CARPAL INSTABILITY (CID)

1. CARPAL INSTABILITY (CID) DR. AHMED ALZEYADI (SB-ORTHO) SENIOR REGISTRAR (KAASH)

2. Nowadays, the most accepted definition of “carpal instability” means any disturbance of the static and dynamic balance of forces at the wrist under the conditions of daily living

3. According to this definition, a wrist joint should be considered unstable when it is not capable of preserving a normal kinematic and kinetic relationship instability should be associated not only with the concept of abnormal transfer of loads (dyskinetics) but also with the concept of abnormal motion (dyskinematics)

5. Ligamentous system • intrinsic (interosseous) ligaments: 2. Intermediate: • Scapholunate ligament : divided into dorsal,proximal, and palmar regions The thickest and strongest region of the is located dorsally • lunotriquetral ligaments: are divided into dorsal, and palmar regions. The thickest and strongest region is located palmarl. • Scaphotrapezial ligament

7. Important secondary stabilizers are the volar STTL, the RSCL

8. Carpal biomechanics • (How the Wrist Moves): • the proximal carpal row has no direct tendinous attachments. Hence, the moments generated by muscle contraction result in rotational motion starting always at the distal carpal row • very little motion exists between the bones of the distal carpal row

9. During flexion of the wrist, the distal row synchronously rotates into flexion but also into some degree of ulnar deviation. In contrast, during wrist extension, the tendency of all distal carpal bones is to rotate into extension and a slight radial deviation. This so-called "physiologic flexion-extension" mostly occurs at the midcarpal joint.

10. proximal carpal row appear to be less tightly bound to one another considerable differences in direction and amount of rotation During radioulnar deviation of the wrist, the three proximal carpal bones move synergistically from a flexed position in radial deviation to an extended position in ulnar deviation

11. At the proximal carpal row, opposite torques are acting. Under axial load the scaphoid preferentially flexes, whereas the lunate, as well as the triquetrum, favors extension

12. (How the Wrist Sustains Load Without Yielding) about 50% of the load is present at the radius-scaphoid joint, 30% at the radius-lunate joint, and 20% at the ulnocarpal compartment

13. Mechanism of injury Impact on thenar side of wrist causes hyperextension , ulnar deviation and intercarpal supination Progressive damage around lunate Bony or ligamentous

17. Radiographic assessment: • Six radiographs These include: • posteroanterior, lateral, • radial and ulnar deviation, • flexion and extension • additional view to rule out scapholunate instability. • AP radiograph of the wrist with a clenched and loaded fist is made (dynamic SL inst.)

18. (Gilula's lines)

19. Measurement of Carpal Bone Alignment: Scapholunate Angle Capitolunate Angle (CL): Radiolunate Angle :

20. Carpal Height Ratio(CHR)

21. Radiographic andOther Diagnostic Studies • radionuclide bone scans • Rule out ass injury( chondral or bone fracture) • Cannot rule out instability • Arhrography: • Middcarpal • TFCC • DYNAMIC • CT: • Associated fractures • 3D • MRI: • Most helpful to diagnose OSEONECROSIS • Can diagose occult fracture • TFCC • Gadolinium should be used to evaluate carpal ligament • WRIST ARTHROSCOPE

22. Classification: (Green's operative hand surgery) • Chronicity: • Acute • SUBACUTE • Between 1 and 6 weeks (subacute injury), • Chronic: • After 6 weeks (chronic cases • Severity: • predynamic instabilities (partial ligament tears with no malalignment under stress), • dynamic instabilities (complete ruptures exhibiting carpal malalignment only under certain loading conditions) • static instabilities (complete ruptures with permanent alteration of the carpal alignment). • Etiology:

23. Location: • Direction • (a) dorsal intercalated segment instability (DISI) • (b) volar intercalated segment instability (VISI), • (c) ulnar translocation • often as a result of a dorsally malunited fracture of the radius • (e) dorsal translocation • (d) radial translocation • Pattern • (a) carpal instability dissociative (CID), • (b) carpal instability nondissociative (CIND), • (c) carpal instability complex (CIC), • (d) carpal instability adaptive (CIA),

24. Scapholunate instability The current definition of scapholunate instability has been expanded to include those wrists that exhibit symptomatic dysfunction, are unable to bear loads, and do not demonstrate normal kinematics throughout the complete arc of motion (JHS Vol 33A, July–August 2008)

25. SLD is probably the most frequent CID problem and may appear either as an isolated injury or associated with other local injuries, such as distal radial fractures or displaced scaphoid fractures

26. Pathomechanics: There is a spectrum of injuries, from minor SL sprains to complete perilunar dislocations Complete sectioning of the SL membrane and ligaments results in scaphoid that becomes proximally unconstrained and RS motion increases, whereas RL motion decreases.. When the SL joint has been completely dissociated, with the proximal pole of the scaphoid being subluxed dorsoradially, the forces crossing the wrist cannot be distributed normally this may explain the frequent development of long-term degenerative changes at the dorsolateral edge of the RS joint

27. The lunate, by contrast, appears rotated into extension

28. STAGES OF SLD: • Predynamic SLD • SL membrane is only stretched or partially ruptured • Dynamic SLD • No permanent malalignment exists at this stage • Static Reducible SLD • failure of the secondary stabilizers, is permanent (static instability) but reducible • Static Fixed SLD: • Chronic rupture or insufficiency of both primary and secondary SL ligament stabilizers • carpal malalignment is hardly reducibl • Osteoarthritis Secondary to SLD (SLAC Wrist)

