Sean Walsh Orthopaedic Surgeon Dorset County Hospital

Sean Walsh Orthopaedic Surgeon Dorset County Hospital

Shapes and orientation of articular surfaces Ligaments Oblique positioning of scaphoid Tendons surrounding the joints Other soft tissues Peripheral and central nervous system

Initially synonymous with Malalignment Diagnosed on plain radiograph But not every alteration in carpal alignment is pathological e.g. hyper lax wrists Redefined as inability to bear physiological loads with an associated loss of carpal alignment But some patients are asymptomatic most of time with well aligned wrists and are able to sustain physiological loads. Symptomatic on specific tasks with typical sensation of giving way

Dynamic instability with sporadic malalignment under certain loading conditions Static instability when malalignment is permanent regardless of loading conditions

Carpal dysfunction In a normal wrist there is the ability to transfer loads without sudden changes in stress on the articular cartilage ( normal Kinetics) and the capacity to move throughout the normal range without sudden alterations of intercarpal alignment (normal Kinematics)

Osseous Anatomy

Laterally convex distal surface of scaphoid articulates with concavity if trapezium and trapezoid STT joint Central portion lunocapitate joint Medial hamate-triquetral articulation helicoid joint ( screw shaped). Type I lunate single facet, Type II an extra facet articulating with hamate

Tightly packed collagen bundles, mechanically important Mechanoreceptors Proprioception to CNS dynamic stabilisation Wrist proprioception through SLL needs an intact PIN

Extrinsic Palmar radiocarpal, Palmar ulno carpal and dorsal radio carpal. There are no dorsal ligaments between the ulna and the carpus

Radioscaphoid Radioscapho-capitate Long Radiolunate Short Radiolunate

Ulnar Lunate, Ulnar Triquetrum Ulnar Capitate

Dorsal Radial Triquetrum Ligament Wide fan shaped ligament inserting onto dorsal rim of triquetrum (deep fibres onto lunate) Berger R, Ann Plast Surg. 1995 Jul;35(1): 54-9.

Dorsal midpalmar /intercarpal ligament Dorsal ridge triquetrum, along distal edge lunate, inserts dorsal rim of scaphoid, trapezium and trapezoid.

Dorsal and palmar Connect bones of the same carpal row (palmar and dorsal interosseous) Or link the two rows to each other

3 distinct structures Dorsal and palmar SL ligaments, central fibrocartilaginous membrane

Palmar and Dorsal Fibrocartilaginous membrane between Palmar Lig. Thicker and stronger 301N

Distal row is a fixed unit attached to metacarpals Proximal row functions as an Intercalated Segment. The term intercalated segment refers to it being the part in between the proximal segment of the wrist consisting of the radius and the ulna and the distal segment This intercalated segment is the keystone in the coordination of motions of the wrist and in the control of forces that are transmitted from the hand to the forearm and vice versa.

Wrist radial deviation, scaphoid flexes, lunate flexes. Wrist ulnar deviation triquetrum extends, lunate extends Scaphoid tends to flex, Triquetrum tends to extend and the lunate follows

Lunate is influenced by Triquetrum and extends DISI, Dorsal Intercalated Segmental Instability

Lunate is influenced by Scaphoid and flexes VISI Volar Intercalated Segmental Instability VISI can be normal in a lax wrist

Scapho Lunate Interosseous Ligament SLIL Primary stabiliser of the SL joint SLIL failure force of 300N Secondary stabilisers Scaphoid Capitate and STT ligaments Palmar - RSC, LRL,SRL - stabilise scaphoid Dorsal Dorsal Radio Carpal Ligament, Dorsal Inter Carpal Ligament Dynamic stabilisers Flexor carpi radialis, Extensor carpi ulnaris

Wrist Kinematics - how the wrist moves Carpal Kinetics how it sustains physiological loads without giving way Normal wrist : Perfect interaction between wrist tendons, joint surfaces and soft tissue constraints, allows motion and loading without yielding

Kinetic Instability - unable to bear physiological loads without yielding Kinematic Instability- abnormal movements, click or clunk

Mechanical instability ( Kinetic or Kinematic) + Symptoms = CLINICAL INSTABILITY

Four major patterns Carpal Instability Dissociative (CID) Carpal Instability Non-dissociative (CIND) Carpal Instability Complex (CIC) Carpal Instability Adaptive (CIA)

Acute Sub-acute <1 week Maximum potential to heal From 1 to 6 weeks Possible to heal Chronic > 6 weeks Unlikely to heal

Pre-dynamic Dynamic Static reducible Static not reducible

DISI VISI Volar translation Dorsal translation Radial translation Ulnar translation Proximal translation Distal translation

Between bones of same carpal row Scaphoid-Lunate, LunateTriquetrum Capitate-Hamate

Unstable scaphoid non-union distal scaphoid follows distal carpal row Proximal fragment follows the proximal carpal row Scapholunate dissociation Scaphoid rotates around the RC ligament

Extension + Ulnar Deviation +Supination

Yin and Gilula: Imaging of the symptomatic wrist, 2001

Lunotriquetral dissociation

Very unusual Rupture of transverse intercarpal ligaments binding bones of the distal row Dorsopalmar crush or blast injury

Radiocarpal, between radius and proximal carpal row Midcarpal, between proximal and distal rows No disruption between the bones of the proximal or distal rows

Excessive laxity Rupture of radiocarpal ligaments carpus displaced down slope of radius Rheumatoid arthritis Madelung s deformity due to fatigue of ligaments excessive shear forces Trauma- radiocarpal dislocation with or without radius fracture

Group of conditions Dysfunction of the radiocarpal and midcarpal joints

I. Anterior- entire proximal row flexed on lateral view II. Posterior-Normal alignment in standard radiographs, dorsal subluxation with dorsally directed force. III. Combined radiocarpal and midcarpal, both joints abnormally subluxable in a palmar and dorsal direction as a result of increased global laxity IV. Adaptive dysfunction secondary to an extra carpal problem usually a malunited distal radius fracture.

Attenuation or rupture of triquetro-hamate-capitate, STT and scaphocapitate ligaments Often with insufficiency of the dorsal radiocarpal ligament Proximal row remains flexed until near the end of ulnar deviation, where it suddenly rotates into extension with a palpable thud. Catch up clunk Most cases have combined medial and lateral insufficiency

Extra carpal pathology Dorsally malunited distal radius fracture Postural adaption of proximal carpal row to conform to the abnormal radial tilt Flexed midcarpal joint Slackening of palmar midcarpal ligaments Pain, tenderness at midcarpal joint Improves when radial deformity corrected with an osteotomy

CID + CIND Derangement within same row of carpal bone Derangement between rows Within this category 5 groups of carpal dislocations have been identified

Dorsal perilunate dislocations - lesser arc Dorsal perilunate # dislocation - greater arc (Extreme wrist extension, ulnar deviation, midcarpal supination, e.g.motorcycle RTA) Palmar perilunate dislocations lesser or greater arc Axial dislocations Isolated carpal dislocations

Greater arc Lesser arc

Mechanisms of wrist stability Definitions of Instability kinetic and kinematic Common instabilities in clinical practice Carpal malalignment Classifications of wrist instability

Carlos Heras-Palou for loan of clinical photographs and videos Marc Garcia Elias

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