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Ovid: Handbook of Fractures

Authors: Koval, Kenneth J.; Zuckerman, Joseph D.
Title: Handbook of Fractures, 3rd Edition
> Table of Contents > III – Upper Extremity Fractures and Dislocations > 23 – Wrist

23
Wrist
EPIDEMIOLOGY
  • Although wrist injuries are fairly
    common, especially with athletic participation, the true incidence is
    unknown owing to a failure to recognize carpal injuries in the presence
    of associated, more obvious injuries.
ANATOMY
  • The distal radius has articular facets
    for the scaphoid and lunate separated by a ridge. The sigmoid notch
    articulates with the distal ulna.
  • The distal ulna articulates with the
    sigmoid notch of the distal radius. The ulna styloid process serves as
    the attachment for the triangular fibrocartilage complex (TFCC).
  • Carpal bones (Fig. 23.1)
    • Proximal row: This consists of the scaphoid (an oblique strut that spans both rows), lunate, triquetrum, and pisiform.
    • Distal row: The trapezium, trapezoid,
      capitate, and hamate are connected to one another and to the base of
      the metacarpals by strong ligaments, making the distal row relatively
      immobile.
    • The lunate is the key to carpal stability.
      • It is connected to both scaphoid and triquetrum by strong interosseous ligaments.
      • Injury to the scapholunate or
        lunotriquetral ligaments leads to asynchronous motion of the lunate to
        dissociative carpal instability patterns.
  • Joints: These are the distal radioulnar, radiocarpal, and midcarpal.
  • Normal anatomic relationships (see Fig. 23.1)
    • Radial inclination: averages 23 degrees (range, 13 to 30 degrees)
    • Radial length: averages 11 mm (range, 8 to 18 mm)
    • Palmar (volar) tilt: averages 11 to 12° (range, 0 to 28 degrees)
    • The 0-degree capitolunate angle: a
      straight line drawn down the third metacarpal shaft, capitate, lunate,
      and shaft of radius with wrist in neutral position
    • The 47-degree scapholunate angle (normal range, 30 to 70 degrees); less than 2 mm scapholunate space
  • Wrist ligaments (Figs. 23.2 and 23.3)
    • Extrinsic ligaments connect the radius to the carpus and the carpus to the metacarpals.
    • Intrinsic ligaments connect carpal bone to carpal bone (e.g., scapholunate and lunotriquetral ligaments).
    • In general, the volar ligaments are stronger than the dorsal ligaments.
    • Important volar ligaments include:
      • The radioscaphocapitate (guides scaphoid kinematics).
      • The radioscapholunate (stabilizes the scapholunate articulation).

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      • The radiolunate.
        Figure 23.1. The wrist is composed of two rows of bones that provide motion and transfer forces: scaphoid (S), lunate (L), triquetrum (T), pisiform (P), trapezium (Tm), trapezoid (Td), capitate (C), hamate (H).

        (From Bucholz RW, Heckman JD, Court-Brown C, et al., eds. Rockwood and Green’s Fractures in Adults, 6th ed. Philadelphia: Lippincott Williams & Wilkins, 2006.)
      • The radiolunotriquetral (supports the proximal row, stabilizes the radiolunate and lunotriquetral joints).
    • The proximal and distal carpal rows are attached by capsular ligaments on each side of the lunocapitate joint.
      • Injury to these ligaments leads to abnormal motion between the two rows and to nondissociative wrist instability patterns.
    • Space of Poirier: This ligament-free area in the capitolunate space is an area of potential weakness.
    • The TFCC is a major stabilizer of the ulnar carpus and distal radioulnar joint.
      • The TFCC absorbs about 20% of the axial load across the wrist joint.
      • It consists of several components,
        including the radiotriquetral ligament (meniscal homologue), articular
        disc, ulnolunate ligament, and ulnar collateral ligament.
  • Vascular supply (Fig. 23.4)
    • The radial, ulnar, and anterior
      interosseous arteries combine to form a network of transverse arterial
      arches both dorsal and volar to the carpus.

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    • The blood supply to the scaphoid is
      derived primarily from the radial artery, both dorsally and volarly.
      The volar scaphoid branches supply the distal 20% to 30% of the
      scaphoid, whereas branches entering the dorsal ridge supply the
      proximal 70% to 80%.
      Figure
      23.2. The palmar capsule consists of two major ligamentous inclusions:
      the radiolunate ligament is the deeper of the two, which proceeds to
      the triquetrum and composes in effect the radiolunotriquetral ligament.
      The more distal and superficial component is often referred to as the
      arcuate ligament or distal V. The radial component of this ligament is
      the radioscaphocapitate ligament. The ulnar component of the arcuate
      ligament is the triquetrocapitate ligament.

