CARPAL Fractures and dislocations 

Facts

• Fractures and dislocations involving the carpus can be easily misdiagnosed as wrist sprains

• The carpus is made up of 8 bones grouped into 2 rows

  • Distal carpal row: strong ligamentous connections within the row and with the MCs form a rigid transverse arch

    • Includes trapezium (articulates with 1st MC), trapezoid (2nd MC), capitate (3rd), hamate (4th and 5th)

  • Proximal carpal row: articulates with the radius and ulna and includes the scaphoid, lunate, triquetrum

    • Pisiform is a sesamoid of the FCU tendon and articulates only with the triquetrum

• Primary axis of rotation is through the head of the capitate

• In radial deviation, the scaphoid flexes, causing the entire proximal row to flex

• In ulnar deviation, the scaphoid extends and the proximal row extends

• Ligaments:

  • Transverse carpal ligament extends from scaphoid and trapezium to hamate and pisiform

    • Forms the roof to the carpal tunnel

  • Extrinsic: connect radius to carpus and carpus to MCs

    • Volar ligaments stronger than dorsal

    • Volar: radioscaphocapitate (RSC), radiolunatotriquetral (RLT), radioscaphoid, ulnocapitate, ulnotriquetral and ulnolunate

    • Dorsal: radiotriquetral and scaphotriquetral

  • Intrinsic: connect carpal bones to carpal bones and include the scapholunate (SL) and lunotriquetral (LT) ligaments

• Space of Poirier: ligament free space and potential area of weakness along proximal capitate

  • Lies between the RSC and RLT ligaments

  • Allows escape of distal carpal row from lunate in perilunate dislocations

• Midcarpal instability:

  • Proximal row acts as "intercalated segment", connecting radius/ulna to a rigid distal row

  • Volar intercalated segment instability (VISI): commonly results from LT dissociation due to LT ligament injury

    • Lunate flexes due to loss of support from triquetrum

    • Scapholunate angle: < 30°

    • Radiolunate angle: > 15° of flexion

  • Dorsal intercalated segment instability (DISI): commonly due to scaphoid fracture or SL ligament injury

    • Lunate extends due to loss of support from radius (via the scaphoid)

    • Scapholunate angle: > 70°

    • Radiolunate angle: > 10° of extension

Intercalated segment instability

• Triangular fibrocartilage complex (TFCC): stabilizer of ulnar carpus and DRUJ

  • Attaches at the base of the styloid process

  • Absorbs about 20% of load across wrist joint

  • Components: meniscal homologue, articular disk, ulnocarpal ligaments (ulnolunate and ulnotriquetral) and extensor carpi ulnaris sheath

Perilunate dislocations and fracture-dislocations:

• Most common wrist dislocation

• Typically occurs after fall on an outstretched, ulnarly deviated and extended hand

• Represents a continuum of injury to the ligamentous connections around the lunate

• Lesser arc injury: energy passes around circumference of lunate and results in intrinsic ligament disruption

• Greater arc injury: energy passes more distally through the scaphoid, capitate and triquetrum, resulting in fractures of one or more of these bones

  • Twice as common as lesser arc injuries

  • Most common is the transscaphoid, perilunate fracture-dislocation (de Quervain) in which the scaphoid is fractured

• Distal carpal row generally dislocates dorsally

Lesser and Greater arcs

• Patients present with pain, deformity and digital flexion (stage IV dislocation)

• Assess NV status and identify associated injuries

  • Median nerve paresthesias are common with stage IV dislocations

  • Ulnar nerve, arterial injuries and tendon injuries can also occur

Radiocarpal fracture-dislocations:

• Uncommon injury associated with high-energy trauma

• May occur as a pure ligamentous injury (rare) or fracture-dislocation

• Most common avulsion fragments include: Barton's fracture (dorsal or volar lip fracture of the distal radius), radiostyloid (avulsion of the RSC ligament), volar lunate facet (RL ligament) and the ulnar styloid

• Ulnar translation is most common

• Patients present with pain, swelling and wrist deformity if spontaneous reduction has not occurred

• Assess NV status and identify associated injuries

  • Neurovascular compromise is common due to compression

  • Hand ischemia warrants immediate relocation

  • Median nerve is more commonly involved than ulnar nerve

Scapholunate instability:

• Most common ligamentous disruption in the wrist

• Represents injury to the scapholunate (SL) ligament, decoupling lunate and scaphoid motion

  • Complete tears demonstrate widening of the SL interval on AP radiographs

  • Scaphoid tends to flex without this constraint while the lunate extends (DISI)

• The result of stress loading of the carpus while in extension and ulnar deviation

