Wrist biomechanics and instability ASHT Flashcards
What does CIC stand for?
Carpal instability complex - features of CID and CIND, i.e., perilunate injury.
What is CIA?
Carpal Instability adaptive - malalignment is an adaptation to an abnormally tilted distal radius fracture or malunion, i.e., instability following DRFx.
What does CID refer to?
Carpal instability dissociative - fracture/ligament disruption within or between bones of the same carpal row, i.e., SL injury or LT injury.
What is CIND?
Carpal Instability nondissociative - dysfunction at radiocarpal level, midcarpal level, or both, collapse into VISI deformity with weightbearing.
What is scapholunate dissociation?
CID: 44% of DRFx, limitations in passive wrist flexion, pain with radial deviation, SL angle >70 degrees on X-ray, SL space >5mm.
What does VISI stand for?
Lunate bowl/moon faces volar - flexion. LT injury, lunate moves with scaphoid and flexes.
What does DISI refer to?
Lunate bowl/moon faces dorsal - extension. Most common, subluxation of scaphoid if STT and SC ligaments have failed, lunate moves with triquetrum = extension of lunate.
What is SLAC?
Scapholunate advanced collapse - capitate wedges between scaphoid and lunate, end stage OA.
What are SL friendly structures?
ECRL, ECRB, FCU, APB (FCR if SL intact).
What are SL unfriendly structures?
ECU, FCR (if SL complete tear). ? Bc they’re opposite of dart throwers ?
What is the dart-throwing motion?
Action at midcarpal joint (limits stress to radiocarpal joint, scaphoid, and lunate).
RD+extension and UD+flexion
What are the treatments for SLAC?
Proximal row carpectomy (non-arthritic capitate) 30-50% wrist motion, 20-50% grip strength; lengthens flexors and extensors;
scaphoidectomy + four corner fusion (mid carpal fusion) if capitate arthritic;
total wrist fusion;
wrist arthroplasty;
wrist denervation.
What is the mechanism of injury for lunotriquetral dissociation?
Fall backward with arm ER, supinated wrist extension, radial deviation.
What are the symptoms of LT dissociation?
Ulnar sided wrist pain, crepitation, weakness, limitation in passive wrist extension. X-ray: SL angle <30, VISI.
What are LT friendly muscles?
ECU, FCU, hypothenars, FCR.
What are LT unfriendly muscles?
ECRL, ECRB, APL/B.
What is the treatment for mid carpal instability (MCI)?
Pisiform boost orthosis, avoid aggravating, proprioception, isometrics to ECU, FCU, hypothenars. OR: arthroscopic palmar midcarpal capsular shrinkage, tendon reconstruction, midcarpal fusion, radio-lunate fusion.
What is perilunate wrist dislocation (CIC)?
Fall with body rotates over the hand, lesser arc - no fracture, greater arc S, C Tq fracture, stage 4 lunate into carpal tunnel = median nerve symptoms, treatment always surgical, ROM and strength 50-80%.
What is proprioception as treatment?
Kinesthesia, joint position sense, neuromuscular control: 1. edema/pain ROM 2. mirror therapy 3. active and passive joint position sense 4. mirror therapy/biodex 5. isokinetic, isometric coactivation, balance 6. perturbation training, sensorimotor.