      (From Bucholz RW, Heckman JD, Court-Brown C, et al., eds. Rockwood and Green’s Fractures in Adults, 6th ed. Philadelphia: Lippincott Williams & Wilkins, 2006.)
    • The lunate receives blood supply from
      both its volar and dorsal surfaces in most cases (80%). About 20% of
      lunates have only a volar blood supply.
  • Kinematics
    • The global motion of the wrist is
      composed of flexion and extension, radioulnar deviation at the
      radiocarpal joint, and axial rotation around the distal radioulnar
      joint.
    • The radiocarpal articulation acts as a
      universal joint allowing a small degree of intercarpal motion related
      to rotation of individual carpal bones.
    • The forearm accounts for about 140 degrees of rotation.
    • Radiocarpal joint motion is primarily
      flexion and extension of nearly equal proportions (70 degrees), and
      radial and ulnar deviation of 20 and 40 degrees, respectively.

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    • The scaphoid rests on the
      radioscaphocapitate ligament at its waist. Using the ligament as an
      axis, it rotates from a volar flexed perpendicular position to a
      dorsiflexed longitudinal position.
      Figure 23.3. The intraarticular intrinsic ligaments connect adjacent carpal bones.

      (From Bucholz RW, Heckman JD, Court-Brown C, et al., eds. Rockwood and Green’s Fractures in Adults, 6th ed. Philadelphia: Lippincott Williams & Wilkins, 2006.)
  • Pathomechanics (Fig. 23.5)
    • Classically, the radius, lunate, and capitate have been described as a central “link” that is colinear in the sagittal plane.
    • The scaphoid serves as a connecting
      strut. Any flexion moment transmitted across the scaphoid is balanced
      by an extension moment at the triquetrum.
    • When the scaphoid is destabilized by
      fracture or scapholunate ligament disruption, the lunate and triquetrum
      assume a position of excessive dorsiflexion (dorsal intercalated
      segmental instability [DISI]) and the scapholunate angle becomes
      abnormally high (>70 degrees).
    • When the triquetrum is destabilized
      (usually by disruption of the lunotriquetral ligament complex) the
      opposite pattern (volar intercalated segmental instability [VISI]) is
      seen as the intercalated lunate segment volarflexes.
MECHANISM OF INJURY
  • The most common mechanism of carpal
    injury is a fall onto the outstretched hand, resulting in an axial
    compressive force with the wrist in hyperextension. The volar ligaments
    are placed under tension with compression and shear forces applied
    dorsally, especially when the wrist is extended beyond its physiologic
    limits.
  • Excessive ulnar deviation and intercarpal supination result in a predictable pattern of injury, progressing from the radial

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    side of the carpus to the mid carpus and finally to the ulnar carpus.

Figure
23.4. Schematic drawing of the arterial supply of the palmar aspect of
the carpus. Circulation of the wrist is obtained through the radial,
ulnar, and anterior interosseous arteries and the deep palmar arch: 1, palmar radiocarpal arch; 2, palmar branch of anterior interosseous artery; 3, palmar intercarpal arch; 4, deep palmar arch; and 5, recurrent artery.

(From Bucholz RW, Heckman JD, Court-Brown C, et al., eds. Rockwood and Green’s Fractures in Adults, 6th ed. Philadelphia: Lippincott Williams & Wilkins, 2006.)
CLINICAL EVALUATION
  • The clinical presentation of individual
    carpal injuries is variable, but in general, the most consistent sign
    of carpal injury is well-localized tenderness.
  • Gross deformity may be present, ranging from displacement of the carpus to prominence of individual carpal bones.
  • Provocative tests may reproduce or
    exacerbate pain, crepitus, or displacement indicative of individual
    carpal injuries (see specific carpal injuries).
RADIOGRAPHIC EVALUATION
  • Posteroanterior (PA) and lateral x-rays are each taken in the neutral position.
    • Gilula lines (three smooth radiographic arcs) should be examined on the PA view. Disruption of these arcs indicates ligamentous instability.
  • For further diagnosis of carpal and mainly scaphoid fractures.

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    • A scaphoid view (anteroposterior [AP] x-ray with wrist supinated 30 degrees and in ulnar deviation) is obtained.
      Figure
      23.5. Schematic drawing of carpal instability. (A) Normal longitudinal
      alignment of the carpal bones with the scaphoid axis at a 47-degree
      angle to the axes of the capitate, lunate, and radius. (B) A volar
      intercalated segmental instability (VISI) deformity is usually
      associated with disruption of the lunatotriquetral ligament. (C) A
      dorsal intercalated segmental instability (DISI) deformity is
      associated with scapholunate ligament disruption or a displaced
      scaphoid fracture.

      (From Bucholz RW, Heckman JD, Court-Brown C, et al., eds. Rockwood and Green’s Fractures in Adults, 6th ed. Baltimore: Lippincott Williams & Wilkins, 2005.)
    • A pronated oblique view is indicated.
  • If there is the suspicion of carpal
    instability, additional views in maximal radial and ulnar deviation are
    recommended as well as a clenched-fist PA.
  • Further views can be done in maximal flexion and extension.
  • Arthrography, magnetic resonance (MR),
    wrist arthrography, videoradiography, and arthroscopy can assist in the
    diagnosis of carpal ligament injuries.
  • Computed tomography (CT) scans are helpful in evaluating carpal fractures, malunion, nonunion, and bone loss.
  • MRI scans are sensitive to detect occult
    fractures and osteonecrosis of the carpal bones as well as detecting
    soft tissue injury, including ruptures of the scapholunate ligament and
    TFCC.

