fractures and dislocations of the carpus

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Fractures and dislocations of the carpus By Gatobu 6A

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Fractures and dislocations of the carpus. By Gatobu 6A. Scope. Introduction Anatomy Imaging of carpal bones Lunate fractures/lunate dislocation Perilunate dislocation. Introduction. - PowerPoint PPT Presentation

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  • Fractures and dislocations of the carpusBy Gatobu6A

  • ScopeIntroductionAnatomyImaging of carpal bonesLunate fractures/lunate dislocationPerilunate dislocation

  • Introduction Carpus is a complex unit of bony articulations that transfers the forces of the hand to the supporting forearm and upper extremityAllows wide range of motion in 2 planesCarpal bones are 8 in number arranged in 2 rowsMain motionsExtensionFlexionRadial and ulnar deviationThe primary axis of motion resides within the head of carpitate.

  • General, surgical and applied anatomyBones and jointsComposed of 8 bones in 2 rowsThe 8 bones are influenced byShape of distal radiusThe distal ulnarTriangular fibrocartilage complex

  • Anatomy of the WristCarpal bones tightly linked by capsular and interosseous ligaments.Capsular (extrinsic) ligaments originate from the radius and insert onto the carpus.Interosseous (intrinsic) ligaments traverse the carpal bones.The lunate is the key to carpal stability.

  • Extrinsic ligamentsExtrinsic ligaments link the carpal bones to the radius, ulna, and metacarpals.

  • Intrinsic ligamentsThe intra-articular intrinsic ligaments connect adjacent carpal bones.

  • LunateConnected to both scaphoid and triquetrum by strong interosseous ligaments.

    Injury to the scapholunate or lunotriquetral ligaments leads to asynchronous motion of the lunate and leads to dissociative carpal instability.

  • Intercarpal Ligaments

    Injury to these ligaments leads to abnormal motion between the two rows, and non-dissociative wrist instability patterns.

  • Neurovascular anatomy Circulation of the wrist is obtained through the radial, ulnar, and anterior interosseous arteries and the deep palmar arch

  • Neurovascular anatomyThe scaphoid, capitate, and about 20% of all lunates are supplied by a single vessel and thus are at risk for avascular necrosis.The trapezium, triquetrum, pisiform, and 80% of lunates receive nutrient arteries through two nonarticular surfaces and have consistent intraosseous anastomoses. AVN is therefore rare.The trapezoid and hamate lack an intraosseous anastomosis and, after fracture, can have avascular fragments.

  • Mechanism of injuryMost common is an axial compression force applied with the wrist in hyperextension

    Most common injury is a fall on the outstretched handOther mechanismsPalmer flexion,twisting injuries

  • Mechanism of injuryHigh energy forcesResults in carpal bone fractures or ligamentous disruption of both extrinsic and extrinsic ligaments and perilunate dislocationLow energy forces results in minor injuries such as sprains

  • ImagingPlain radiographs: multiple views necessary:AnteroposteriorLateral ObliqueClenched-fist APRadial and ulnar deviation

  • ImagingGilula's lines. A. AP views show three smooth Gilula arcs in a normal wrist. These arcs outline proximal and distal surfaces of the proximal carpal row and the proximal cortical margins of capitate and hamate. B. Arc I is broken, which indicates an abnormal lunotriquetral joint due to a perilunate dislocation. .

  • Imaging Standard scaphoid views detect most carpal injuriesPA x-ray with wrist neutral and in ulnar deviationelongates scaphoid to better visualize

    MRI scans are useful in detecting occult fractures, AVN of the carpal bones, and ligamentous injuries.Perilunate dislocations are easily missed if the continuity of Gilula's line is not assessed.

  • General Principles of TreatmentCarefully evaluate x-rays for subtle fractures and/or evidence of carpal instability.

    Reduce and immobilize scaphoid fractures or perilunate injuries pending definitive treatment.

    Diagnose and appropriately treat ligament and bony injuries.

  • Lunate fracturesRare
  • Lunate anatomy

    Sits like a keystone in the proximal rowWell protected in concavity of the lunate fossa of the radiusVascular supply-proximal carpal arcade dorsally,palmarly7-26% of lunates have single volar or dorsal blood supply

  • Mechanism of injuryHyperextension injuryOthers:repetitive stresses of the wristStrenuous push Avulsion of the dorsal pole( S-L tension)

  • Classification of lunate fracturesAcute fractures are classified in 5 groups:Frontal fracture of palmer poleOsteochondral fractures of the proximal articular surfaceFrontal fracture of the dorsal pole Transverse fracture of the bodyTrans articular fracture of the body

  • Imaging Plain radiographsTechnetium 99m bone scanCT scanArthroscopic exam

  • Lunate fracturesMRI

  • Management of lunate fracturesUndisplaced-cast immobilization for 4wksORIFDisplaced fracturesAssociated carpal instabilityNon-union

