Hip Dislocations

Ovid: Handbook of Fractures

Authors: Koval, Kenneth J.; Zuckerman, Joseph D.
Title: Handbook of Fractures, 3rd Edition
> Table of Contents > IV – Lower Extremity Fractures and Dislocations > 27 – Hip Dislocations

Hip Dislocations
  • Up to 50% of patients sustain concomitant fractures elsewhere at the time of hip dislocation.
  • Unrestrained motor vehicle accident
    occupants are at a significantly higher risk for sustaining a hip
    dislocation than passengers wearing a restraining device.
  • Anterior dislocations constitute 10% to
    15% of traumatic dislocations of the hip, with posterior dislocations
    accounting for the remainder.
  • Sciatic nerve injury is present in 10% to 20% of posterior dislocations (Fig. 27.1).
  • The hip articulation has a
    ball-and-socket configuration with stability conferred by bony and
    ligamentous restraints, as well as the congruity of the femoral head
    with the acetabulum.
  • The acetabulum is formed from the confluence of the ischium, ilium, and pubis at the triradiate cartilage.
  • Forty percent of the femoral head is
    covered by the bony acetabulum at any position of hip motion. The
    effect of the labrum is to deepen the acetabulum and increase the
    stability of the joint.
  • The hip joint capsule is formed by thick
    longitudinal fibers supplemented by much stronger ligamentous
    condensations (iliofemoral, pubofemoral, and ischiofemoral ligaments)
    that run in a spiral fashion, preventing excessive hip extension (Fig. 27.2).
  • The main vascular supply to the femoral
    head originates from the medial and lateral femoral circumflex
    arteries, branches of the profunda femoral artery. An extracapsular
    vascular ring is formed at the base of the femoral neck with ascending
    cervical branches that pierce the hip joint at the level of the
    capsular insertion. These branches ascend along the femoral neck and
    enter the bone just inferior to the cartilage of the femoral head. The
    artery of the ligamentum teres, a branch of the obturator artery, may
    contribute blood supply to the epiphyseal region of the femoral head (Fig. 27.3).
  • The sciatic nerve exits the pelvis at the
    greater sciatic notch. A certain degree of variability exists in the
    relationship of the nerve with the piriformis muscle and short external
    rotators of the hip. Most frequently, the sciatic nerve exits the
    pelvis deep to the muscle belly of the piriformis.
  • Hip dislocations almost always result
    from high-energy trauma, such as motor vehicle accident, fall from a
    height, or industrial accident. Force transmission to the hip joint
    occurs with application to one of three common sources:
    • The anterior surface of the flexed knee striking an object
    • P.303

    • The sole of the foot, with the ipsilateral knee extended
      27.1. Left: Sciatic nerve impingement by the posteriorly dislocated
      femoral head. Right: Sciatic nerve impingement by a posterior
      acetabular fracture fragment in a posterior fracturedislocation of the

      (From Rockwood CA Jr, Green DP, Bucholz RW, Heckman JD, eds. Rockwood and Green’s Fractures in Adults, 4th ed, vol. 1. Philadelphia: Lippincott-Raven, 1996:1756 with permission.)
    • The greater trochanter
  • Less frequently, the dislocating force
    may be applied to the posterior pelvis with the ipsilateral foot or
    knee acting as the counterforce.
  • Direction of dislocation—anterior versus
    posterior—is determined by the direction of the pathologic force and
    the position of the lower extremity at the time of injury.
Anterior Dislocations
  • These comprise 10% to 15% of traumatic hip dislocations.
  • They result from external rotation and abduction of the hip.
  • The degree of hip flexion determines whether a superior or inferior type of anterior hip dislocation results:
    • Inferior (obturator) dislocation is the result of simultaneous abduction, external rotation, and hip flexion.
    • Superior (iliac or pubic) dislocation is the result of simultaneous abduction, external rotation, and hip extension.
Posterior Dislocations
  • They are much more frequent than anterior hip dislocations.
  • They result from trauma to the flexed knee (e.g., dashboard injury) with the hip in varying degrees of flexion:
    • If the hip is in the neutral or slightly
      adducted position at the time of impact, a dislocation without
      acetabular fracture will likely occur.
    • If the hip is in slight abduction, an associated fracture of the posterior-superior rim of the acetabulum usually occurs.
Figure 27.2. The hip capsule and its thickenings (ligaments) as visualized from anteriorly (A) and posteriorly (B).

