SLAC & SNAC wristsManagement & Results

Satyam PatelJanuary 19th, 2007

Overview

• Definitions• Natural history • Treatment Options• Results

Definition

• SLAC = Scapho-Lunate Advanced Collapse

• SNAC = Scaphoid Nonunion Advanced Collapse

• PRC = proximal row carpectomy• 4CF = 4 corner (Capito-Hamate-

Lunate-Triquetrum) Fusion

Natural History

• Ligament disruption– Scapholunate– Radioscaphoid

Natural History

• Scaphoid flexes abnormally

Natural History

• Increased contact– Proximal pole + scaphoid fossa– Distal pole + radial styloid

– Arthritic changes

Natural History

• DISI deformity develops– Lunate and triquetrum extend

Natural History

• Capitate migrates into scapholunate interval

• Midcarpal arthritis at capitolunate articulation

Natural History

• SLAC wrist– Scapholunate advanced collapse

– Constellation of findings• DISI• Radioscaphoid arthritis• Midcarpal arthritis• Sparing of radiolunate joint• Carpal collapse

Natural History

• SLAC wrist– Scapholunate advanced

collapse

• I radial styloid + distal pole scaphoid

• II scaphoid fossa + proximal pole

• III capitolunate

Radioscaphoid

Midcarpal

Natural History

• SLAC wrist– Scapholunate advanced collapse

• I radial styloid + distal pole scaphoid• II scaphoid fossa + proximal pole• III capitolunate

Natural History

• SLAC wrist– Scapholunate advanced

collapse

• I radial styloid + distal pole scaphoid

• II scaphoid fossa + proximal pole

• III capitolunate

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)

Treatment Options

• Relevant factors– Patient age– Activity Level– State of Degeneration

Treatment Options

• Conservative– Activity modification– Splinting– Steroid injection– NSAIDs

Treatment Options

• Surgical– PIN neurectomy– Total or partial wrist arthrodesis– Proximal row carpectomy– Distraction arthroplasty– Total wrist arthroplasty

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)

Irreducible Carpus And Arthritis

• RECALL:• SLAC wrist

– Scapholunate advanced collapse• I radial styloid + distal pole scaphoid• II scaphoid fossa + proximal pole• III capitolunate

Irreducible Carpus And Arthritis

• I– 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

Irreducible Carpus And Arthritis

• I– Radial styloidectomy

• Removes arthritic joint• Does not prevent progression to stage II and III

Irreducible Carpus And Arthritis

• II– Proximal row carpectomy

• Converts wrist into ball and socket joint• Mismatching radiocapitate joint allows translation• Removal of arthritic joints while motion maintained

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

Irreducible Carpus And Arthritis

• III– SLAC wrist procedure

• Proximal row carpectomy not suitable due to midcarpal arthritis

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)

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

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

SLAC Wrist ProcedureFour-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

Technique

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

Salvage

• Total wrist fusion– All arthritic joints fused– (radius - 3rd MC axis

mandatory, others optional)– No motion / good strength

Results

• Limited fusions– STT

• 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

Results

Degenerative Arthritis of the Wrist : Proximal Row Carpectomy versus Scaphoid excision and four-corner arthrodesis.M. Cohen S. Kozin J. Hand Surg. 2001 26A: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, ROM4CF group scored higher on mental-health component of SF-36 and

retained a slightly greater radial-ulnar deviation arc.

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)

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 & 2002

11% required arthrodesis (9 patients)• 34 returned to work (avg. 6/12)• F 66% E 73% RD 74% UD 76%• Grip 70%

Results of 4CF & scaphoidectomy

• Ashmead et. al • 44/12 100 patients• E 32deg F 42deg (53%)• Grip strength 80%• 78/85 satisfied (would undergo operation again)• 3% nonunion rate• Dorsal impingement 13%

Results

• Wrist fusion– 85% total pain relief– 65% return to former occupation

Hastings and Silver

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

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

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

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

STT Fusion• 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 0.045 K-wires across STT

Technique

ResultsPRC SLAC

procedureROM maintained

64% 45%

Grip strength 75% 75%

Pain relief “good” “good”

Satisfaction “good” “good”

Failure rate 20%, 0 0-7%, 30% Krakauer et al, 1994Wyrick et al, 1995Tomaino et al, 1994