Download Ulnar Collateral Ligament - SCBT-MR

ELBOW MR
throwing athlete
emphasis on the UCL
Throwing athlete
• baseball pitchers
• elbow complaints: > 90% medial
• valgus stress: medial distraction
• ulnar collateral ligament
• flexor-pronator mass
Ulnar collateral ligament
• anterior bundle
– 1° valgus stabilizer
• posterior bundle
– floor of cubital tunnel
• transverse ligament
Gray, Henry. Anatomy of the Human Body. 1918
Flexor-pronator mass
• pronator teres
• flexor carpi radialis
• palmaris longus
• flexor carpi ulnaris
• flexor digitorum superficialis
UCL & FPM
• functional relationship
– during pitch, UCL load >> failure strength
– FPM muscles protect UCL
· dynamic stabilization of medial elbow
· FCU primary, FDS secondary
· pronator teres least contributory
• anatomical relationship: FDS
Park MC, Ahmad CS. JBJS(Am) 2004;86:2268-2274
Pronator teres
• major head originates from:
– humerus, just prox to med epicondyle
– common flexor tendon, intermusc fascia
• minor head originates from:
– medial aspect of coronoid process
FDS: 3 heads
• radius (obl line)
• coronoid process
– prox to pronator teres
• med epicondyle
– UCL, intermusc fascia
Gray, Henry. Anatomy of the Human Body. 1918
FDS: 2 heads
• radial head (oblique line)
• humeroulnar head
– superficial (muscular) fibers
· medial epicondyle (common flexor tendon)
– deep (tendinous) fibers
· surface of UCL anterior bundle
· coronoid process, medial aspect
Munshi, Resnick et al. Radiology 2004; 231:797-803
• AP, extended
• F= flex dig superficialis
• mF= superficial muscle
• tF= deep FDS tendon
• aU= anterior bundle
• pU= posterior bundle
• me= med epicondyle
• c= coronoid process
Munshi, Resnick et al. Radiology 2004; 231:797-803
• medial, flexed
• F= flex dig superficialis
• mF= superficial muscle
• tF= deep FDS tendon
• aU= anterior bundle
• pU= posterior bundle
• me= med epicondyle
• c= coronoid process
Munshi, Resnick et al. Radiology 2004; 231:797-803
Anterior bundle: dissection
• single layer of parallel bundles
– pseudolaminar appearance
– overlying FDS tendinous fibers
• arises: medial epicondyle
– inferior surface (base), anterior margin
– interdigitating fat near attachment site
• inserts: medial ulna (sublime tubercle)
– up to 3-4mm distal to articular margin
Munshi, Resnick et al. Radiology 2004; 231:797-803
Anterior bundle & FDS
• dissection
– FDS intimate w/ UCL: deep tendinous fibers can
merge w/ anterior bundle
• MR imaging
– deep tendinous fibers of FDS difficult or impossible
to visually separate from UCL and coronoid
attachment sites
– prox UCL tear may reflect FDS incompetence,
suggest poor prognosis, performance
Elbow: overuse injury
• repetitive, cumulative stress
• soft tissue, osseous changes
– calcification, bony proliferation
• degenerative arthropathy
– osteophyte, intra-artic loose bodies
medial distraction
lateral impaction
The American Journal of Sports Medicine 33:231-239 (2005)
Elbow: overuse injury
• UCL: chronic v. acute Δ
– thickening (6.3 v. 5mm, 30° flexion)
– stretching, partial tearing
– degeneration, heterotopic ossification
• valgus laxity, microinstability
– degenerative joint disease
Medial ossific fragment
• post-traumatic phenomenon
• old fracture fragment
• heterotopic ossification
– old acute ST trauma
– chronic, recurrent injury
Medial elbow pain
• ulnar collateral ligament
– UCL tear (distal, proximal, mid-substance)
• flexor-pronator mass
– tendon tear, MT strain
– flexor digitorum superficialis
– pronator teres