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CLASSIFICATION
OTA Classification of Carpal Fractures and Fracture-Dislocations
See Fracture and Dislocation Compendium at http://www.ota.org/.compendium/index.htm.
SPECIFIC FRACTURES
Scaphoid
  • Fractures of the scaphoid are common and account for about 50% to 80% of carpal injuries.
  • Anatomically, the scaphoid is divided
    into proximal and distal poles, a tubercle, and a waist; 80% of the
    scaphoid is covered with articular cartilage (Fig. 23.6).
  • Ligamentous attachments to the scaphoid
    include the radioscaphocapitate ligament, which variably attaches to
    the ulnar aspect of the scaphoid waist, and the dorsal intercarpal
    ligament, which provides the primary vascular supply to the scaphoid.
  • The major vascular supply is derived from
    scaphoid branches of the radial artery, entering the dorsal ridge and
    supplying 70% to 80% of the scaphoid, including the proximal pole. The
    remaining distal aspect is supplied through branches entering the
    tubercle. Fractures at the scaphoid waist or proximal third depend on
    fracture union for revascularization (Fig. 23.7).
  • The most common mechanism is a fall onto
    the outstretched hand that imposes a force of dorsiflexion, ulnar
    deviation, and intercarpal supination.
  • Clinical evaluation
    Figure 23.6. Types of scaphoid fractures. The scaphoid is susceptible to fractures at any level.

    (From Bucholz RW, Heckman JD, Court-Brown C, et al., eds. Rockwood and Green’s Fractures in Adults, 4th ed., vol. 1. Philadelphia: Lippincott-Raven, 1996:826.)
    Figure 23.7. The vascular supply of the scaphoid is provided by two vascular pedicles.

    (From Bucholz RW, Heckman JD, Court-Brown C, et al., eds. Rockwood and Green’s Fractures in Adults, 6th ed. Philadelphia: Lippincott Williams & Wilkins, 2006.)

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  • Patients present with wrist pain and
    swelling, with tenderness to palpation overlying the scaphoid in the
    anatomic snuffbox. Provocative tests include:
    • The scaphoid lift test: reproduction of pain with dorsal-volar shifting of the scaphoid.
    • The Watson test: painful dorsal scaphoid
      displacement as the wrist is moved from ulnar to radial deviation with
      compression of the tuberosity.
  • Differential diagnoses
    • Scapholunate instability
    • Lunate dislocation
    • Flexor carpus radialis tendon rupture
    • Radial styloid fracture
    • Trapezium fracture
    • De Quervain disease
    • Carpometacarpal (basal) joint arthrosis
  • Radiographic evaluation
    • This includes a PA view with the hand
      clenched in a fist to extend the scaphoid, a lateral, a radial oblique
      (supinated AP) and an ulnar oblique view.
    • Initial films are nondiagnostic in up to 25% of cases.
    • If the clinical examination suggests
      fracture but radiographs are not diagnostic, a trial of immobilization
      with follow-up radiographs 1 to 2 weeks after injury may demonstrate
      the fracture.

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    • Technetium bone scan, MRI, CT, and ultrasound evaluation may be used to diagnose occult scaphoid fractures.
  • Classification
    • Based on fracture pattern (Russe)
      • Horizontal oblique
      • Transverse
      • Vertical oblique
    • Based on displacement
      • Stable: nondisplaced fractures with no step-off in any plane
      • Unstable: displacement with 1 mm or more
        step-off scapholunate angulation >60 degrees or radiolunate
        angulation >15 degrees
    • Based on location
      • Tuberosity: 17% to 20%
      • Distal pole: 10% to 12%
      • Waist: 66% to 70%
        • Horizontal oblique: 13% to 14%
        • Vertical oblique: 8% to 9%
        • Transverse: 45% to 48%
      • Proximal pole: 5% to 7%
Treatment
  • Indications for nonoperative treatment
    • Nondisplaced distal third fracture
    • Tuberosity fractures
  • Nonoperative treatment
    • Long arm thumb spica cast for 6 weeks
    • Immobilization in slight flexion and slight radial deviation
    • Replacement with short arm thumb spica cast at 6 weeks until united
    • Expected time to union:
      • Distal third: 6 to 8 weeks
      • Middle third: 8 to 12 weeks
      • Proximal third: 12 to 24 weeks
  • Management of suspected scaphoid fractures
    • In patients with an injury and positive
      examination findings but normal x-rays, immobilization for 1 to 2 weeks
      (thumb spica) is indicated.
    • Repeat x-rays if the patient is still symptomatic.
    • If pain is still present but x-rays continue to be normal, consider MRI (or bone scan).
    • If an acute diagnosis is necessary, consider MRI or CT immediately.
  • Healing rates with nonoperative treatment depends on fracture location:

