Wrist Instability

Question 1

What is DISI?

Answer 1

• Dorsal Intercalated Scaphoid Injury
• An instability of the Scaphoidlunate Joint

Question 2

What causes DISI?

Answer 2

1. Scapholunate ligament Injury - most common cause / ligament injury in wrist

• Caused by HYPEREXTENSION of Pronated wrist
• Dorsal Scapholunate ligament is Stronger than Volar scapholunate ligament

2. Scaphoid Fractures
3. Kienbock’s disease

Question 3

What is the outcome of DISI if left untreated?

Answer 3

Cause a SLAC wrist- Scapholunate advanced collapse

Question 4

What are the signs of DISI?

Answer 4

• Snuffbox test
• Watson Test- when deviating from ulnar to radial, pressure over volar aspect of scaphoid produces a clunk secondary to dorsal subluxation of the scaphoid over the dorsal rim of the radius

dorsal wrist pain or a clunk during this maneuver may indicate instability of scapholunate ligament

• too see video click link below and scroll to watson’s test
• http://www.orthobullets.com/hand/6041/scapholunate-ligament-injury-and-disi

Question 5

What investigations are helful in DX DISI and what do you see?

Answer 5

AP radiographs

• Clenched fist AP view of hand = Increase in space between scaphoid/lunate >3mm
• Cortical ring sign- due to scaphoid malalignment
• Humpback deformity with DISI in unstable scaphoid fracture

Lateral

• Dorsal tilt of LUNATE-> Scapholunate angle of >70^o on neutral rotation view
• Radiolunate angle >15^o

Arthroscopy- Gold standard for diagnosis

MRI- High specificity , medium sensitivity

Question 6

What is the TX of DISI?

Answer 6

Non operative

casting alone is insuffucient- most peoples view

Operative

• Scapholunate ligament repair/ reconstruction
• in acute scapholunate ligament injury or chronic SL injury with reducible SL injuries
• Primary repair can be done up to 17 months from injury
• Blatt dorsal capsulodesis often added and can be useful in chronic instability when repair is not feasible
• if Path is Scaphoid Fx= ORIF and CRPP
• Stabilisation and wrist fustion- irreducible & rigid DISI deformity, DISI & Distal joint degeneration
  
  • STT- scaphotripezialtrapezoidal fusion
  • SLC- scapholunatecapitate
  • SL= Scaphoilunate- highest risk of non union

Question 7

What is VISI?

Answer 7

Volar incalcated scaphoid injury

A type of carpal instability dissociative

Question 8

What is the pathoanatomy of VISI?

Answer 8

Advanced injury to

• Lunotriquetral ligament- LT- C shaped comprised a thick dorsal/ volar component, dorsal important for rotational stability, volar thickness and transmit extension moment
• Dorsal radiotriquetral ligament- dorsal RT ( aka radiocarpal lig), loss allow lunate to flex more easily
• Volar radiolunate ligament short& long- Volar RL, extrinisic ligaments

Mechanism is:

Lt injured in Wrist Hyperextension or Extension and radial deviation

scaphoid induced the lunate into further flexion while triquetrum extends

Occasionally VISI seen in pts with ligamentous laxity and no hx of trauma ( unlike DISI)

Question 9

What are the symptoms and signs of VISI?

Answer 9

• Ulnar sided wrist that is worse with pronation /supination- grip
• Signs: positive Ballottement test-

Grasp the lunate between the thumb and index finger of one hand while applying alternative dorsal and palmar loads across the triquetrum with the thumb and index of the other hand

* positive test **elicits pain, crepitus or increased laxity**, suggesting **LT interosseous injury**

Question 10

What investigations would help you dx VISI and what do you see?

Answer 10

Radiographs

Lateral

• Volar flexion of lunate - increase in Scapholunate angle ^o Normal is 45^o
• Capitolunate zigzag deformity with capitolunate angle increase >15^o

AP

• Break in Gilula’s arc
• May not see increase in space between LT
• May see proximal migration of triquetrum on lunate

Arthroscopy may be helpful in dx

-

Question 11

What are the tx options for VISI?

Answer 11

Non operative

Observations- attempted initally

Operative

Acute instability = CRPP ( mutliple K wires)+ acute ligament repair+/- Dorsal capsulodesis

Chronic instability=LT fusion- non union complication

Arthroscopic Debridment of LT Ligament with ulnar shortening- Chronic instability and Positive UV

Question 12

What is SLAC?

Answer 12

• Scaphoid Lunate advanced collapse
• A condition of progressive instability-> advanced arthritis of radiocarpal/ midcarpal joints
• degenerative arthritis seen in chronic dissocation between scaphoid and lunate

Question 13

Describe the pathoanatomy of SLAC wrist?

Answer 13

Chronic SL ligament injury-> DISI deformity

• Scaphoid is flexed and lunate is extended as scapholunate ligament no longer restrains this articulation
• SL angle > 70 degrees
• Lunate extended >10 degrees past neutral
• Resultant flexion/extension of S &L -> abnormal forces across midcarpus/radiocarpus and maligalignment of concentric joint surfaces
• initally effects RADIOSCAPHOID JOINT and progresses to CAPITOLUNATE joint
• IMPORTANT- the RADIOLUNATE JOINT is spared beacuse of its spheriod shape so it is congruently loaded

Question 14

What is the classification system for SLAC & TX ?