29. Diagnosis: • SLD is frequently missed at presentation • masked by other more obvious injuries • A history of a fall on the outstretched hand • A high index of suspicion is recommended in order not to miss this injury. • Weakness of grasp • Pain is common and may be aggravated by heavy use • dorsoradial swelling • snapping or clicking sensation with movement • Physical Examination: • Palpation for areas of maximal tenderness • Scaphoid Shift Test (Watson

31. Treatment: (JHS Vol 33A, July–August 2008) • Most commonly, the SLD is discovered in the late stages • Principles of management • Garcia-Elias et al. developed a set of 5 questions that provide a useful treatment algorithm for the various stages of scapholunate instability. 1. Is the dorsal scapholunate ligament intact? 2. Does the dorsal scapholunate ligament have sufficient tissue to be repaired? 3. Is the scaphoid posture normal? 4. Is any carpal malalignment reducible? 5. Is the cartilage on radiocarpal and midcarpal surfaces normal?

32. (JHS Vol 33A, July–August 2008) • Predynamic (Occult) Scapholunate Dissociation: • in the acute phase • a percutaneous or arthroscopically guided Kirschner wire fixation is recommended • In the chronic predynamic instability, • three different approaches have been proposed: • 1) proprioception reeducation of the flexor carpi radialis muscle, • (2) arthroscopic débridement alone of the torn ligament edges • (3) electrothermal ligament shrinkage

33. (JHS Vol 33A, July–August 2008) Weiss et al. reported satisfactory improvement in 11 of 13 patients underwent Arthroscopic debridement and Ruch and Poehling reported satisfactory improvement in 7 of 7 patients with no progression to instability in the short term.

34. (JHS Vol 33A, July–August 2008) • Dynamic Scapholunate Dissociation • each component of instability should be addressed separately, including a direct scapholunate repair for the coronal plane and a dorsal capsulodesis for instability in the sagittal plane • A direct repair of the dorsal SL ligament is recommended • Augment repaire with using either local tissues from adjacent ligaments or utilize a bone-ligament-bone autograft • with a percutaneous SL joint fixation • Immobilization (full supination, mid extension, and ulnar deviation)

36. Dorsal RadioscaphoidCapsulodesis (Blatt):

37. Static Reducible Scapholunate Dissociation • two different strategies have been proposed: tendon reconstructions and the so-called RASL procedure (reduction-association of the SL joint)

38. Reduction-Association of the SL Joint (RASL Procedure): • Rosenwasser et al. presented early and encouraging results of the concept of a scapholunate pseudarthrosis supplemented by a permanent screw, called the RASL procedure • This method consists of an open reduction, repair of the ligament remnants, and protection of the repair by internally blocking the SL joint with a transverse Herbert screw

40. Brunelli proposed a flexor carpi radialis tendon graft reconstruction, intended to simultaneously address the scaphotrapezial and scapholunate ligament deficiencies, This technique reconstruct not only the scaphotrapezial and scapholunate ligaments but the dorsal radiotriquetral ligament as well, thereby addressing both thecoronal and sagittal plane abnormalities and intrinsic and extrinsic ligament pathology

41. Four to 5-year follow-up of this triligament tenodesis revealed on average a 30% loss of flexion extension arc, maintenance of 65% to 80% of contralateral grip strength, and subjective pain relief in a majority of patients with 1 series reporting a satisfaction rate of 79%

42. Static Irreducible Scapholunate Dissociation • The most frequently recommended treatment for the symptomatic, irreducible carpal malalignment secondary to an SLD is a partial fusion

43. Scaphotrapezoid-TrapezialArthrodesis: • goal of the procedure is to realign the proximal pole of the scaphoid relative to the scaphoidfossa, • Painful RS impingement is a frequent problem • Rogers and Watson recommend incorporating a dorsolateralstyloidectomy as a routine part of the STT fusion

44. (SLAC Wrist) Radial Styloidectomy Watson and Ballet) the so-called SLAC procedure (scaphoid excision plus a capitate-lunate-triquetrum-hamate fusion, also known as "four corner" fusion) has gained an excellent reputation for the treatment of chronic SLD. Indications most commonly include stage II and III SLAC wrist deformity with degeneration of the RS and CL joints A frequent complication (12% ) is the development of dorsal impingement between the dorsal edge of the radius and the capitate. An important step to avoid this is to fully correct the DISI deformity before placing the Kirschner wires across the LC joint

45. Proximal Row Carpectomy Compared with the SLAC procedure, this technique avoids long immobilization and the risk of nonunion convertible to a wrist arthrodesis or arthroplasty Long-term radiocapitate degeneration with more than 10 years of follow-up in about 10% of the patients

46. Total Wrist Arthroplasty. • Total Wrist Arthrodesis • pain relief is expected in 85% of wrist fusion patients, with 65% returning to their former occupations

47. SUMMARY The scapholunate interosseous ligament is the critical stabilizer of a delicately balanced system of joints. Carpal alignment may be maintained after isolated disruption of this ligament because of a complex array of secondary stabilizers A high index of suspicion is recommended Treatment should be tailored to the stage of injury and is individualized to address the degree of anatomic and kinematic alteration.