Hip dislocations, most often caused by motor vehicle accidents or similar high-energy trauma, traverse a large subset of distinct injury patterns. Understanding these patterns and their associated injuries allows surgeons to provide optimal care for these patients both in the early and late postinjury periods. Nonoperative care requires surgeons to understand the indications. Surgical care requires the surgeon to understand the benefits and limitations of several surgical approaches. This article presents the current understanding of hip dislocation treatment, focusing on anatomy, injury classifications, nonoperative and operative management, and postinjury care.
Key points
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Time to initial hip relocation is considered an orthopedic emergency.
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Dislocations can be classified according to associated adjacent injuries, including acetabular, femoral head, and femoral neck fractures.
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Choice of open approach depends on visualization needed to treat associated hip injury.
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Complications include osteoarthritis, osteonecrosis, heterotopic ossification, and sciatic nerve palsy.
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Outcomes depend on the degree of initial trauma to the joint.
Introduction
Dislocations of the hip joint embody a wide range of injury patterns. However, all are similar in that they largely suggest a high-energy injury with considerable potential for both soft tissue and osseous injury. The hip is a stable, well-constrained ball-and-socket joint, requiring 40 to 60 kg (90–135 lb) of axial traction to simply distract and considerably more force to dislocate. This high level of energy often results in associated injury to the labrum, femoral head, femoral neck, or acetabulum. These injuries may lead to protracted disability and dysfunction from complications such as osteoarthritis and avascular necrosis.
Hip dislocations have been reported in medical literature since the early nineteenth century ; however, the first considerable series of hip dislocations was published in 1938 by Funsten and colleagues after the popularization of the ever-quickening automobile. Subsequent series have revealed that most hip dislocations, 46% to 84%, occur secondary to traffic accidents, even with the advent of newer safety features. The remaining minority most commonly occur because of falls, industrial accidents, or sporting injury.
The treatment of hip dislocations, regardless of concomitant injury pattern, remains directed toward emergent reduction and attainment of a congruent joint through removal of imposing injured tissues and fixation of associated fractures. This article familiarizes readers with the classification, care, complications, and outcomes of hip dislocations and their associated injuries.
Introduction
Dislocations of the hip joint embody a wide range of injury patterns. However, all are similar in that they largely suggest a high-energy injury with considerable potential for both soft tissue and osseous injury. The hip is a stable, well-constrained ball-and-socket joint, requiring 40 to 60 kg (90–135 lb) of axial traction to simply distract and considerably more force to dislocate. This high level of energy often results in associated injury to the labrum, femoral head, femoral neck, or acetabulum. These injuries may lead to protracted disability and dysfunction from complications such as osteoarthritis and avascular necrosis.
Hip dislocations have been reported in medical literature since the early nineteenth century ; however, the first considerable series of hip dislocations was published in 1938 by Funsten and colleagues after the popularization of the ever-quickening automobile. Subsequent series have revealed that most hip dislocations, 46% to 84%, occur secondary to traffic accidents, even with the advent of newer safety features. The remaining minority most commonly occur because of falls, industrial accidents, or sporting injury.
The treatment of hip dislocations, regardless of concomitant injury pattern, remains directed toward emergent reduction and attainment of a congruent joint through removal of imposing injured tissues and fixation of associated fractures. This article familiarizes readers with the classification, care, complications, and outcomes of hip dislocations and their associated injuries.
Relevant anatomy
Overall stability of the hip joint is reliant on the bony architecture and the joint’s soft tissue constraints. As one of the most stable joints in the body, around 82% of the articular surface of the femoral head is enclosed by the bony acetabulum at neutral position. This coverage is further extended by the labrum attached to the perimeter of the acetabulum. The labrum ensures that at least 50% of the femoral head is covered by the labral-acetabular complex in any position of hip motion.
A thick capsule of longitudinally oriented fibers, save those circumferential fibers of the zona orbicularis, envelop the hip. The longitudinal fibers thicken to form 3 distinct ligaments named for their origins and insertions.
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The iliofemoral ligament, also known as the Y ligament or ligament of Bigelow, arises in 2 distinct bands. The medial band originates between the anterior-inferior iliac spine (AIIS) and the iliac portion of the acetabular rim and inserts on the distal intertrochanteric line. The lateral band originates superior to the medial band, closer to the AIIS, and runs oblique, downward, and lateral, to insert on the anterior greater trochanteric crest. Together, the 2 bands comprise the major static stabilizers of the hip in external rotation, whereas only the lateral band contributes significantly to stability in internal rotation.
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The pubofemoral ligament originates from the anterior border of the superior pubic ramus and obturator crest with some fibers blending with the medial arm of the iliofemoral ligament and others wrapping inferiorly around the neck of the femur to insert on the posterior intertrochanteric crest. It controls external rotation in extension with contributions from the medial and lateral arms of the iliofemoral ligament.
