Wrist Instability Flashcards
What is DISI?
- Dorsal Intercalated Scaphoid Injury
- An instability of the Scaphoidlunate Joint
What causes DISI?
- Scapholunate ligament Injury - most common cause / ligament injury in wrist
- Caused by HYPEREXTENSION of Pronated wrist
- Dorsal Scapholunate ligament is Stronger than Volar scapholunate ligament
- Scaphoid Fractures
- Kienbock’s disease
What is the outcome of DISI if left untreated?
Cause a SLAC wrist- Scapholunate advanced collapse
What are the signs of DISI?
- Snuffbox test
- Watson Test- when deviating from ulnar to radial, pressure over volar aspect of scaphoid produces a clunk secondary to dorsal subluxation of the scaphoid over the dorsal rim of the radius
dorsal wrist pain or a clunk during this maneuver may indicate instability of scapholunate ligament
- too see video click link below and scroll to watson’s test
- http://www.orthobullets.com/hand/6041/scapholunate-ligament-injury-and-disi
What investigations are helful in DX DISI and what do you see?
AP radiographs
- Clenched fist AP view of hand = Increase in space between scaphoid/lunate >3mm
- Cortical ring sign- due to scaphoid malalignment
- Humpback deformity with DISI in unstable scaphoid fracture
Lateral
- Dorsal tilt of LUNATE-> Scapholunate angle of >70o on neutral rotation view
- Radiolunate angle >15o
Arthroscopy- Gold standard for diagnosis
MRI- High specificity , medium sensitivity
What is the TX of DISI?
Non operative
casting alone is insuffucient- most peoples view
Operative
- Scapholunate ligament repair/ reconstruction
- in acute scapholunate ligament injury or chronic SL injury with reducible SL injuries
- Primary repair can be done up to 17 months from injury
- Blatt dorsal capsulodesis often added and can be useful in chronic instability when repair is not feasible
- if Path is Scaphoid Fx= ORIF and CRPP
-
Stabilisation and wrist fustion- irreducible & rigid DISI deformity, DISI & Distal joint degeneration
- STT- scaphotripezialtrapezoidal fusion
- SLC- scapholunatecapitate
- SL= Scaphoilunate- highest risk of non union
What is VISI?
Volar incalcated scaphoid injury
A type of carpal instability dissociative
What is the pathoanatomy of VISI?
Advanced injury to
- Lunotriquetral ligament- LT- C shaped comprised a thick dorsal/ volar component, dorsal important for rotational stability, volar thickness and transmit extension moment
- Dorsal radiotriquetral ligament- dorsal RT ( aka radiocarpal lig), loss allow lunate to flex more easily
- Volar radiolunate ligament short& long- Volar RL, extrinisic ligaments
Mechanism is:
Lt injured in Wrist Hyperextension or Extension and radial deviation
scaphoid induced the lunate into further flexion while triquetrum extends
Occasionally VISI seen in pts with ligamentous laxity and no hx of trauma ( unlike DISI)
What are the symptoms and signs of VISI?
- Ulnar sided wrist that is worse with pronation /supination- grip
- Signs: positive Ballottement test-
Grasp the lunate between the thumb and index finger of one hand while applying alternative dorsal and palmar loads across the triquetrum with the thumb and index of the other hand
* positive test **elicits pain, crepitus or increased laxity**, suggesting **LT interosseous injury**
What investigations would help you dx VISI and what do you see?
Radiographs
Lateral
- Volar flexion of lunate - increase in Scapholunate angle o Normal is 45o
- Capitolunate zigzag deformity with capitolunate angle increase >15o
AP
- Break in Gilula’s arc
- May not see increase in space between LT
- May see proximal migration of triquetrum on lunate
Arthroscopy may be helpful in dx
-
What are the tx options for VISI?
Non operative
Observations- attempted initally
Operative
Acute instability = CRPP ( mutliple K wires)+ acute ligament repair+/- Dorsal capsulodesis
Chronic instability=LT fusion- non union complication
Arthroscopic Debridment of LT Ligament with ulnar shortening- Chronic instability and Positive UV
What is SLAC?
- Scaphoid Lunate advanced collapse
- A condition of progressive instability-> advanced arthritis of radiocarpal/ midcarpal joints
- degenerative arthritis seen in chronic dissocation between scaphoid and lunate
Describe the pathoanatomy of SLAC wrist?
Chronic SL ligament injury-> DISI deformity
- Scaphoid is flexed and lunate is extended as scapholunate ligament no longer restrains this articulation
- SL angle > 70 degrees
- Lunate extended >10 degrees past neutral
- Resultant flexion/extension of S &L -> abnormal forces across midcarpus/radiocarpus and maligalignment of concentric joint surfaces
- initally effects RADIOSCAPHOID JOINT and progresses to CAPITOLUNATE joint
- IMPORTANT- the RADIOLUNATE JOINT is spared beacuse of its spheriod shape so it is congruently loaded
What is the classification system for SLAC & TX ?
