SLAC & SNAC wrists Management & Results

Satyam Patel January 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 – 2 decades after fracture - scaphoid nonunion cystic changes - radioscaphoid degeneration – 3 decades • Stage I - pancarpal arthritis - radial styloid - scaphoid joint • Stage II joints • Stage III - degeneration of radioscaphoid and scaphocapitate - 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) PRC • 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 • 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

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

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, ROM 4CF 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% • Grip 70% RD 74% UD 76%

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

Technique

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

PRC ROM maintained 64% Grip strength 75%

Results

SLAC procedure 45% 75% Pain relief Satisfaction Failure rate “good” “good” 20%, 0 “good” “good” 0-7%, 30% Krakauer et al, 1994 Wyrick et al, 1995 Tomaino et al, 1994