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Posteriorly, the ischiofemoral ligament is broad and less dense than the other two named ligaments, originating from the ischial portion of the acetabular rim and extending in an oblique and horizontal fashion to insert medial to the anterosuperior base of the greater trochanter and along the posterior intertrochanteric crest.
In adults, the principal blood supply to the femoral head originates from the deep branch of the medial femoral circumflex artery. The chief division of the deep branch crosses posterior to the tendon of obturator externus and anterior to the superior gemellus, obturator internus, and inferior gemellus. It then perforates the hip capsule just cephalad to the insertion of the tendon of the superior gemellus and caudal to the tendon of piriformis before dividing into 2 to 4 superior retinacular arteries. Lesser contributions arise through 2 central anastomoses (obturator and lateral femoral circumflex arteries [LFCA]) and 5 peripheral anastomoses (first perforating, LFCA, superior gluteal, inferior gluteal, and pudendal arteries).
After confluence of nerves from nerve roots L4 to S3, the sciatic nerve exits the pelvis through the greater sciatic notch. Despite grossly appearing as a single nerve, the tibial and peroneal divisions have already formed before leaving the true pelvis. In around 83% of patients, the sciatic nerve courses anterior to the muscle body of the piriformis; however, in the remaining 17% the nerve varies from partially perforating the piriformis muscle body to coursing entirely posterior to the muscle body and any assortment in between. This relationship may play a role in risk or protection of the nerve during dislocation, but is also an important consideration in surgical approach.
History, examination, and imaging
History
Patients with hip dislocations generally present after high-energy trauma. For this reason, patients often have distracting injuries or present in an obtunded state. It is imperative for physicians to recognize the signs and symptoms of a dislocation because delayed diagnosis in unconscious or obtunded patients can have serious results. Patients who are able to participate in an examination often complain of inability to move the lower extremity because of the semiconstrained position of the dislocated femoral head. They often endorse numbness or tingling in the affected extremity caused by neuropraxia of the sciatic nerve.
Examination
After appropriate Advanced Trauma Life Support (ATLS) management of a traumatized patient, examination of the lower extremity often reveals not only the presence of a dislocation but also the direction of dislocation.
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Patients with a posterior dislocation show hips that are flexed, adducted, and internally rotated.
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Patients with an anterior dislocation generally present with hips that are flexed, abducted, and strikingly externally rotated.
When a dislocation is present, after evaluation of limb position, careful attention must be paid to rule out both vascular and neurologic injury before any attempt at closed or open reduction. Sciatic nerve injuries are common, occurring in 10% to 15% of posterior dislocations. The peroneal branch is most commonly affected, likely because of its posterior position and being tauter from tethering at the pelvis and the fibular neck. However, tibial branch injury and even lumbosacral root avulsion have previously been reported with this injury. Anterior dislocations have been, in rare cases, associated with vascular injury to the common femoral artery and vein.
Urgent reduction may diminish the incidence or severity of nerve injury associated with dislocation, because time to reduction seems to be an independent risk factor for neurologic injury. In a retrospective review of 106 posterior hip dislocations by Hillyard and Fox, patients reduced at the initial presenting hospital (n = 69), at an average of 3.43 ± 1.59 hours from injury, showed a lower incidence (15% vs 30%, P = .0453) of major sciatic nerve injury (complete sciatic or peroneal motor deficit) than those transferred before reduction (n = 36), in whom reduction occurred at an average of 7.45 ± 4.15 hours from injury.
The most common cause of dislocation, dashboard injury, often results in concurrent injury to the knee. Although it may be difficult to accurately examine the ligamentous stability of the knee before reduction, abrasion, ecchymosis, contusion, or laceration of the knee should alert physicians to the high likelihood of an associated injury to the knee. Schmidt and colleagues reported that up 89% of patients show signs of visible soft tissue injury on examination, whereas less than 10% of patients showed gross instability on ligamentous examination. Despite this, Schmidt and colleagues reported that up to 93% of patients may have an injury to the ipsilateral knee on MRI, which is significantly higher than had previously been reported (24%–26%) and should warrant absolute diligence in inspection of the knee during tertiary examination ( Table 1 ).
| Injury | Number of Patients (n = 27) | Percentage of Patients |
|---|---|---|
| Posterior cruciate | 5 | 19 |
| Anterior cruciate | 2 | 7 |
| Collateral ligament | 6 | 22 |
| Meniscus | 8 | 30 |
| Extensor rupture | 2 | 7 |
| Periarticular fracture | 4 | 15 |
| Effusion | 10 | 37 |
| Bone bruise | 9 | 33 |
Imaging
All patients with polytrauma, especially those presenting with altered mental status, should undergo a screening chest and pelvis radiograph performed in the trauma bay. The evaluating orthopedist must perform a careful and systematic evaluation of the anteroposterior (AP) pelvic radiograph for signs of lower lumbar injury, pelvic ring or acetabular injury, hip dislocation, or proximal femoral fracture.
