VISI

Definition

 

Volar Intercalated Segmental Instability

- secondary to injury to the lunate-triquetral ligament

 

Epidemiology

 

Less common

 

Aetiology

 

Caused by fall on outstretched extended wrist

- hypothenar eminence strikes ground first 

- isolated LT ligament injury

 

Can be part of perilunate dislocation

- SL heals

- residual LT laxity

 

Anatomy

 

LT ligament

- also C shaped

- strongest palmar

 

Pathomechanics

 

Normally

- scaphoid imparts a flexion moment on proximal row

- triquetrum imparts an extension moment

- balanced by ligamentous attachments to lunate

 

Palmarflexion of lunate with dorsiflexion of triquetrum

 

Probably need injury to dorsal extrinsics to impart static collapse

- DRC ligament (radio-triquetral)

- ulnocarpal ligament

 

Classification

 

CID

 

Static

 

Dynamic

 

CIND VISI

 

Secondary to ligamentous laxity

- seen in teenage girls

- clunk on radial and ulna deviation with axial compression

 

Whole proximal row is flexed

- lunate triangular

- scaphoid cortical ring sign

- no SL disassociation

 

Non operative treatment

- no progression to OA

 

Symptoms

 

History of injury 

 

Pain on ulnar side of wrist 

 

Weakness of wrist

 

Signs

 

Swelling and tenderness over triquetro-lunate joint 

 

Ulna deviation / pronation / axial compression

- pain and clicks

 

Reagan Ballotment 

- Triquetro-lunate ballottement

- pisiform-triquetral with thumb and index finger

- lunate with other hand

 

 

DDx

 

DRUJ instability

TFCC tear

Ulna head OA

Pisiform triquetral OA

Hamate fracture

ECU subluxation

 

AP Xray

 

Palmarflexion of scaphoid 

- Scaphoid shortened 

- Ring sign 

 

Palmarflexion of lunate 

- Appears triangular 

- Triquetrum distally displaced 

 

Broken Shenton's line (of proximal carpal row)

 

Lateral Xray

 

Decreased scapholunate angle 

- < 30^o

 

Palmarflexion of lunate 

- capitate - lunate angle > 10^o

- radio - lunate angle > 10^o

 

Arthroscopy

 

Diagnostic and therapeutic

 

Management

 

Early

 

Options

 

A.  Repair

- dorsal approach

- restore LT orientation with K wires

- repair ligament with intra-osseous sutures

 

B Reconstruct with ECU

- if insufficient ligament for repair

- radial half of ECU

- pass through drill holes

 

Late

 

> 6 weeks 

 

Lunate-triquetral fusion

- very difficult

- high failure with k wires

- need compression screws

- insert bone graft