(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.)



27.3. Vascular anatomy of the femoral head and neck. Top: Anterior
aspect. Bottom: Posterior aspect. LFC, lateral femoral circumflex

(From Rockwood CA Jr, Green DP, Bucholz RW, Heckman JD, eds. Rockwood and Green’s Fractures in Adults, 4th ed, vol. 2. Philadelphia: Lippincott-Raven, 1996:1662.)
  • Full trauma survey is essential because
    of the high-energy nature of these injuries. Many patients are obtunded
    or unconscious when they arrive in the emergency room as a result of
    associated injuries. Concomitant intraabdominal, chest, and other
    musculoskeletal injuries, such as acetabular, pelvic, or spine
    fractures, are common.
  • Patients presenting with dislocations of the hip typically are unable to move the lower extremity and are in severe discomfort.
  • The classic appearance of an individual
    with a posterior hip dislocation is a patient in severe pain with the
    hip in a position of flexion, internal rotation, and adduction.
    Patients with an anterior dislocation hold the hip in marked external
    rotation with


    flexion and abduction. The appearance and alignment of the extremity,
    however, can be dramatically altered by ipsilateral extremity injuries.

  • A careful neurovascular examination is
    essential, because injury to the sciatic nerve or femoral neurovascular
    structures may occur at time of dislocation. Sciatic nerve injury may
    occur with stretching of the nerve over the posteriorly dislocated
    femoral head. Posterior wall fragments from the acetabulum may also
    pierce or partially lacerate the nerve. Usually, the peroneal portion
    of the nerve is affected, with little if any dysfunction of the tibial
    nerve. Rarely, injury to the femoral artery, vein, or nerve may occur
    as a result of an anterior dislocation. Ipsilateral knee, patella, and
    femur fractures are common. Pelvic fractures and spine injuries may
    also be seen.
  • An anteroposterior (AP) radiograph of the pelvis is essential, as well as a cross-table lateral view of the affected hip.
  • On the AP view of the pelvis:
    • The femoral heads should appear similar
      in size, and the joint spaces should be symmetric throughout. In
      posterior dislocations, the affected femoral head will appear smaller
      than the normal femoral head. In anterior dislocation, the femoral head
      will appear slightly larger than the normal hip because of
      magnification of the femoral head to the x-ray cassette.
    • The Shenton line should be smooth and continuous.
    • The relative appearance of the greater
      and lesser trochanters may indicate pathologic internal or external
      rotation of the hip. The adducted or abducted position of the femoral
      shaft should also be noted.
    • One must evaluate the femoral neck to rule out the presence of a femoral neck fracture before any manipulative reduction.
  • A cross-table lateral view of the affected hip may help distinguish a posterior from an anterior dislocation.
  • Use of 45-degree oblique (Judet) views of
    the hip may be helpful to ascertain the presence of osteochondral
    fragments, the integrity of the acetabulum, and the congruence of the
    joint spaces. Femoral head depressions and fractures may also be seen.
  • Computed tomography (CT) scans are
    usually obtained following closed reduction of a dislocated hip. If
    closed reduction is not possible and an open reduction is planned, a
    computed tomography scan should be obtained to detect the presence of
    intra-articular fragments and to rule out associated femoral head and
    acetabular fractures.
  • The role of magnetic resonance imaging in
    the evaluation of hip dislocations has not been established; it may
    prove useful in the evaluation of the integrity of the labrum and the
    vascularity of the femoral head.
Hip dislocations are classified based on (1) the
relationship of the femoral head to the acetabulum and (2) whether or
not associated fractures are present.


Thompson and Epstein Classification of Posterior Hip Dislocations (Fig. 27.4)
Figure 27.4. Thompson and Epstein classification of posterior hip dislocations.

