266. Wrist Injuries

Anatomy

8 carpal bones: Scaphoid, Lunate, Triquetrum, Pisiform (proximal row – noted as crease on volar as of wrist), Trapizeum (umm..beside the thUMb), Trapezoid, Capitate, Hamate (Distal row – very stable) (Mneumonic: Some Lovers Try Positions They Can’t Handle – Scrubs Video).

Carpal Bones

No direct tendons on carpal bones.Two arches of ligaments basically centered around the lunate. Space between them is Space of Poirier which is a weakness point (dislocations).

Anatomic Snuffbox: scaphoid location. Triangle of bony radial styloid proximally, extensor pollicis brevis tendon radially, and extensor pollis longus (big tendon connected to thumb when you abduct) ulnarally.

Radiographs

PA view: No radius/ulnar overlap, 3rd metacarpal should be parallel with radius. Gilula arcs (3 arcs): proximal and distal lines of proximal row, proximal line of capitate/hamate. All should be 1-2mm separation between each other. Scaphoid should be elongated. Distal radius should articulate with 1/2 the lunate. Best view for looking for: scapholunate dissociation,

Lateral view: Three Cs: radius, lunate, and capitate. Look at angles of axis of scaphoid and lunate (should be between 30-60 degrees). Radius volar tilt should be less than 10-15 degrees. Best view for looking for: perilunate/lunate dislocation, distal radius fractures, capitate fracture.

Scaphoid view: cone-down PA view of scaphoid in ulnar deviation. Best view for looking for: scaphoid fractures.

Oblique view: Best view for looking for: trapezium fracture.

Carpal tunnel view: view thru carpal tunnel. Best view for looking for: pisiform and hook of hamate fractures.

Injuries

3 Dislocations of worsening severity in carpal instability: scapholunate dissociation, perilunate dislocation, and lunate dislocation. All outstretched hand, forceful dorsiflexion.

Scapholunate dissociation: MCC injuried wrist ligament. Look for >3mm (usually 5mm) of widening between scaphoid and lunate on PA view. Terry Thomas sign. Scaphoid tilts shortening it on PA view and appears as signet ring. Can get clenched fist view to furthur separate space. Treatment: radial gutter splint or short arm volar posterior mold. Usually require pinning or ORIF.

Scapholunate Dissociation

Perilunate dislocation: continued tear around volar ligament. Usually associated carpal bone fractures. Swelling/pain, usually no gross deformity. Lateral view: capitate displaced dorsally from the lunate. Lunate keeps contact with radius. PA view: capitolunate space is missing, bones overlapping. Add trans + carpal bones to beginning of nomenclature is associated fracture. Treatment: emergent reduction, ortho consult. If able to reduce, long arm splint. Usually will have failed reduction and need OR.

Perilunate Dislocation

Lunate dislocation: Most severe of the 3. PA view: lunate appears triangle shape (‘piece of the pie’). Lateral view: lunate has dislocated off radius (spilled teacup). Treatment: same as perilunate: emergent reduction, ortho consult. Likely reduction unsuccessful and needs OR. Complications: median nerve compression.

Lunate Dislocation

Scaphoid fracture: MCC carpal bone fractured. Axial load to thumb. Anatomic snuffbox tenderness. Look at soft tissue fat pad adjacent to radial aspect. Has distal radial blood supply leading to avascular necrosis if not properly treated. 10-20% missed on xrays. If clinical suspicion, treat. Splint in dorsiflexion/radial deviation short arm thumb spica. Usually will need pinning.

Triquetrum fracture: Second most common carpal fracture. Dorsal tenderness distal to ulnar styloid.  Avulsion (resisted twisting) has excellent prognosis and if minimally tender, early ROM is fine. Stable body fractures (direct trauma) require cast for 6 weeks.

Lunate fracture: usually associated with other fractures. Distal blood supply as well (Kienbock disease – avascular necrosis of lunate). Treatment: short arm thumb spica splint.

Trapezium fracture: saddle shaped bone articulates with thumb metacarpal. Painful thumb movement and weak pinch. Best viewed on oblique view xray. Treatment: short arm thumb spica splint.

Pisiform fracture: sesamoid bone in flexor carpi ulnar tendon. Both pisiform and hook of hamate form Guyon canal (contains ulnar artery/nerve). Last bone to ossify (12yo). Treatment: 30 degree flexion/ulnar deviation.

