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18 Cards in this Set

  • Front
  • Back
The Distal Radioulnar Joint involves the radius, ulna, and
the interosseus membrane
fiber types of IOM
Oblique A & Oblique B
OA Fibers are important in
WB and supination

distal ulna to proximal radius
increase tension in WB & supination
OB Fibers are important in
Radial Txn

proximal ulna to distal radius
increase tension with radial traction & pronation
WBing F goes through what
2 bones: ulna & radius

not the IOM
IOM is maximally tensioned at

--most relaxed at
0-5 dd supination

most relaxed in full pronation/full supination bc UH pushes radius away - distal & radial rotation helps to clear biceps T for pronation
almost no nociceptors - no pain
optimize ability to carry
transfer of load system: valgus elbow = min load transfer
most tense in varus
plane of Rx is always
perpendicular to dorsum of hand & wrist
distal radius = concave
distal ulna = convex

2ry osteokinematic motions
pronation = volar radius translation

supination = dorsal radius translation
DRUJ Capsule
lax / loose + synovial membrane
high level of mobility there
not directly controlled by MM

CP: Pain @ end ROM

1ry source of stability to DRUJ
radioulnar disc and continuation of the articular cartilage of the distal radius
extension of distal radius bt radius and ulna, radius & prox wrist, bt ulna & triquetrum
--transmits load through ulna
--if radius fx=>TFC tension=>TFC lesion (ulnar side of wrist)
TFCC vascular / nerve supply
outer - type 1 collagen for tension loading - more vascular/innervation, better chance of healing

inner - type 2 for compression - less vascularized/innervated

think: compression on inside expands to create tension on outside
TFCC complex
more specific on ulnar side -- more so to ulna than radius
-TFC acts as keystone
-acts in concert with UCL for stability
-ulnocarpal LL enhance support
-ECU sheath is an additional contributor to support
UCL and the TFCC
UCL has 2 divisions - originated from styloid process
trauma affects/irritates only one part of it
UCL is not a true collateral 2ry to increased motion: needs dynamization
1) dorsal carpus w/ ECU + disc
2) palmar carpus w/ FCU
other functions of TFCC
controls pronation & supination
controls both rotation & translation of R on U
increases congruency bt carpus & distal ulna
increases stability of DRUJ & UCL to produce smooth motion
TFCC Load Transmission
normal case:
--83% load transmitted through radius (most F through R)
--17% through TFCC or ulna

with discectomy - post-op:
--95% trasmitted through radius
--increased likelihood for degeneration in R & C columns
--more likely to fail when add 12% to other side
TFCC Complex
Dorsal branch taut in Supination
orientation allows LL to relax in Neutral
Palmar branch taut in Pronation