WATSON
Stage 1- Arthritis between scaphoid & radial styloid
Tx- Radial styoidectomy+ scapholunate reduction+stabilisation
Stage 2- Arthritis of entire radioscaphoid joint
TX- Eliminate radioscaphoid joint by…
Proximal row carpectomy
Four corner fusion: lunate/hamate/capitate/triquetrum
Radioscapholunate fusion, total wrist arthrodesis, total wirst arthroplasty
Stage 3- Arthritis between CAPITATE and LUNATE (pic)
Tx- SLAC procedure- Prox row carpectomy
Total wrist arthrodesis
**Stage IV- not decribed by Watson by bascally pancarpal arthritis**
What are the symptoms and signs of SLAC wrist?
Symptoms
- Difficulty putting weight across wrist
- Pain localised in scapholunate interval
- Progressive weakness of hand
- Wrist stiffness
Signs
- Tenderness over SL Ligament
- Decreased ROM
- Weakness of grip strength
- Watson’s Shift test-
with firm pressure over the palmar tuberosity of the scaphoid, wrist is moved from ulnar to radial deviation
positive test seen in patients with scapholunate ligament injury or patients with ligamentous laxity, where the scaphoid is no longer constrained proximally and subluxates out of the scaphoid fossa resulting in pain.
when pressure removed from the scaphoid, the scaphoid relocates back into the scaphoid fossa, and typical snapping or clicking occurs.
must compare to contralateral side
What is seen in SLAC stage 1 on xray
PA radiograph
- Radial styloid beaking
- sclerosis
- Joint space narrowing
What are seen on xray for a SLAC stage 2 wrist?
PA radiograph
sclerosis
joint space narrowing- between scaphoid and entire scaphoid fossa of distal radius
What are seen on xray for a SLAC stage 3 wrist?
Pa radiograph
- Sclerosis
- Joint space narrowing between lunate and capitate
- Capitate wil migrate proximally into space created
What are seen on a lateral xray for a SLAC wrist
- DISI deformity of the wrist
- with subluxation of capitate dorsally
TX of SLAC wrist
Non operative
NSAIDs, wrist splinting, ? corticosteriod injections
Operative
- Radial styloidectomy+ scaphoid stabilisation= stage 1- prevents impingement between scaphoid and radius
open or arthroscopic
- PIN/ AIN denervation- stage 2/3
- Proximal row carpectomy= Stage 2
Excise - scaphoid/lunate/triquetrum
CI if incompetet radioscaphocapitate ligament/ capitolunate arthritis as lunate articulates with lunate fossa of distal radius
Preserves relative strength/ motion
- Scaphoid excision and 4 corner fusion- stage 2/3
wrist motion occurs thru perserved lunate & distal radius
similar longterm results between this and prox row carpect
- __Fusion-stage 3/ pancarpus arthritis
Gives best for pain relief adn good grip strength at cost of wrist motion
Define a SNAC wrist?
- Scaphoid NON union advanced collapse
- Joint space narrowing is seen between the distal pole of the scaphoid and the radial styloid/ distal pole of scaphoid + trapezium and trapezoid
- Proximal scaphoid articular surface involved, radius is spared
- History, staging and tx are similar to SLAC wrist
Describe the radiographic and tx of SNAC?
- Stage 1- Arthritis between distal scaphoid and radius
Tx- Radial styloidectomy + fixation of scaphoid Non union w Bone Graft
- Stage 2- Scaphocapitate arthritis & 1
Proximal row carpectomy, SLAC procedure(excision sacphoid and 4 corner fusion), Total wrist arthroplasty/ total wrist fusion
- Stage 3- Periscaphoid arthritis
- SLAC procedure,Total wrist arthroplasty/ total wrist fusion
What is carpal instability non dissociative?
Instability between rows either
Midcarpal -between prox and distal row
Radiocarpal- between radius & prox row
Describe the incidence and pathoanatomy of Carpal instability non dissociative?
- Rare
- Radiocarpal-aka inferior arc injury
- High energy Trauma, extrinsic rupture
- ligamentous, radial/ ulna styloid fractures
- assoc injuries compartment syndrome/ acute carpal tunnel
- Volar dissocations worse than dorsal
What are the Signs and symptoms of Carpal instability non dissociative?
- HX of trauma ( radiocarpal) or no trauma ( midcarpal)
- Subluxation may/ not be painful
- Wrist giving way
- Clunk sign when moving ulnar from flexion/extension
What Investigations useful in Carpal instability non dissociative?
- Subluxation of proximal row on radiographic screening
- Diagnosis made when >50% of lunate width is ulnarly translated off the lunate fossa of the radius
What is the Tx of carpal instability non dissocaitive?
Non operatively
Immobilisation +/- Splinting- Midcarpal most amenible
Operatively
- Immediate repair, reduction repair & pinning - for ulnar translation w styloid fractures- gd results with EARLY fixatn
- Midcarpal Joint fusion- for midcarpal instability->20-30% loss of motion
- Osteotomy for malunion distal radius- fusion of radiocarpal joint-> loss 55-60% loss of motion