Hamate fracture: most are hook of hamate fractures – interrupted swing with club. Hypothenar pain and gripping pain. Hook of Hamate pull test: supinated, ulnar deviated wrist, resisted flexion of 4th-5th fingers. Best view with carpal tunnel view. Look for Guyon canal injury. Treatment: splint.

Capitate fracture: Usually associated with scaphoid fracture – scaphocapitate syndrome. Best viewed on lateral view. Treatment: splint.

Trapezoid fracture: extremely rare.

Colles fracture: distal radius metaphysis fracture with dorsal angulation. Outstretched hand, wrist extended. Dinner-fork deformity. Unstable fracture > 20 degrees. Treatment: Reduce by push fracture distal and palmarly. Splint 15 degree flexion/ulnar in sugar tong. F?u 7-10 days. Complications: median nerve compression, extensor pollicus longus (EPL) rupture (long term, due to blood supply).

Smith fracture: reverse Colles fracture. volar angulated fracture. Treatment: same as Colles.

Barton fracture: Colles or Smith fracture (more common of the two) with intraarticular involvement. Treatment: sugar tong, unstable fractures require ORIF.

Radial styloid fracture: usually associated with lunate dislocation.

Distal Radioulnar Joint Disruption (DRUJ): associated with intraarticular or distal radius shaft fractures (Galeazzi). Lateral view shows volar (most common) /dorsal ulna displacement. Can occur in isolation, though rare. Pronation limited. Treatment: splint, may require reconstructive surgery.


Board Questions

Q1.  Whats the difference between a Colles fracture and a Barton fracture?

A1. Barton’s has intra-articular involvement. Other wrong answers: reverse colles (volar angulation), scaphoid involvement, Galleazzi fracture, etc.

Q2. What other carpal bone is fractured with a captitate fracture?

A2. Scaphoid. Other wrong answers: lunatate, hamate, trapezius, 3rd metacarpal.

Q3. What carpal fractures are best viewed with a carpal tunnel view xray?

A3. Pisiform and hook of hamate. Other wrong answers: Scaphoid and lunate, scaphoid and capitate, colles fracture, etc.

Q4. Which fracture occurs with resisted twisting on the wrist and has excellent prognosis?

A4. Triquetrum avulsion fracture. Other wrong answers: hook of hamate, pisiform, trapezium fracture.

Q5. Whats the most common carpal bone fractured?

A5. Scaphoid. Other wrong answers: Lunate, capitate, hook of hamate, etc.

Q6. What type of injury is this?

Lunate Dislocation

A6. Lunate dislocation. Other wrong answer: perilunate dislocation, capitate dislocation, normal wrist, etc.


Clinical Cases

Life in the Fast Lane, Stairs vs Wrist (FREE)

Life in the Fast Lane, FOOSH Interpretation (FREE)

Life in the Fast Lane, FOOSH Interpretation 002 (FREE)

Life in the Fast Lane, FOOSH Interpretation 003 (FREE)


References / Resources

Tintinalli, Seventh Edition, Chapter 266: Wrist Injuries

CrashingPatient, Scott Weingart, Wrist and Forearm, Reviewed 11/9/15 (FREE)

EMedHome, Wrist Injuries, Josh Broder

Emergency Medicine Ireland, Andy Neill, Anatomy of EM 018: Scapholunate Injurie (FREE)

Emergency Medicine Ireland, Andy Neill, Anatomy of EM 019: Scaphoid Fractures (FREE)

Emergency Medicine Ireland, Andy Neill, Anatomy of EM 017: Colles Fractures (FREE)

ERCast, Rob Orman, Distal Radius Fractures (FREE)

Radiopedia.org (FREE)

Life in the Fast Lane, Peter Allely, Scaphoid Fractures: The ED Perspective (FREE)

Life in the Fast Lane, Mike Cadogan, Isolated Volar Distal Ulnar Dislocation (FREE)

YouTube, Larry Mellick, Distal Radius Fracture Reduction and Hematoma Block Video (FREE)

YouTube, Julie B, Ultrasound Reduction Video (FREE)

Wheeless Online, Wrist Menu (FREE)


266. Wrist Injuries

223. Thyroid Disorders: Hypothyroidism and Myxedema Crisis

Hypothyroidism

High TSH, low free T4/T3.