    Tuberosity and distal third 100%
    Waist 80% to 90%
    Proximal pole
    Proximal fractures are prone to nonunion and osteonecrosis    		 60% to 70%
  • Operative treatment
    • Indications for surgery
      • Fracture displacement >1 mm

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      • Radiolunate angle >15 degrees
      • Scapholunate angle >60 degrees
      • “Humpback” deformity
      • Nonunion
    • Surgical techniques
      • Most involve the insertion of screws.
      • Controversy exists about open versus percutaneous techniques.
      • Open techniques are needed for nonunions and fractures with unacceptable displacement.
      • Closed techniques are appropriate for acute fractures with minimal displacement.
    • The volar approach between the flexor
      carpi radialis and the radial artery provides good exposure for open
      reduction and internal fixation and repair of the radioscapholunate
      ligament. The volar approach is the least damaging to the vascular
      supply of the vulnerable proximal pole.
    • Postoperative immobilization consists of a long arm thumb spica cast for 6 weeks.
  • Complications
    • Delayed union, nonunion, and malunion:
      These are reported to occur with greater frequency when a short arm
      cast is used as compared with a long arm cast, as well as with proximal
      scaphoid fractures. They may necessitate operative fixation with bone
      grafting to achieve union.
    • Osteonecrosis: This occurs especially with fractures of the proximal pole, owing to the tenuous vascular supply.
Lunate
  • The lunate is the fourth most fractured carpal bone after the scaphoid, triquetrum, and trapezium.
  • Fractures of the lunate are often
    unrecognized until they progress to osteonecrosis, at which time they
    are diagnosed as Kienboeck disease.
  • The lunate has been referred to as the
    “carpal keystone,” because it rests in the well-protected concavity of
    the lunate fossa of the distal radius, anchored by interosseous
    ligaments to the scaphoid and triquetrum, and distally is congruent
    with the convex head of the capitate.
  • Its vascular supply is derived from the
    proximal carpal arcade dorsally and volarly, with three variable
    intralunate anastomoses.
  • The mechanism of injury is typically a
    fall onto an outstretched hand with the wrist in hyperextension, or a
    strenuous push with the wrist in extension.
  • Clinical evaluation reveals tenderness to
    palpation on the volar wrist overlying the distal radius and lunate,
    with painful range of motion.
  • Radiographic evaluation: PA and lateral
    views of the wrist are often inadequate to establish the diagnosis of
    lunate fracture because osseous details are frequently obscured by
    overlapping densities.
    • Oblique views may be helpful, but CT, MRI, and technetium bone scanning best demonstrate fracture.

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    • MRI has been used with increasing
      frequency to appreciate the vascular changes associated with injury and
      healing and is the imaging test of choice for evaluation of Kienboeck
      disease.
  • Classification: Acute fractures of the lunate can be classified into five groups:
    • Frontal fractures of the palmar pole with involvement of the palmar nutrient arteries
    • Osteochondral fractures of the proximal articular surface without substantial damage to the nutrient vessels
    • Frontal fractures of the dorsal pole
    • Transverse fractures of the body
    • Transarticular frontal fractures of the body of the lunate
  • Treatment
    • Nondisplaced fractures should be treated
      in a short or long arm cast or splint with follow-up at close intervals
      to evaluate progression of healing.
    • Displaced or angulated fractures should
      be treated surgically to allow adequate apposition for formation of
      vascular anastomoses.
  • Complications
    • Osteonecrosis: Established Kienboeck
      disease represents the most devastating complication of lunate
      fractures, with advanced collapse and radiocarpal degeneration. This
      may require further operative intervention for pain relief, including
      radial shortening, radial wedge osteotomy, ulnar lengthening, or
      salvage procedures such as proximal row carpectomy, wrist denervation,
      or arthrodesis.
Triquetrum
  • The triquetrum is the carpal bone that is most commonly fractured after the scaphoid.
  • Most fractures of the triquetrum are avulsion injuries that may be associated with ligament damage.
  • Most commonly, injury occurs with the
    wrist in extension and ulnar deviation, resulting in an impingement
    shear fracture by the ulnar styloid against the dorsal triquetrum.
  • Clinical evaluation reveals tenderness to
    palpation on the dorsoulnar aspect of the wrist as well as painful
    range of wrist motion.
  • Radiographic evaluation
    • Transverse fractures of the body can generally be identified on the PA view.
    • Dorsal triquetral fractures are not
      easily appreciated on AP and lateral views of the wrist owing to
      superimposition of the lunate. An oblique, pronated lateral view may
      help to visualize the dorsal triquetrum.
  • Treatment
    • Nondisplaced fractures of the body or
      dorsal chip fractures may be treated in a short arm cast or ulnar
      gutter splint for 6 weeks.
    • Displaced fractures may be amenable to open reduction and internal fixation.