• Patients present with swelling acutely

• Assess NV status and identify associated injuries

• Tenderness to palpation of scapholunate region is often present

  • Pain is reproduced with vigorous grasp and loading activities (i.e. push ups)

  • Watson test: pressure applied to scaphoid tubercle volarly

    • Pain or a clunk elicited when wrist is brought from ulnar to radial deviation is suggestive of SL instability

    • Helps diagnose dynamic scapholunate deformity

• Static deformity presents with abnormal static radiographs

• Dynamic deformity presents with normal radiographs but abnormal stress testing and stress radiographs
  
  Lunotriquetral dissociation:

• Result from disruption of the LT ligament, commonly from an axial load

  • Triquetrum tends to extend without LT ligament constraint while lunate tends to flex (VISI)

• Assess NV status and identify associated injuries

• Patients present with tenderness dorsally one finger breadth distal to ulnar head

• May demonstrate a painful clunk with wrist deviation

• LT shear test: dorsally directed pressure on the pisiform and volarly directed pressure on the lunate creates a shear force that can reproduce pain

Imaging

Radiographs

• PA, lateral and oblique views of the wrist should be obtained

Normal PA wrist

Normal lateral wrist

• Normal alignment:

  • Capitolunate angle (lateral): 0°

  • Scapholunate angle (lateral): 45°

Scapholunate angle

• Scapholunate space (AP): < 2 mm

• Radiolunate angle (lateral): 0°

• Gilula's lines (AP): three arcs outlining the radiocarpal, proximal midcarpal and distal midcarpal joints should be concentric

  • Lack of concentricity suggests instability and disruption of normal carpal relationships

Gilula's lines

• Scaphoid series: in addition to lateral and oblique views

  • PA wrist in ulnar deviation: scaphoid extends with ulnar deviation, provides a better en face view

  • Scaphoid view: PA with beam angled 20°-30° from perpendicular with wrist in ulnar deviation produces a true en face view

• CT: further characterize fracture patterns, evaluate cortical rim fractures and articular depressions

• MRI: useful in evaluating ligamentous injury
  
  Perilunate dislocations and fracture-dislocations:

• PA: dislocated lunate looks triangular or wedge shaped

  • Gilula's lines are disrupted

• Lateral: "spilled teacup" sign with volar angulation of lunate, dissociation of capitate from lunate and loss of radius-lunate-capitate colinearity

• Clenched fisted PA: obtain after reduction to check for residual SL or LT dissociation and fractures
  
  Radiocarpal fracture-dislocations:

• PA: a minimum of 2/3 of the lunate should articulate with the radius.

  • Complete radiocarpal ligament disruption results in ulnar translation of the carpus down the radial inclination

  • Evaluate ligament injury with stress radiographs, particularly when reduction occurred spontaneously

• Lateral: demonstrates direction of dislocation
  
  Scapholunate instability:

• PA and lateral views of the wrist can reveal diagnosis of static deformity

  • High suspicion if radial styloid fracture exits at level of scapholunate interval

• Lateral: DISI deformity

  • Scapholunate angle > 70° is abnormal

  • Capitolunate angle > 20° is abnormal

• Terry Thomas sign: scapholunate interval widening (> 2 mm compared to contralateral side)

• Cortical ring sign: represents flexed scaphoid overlapping trapezoid

• Clenched fisted or ulnar deviation PA: accentuates scapholunate interval widening

• Flexion/extension lateral views: can demonstrate uncoupling of scapholunate motion
  
  Lunotriquetral dissociation:

• PA and lateral views of the wrist can reveal diagnosis through disruption in Gilula's lines

  • Increased LT space may be observed

• Lateral: may reveal VISI deformity

  • Volarflexion of the lunate in neutral wrist position with lunocapitate angle > 10°

  • Radial deviation lateral view: may demonstrate dorsiflexed triquetrum with palmar flexed SL complex

• LT dissociation is difficult to identify on radiographs, may require arthroscopy to confirm

Classification

Perilunate dislocations and fracture-dislocations:

• Mayfield classification: perilunate dislocation injury progression (lesser arc):
  Stage I: scapholunate interval disruption
  Stage II: midcarpal/capitolunate interval disruption (Space of Poirier)
  Stage III: lunotriquetral interval disruption leading to separation of carpus from lunate dorsally
  Stage IV: disruption of the radiolunate articulation leading to volar dislocation of lunate

Mayfield classification

• Perilunate fracture-dislocation injury progression (greater arc):
  Stage I: transscaphoid dislocation
  Stage II: Stage I + transcapitate dislocation
  Stage III: Stage II + transtriquetral dislocation with or without hamate injury