Answer 14

WATSON

Stage 1- Arthritis between scaphoid & radial styloid

Tx- Radial styoidectomy+ scapholunate reduction+stabilisation

Stage 2- Arthritis of entire radioscaphoid joint

TX- Eliminate radioscaphoid joint by…

Proximal row carpectomy

Four corner fusion: lunate/hamate/capitate/triquetrum

Radioscapholunate fusion, total wrist arthrodesis, total wirst arthroplasty

Stage 3- Arthritis between CAPITATE and LUNATE (pic)

Tx- SLAC procedure- Prox row carpectomy

Total wrist arthrodesis

**Stage IV- not decribed by Watson by bascally pancarpal arthritis**

Question 15

What are the symptoms and signs of SLAC wrist?

Answer 15

Symptoms

• Difficulty putting weight across wrist
• Pain localised in scapholunate interval
• Progressive weakness of hand
• Wrist stiffness

Signs

• Tenderness over SL Ligament
• Decreased ROM
• Weakness of grip strength
• Watson’s Shift test-

with firm pressure over the palmar tuberosity of the scaphoid, wrist is moved from ulnar to radial deviation

positive test seen in patients with scapholunate ligament injury or patients with ligamentous laxity, where the scaphoid is no longer constrained proximally and subluxates out of the scaphoid fossa resulting in pain.

when pressure removed from the scaphoid, the scaphoid relocates back into the scaphoid fossa, and typical snapping or clicking occurs.

must compare to contralateral side

Question 16

What is seen in SLAC stage 1 on xray

Answer 16

PA radiograph

• Radial styloid beaking
• sclerosis
• Joint space narrowing

Question 17

What are seen on xray for a SLAC stage 2 wrist?

Answer 17

PA radiograph

sclerosis

joint space narrowing- between scaphoid and entire scaphoid fossa of distal radius

Question 18

What are seen on xray for a SLAC stage 3 wrist?

Answer 18

Pa radiograph

• Sclerosis
• Joint space narrowing between lunate and capitate
• Capitate wil migrate proximally into space created

Question 19

What are seen on a lateral xray for a SLAC wrist

Answer 19

• DISI deformity of the wrist
• with subluxation of capitate dorsally

Question 20

TX of SLAC wrist

Answer 20

Non operative

NSAIDs, wrist splinting, ? corticosteriod injections

Operative

• Radial styloidectomy+ scaphoid stabilisation= stage 1- prevents impingement between scaphoid and radius

open or arthroscopic

• PIN/ AIN denervation- stage 2/3
• Proximal row carpectomy= Stage 2

Excise - scaphoid/lunate/triquetrum

CI if incompetet radioscaphocapitate ligament/ capitolunate arthritis as lunate articulates with lunate fossa of distal radius

Preserves relative strength/ motion

• Scaphoid excision and 4 corner fusion- stage 2/3

​wrist motion occurs thru perserved lunate & distal radius

similar longterm results between this and prox row carpect

• _​_Fusion-stage 3/ pancarpus arthritis

Gives best for pain relief adn good grip strength at cost of wrist motion

Question 21

Define a SNAC wrist?

Answer 21

• Scaphoid NON union advanced collapse
• Joint space narrowing is seen between the distal pole of the scaphoid and the radial styloid/ distal pole of scaphoid + trapezium and trapezoid
• Proximal scaphoid articular surface involved, radius is spared
• History, staging and tx are similar to SLAC wrist

Question 22

Describe the radiographic and tx of SNAC?

Answer 22

• Stage 1- Arthritis between distal scaphoid and radius

Tx- Radial styloidectomy + fixation of scaphoid Non union w Bone Graft

• Stage 2- Scaphocapitate arthritis & 1

Proximal row carpectomy, SLAC procedure(excision sacphoid and 4 corner fusion), Total wrist arthroplasty/ total wrist fusion

• Stage 3- Periscaphoid arthritis
• SLAC procedure,Total wrist arthroplasty/ total wrist fusion

Question 23

What is carpal instability non dissociative?

Answer 23

Instability between rows either

Midcarpal -between prox and distal row

Radiocarpal- between radius & prox row

Question 24

Describe the incidence and pathoanatomy of Carpal instability non dissociative?

Answer 24

• Rare
• Radiocarpal-aka inferior arc injury
• High energy Trauma, extrinsic rupture
• ligamentous, radial/ ulna styloid fractures
• assoc injuries compartment syndrome/ acute carpal tunnel
• Volar dissocations worse than dorsal

Question 25

What are the Signs and symptoms of Carpal instability non dissociative?

Answer 25

* HX of trauma ( radiocarpal) or no trauma ( midcarpal) * Subluxation may/ not be painful * Wrist giving way * Clunk sign when moving ulnar from flexion/extension

Question 26

What Investigations useful in Carpal instability non dissociative?

Answer 26

* Subluxation of proximal row on radiographic screening * Diagnosis made **when \>50% of lunate width is ulnarly translated off the lunate fossa of the radius**

Question 27

What is the Tx of carpal instability non dissocaitive?

Answer 27

_Non operatively_ Immobilisation +/- Splinting- Midcarpal most amenible _Operatively_ * **Immediate repair, reduction repair & pinning -** for ulnar translation w styloid fractures- gd results with _EARLY_ fixatn * **Midcarpal Joint fusion-** for **midcarpal instability-\>20-30% loss of motion** * **Osteotomy for malunion distal radius- fusion of radiocarpal joint-\> loss 55-60% loss of motion**