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Pisiform
  • Fractures of the pisiform are rare.
  • The mechanism of injury is either a
    direct blow to the volar aspect of the wrist or a fall onto an
    outstretched, dorsiflexed hand.
  • Clinical evaluation demonstrates
    tenderness on the volar ulnar aspect of the ulnar wrist with painful
    passive extension of the wrist as the flexor carpi ulnaris is placed
    under tension.
  • Radiographic evaluation: Pisiform
    fractures are not well visualized on standard views of the wrist;
    special views include a lateral view of the wrist with forearm
    supination of 20 to 45 degrees or a carpal tunnel view (20-degree
    supination oblique view demonstrating an oblique projection of the
    wrist in radial deviation and semisupination).
  • Treatment of nondisplaced or minimally
    displaced fractures consists of an ulnar gutter splint or short arm
    cast for 6 weeks. Displaced fractures may require fragment excision,
    either early, in the case of a severely displaced fragment, or late, in
    the case of a pisiform fracture that has resulted in painful nonunion.
Trapezium
  • Fractures of the trapezium comprise approximately 3% to 5% of all carpal bone fractures.
  • About 60% of the reported cases have an unsatisfactory outcome secondary to degenerative changes.
  • Most are ridge avulsion fractures or vertical fractures of the body.
  • The mechanism of injury is axial loading
    of the adducted thumb, driving the base of the first metacarpal onto
    the articular surface of the trapezium.
    • Avulsion fractures may occur with forceful deviation, traction, or rotation of the thumb.
    • Direct trauma to the palmar arch may result in avulsion of the trapezial ridge by the transverse carpal ligament.
  • Clinical evaluation reveals tenderness to
    palpation of the radial wrist, accompanied by painful range of motion
    at the first carpometacarpal joint.
  • Radiographic evaluation: Fractures are usually identifiable on standard PA and lateral views.
    • Superimposition of the first metacarpal
      base may be eliminated by obtaining a Robert view, or a true PA view of
      the first carpometacarpal joint and trapezium, taken with the hand in
      maximum pronation.
    • A carpal tunnel view may be necessary for adequate visualization of dorsal ridge fractures.
  • Treatment
    • Nondisplaced fractures are generally
      amenable to thumb spica splinting or casting to immobilize the first
      carpometacarpal joint for 6 weeks.
    • Indications for open reduction and
      internal fixation include articular involvement of the carpometacarpal
      articulation, comminuted fractures, and displaced fractures.
    • Comminuted fractures may require supplemental bone grafting.

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  • Complications
    • Posttraumatic osteoarthritis may result
      in decreased or painful range of motion at the first carpometacarpal
      joint. Irreparable joint damage may necessitate fusion or excisional
      arthroplasty.
Trapezoid
  • Because of the shape and position of the
    trapezoid, fractures are rare. An axial load transmitted through the
    second metacarpal may lead to dislocation, more often dorsal, with
    associated capsular ligament disruption.
  • Direct trauma from blast or crush
    injuries may cause trapezoid fracture, although this is often in
    conjunction with other injuries.
  • Clinical evaluation demonstrates
    tenderness proximal to the base of the second metacarpal with a
    variable dorsal prominence representing a dislocated trapezoid. Range
    of motion of the second carpometacarpal joint is painful and limited.
  • Radiographic evaluation: fractures can be
    identified on the PA radiograph based on a loss of the normal
    relationship between the second metacarpal base and the trapezoid.
    Comparison with the contralateral, uninjured wrist may aid in the
    diagnosis. The trapezoid, or fracture fragments, may be superimposed
    over the trapezium or capitate, and the second metacarpal may be
    proximally displaced.
    • Oblique views or CT may aid in the diagnosis if osseous details are obscured by overlap.
  • Treatment
    • Nondisplaced fractures may be treated with a splint or short arm cast for 6 weeks.
    • Indications for open reduction and
      internal fixation include displaced fractures, especially those
      involving the carpometacarpal articulation. These may be addressed with
      open reduction and internal fixation with Kirschner wires with
      attention to restoration of articular congruity.
  • Complications
    • Posttraumatic osteoarthritis may result at the second carpometacarpal articulation if joint congruity is not restored.
Capitate
  • This is uncommon as an isolated injury owing to its relatively protected position.
  • A fracture of the capitate is more
    commonly associated with greater arc injury pattern (transscaphoid,
    transcapitate perilunate fracture-dislocation). A variation of this is
    the “naviculocapitate syndrome,” in which the capitate and scaphoid are
    fractured without associated dislocation.
  • The mechanism of injury is typically
    direct trauma or a crushing force that results in associated carpal or
    metacarpal fractures.
  • Clinical evaluation reveals point
    tenderness as well as variable painful dorsiflexion of the wrist as the
    capitate impinges on the dorsal rim of the radius.
  • Fractures of the capitate can usually be
    identified on standard scaphoid views, although motion studies are
    recommended to look for displacement.