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In assessment of a possible dislocation, the femoral heads should appear symmetric in size with similar profiles of the greater and lesser trochanters. The femoral head should always clearly be positioned caudal to the acetabular dome.
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In an anterior dislocation, the dislocated femoral head appears larger than the contralateral hip, with a more en profile view of the lesser trochanter. Posterior dislocations most often display reduction in magnification of the dislocated femoral head, with a less apparent lesser trochanter profile.
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In a reduced hip, the joint space of the hip should show congruency throughout with a continuous flow to the Shenton lines. As always, vigilant assessment of the femoral neck must be performed to rule out a femoral neck fracture before an attempted reduction.
Once reduction has been obtained, repeat AP pelvis, Judet views, as well as AP and lateral hip radiographs should be carefully reviewed to confirm congruency of the joint and rule out concurrent fracture and fragment incarceration.
In general, it is our preference to forego computed tomography (CT) scanning before emergent reduction unless there is suspicion for a nondisplaced femoral neck fracture. After reduction, or in the case of an irreducible dislocation, CT should be routinely performed before any open procedure. In the case of an irreducible dislocation, CT scanning should be performed emergently to prevent delay of surgical intervention.
Based on the protocol by Tornetta and colleagues for evaluation of the femoral neck following femoral shaft fracture, 2-mm or smaller cuts through the pelvis and femoral neck should be obtained to rule out occult femoral neck fracture. In patients undergoing dedicated pelvic CT ordered by the orthopedic team, our preference is to obtain 1-mm slices; however, in patients undergoing a standard chest, abdomen, and pelvis CT for trauma work-up, our institutional protocol is to perform 2-mm cuts through the pelvis. Thin slices through the pelvic region also allow appreciation of small osteochondral fragments that may remain in what may otherwise appear to be a congruently reduced joint on plain radiographs. Ebraheim and colleagues previously revealed that evaluation of CT images under soft tissue windowing in addition to standard bone windowing increased the identification of intraarticular osteochondral fragments.
The role of MRI after hip dislocation is not yet clearly defined. The sensitivity of MRI has, in small series, been shown to make it more accurate than CT in recognizing labral tears and osteochondral lesions associated with dislocation. However, osseous evaluation on MRI is more difficult to interpret for surgical planning. MRI may play a role in evaluating a widened hip joint in the presence of a normal CT scan, decreasing radiation exposure in young or pregnant patients, or evaluating the hip joint in patients with worsening pain after resumption of ambulation and normal activities.
Classification
Several classification systems have been developed for hip dislocations and their associated injuries. The first division in classification of hip dislocations is based on the direction of displacement of the femoral head in relation to the acetabulum.
Anterior Dislocations
Anterior dislocations account for around 9% to 24% of all dislocations and patients generally present with a hip that is flexed, abducted, and externally rotated. This injury pattern was first classified by Epstein into type A (superior/pubic) dislocations, wherein the femoral head dislocates superiorly abutting the superior pubic ramus, and type B (inferior/obturator) dislocations, in which the femoral head dislocates inferomedially into the obturator ring. Each type is further classified into 3 subtypes based on associated fractures. The mechanism for an anterior-inferior (type B) dislocation, as shown in a cadaveric model by Pringle and Edwards, is that of simultaneous abduction, flexion, and external rotation of the hip, whereas anterior-superior (type A) dislocations occur secondary to extension and abduction.
Epstein classification:
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Type A: pubic (superior)
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1: With no fracture (simple)
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2: With fracture of the head of the femur
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3: With fracture of the acetabulum
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Type B: obturator (inferior)
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1: With no fracture (simple)
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2: With fracture of the head of the femur
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3: With fracture of the acetabulum
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Posterior Dislocations
The far more common posterior dislocation generally presents with a patient whose hip is flexed, adducted, and internally rotated. The most common mechanism is an axial load transmitted posteriorly through an adducted and flexed femur, such as occurs when a knee strikes the dashboard in a head-on collision. Armstrong first classified these injuries in 1948; however, several classification systems have since been proposed for this injury, with the most common being the Stewart and Milford or Thompson and Epstein classifications.