Type I: Simple dislocation with or without an insignificant posterior wall fragment
Type II: Dislocation associated with a single large posterior wall fragment
Type III: Dislocation with a comminuted posterior wall fragment
Type IV: Dislocation with fracture of the acetabular floor
Type V: Dislocation with fracture of the femoral head
Epstein Classification of Anterior Hip Dislocations (Fig. 27.5)

Type I: Superior dislocations, including pubic and subspinous
IA: No associated fractures
IB: Associated fracture or impaction of the femoral head
IC: Associated fracture of the acetabulum
Type II: Inferior dislocations, including obturator, and perineal
IIA: No associated fractures
IIB: Associated fracture or impaction of the femoral head
IIC: Associated fracture of the acetabulum
OTA Classification of Hip Dislocations
See Fracture and Dislocation Compendium at http://www.ota.org/compendium/index.htm.
  • One should reduce the hip on an emergency
    basis to decrease the risk of osteonecrosis of the femoral head; it
    remains controversial whether this should be accomplished by closed or


    methods. Most authors recommend an immediate attempt at a closed
    reduction, although some believe that all fracture-dislocations should
    have immediate open surgery to remove fragments from the joint and to
    reconstruct fractures.

    Figure 27.5. Epstein classification of anterior hip dislocations.

    (From Rockwood CA Jr, Green DP, eds. Rockwood and Green’s Fractures in Adults, 3rd ed. Philadelphia: Lippincott-Raven, 1996:1576–1579.)
  • The long-term prognosis worsens if
    reduction (closed or open) is delayed more than 12 hours. Associated
    acetabular or femoral head fractures can be treated in the subacute
Closed Reduction
Regardless of the direction of the dislocation, the
reduction can be attempted with in-line traction with the patient lying
supine. The preferred method is to perform a closed reduction using
general anesthesia, but if this is not feasible, reduction under
intravenous sedation is possible. There are three popular methods of
achieving closed reduction of the hip:
This consists of traction applied in line with the
deformity. The patient is placed supine with the surgeon standing above
the patient on the stretcher. Initially, the surgeon applies in-line
traction while the assistant applies countertraction by stabilizing the
patient’s pelvis. While increasing the traction force, the surgeon
should slowly increase the degree of flexion to approximately 70
degrees. Gentle rotational motions of the hip as well as slight
adduction will often help the femoral head to clear the lip of the
acetabulum. A lateral force to the proximal thigh may assist in
reduction. An audible “clunk” is a sign of a successful closed
reduction (Fig. 27.6).
The patient is placed prone on the stretcher with the
affected leg hanging off the side of the stretcher. This brings the
extremity into a position of hip flexion and knee flexion of 90 degrees
each. In this position, the assistant immobilizes the pelvis, and the
surgeon applies an anteriorly directed force on the proximal calf.
Gentle rotation of the limb may assist in reduction (Fig. 27.7).
These have been associated with iatrogenic femoral neck
fractures and are not as frequently used as reduction techniques. In
the Bigelow maneuver, the patient is supine, and the surgeon applies
longitudinal traction on the limb. The adducted and internally rotated
thigh is then flexed at least 90 degrees. The femoral head is then
levered into the acetabulum by abduction, external rotation, and
extension of the hip. In the reverse Bigelow maneuver, used for
anterior dislocations, traction is again applied in the line of the
deformity. The hip is then adducted, sharply internally rotated, and
  • Following closed reduction, radiographs
    should be obtained to confirm the adequacy of reduction. The hip should
    be examined for stability while the patient is still sedated or under
    anesthesia. If there is an obvious large displaced acetabular fracture,
    the stability examination need not be performed.
    • Stability is checked by flexing the hip
      to 90 degrees in neutral position. A posteriorly directed force is then
      applied. If any sensation of subluxation is detected, the patient will
      require additional diagnostic studies and possibly surgical exploration
      or traction.
      Figure 27.6. The Allis reduction technique for posterior hip dislocations.