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  • Diagnosis may require an MRI scan.
  • Treatment: Capitate fractures require
    reduction to diminish the risk of osteonecrosis. If closed reduction is
    unattainable, open reduction and internal fixation are indicated,
    usually with Kirschner wires or lag screws, to restore normal anatomy.
  • Complications
    • Midcarpal arthritis: This is caused by capitate collapse as a result of displacement of the proximal pole.
    • Osteonecrosis: This is rare but results
      in functional impairment; it emphasizes need for accurate diagnosis and
      stable reduction.
Hamate
  • Hamate fractures are quite rare.
  • The hamate may be fractured through its
    distal articular surface, through other articular surfaces, or through
    its hamulus, or hook.
  • A distal articular fracture accompanied
    by fifth metacarpal subluxation may occur when axial force is
    transmitted down the shaft of the metacarpal, such as with a fist
    strike or a fall.
  • Fractures of the body of the hamate generally occur with direct trauma or crush injuries to the hand.
  • Fracture of the hook of the hamate is a
    frequent athletic injury sustained when the palm of the hand is struck
    by an object (e.g., baseball bat, golf club, hockey stick), and it
    generally occurs at the base of the hook, although avulsion fractures
    of the tip may occur.
  • Clinical evaluation: Patients typically
    present with pain and tenderness over the hamate. Ulnar and median
    neuropathy can also be seen, as well as rare injuries to the ulnar
    artery.
  • Radiographic evaluation: The diagnosis of
    hamate fracture can usually be made on the basis of the PA view of the
    wrist. Fracture of the hamate is best visualized on the carpal tunnel
    or a 20-degree supination oblique view (oblique projection of the wrist
    in radial deviation and semisupination). CT and bone scan are sometimes
    necessary to visualize the fracture. A hamate fracture should not be
    confused with an os hamulus proprium, which represents an ossification
    center that has failed to fuse.
  • Classification of hamate fractures is descriptive.
  • Treatment
    • Nondisplaced hamate fractures may be treated with immobilization in a short arm splint or cast for 6 weeks.
    • Displaced fractures of the body may be
      amenable to Kirschner wire or screw fixation. Fractures of the hook of
      the hamate may be treated with excision of the fragment for displaced
      fragments or in cases of symptomatic nonunion.
  • Complications
    • Symptomatic nonunion: This may be treated with excision of the nonunited fragment.
    • Ulnar or median neuropathy: This is
      related to the proximity of the hamate to these nerves and may require
      surgical exploration and release.
    • Ruptures of the flexor tendons to the small finger: They result from attritional wear at the fracture site.

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PERILUNATE DISLOCATIONS AND FRACTURE-DISLOCATIONS
  • The lunate, which is normally securely
    attached to the distal radius by ligamentous attachments, is commonly
    referred to as the “carpal keystone.”
  • Greater arc injury: This passes through
    the scaphoid, capitate, and triquetrum and often results in
    transscaphoid or transscaphoid transcapitate perilunate
    fracture-dislocations (Fig. 23.8).
  • Lesser arc injury: This follows a curved
    path through the radial styloid, midcarpal joint, and lunatotriquetral
    space and results in perilunate and lunate dislocations.
  • The most common injury is transscaphoid perilunate fracture-dislocation (de Quervain injury).
  • Mechanism of injury
    • Perilunate injuries: Load is applied to the thenar eminence, forcing the wrist into extension.
    • Injury progresses through several stages (Mayfield progression):
      • It usually begins radially through the body of scaphoid (fracture) or thru scapholunate interval (dissociation).
      • The scaphoid bridges the proximal and distal carpal rows.
      • With dislocation between these rows, the scaphoid must either rotate or fracture.
      • Force is transmitted ulnarly through the space of Poirier (between the lunate and capitate).
      • Finally, force transmission disrupts the lunotriquetral articulation (Fig. 23.9).
  • Clinical evaluation: Scapholunate or perilunate injuries typically cause tenderness just distal to Lister tubercle. Swelling is

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    generalized about the wrist with variable dorsal prominence of the entire carpus in cases of frank perilunate dislocation.

    Figure
    23.8. Vulnerable zones of the carpus. (A) A lesser arch injury follows
    a curved path through the radial styloid, midcarpal joint, and the
    lunatotriquetral space. A greater arc injury passes through the
    scaphoid, capitate, and triquetrum. (B) Lesser and greater arc injuries
    can be considered as three stages of the perilunate fracture or
    ligament instabilities.

    (From Johnson RP. The acutely injured wrist and its residuals. Clin Orthop 1980;149:33–44.)
    Figure
    23.9. Mayfield stages of progressive perilunate instability. Stage I
    results in scapholunate instability. Stages II to IV result in
    progressively worse perilunate instability.

