1. SLAC & SNAC wrists Management & Results
Satyam Patel
January 19th, 2007

2. Overview
Definitions
Natural history
Treatment Options
Results

3. Definition SLAC = Scapho-Lunate Advanced Collapse
SNAC = Scaphoid Nonunion Advanced Collapse
PRC = proximal row carpectomy
4CF = 4 corner (Capito-Hamate-Lunate-Triquetrum) Fusion

4. Natural History
Ligament disruption
Scapholunate
Radioscaphoid

5. Natural History
Scaphoid flexes abnormally

6. Natural History Increased contact Proximal pole + scaphoid fossa
Distal pole + radial styloid
Arthritic changes

7. Natural History
DISI deformity develops
Lunate and triquetrum extend

8. Natural History Capitate migrates into scapholunate interval
Midcarpal arthritis at capitolunate articulation

9. Natural History SLAC wrist Scapholunate advanced collapse
Constellation of findings
DISI
Radioscaphoid arthritis
Midcarpal arthritis
Sparing of radiolunate joint
Carpal collapse

10. Natural History SLAC wrist Scapholunate advanced collapse
I radial styloid + distal pole scaphoid
II scaphoid fossa + proximal pole
III capitolunate
Radioscaphoid
Midcarpal

11. Natural History SLAC wrist Scapholunate advanced collapse
I radial styloid + distal pole scaphoid
II scaphoid fossa + proximal pole
III capitolunate

12. Natural History SLAC wrist Scapholunate advanced collapse
I radial styloid + distal pole scaphoid
II scaphoid fossa + proximal pole
III capitolunate

13. SNAC - Natural History
Scaphoid nonunion leads to a series of degenerative changes that are similar to SLAC.
In general
1 decade after fracture - scaphoid nonunion cystic changes
2 decades - radioscaphoid degeneration
3 decades - pancarpal arthritis
Stage I - radial styloid - scaphoid joint
Stage II - degeneration of radioscaphoid and scaphocapitate joints
Stage III - capitolunate degeneration
(proximal radioschaphoid and radiolunate joints are relatively well preserved)

14. Treatment Options Relevant factors Patient age Activity Level
State of Degeneration

15. Treatment Options Conservative Activity modification Splinting
Steroid injection
NSAIDs

16. Treatment Options Surgical PIN neurectomy
Total or partial wrist arthrodesis
Proximal row carpectomy
Distraction arthroplasty
Total wrist arthroplasty

17. Biomechanical basis for treatment
4-CF (+scaphoid excision)
Wrist motion occurs through preserved radiolunate and ulnocarpal joints
Including hamate and triquetrum increases fusion rate without sacrificing further motion
CI’s = radiolunate degeneration, ulnar carpal translation
PRC
Capitate articulates with lunate fossa
Difference in arc of rotation between C & L allows for radial and ulnar deviation
Preserving radio-scapho-capitate ligament is important for stability (N.B. if doing styloidectomy)

18. Irreducible Carpus And Arthritis
RECALL:
SLAC wrist
Scapholunate advanced collapse
I radial styloid + distal pole scaphoid
II scaphoid fossa + proximal pole
III capitolunate

19. Irreducible Carpus And Arthritis
Radial styloidectomy +/- scaphoid fixation & bone graft II
Proximal row carpectomy
4 corner fusion +/- radial styloidectomy / scaphoid excision
III
4 corner fusion with scaphoid excision or arthrodesis
Proximal row carpectomy unsuitable due to midcarpal OA

20. Irreducible Carpus And Arthritis
Radial styloidectomy
Removes arthritic joint
Does not prevent progression to stage II and III

21. Irreducible Carpus And ArthritisII
Proximal row carpectomy
Converts wrist into ball and socket joint
Mismatching radiocapitate joint allows translation
Removal of arthritic joints while motion maintained

22. Irreducible Carpus And Arthritis
II - SLAC wrist procedure
Four corner fusion (capitate-lunate-hamate-triquetrum)
Scaphoid excision
Removes arthritic joints
Makes use of preserved radiolunate joint
Higher loss of motion, strength maintained

23. Irreducible Carpus And Arthritis
III
SLAC wrist procedure
Proximal row carpectomy not suitable due to midcarpal arthritis

24. Indications for total wrist arthrodesis
Diffuse arthritic change (capitate or lunate fossa involved)
Motion less than 30 / 30
Contraindication = if wrist dorsiflexion is required for tenodesis (e.g. tetraplegic patients)

25. PRC - Technique Longitudinal incision through EPL sheath Capsulotomy
Excise lunate first
Then triquetrum and scaphoid via sharp dissection to preserve ligaments.
+/- radial styloidectomy
Dorsal capsular repair
2-3/52 in cast

26. PRC - variations Pre-op arthroscopy to evaluate condition of cartilage
Temporary internal fixation with K-wires
dorsal capsule interposition
Radial styloidectomy
Proximal capitate excision (?)
N.B. caution in pts < 35 y.o., rheumatoid patients