      (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.)
    • P.309


    • Following successful closed reduction and completion of the stability examination, the patient should undergo CT evaluation.
Figure 27.7. The Stimson gravity method of reduction

(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.)
Open Reduction
  • Indications for open reduction of a dislocated hip include:
    • Dislocation irreducible by closed means.
    • Nonconcentric reduction.
    • Fracture of the acetabulum or femoral head requiring excision or open reduction and internal fixation.
    • Ipsilateral femoral neck fracture.
  • A standard posterior approach
    (Kocher-Langenbeck) will allow exploration of the sciatic nerve,
    removal of posteriorly incarcerated fragments, treatment of major
    posterior labral disruptions or instability, and repair of posterior
    acetabular fractures.
  • An anterior (Smith-Peterson) approach is
    recommended for isolated femoral head fractures. A concern when using
    an anterior approach for a posterior dislocation is the possibility of
    complete vascular disruption. By avoiding removal of the capsule from
    the femoral neck and trochanters (i.e., taking down the capsule from
    the acetabular side), injury to the lateral circumflex artery or its
    branches should not occur.
  • An anterolateral (Watson-Jones) approach
    is useful for most anterior dislocations and combined fracture of both
    femoral head and neck.
  • A direct lateral (Hardinge) approach will allow exposure anteriorly and posteriorly through the same incision.
  • In the case of an ipsilateral displaced or nondisplaced femoral neck fracture, closed reduction of the hip should not be


    attempted. The hip fracture should be provisionally stabilized through
    a lateral approach. A gentle reduction is then performed, followed by
    definitive fixation of the femoral neck.

  • Management after closed or open reduction
    ranges from short periods of bed rest to various durations of skeletal
    traction. No correlation exists between early weight bearing and
    osteonecrosis. Therefore, partial weight bearing is advised.
    • If reduction is concentric and stable: A short period of bed rest is followed by protected weight bearing for 4 to 6 weeks.
    • If reduction is concentric but unstable: Skeletal traction for 4 to 6 weeks is followed by protective weight bearing.
  • The outcome following hip dislocation ranges from an essentially normal hip to a severely painful and degenerated joint.
  • Most authors report a 70% to 80% good or
    excellent outcome in simple posterior dislocations. When posterior
    dislocations are associated with a femoral head or acetabular fracture,
    however, the associated fractures generally dictate the outcome.
  • Anterior dislocations of the hip are
    noted to have a higher incidence of associated femoral head injuries
    (transchondral or indentation types). The only patients with excellent
    results in most authors’ series are those without an associated femoral
    head injury.
  • Osteonecrosis: This is observed in 5% to
    40% of injuries, with increased risk associated with increased duration
    of dislocation (>6 to 24 hours); however, some authors suggest that
    osteonecrosis may result from the initial injury and not from prolonged
    dislocation. Osteonecrosis may become clinically apparent up to 5 years
    after injury. Repeated reduction attempts may also increase its
  • Posttraumatic osteoarthritis: This is the
    most frequent long-term complication of hip dislocations; the incidence
    is dramatically higher when dislocations are associated with acetabular
    fractures or transchondral fractures of the femoral head.
  • Recurrent dislocation: This is rare
    (<2%), although patients with decreased femoral anteversion may
    sustain a recurrent posterior dislocation, whereas those with increased
    femoral anteversion may be prone to recurrent anterior dislocations.
  • Neurovascular injury: Sciatic nerve
    injury occurs in 10% to 20% of hip dislocations. It is usually caused
    by a stretching of the nerve from a posteriorly dislocated head or from
    a displaced fracture fragment. Prognosis is unpredictable, but most
    authors report 40% to 50% full recovery. Electromyographic studies are
    indicated at 3 to 4 weeks for baseline information and prognostic
    guidance. If no clinical or electrical improvement is seen by 1 year,
    surgical intervention may be considered. If a sciatic nerve injury
    occurs after closed reduction is performed, then entrapment of the
    nerve is likely and surgical exploration is indicated. Injury to the
    femoral nerve and femoral vascular structures has been reported with
    anterior dislocations.
  • P.312

  • Femoral head fractures: These occur in
    10% of posterior dislocations (shear fractures) and in 25% to 75% of
    anterior dislocations (indentation fractures).
  • Heterotopic ossification: This occurs in
    2% of patients and is related to the initial muscular damage and
    hematoma formation. Surgery increases its incidence. Prophylaxis
    choices include indomethacin for 6 weeks or use of radiation.
  • Thromboembolism: This may occur after hip
    dislocation owing to traction-induced intimal injury to the
    vasculature. Patients should be given adequate prophylaxis consisting
    of compression stockings, sequential compression devices, and
    chemoprophylaxis, particularly if they are placed in traction.

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