• OTA: intercarpal dislocation (70-B)
  
  Scapholunate instability

• Descriptive:

Acute or chronic
Static or dynamic

Radiocarpal fracture-dislocations:

• Moneim:
  Type I: radiocarpal fracture-dislocation without associated intercarpal dissociation
  Type II: radiocarpal fracture-dislocation with associated intercarpal dissociation

• Dumontier:
  Group 1: radiocarpal fracture-dislocation, purely ligamentous or small avulsion off radius
  Group 2: radiocarpal fracture-dislocation, associated with large radial styloid fracture

• OTA: radiocarpal (70-A)

  1. Anterior (volar)

  2. Posterior (dorsal)

  3. Radial

  4. Ulnar

  5. Other

Treatment

Perilunate dislocations and fracture-dislocations:

• Urgent closed reduction followed by surgery

  • Timing based on degree of swelling

• Reduction can be achieved with 10 lb of hanging traction

  • After time to allow muscle spams to subside, a dorsal directed force is applied to stabilize the lunate while a volar directed force is used to relocate the carpus

  • Volarflexion of the carpus can reduce the capitate into the lunate concavity

  • Irreducible dislocations are usually due to interposed capsule

  • Postreduction films should be obtained to evaluate distal radius, ulna, carpal height, Gilula's lines, interosseous spaces, scapholunate and radiolunate angles

  • Instability and/or displacement almost always persists postreduction necessitating fixation

• Percutaneous pinning: can be considered when closed reduction can be obtained

  • Limited ability to reduce rotation and fracture fragments

  • K-wire placed through lunate into radius

  • Triquetrum is pinned to lunate

• ORIF: current standard of care for most perilunate injuries

  • Preferred to achieve restoration of normal alignment and fracture reduction

  • Dorsal approach allows for reduction and ligament repair

  • Volar approach allows for decompression of the carpal tunnel and repair of the volar capsule

Radiocarpal fracture-dislocations:

• Goals include: concentric reduction, identification and treatment of intercarpal injuries and repair of osseous ligamentous avulsions

• Closed reduction with traction and reversal of deformity should be performed acutely with splint immobilization

• Nonoperative: closed reduction and casting has been reported with satisfactory results

• Operative: generally preferred

  • Provisional reduction with longitudinal traction

  • Decompression of the carpal tunnel and Guyon canal through a volar approach

  • Exposure, irrigation and debridement of the radiocarpal joint

  • Treatment of intercarpal injuries via a dorsal approach

  • Fracture fixation with K-wires, screws or plates

  • Repair of the ligamentous and capsular structures with sutures or suture anchors

Scapholunate instability:

• Nonoperative: can be considered for cases of isolated dynamic instability (normal static radiographs)

  • Cast or splint immobilization for 6-8 weeks

• Operative: when static instability exists, scaphoid requires wrist extension, lunate require wrist flexion to maintain reduction (not achievable nonoperatively)

  • Percutaneous pinning: can be performed in conjunction with cast immobilization for 8 weeks

  • Open reduction with ligament reconstruction can be considered acutely

    • Performed via a dorsal approach to repair SL ligament with sutures or anchors

    • Capsulodesis augmentation is considered for subacute presentations (> 4 weeks but < 24 weeks)

Lunotriquetral dissociation:

• Acutely treat with SAC or splint for 6-8 weeks when reduction can be achieved

• Percutaneous pinning can be performed to maintain reduction

• Residual deformity or malalignment requires open reduction, ligament reconstruction and pinning via a dorsal ± volar approach

Complications

Perilunate dislocations and fracture-dislocations

• Chronic dislocation can result in persistent pain, instability, tendon ruptures and nerve injury

• Median neuropathy: associated with stage IV dislocations

• Posttraumatic arthritis: can develop secondary to chondrolysis, scaphoid nonunion, persistent instability

  • May require salvage procedure such as proximal row carpectomy or radiocarpal fusion

  • Wrist stiffness: often related dissection associated with open treatment

  • Percutaneous techniques (application of K-wire joysticks for reduction or percutaneous screw placement) may decrease stiffness

Radiocarpal fracture-dislocations:

• Chronic instability

• Posttraumatic arthritis

• Wrist stiffness: loss of 30% of motion is typical
  
  Scapholunate instability:

• Residual instability: may require capsulodesis or tendon augmentation

• Chronic instability: can lead to scapholunate advanced collapse (SLAC) and arthritis

  • Can treat with scaphotrapeziotrapezoidal fusion, proximal row carpectomy or four-corner fusion (capitate, lunate, hamate, triquetrum)

Lunotriquetral dissociation:

• Recurrent instability: may require capsular augmentation or LT fusion