    (From Bucholz RW, Heckman JD, Court-Brown C, et al., eds. Rockwood and Green’s Fractures in Adults, 6th ed. Philadelphia: Lippincott Williams & Wilkins, 2006.)
  • Radiographic evaluation: Diagnosis can
    often be made without accompanying radiographs, but PA and lateral
    views should be obtained to confirm the diagnosis and rule out
    associated injuries. CT, MRI, and arthrography are generally
    unnecessary but may be useful in further defining injury pattern.
    • PA view: The dislocated lunate appears to be wedge-shaped, with an elongated volar lip.
    • Loss of normal carpal greater and lesser “arcs” and abnormal widening of the scapholunate interval are noted.
    • Look for associated fractures, such as “transscaphoid” injuries.
    • Lateral view: The “spilled teacup sign” occurs with volar tilt of the lunate.
    • A clenched-fist PA view obtained after
      closed reduction of the midcarpal joint is useful for checking residual
      scapholunate or lunotriquetral dissociation as well as fractures.
  • Classification: A sequence of progressive perilunate instability is seen as the injury spreads:
    • From the scapholunate joint (radioscapholunate ligament) → midcarpal joint (radioscaphocarpal ligament) →

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      lunotriquetral joint (distal limb of radiolunotriquetral ligament) →
      dorsal radiolunotriquetral ligament → volar dislocation of the lunate.

      Stage I: Disruption of the scapholunate joint: The radioscapholunate and interosseous scapholunate ligaments are disrupted.
      Stage II: Disruption of the midcarpal (capitolunate) joint: The radioscaphocapitate ligament is disrupted.
      Stage III: Disruption of the lunotriquetral joint: The distal limb of the radiolunotriquetral ligament is disrupted.
      Stage IV: Disruption of the radiolunate
      joint: The dorsal radiolunotriquetral ligament is disrupted, ultimately
      causing volar dislocation of the lunate.
  • Treatment
    • Closed reduction should be performed with adequate sedation.
    • Technique of closed reduction
      • Longitudinal traction is applied for 5 to 10 minutes.
      • For dorsal perilunate injuries, volar pressure is applied to the carpus while counterpressure is applied to the lunate.
      • Palmar flexion then reduces the capitate into the concavity of the lunate.
    • Early surgical reconstruction is
      performed if swelling allows. Immediate surgery is needed if there are
      signs of median nerve compromise.
    • Closed reduction and pinning
      • The lunate is reduced and pinned to the radius in neutral alignment.
      • The triquetrum or scaphoid can then be pinned to the lunate.
    • Transscaphoid perilunate dislocation
      • This requires reduction and stabilization of the fractured scaphoid.
      • Most of these injuries are best treated by open volar and dorsal reduction and repair of injured structures.
      • Open repair may be supplemented by pin fixation.
    • Delayed reconstruction is indicated if early intervention is not feasible.
  • Complications
    • Median neuropathy: This may result from carpal tunnel compression, necessitating surgical release.
    • Posttraumatic arthritis: This may result from the initial injury or secondarily from small, retained osseous fragments.
    • Chronic perilunate injury: This may
      result from untreated or inadequately treated dislocation or
      fracture-dislocation resulting in chronic pain, instability, and wrist
      deformity, often associated with tendon rupture or increasing nerve
      symptoms. Repair may be possible, but a salvage procedure, such as
      proximal row carpectomy or radiocarpal fusion, may be necessary.

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CARPAL DISLOCATIONS
  • Carpal dislocations represent a continuum
    of perilunate dislocations, with frank lunate dislocation representing
    the final stage. All such injuries reflect significant ligamentous
    injury.
  • Associated fractures are common and may
    represent avulsion injuries (e.g., volar or dorsal intercalated
    segmental instability with associated radial rim fracture).
  • Mechanism of injury: A fall onto an
    outstretched hand represents the most common cause, although direct
    force can cause traumatic carpal dislocations as well.
  • Clinical evaluation: Patients typically
    present with painful, limited wrist range of motion. Median neuropathy
    may be present. Specific tests for carpal instability include the
    following:
    • Midcarpal stress test: Dorsal-palmar
      stressing of the midcarpal joint results in a pathologic clunk
      representing subluxation of the lunate.
    • Dynamic test for midcarpal instability:
      Wrist extension with radioulnar deviation produces a “catchup” clunk as
      the proximal row snaps from flexion to extension.
  • Radiographic evaluation: Most dislocations may be diagnosed on PA and lateral views of the wrist.
    • CT and MRI may aid in further injury definition.
  • Treatment of carpal dislocations consists
    of closed reduction of the midcarpal joint, which is often accomplished
    with traction, combined with direct manual pressure over the capitate
    and lunate.
    • Irreducible dislocations or unstable
      injuries should be treated with open reduction and internal fixation
      utilizing a combined dorsal and volar approach. Dorsally, the osseous
      anatomy is restored and stabilized using Kirschner wire fixation.
      Volarly, the soft tissues are repaired.
  • Complications
    • Posttraumatic arthritis: This may result
      from unrecognized associated fractures or malreduction, with subsequent
      functional limitation and pain.
    • Recurrent instability: This may result
      from inadequate repair of ligamentous structures on the volar aspect or
      insufficient fixation dorsally.
SCAPHOLUNATE DISSOCIATION
  • This is the ligamentous analog of a
    scaphoid fracture; it represents the most common and significant
    ligamentous disruption of the wrist.
  • The underlying pathologic process is a disruption of the radioscapholunate and the interosseous scapholunate ligaments.
  • The mechanism of injury is loading of the extended carpus in ulnar deviation.
  • Clinical findings include ecchymosis and
    tenderness on the volar wrist. The proximal pole of the scaphoid is
    prominent dorsally. Signs of scapholunate dissociation include a
    vigorous grasp that induces pain, decreasing repetitive grip strength,
    a positive Watson test (see earlier, under scaphoid fractures), and painful flexion-extension or ulnar-radial deviation of the wrist.