No perfect thyroid test. TSH is monitoring pituitary T3. Accurate only under ideal health. Free T4 is likely better test with TSH is the new state. Hypothyroid is a clinical diagnosis. (USC Rounds, 2017)

Causes: Autoimmune (Hashimoto), Thyroiditis (subacute, silent, postpartum), ablation, Drugs (amiodarone, lithium, alpha-Interferon, interleukin-2).

Symptoms: weight gain, weakness, fatigue, vocal changes (hoarse/deep), delayed DTRs, non-pitting edema (myxedema – periorbital, nondependent areas), paresthesias, poor memory/confusion, constipation, dysfunctional uterine bleeding. 5% of carpal tunnel patients have it.

Low voltage EKG.

Hypothyroidism usually cannot produce WBC. Usually 3-4k, lymphocytic predominant. If higher around 8-10k, really consider infection.

Initial ED Management with simple hypothyroidism: Likely discharge with followup with PCP for outpatient workup/treatment.

Myxedema Coma/Crisis

Extreme presentation of hypothyroidism. High mortality, life-threatening. Misleading name: usually not myxedema apparent, rarely in coma.

90% are women in winter months. Usually elderly > 60yo.

Clinical diagnosis. Altered (some big degree of AMS), hypothermia, body habitus for hypothyroidism. Usually bradycardia, hypotension, hypothermia. Stressor involved: infection (MCC), trauma, MI/CHF, surgery, medications, etc. Usually does not have a temperature and if has a normal temperature, have high suspicion for infection. Pleural effusions can be present. Look for thyroidectomy scar in altered patient. Usually hyponatremia. CPK almost always > 500.

Treatment

Supportive care: usually dehydrated, passive warming with warming blankets, vasopressors if unresponsive to fluids. ICU admission.

Usually adrenal insufficiency involved so give hydrocortisone 100mg q8h before thyroid medication. Send random cortisol level before doing this if able.

Start with T4 over T3. Smooth/gradual rise, no high peaks and increased potential for arrhythmias/MI as T3. T3 though has advantage of quicker onset and no potential for decreased peripheral conversion (T4 to T3), though usually not recommended over T3. T4 500mcg or 200-400mcg (4mcg/kg) IV bolus, then 100mcg daily after that. Likely just stick with T4 only. If you’re going to give T3 (probably stay away from), give T3 5-20mcg IV bolus or consider giving very small bolus of T3 along with T4 if you really want to give T3 as well. Since body is converting T4 to T3, with giving a high dose of T4, the body will adjust to convert the appropriate amount to T3 so pretty safe to give high dose T4 (not T3 though). IV dose still takes around 12 hours before HR response.

Give antibiotics regardless of if theres an apparent infection initially since the myxedema coma masks many of the signs of infection.


References / Resources

Tintinalli, 7th Edition, Chapter 223: Thyroid Disorders: Hypothyroidism and Myxedema Coma

CrashingPatient.com, Scott Weingart, Thyroid Disorders, Reviewed 11/6/15 (FREE)

EBMedicine, Identifying and Treating Thyroid Storm and Myxedema Coma in the ED, 2009 (FREE)

EMRAP, Stuart Swadron / John LoPresti, Severe Hypothyroidism, 2010

WikiEM, Myxedema Coma (FREE)


Clinical Cases


Board Questions

Q1. Which type of patient is most characteristic to be in myxedema coma?

A1. Elderly woman with pneumonia in January. Incorrect answers: Dehydrated marathon runner, Male with MI that he presented 3-4 days later, Obese young female collapses and comes in unresponsive by EMS, etc.

Q2. Which drug does not cause affect the thyroid and can cause hypothyroidism?

A2. Droperidol. Incorrect answers: Lithium, Amiodarone, Phenytoin, All the above.

Q3. With a patient in myxedema coma from a MI/CHF, which medication should be given?

A3. T4. Incorrect answers: T3, Amiodarone, Beta-blocker, All the above.

Q4. Besides T4 and supportive measures, what other medication should be likely given with severe myxedema coma?

A4. Hydrocortisone. Incorrect answers: Amiodarone, Beta-Blocker, Methamazole, etc.

Q5. Whats the most common EKG finding in myxedema coma?

A5. Sinus bradycardia. Incorrect answers: Slow atrial fibrillation, bigimeny, ventricular tachycardia, second degree heart block, etc.

Q6. What lab abnormality is usually present with myxedema coma?

A6. Elevated CPK. Incorrect answers: Significant leukocytosis, hypernatremia, positive HCG, etc.

223. Thyroid Disorders: Hypothyroidism and Myxedema Crisis