  • Perilunate dislocationTriquetral and scaphoid malrotationResult of a fall on an outstretched, hyperextended handRelatively rare Occurs when the lunate maintains normal position with respect to the distal radius while all other carpal bones are dislocated posteriorly

  • Perilunate dislocation Very commonly associated with a scaphoid waist fracture Sometimes ulnar styloid as wellLunate appears triangular in shape on PA viewLunate rotates forward slightly on lateral viewIn lateral view, all other carpal bones are dislocated posterior with respect to lunate

  • Perilunate dislocation

  • Perilunate dislocation Represents 2nd of the 4 stages of ligamentous injury around lunate bone resulting from forced hyperextensionThey are referred to as lesser arc injuriesThe 4 stages of injury are:Scapholunate dissociation(stage I)Perilunate dislocation(II)Midcarpal dislocation(III)Lunate dislocation(IV)With increasing hyperextension perilunate dislocation may become a lunate dislocation

  • Mechanism of InjuryLoad applied to hand forcing the wrist into extension and ulnar deviationSevere ligament injury necessary to tear the distal row from the lunate to produce perilunate dislocation

  • Physical ExamDorsal displacement of the carpus may be seenSignificant swelling commonEvaluate for compartment syndromeIf lunate is dislocated, median nerve symptoms may be present

  • Imaging

  • ImagingNote lack of colinearity among the radius, lunate, and capitate on the lateral x-ray.

  • ImagingNote loss of normal carpal arcs and abnormal widening of the scapholunate interval.

    Look for associated fractures trans-scaphoid injuries

  • X-ray usually Obvious

  • X-ray may be subtle

  • Initial TreatmentClosed reduction is performed with adequate sedation.

    Early surgical reconstruction if swelling allows.

    Immediate surgery needed if there are signs of median nerve compromise.

    Delayed reconstruction if early intervention is not necessary.

  • Technique of Closed ReductionLongitudinal traction for 5 -10 minutesFor dorsal perilunate injuries: apply dorsal directed pressure to the lunate volarly while a reduction maneuver is applied to the hand and distal carpal rowPalmar flexion then reduces the capitate into the concavity of the lunate.

  • Closed Reduction and PinningPoor results with closed reduction and pinning alone

    Very difficult to reduce adequately wrist needs to be ulnarly deviated to correct scaphoid flexion radial deviation needed to close S-L gap

  • ORIF with volar and dorsal approaches Procedure of Choice

  • Dorsal ApproachRepair S-L ligament

  • Volar Approach

  • Reduce lunate first- may need to temporary pin to radius

  • Pin Carpus: S-L, L-T and mid-carpal joints

  • Trans-scaphoid Perilunate InjuriesRequire reduction and fixation of the fractured scaphoid.Most of these injuries best treated ORIF with volar and dorsal approaches repair of injured structures.Open repair supplemented by pin and screw fixation.

  • Fix scaphoid first: dorsal approach

  • Pin L-T and Mid-carpal joints

  • Make sure Radius-Lunate-Capitate are colinear and S-L angle restored

  • Perilunate Injuries ConclusionPerilunate fracture dislocations are high-energy injuriesMust recognize different injury patterns transcaphoid pure ligamentous trans radial-styloidEarly open and anatomic fixation with volar and dorsal approaches provides the best chance at a reasonable functional result

  • Perilunate dislocation conclusion Median nerve dysfunction- 16% of the patients16-25% of perilunate dislocations are missed initially

  • Lunate dislocation Most severe of carpal instabilities Most frequently dislocated carpal bone

    Most commonly associated with a trans-scaphoid fracture Involves all the intercarpal joints and disruption of most of the major carpal ligaments Produces volar dislocation and forward rotation of lunate Concave distal surface of lunate comes to face anteriorly

  • Lunate dislocationCapitate drops into space vacated by lunate Results in dislocation of other carpal bones Capitate and all other carpal bones lie posterior to lunate on lateral radiograph Triangular appearance of lunate on frontal projection (piece of pie sign)Spilled tea cup sign (lateral view)

  • Lunate dislocation

  • Lunate dislocation

  • Dislocated Lunates/s tendernessSwelling ROM painful & limitedMay compress median nerve

  • Lunate dislocationDislocation usually occurs in two steps 1st the ligaments are torn and then the bone dislocates+ Murphys sign

    Murphys Sign pt makes a fist. Indication lunate dislocation

  • Lunate dislocation-imaging

  • comparison

  • Other imaging modalitiesCT scanMRI

  • Treatment Closed reduction at A/E ORIF

  • Complications Wrist arthritisPersistent painJoint instabilityRecovery takes at least 6months

  • Thank you

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