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  • Radiographic evaluation: PA, lateral,
    clenched fist PA, and radial and ulnar deviation views are obtained.
    Classic signs of scapholunate dissociation on the PA view include:
    • The “Terry Thomas sign”: widening of the scapholunate space (normal, <3 mm).
    • The “cortical ring sign” caused by the abnormally flexed scaphoid.
    • A scapholunate angle of >70 degrees visualized on the lateral view.
  • Treatment
    • The scaphoid can often be reduced with an
      audible and palpable click, followed by immobilization for 8 weeks in a
      long arm thumb spica cast. Good results with anatomic reduction are
      reported.
    • Arthroscopically assisted reduction with percutaneous pin fixation has been described with good results.
    • An inability to obtain or maintain
      reduction is an indication for open reduction and internal fixation.
      This may be accomplished by a combined dorsal and volar approach with
      reduction and stabilization of the scapholunate joint dorsally using
      Kirschner wires and repair of the ligaments volarly.
  • Complications
    • Recurrent instability: Failure of closed
      or open reduction and internal fixation with ligament repair may
      necessitate ligament augmentation, intercarpal fusion, proximal row
      carpectomy, or wrist fusion. It may progress to a DISI pattern or a
      scaphoid-lunate advanced collapse of the wrist.
LUNOTRIQUETRAL DISSOCIATION
  • These injuries involve disruption of the
    distal limb of the volar radiolunotriquetral ligament either as a stage
    III lesser arc injury of perilunate instability or as a result of a
    force causing excessive radial deviation and intercarpal pronation. The
    lunotriquetral interosseous and dorsal radiolunotriquetral ligaments
    are also injured.
  • Clinical findings include swelling over
    the peritriquetral area and tenderness dorsally, typically one
    fingerbreadth distal to the ulnar head.
    • Ballottement test (shear or shuck test):
      Dorsal-volar displacement of the triquetrum on the lunate results in
      increased excursion as compared with the normal, contralateral side, as
      well as painful crepitus.
  • Radiographic evaluation: PA radiographs
    of the hand rarely reveal frank gapping of the lunotriquetral space,
    but a break in the normal smooth contour of the proximal carpal row can
    be appreciated.
    • Radial deviation view: This may
      demonstrate the triquetrum to be dorsiflexed with the intact
      scapholunate complex palmar-flexed. A lateral projection may reveal a
      volar intercalated segmental instability pattern.
  • Treatment
    • Acute lunotriquetral dissociation with minimal deformity may be treated with a short arm cast or splint for 6 to 8 weeks.
    • Closed reduction with pinning of the lunate to the triquetrum may be necessary to maintain reduction.

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    • Angular deformity or unacceptable
      reduction from nonoperative treatment may necessitate open reduction
      and internal fixation utilizing a combined dorsal and volar approach,
      with pinning of the triquetrum to the lunate and ligamentous repair.
  • Complications
    • Recurrent instability may necessitate
      ligament reconstruction with capsular augmentation. If recurrent
      instability persists, lunotriquetral fusion may be necessary, with
      possible concomitant ulnar shortening to tension the volar ulnocarpal
      ligaments.
ULNOCARPAL DISSOCIATION
  • Avulsion or rupture of the TFCC from the ulnar styloid results in a loss of “sling” support for the ulnar wrist.
  • The lunate and triquetrum “fall away”
    relative to the distal ulna and assume a semisupinated and palmar
    flexed attitude, with the distal ulna subluxed dorsally.
  • Clinical evaluation reveals dorsal prominence of the distal ulna and volar displacement of the ulnar carpus.
  • Radiographic evaluation: The PA view may
    reveal avulsion of the ulnar styloid. Dorsal displacement of the distal
    ulna on true lateral views suggests disruption of the TFCC in the
    absence of an ulnar styloid avulsion fracture.
    • MRI may demonstrate a tear of the TFCC and may additionally provide evidence of chondral lesions and effusion.
  • Treatment: Operative repair of the TFCC may be achieved via a dorsal approach between the fifth and sixth extensor compartments.
    • Open reduction and internal fixation of large displaced ulnar styloid fragments are necessary.
  • Complications
    • Recurrent instability: This may occur
      with or without previous operative intervention and may result in pain
      and functional debilitation that may be progressive.
    • Ulnar neuropathy: Transient sensory
      symptoms may result from irritation of the ulnar nerve in Guyon canal
      or its dorsal sensory branch. Permanent damage is rare, but persistence
      of symptoms beyond 12 weeks may necessitate exploration.

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