SLAC - Scaphoid lunate adavanced collapse

Question 1

what is scaphoid lunate advanced collapse?

Answer 1

A condition of progressive instability causing ADVANCED arthritis of radiocarpal and midcarpal joints

Question 2

What is the pathology?

Answer 2

CHRONIC Scaphoidlunate Ligament injury->DISI deformity of scaphoid- dorsal intercalated segemental insatablity
SCAPHOID FLEXES and LUNATE EXTENDS as scapholunate ligament no longer restrains this articulation= scapholunate angle >70

This position of the scpahoid and lunate-> abnormal disruption of forces across midcarpus and radio carpal joints
initially effects the radioscaphoid joint then progresses to capitolunate joint

Question 3

What is the classification system for SLAC?

Answer 3

Watson

Question 4

Can you describe the watson classification?

Answer 4

Stage 1 - arthritis between scaphoid and radial styloid
Stage 2- arthritis between scaphoid and ENTIRE facet of the radius
Stage 3- Arthritis between CAPITATE and LUNATE

Question 5

What joint is spared?

Answer 5

RADIOLUNATE joint unlike other forms of arhtirits

Question 6

What does the pt describe?

Answer 6

difficulty in Wb across wrist
PT Localises pain across SL interval
Progressive weakness of affected hand
wrist stiffness

Question 7

What do yo find on examination?

Answer 7

Tenderness directly over scapholunate ligament dorsally
decreased wrist rom
weakness of grip strength

Question 8

What specific test is useful?

Answer 8

Watson scaphoid shift test
will not be positive in adv stages as scaphoid stabilised
firm pressure over scaphoid , wrist is moved from ulna to radial deviation
pressure removed scaphoid relocates back into scaphoid fossa with snapping/clicking

Question 9

what is seen on x ray?

Answer 9

stage 1- radial styloid beaking, sclerosis sand joint space narrowing between scaphoid and radial styloid
stage 2- sclerosis and joint space narrowing between scaphoid and entire scaphoid fossa of distal radius
satge 3- sclerosis and joint space narrowing between lunate and capitate- capitate will eventually migrate proximally itnoe space created by scapholunate dissociation

LATERAL= DISI deformity- flexion scaphoid and lunate extended

Question 10

What are the non surgical tx options?

Answer 10

NSAID , splinting and possible cortical injections- mild disease

Question 11

What are the surgical TX?

Answer 11

1)Radial styloidectomy and scaphoid stabilisation = stage 1

2) PIN and AIN denervation
since PIN and AIN only provide prioception and sensation to the wrist capsule at their most distal branches they can be safely denervated

3) Proximal row carpecectomy- stage 2 disease
CI if capitolunate oa as capitate articulates with lunate fossa of distal radius
excise- scaphoid, lunate and triquetrum with preserving RADIOSCAPHOCAPITATE LIGAMENT- TO prevent ULNAR SUBLUXATION after proximal row carpectomy

4)Scaphoid excision and 4 corner fusion
for stage 2/3- worst motion occurs thru preserved articulation between lunate and distal radius

5) wrist ARTHRODESIS
stage 3 and any signs of pan carpal arthritis