27. SLAC Wrist Procedure Four-Corner-Fusion With Scaphoid Excision
Technique
SLAC Wrist Procedure Four-Corner-Fusion With Scaphoid Excision
Exposure as in PRC
Scaphoid excision
Radioscaphocapitate ligament preserved
Joints decorticated
ICBG or distal radius bone graft
Lunate reduced to capitate (slight flexion)
K-wires, staples, screws, “spider” plate
Avoid silastic scaphoid (synovitis)
6/52 – 8/52 cast

28. Variations of 4 -corner fusion
Use of k-wires vs. use of spider plate
Trade-off between increased fusion rate and incidence of dorsal impingement
P. Stern
Excision of triquetrum (3 corner fusion / Capito-lunate fusion)
Better dorsiflexion in cadaveric study, no significant increase in ROM clinically thus far.
G. Bain, J. Calandruccio, R. Gelberman

30. Salvage Total wrist fusion All arthritic joints fused
(radius - 3rd MC axis mandatory, others optional)
No motion / good strength

31. Results Limited fusions STT SL SLC
14% nonunion (385 cases from multiple series)
Pain relief unpredictable
Add styloidectomy if impingement present SL
50% nonunion
SLC
50% decrease in wrist motion
4/11 required total wrist fusion

32. Results
Degenerative Arthritis of the Wrist : Proximal Row Carpectomy versus Scaphoid excision and four-corner arthrodesis.
M. Cohen S. Kozin J. Hand Surg A:94-104
2 cohorts of 19 patients each largely stage 2 arthritis, most SLAC, 3 SNAC in one arm 6 in the other.
- Early follow-up results (DASH, SF-36)
No significant differences in pain, grip strength, ROM
4CF group scored higher on mental-health component of SF-36 and retained a slightly greater radial-ulnar deviation arc.

33. Results Acta Orthop Belg 2006
Salvage procedures for degenerative osteoarthritis of the wrist due to advanced carpal collapse
63 patients - 19 fused, PRC 26, scaphoidectomy +4CF 18
PRC significantly better (DASH =16)
No significant differences between 4CF and arthrodesis (DASH = 39, 45)

34. PRC - results Jorgenson 22 PRC cases over 20 years
Increased ROM, subjective feeling of weakness
Scand J Plast Reconstr Surg & Hand Surg 2006
51 patients PRC between 1992 & % required arthrodesis (9 patients)
34 returned to work (avg. 6/12)
F 66% E 73% RD 74% UD 76%
Grip 70%

35. Results of 4CF & scaphoidectomy
Ashmead et. al
44/ patients
E 32deg F 42deg (53%)
Grip strength 80%
78/85 satisfied (would undergo operation again)
3% nonunion rate
Dorsal impingement 13%

36. Results Wrist fusion 85% total pain relief
65% return to former occupation
Hastings and Silver

37. Summary: No Arthritis Reducible + adequate ligament
Reduction, repair, pinning
Reducible + inadequate ligament
Soft tissue vs. bony procedure
Irreducible
Treat as SLAC wrist vs. Limited fusion (STT)
Next page

38. Summary: Arthritic Wrist
Stage I
Radial styloidectomy
Stage II
Proximal row carpectomy: maintain motion, fast recovery
Four corner fusion + scaphoidectomy : strength ?
SLAC III
Four corner fusion + scaphoidectomy
Salvage
Wrist fusion

41. Irreducible Carpus Without Arthritis
Why is it not reducible?
Fibrous tissue in joints
Deformed articular surfaces
Ligament shortening and laxity
Solution
Remove fibrous tissue from joints
Remove deformed articular surfaces
Remove lax / stiff ligaments
Limited carpal fusion
Removes intraarticular block to reduction
Fixes reduced scaphoid position to carpus
Prevents further carpal collapse
Spares uninvolved joints

42. Irreducible Carpus Without Arthritis
STT fusion + dorsolateral styloidectomy
SL / SC / SLC fusion
Without reduction of deformity, progression to SLAC wrist
Results of limited wrist carpal fusions may not be good enough or predictable enough to justify using them -- safer option is to treat as SLAC wrist

43. STT Fusion Technique Transverse dorsal incision
Retract superficial radial n. and v.
Open retinaculum along EPL
B/w ECRL and ECRB
Open STT
Open radioscaphoid joint
If arthritic go to SLAC wrist reconstruction
Reduce scaphoid and fix to carpus
Remove STT joint preserving height
Distal radius graft
3 x K-wires across STT

44. Results PRC SLAC procedure ROM maintained 64% 45% Grip strength 75%
Pain relief
“good”
Satisfaction
Failure rate
20%, 0
0-7%, 30%
Krakauer et al, 1994
Wyrick et al, 1995
Tomaino et al, 1994