SLAC & SNAC WRIST

ORTHOPEDICS

1. PRESENTED BY: DR.N.BENTHUNGO TUNGOE P.G, MS(ORTHOPEDICS) CENTRAL INSTITUTE OF ORTHOPEDICS VMMC & SAFDARJUNG HOSPITAL NEW DELHI SNAC & SLAC WRIST

2. INTRODUCTION Scapholunate advanced collapse (SLAC) and scaphoid nonunion advanced collapse (SNAC) are the two most common patterns of post-traumatic wrist arthritis.

3. ETIOLOGY OF SLAC TRAUMATIC CAUSES: Scaphoid fracture non union, Scapholunate ligament dissosciation ATRAUMATIC CAUSES: CPPD(calcium pyro phosphate dehydrate) diseases Rheumatoid arthritis Neuropathic diseases Beta 2 microglobulin assosciated amyloid deposition disease

4. SCAPHO LUNATE LIGAMENTOUS COMPLEX The  scapholunate ligament complex  is a U-shaped ligamentous complex joining the lunate  and the  scaphoid . It is divided into dorsal, volar and intermediate components with surrounding secondary stabilisers.

5. Dorsal component blends with joint capsule, scaphotriquetral and intercarpal ligaments strongest portion of the complex controls flexion/extension Volar component oblique collagen fibres blends with extrinsic volar radioscapholunate ligament controls rotational motion major proprioceptive role

6. Intermediate/ interosseous component located proximally and centrally and therefore may be referred to as the central or proximal component fibrocartilage weakest portion of the complex extends a few millimeters into the joint, akin to a meniscus Secondary stabilisers scapho - trapezial -trapezoidal ligament radio- scapho - capitiate ligament

7. RADIOGRAPHIC FEATURES The pattern is that of a progressive osteoarthritis affecting initially the articulation between the radial styloid and the scaphoid . In later stages of the disease, osteoarthritis affects the whole radioscaphoid articulation, then the articulation between  lunate  and  capitate . Finally it may involve other intercarpal joints. In addition there is widening of the space between  scaphoid  and lunate as well as proximal migration of the scaphoid and the capitate CT FINDINGS:  angulations of the scaphoid and lunate bones (increased scapholunate angle and dorsal or volar intercalated segment instability deformity), radioscaphoid incongruity, cartilage loss, and subchondral bone degenerative changes.

8. SCAPHOLUNATE DISSOSCIATION(TERRY THOMAS SIGN)

9. SLAC

10. Watson  staging (often used by hand surgeons) I : osteoarthritis of the articulation between the radial styloid and the scaphoid II:  osteoarthritis involving the whole radioscaphoid articulation III:  osteoarthritis of the radioscaphoid and capitolunate articulations IV:  osteoarthritis of the radiocarpal and intercarpal articulations +/- distal radioulnar joint (DRUJ) NOTE: Note that the radiolunate joint is almost preserved until very last stages of the disease. It is also worth noting that the scaphoid fossa in the radius may be deep / preserved in cases of CPPD in contrast to post-traumatic SLAC wris

11. SURGICAL TREATMENT Surgical treatment for SLAC wrist includes  four-corner arthrodesis , capitolunate arthrodesis , complete wrist arthrodesis , scaphoidectomy , proximal row carpectomy (PRC), denervation , radial styloidectomy

12. SNAC( scaphoid non union advcance collapse) In a SNAC wrist, the proximal  scaphoid  fragment usually remains attached to the  lunate (which rotate together during extension), while the distal scaphoid fragment rotates into flexion. This results in abnormal contact in the radioscaphoid compartment, characterised by early styloid osteoarthritis between the distal scaphoid fragment and the radial styloid process

13. Jupiter et al classification of non union based on the extent of arthosis : nonunions without arthrosis , nonunions with radiocarpal arthrosis , nonunions with advanced radiocarpal and intercarpal arthrosis

14. Radiographic findings of SNAC radioscaphoid narrowing, capitolunate narrowing, cyst formation, pronounced dorsal intercalated segment instability(DISI) Note: The radiolunate joint usually is spared in early stages but may show degenerative changes as the arthritis becomes more diffuse.

15. Effect of SLAC & SNAC ON JOINT KINEMATICS: Both of these processes lead to abnormal joint kinematics, since the lunate is unrestrained by the distal scaphoid and, therefore, assumes an extended posture. Over time, this may result in a dorsal intercalated segment instability (DISI) deformity, which invariably progresses to degenerative arthritis at the radioscaphoid articulation, followed by carpal collapse and midcarpal arthritis

16. DISI( dorsal intercalated segment instability ) CAUSES: 1. wrist trauma +/- fracture Scaphoid fracture: bony DISI distal radius fracture: compensatory DISI radius malunion : adaptive DISI 2.Scapholunate ligament sissosciation :  ligamentous DISI

17. Radiographic features On an AP view the normal trapezoidal configuration of the scaphoid may be lost and it may appear triangular. On lateral plain film typically shows a dorsal tilt of the lunate : scapholunate angle  > 60º: sign of scapholunate ligament dissociation capitolunate angle   > 30º:  the capitate is displaced posteriorly compared to the distal radius

18. DIFFERENTIAL DIAGNOSIS CARPAL TUNNEL SYNDROME TRIGGER FINGER DE QUERVANS TENOSYNOVITIS FCR TENDONITIS

19. NON OPERATIVE MANAGEMENT WRIST IMMOBILIZATION WITH SPLINTS NSAIDS CORTICO STEROIDS INJECTIONS

20. OPERATIVE MANAGEMENT RADIAL STYLOIDECTOMY WRIST DENERVATION SCAPHOID EXCISION PROXIMAL ROW CARPECTOMY ARTHODESIS Four corner arthodesis Capito-lunate arthodesis Wrist arthodesis

21. Four corner arthodesis

22. THANK YOU