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18 Cards in this Set

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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
functions
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
DRUJ
arthrokinematics
distal radius = concave
distal ulna = convex
DRUJ

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
TFCC at DRUJ

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