Similarly, the posterior fat pad gets displaced out of the olecranon fossa and becomes visible on the lateral radiograph. 

Anterior (sail) and posterior fat signs: http://nypemergency.org/images/Elbowsfatpadarrow.jpg

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• Back pain is the most common musculoskeletal complaint that results in visits to the ED.
• It has a benign course in more than 90% of patients, so we must be vigilant and comfortable looking for warning signs of a neurologically impairing or life-threatening cause.
• We rely on the presence of so-called "red flags" or alarm symptoms to guide further diagnostic tests, specialty evaluation, and treatment. 
• Additionally, always consider 2 important extra-spinal causes of back pain: aortic dissection (sudden onset back pain) and abdominal aortic aneurysm (patients >50, esp. those who you think have a kidney stone- isolated back and groin pain is a common presentation).

• Spondylolysis is a unilateral or bilateral defect in the pars interarticularis portion of the vertebrae.
• It is a stress fracture mostly seen in the lumbar vertebrae, and most commonly L5.
• Pain is relieved with rest and worsened by lateral bending or extension (NOTE: most back pain is worsened by flexion).
• If neurologic symptoms and/or radiculopathy are present, an alternative diagnosis should be considered, because they are rarely associated with spondylolysis.
• Diagnostic imaging should start with plain radiographs with added oblique views.
• Classically, oblique views show the Scotty dog sign with a crack on the dog’s neck/collar, the pars.

http://www.gentili.net/signs/images/400/spinescottyparsdefectdrawing.JPG

The Scotty dog’s head (superior articular facet), nose (transverse process), eye (pedicle), neck (pars interarticularis), and body (lamina) should be easily identified on the oblique radiograph.
 

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Sports Hernia/Athletic pubalgia

Hx: Gradually increasing lower abdominal/proximal adductor pain. Usually activity related, resolves with rest. Frequent return despite rest when sports activity resumes.

Most common in athletes who perform cutting/maneuvers in addition to frequent acceleration/deceleration. Think ice hockey and soccer.

Bilateral symptoms not uncommon.

PE:  Resisted sit up with palpation of the inferolateral edge of the distal rectus may recreate symptoms. Similarly, resisted hip adduction may elicit symptoms. 

If for no other reason than to make the diagnosis harder to make, valsalva induced pain may also occur.

Fluoroscopic guided injections can be helpful to isolate the site of pain generation.

First line therapy is rest, non-narcotic analgesia and physical therapy.

With surgery, >80% return to pre injury level of play.

http://atlantasportsmedicine.com/orthopedic-surgeon/wp-content/uploads/2009/11/groin-injuries.jpg

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https://www.physio-pedia.com/Fulcrum_Test

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4126145/

A recent article in Pediatrics attempted to estimate the association between fluoroquinolone use and tendon injury in an adolescent population.

Fluoroquinolones are thought to negatively impact tendons and cartilage in the load-bearing joints of the lower limbs through collagen degradation, necrosis, and disruption of the extracellular matrix.

Population: 4.4 million adolescents aged 12–18 years with filled outpatient fluoroquinolone prescription vs. an oral broad-spectrum antibiotic for comparison.

Fluoroquinolones included ciprofloxacin, levofloxacin, moxifloxacin, and gatifloxacin

Comparator antibiotics included amoxicillin-clavulanate, azithromycin, cefalexin, cefixime, cefdinir, nitrofurantoin, and bactrim.

Outcomes: Primary outcome was 90-day tendon rupture (Achilles, patellar, quadricep, patellar, tibial) identified by diagnosis and procedure codes. Secondary outcome was tendinitis.

Results: The weighted 90-day tendon rupture risk was 13.6 per 100 000 fluoroquinolone-treated adolescents and 11.6 per 100 000 comparator-treated adolescents.

Fluoroquinolone-associated excess risk: 1.9 per 100 000 adolescents; the corresponding number needed to treat to harm was 52 632.

The weighted 90-day tendinitis risk was 200.8 per 100 000 fluoroquinolone-treated adolescents and 178.1 per 100 000 comparator-treated adolescents

Fluoroquinolone-associated excess risk excess risk: 22.7 per 100 000 adolescents; the corresponding number needed to treat to harm was 4405.

Conclusion:

The excess risk of tendon rupture associated with fluoroquinolone treatment was extremely small, and these events were rare. On average, 50,000 adolescents would need to be treated with a fluoroquinolone for 1 additional tendon rupture to occur

The excess risk of tendinitis associated with fluoroquinolone treatment though larger was also small.

Besides tendon rupture, other more common potential adverse drug effects may be more important to consider for treatment decision-making, in adolescents without other risk factors for tendon injury.

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