Carpal Fractures & Dislocations: Don't Miss These Crucial Signs

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