Armstrong classification:
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Type I: simple dislocation
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Type II: dislocation with fracture of the acetabular rim
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Type III: dislocation with fracture of the acetabular floor
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Type IV: dislocation with fracture of the femoral head
Thompson and Epstein classification:
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Type I: dislocation with or without minor fracture
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Type II: dislocation with large single fracture of the posterior acetabular rim
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Type III: dislocation with comminuted fracture of the rim of the acetabulum, with or without major fragment
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Type IV: dislocation with fracture of the acetabular rim and floor
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Type V: dislocation with fracture of the femoral head
Stewart and Milford classification:
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Grade I: simple dislocation without fracture or with a chip from the acetabulum so small as to be of no consequence
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Grade II: dislocation with 1 or more large rim fragments, but with sufficient socket remaining to ensure stability after reduction
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Grade III: explosive or blast fracture with disintegration of the rim of the acetabulum, which produces gross instability
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Grade IV: dislocation with a fracture of the head or neck of the femur
Levin classification of posterior hip dislocations :
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Type I: no significant associated fractures; no clinical instability after concentric reduction
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Type II: irreducible dislocation without significant femoral head or acetabular fractures (reduction must be attempted under general anesthesia)
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Type III: unstable hip after reduction or incarcerated fragments of cartilage, labrum, or bone
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Type IV: associated acetabular fracture requiring reconstruction to restore hip stability or joint congruity
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Type V: associated femoral head or femoral neck injury (fractures or impactions)
Orthopaedic Trauma Association (OTA)/Arbeitsgemeinschaft für Osteosynthesefragen (AO) Classification
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(A dislocation associated with an acetabular, femoral neck, or femoral head fracture should be coded with a fracture code and a dislocation code):
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30–A1: anterior hip dislocation
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30–A2: posterior hip dislocation
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30–A3: medial or central hip dislocation
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30–A4: obturator hip dislocation
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30–A5: other hip dislocation
Management
Prompt reduction of the femoral head into the acetabulum is the first and foremost goal in treatment of a dislocated hip.
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Delayed reduction is thought to cause decreased blood flow to the femoral head, with several studies advocating reduction as soon as possible.
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At our institution, every hip dislocation, other than those with a relative contraindication such as a femoral neck or shaft fracture, undergoes a closed reduction attempt under deep conscious sedation through propofol, in the emergency department (ED), before advanced imaging.
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Patients should be near or at the point of requiring respiratory assistance during the sedation for adequate muscle relaxation to create the least traumatic environment possible during reduction.
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Fluoroscopic imaging may be used during the reduction.
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Stable and concentric reductions are ranged through flexion-extension, adduction-abduction, and internal-external rotation while under sedation to determine degree of stability.
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Dislocations with apparent interposed osteochondral fragments, those associated with large acetabular fractures affecting congruity, or those attendant to a femoral head fracture are placed into distal femur skeletal traction without ranging.
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Confirmatory AP pelvis and cross-table lateral hip radiographs are taken and the patient is then sent to the CT scanner to more accurately assess for periarticular fractures or intraarticular fragments.
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Judet, inlet, and outlet radiographs may also be obtained if CT scanning is not readily available, or reproduced from the CT scan with volume rendering techniques.
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If CT scanning reveals intraarticular fragments not previously appreciated, skeletal traction is placed until surgery. Postreduction stability examination and CT scans are then used to determine the treatment plan.
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If a hip is found to be irreducible in the ED, the patient is sent emergently to CT and then taken to the operating theater for reduction through either closed or open means.
Closed reduction
Closed reduction is generally performed through disengagement of the femoral head from the acetabulum and recreation of the injury pattern with inline traction. Several reduction techniques, for the more common posterior dislocation, have been described.
The Bigelow maneuver was initially described in 1870:
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The patient is placed in the supine position.
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The primary clinician provides an axial distraction force while an assistant applies a counterforce to the pelvis.
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The hip is then adducted, internally rotated, and flexed to 90°.
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With maintained traction, the hip is externally rotated, abducted, and extended as the femoral head reduces into the acetabulum.
Similar is the Allis maneuver, first described in 1896:
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The patient is placed in the supine position and the physician stands on the stretcher.
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Inline traction is applied while an assistant applies counterpressure to the pelvis.
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Reduction is obtained by traction, internal rotation, and then external rotation once the femoral hip clears the acetabular rim.
The Stimson gravity technique was first described in 1883:
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The patient is placed in the prone position with the injured leg hanging off the side of the bed.
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The hip and knee are each brought to 90° of flexion.
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The surgeon then applies an anteriorly directed force to the posterior calf.
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Although effective, this method has the unfortunate requirement of placing the patient in the prone position, which makes airway management more difficult and may be impossible to perform safely in polytraumatized patients.
Skoff, in 1986, described a new and unique method:
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The patient is placed in the lateral decubitus position with the hip flexed to 100°.
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The deformity is exaggerated with internal rotation of 45° and adduction of 45°.
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Gravity-assisted distraction is allowed while an assistant applies direct posterior pressure to the femoral head as reduction occurs.
Howard described a 3-person technique:
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The patient is placed in the supine position.
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The first assistant leans with both hands on the iliac crest of the affected side.
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The second assistant flexes the femur to 90°, bringing the head of the femur from a posterosuperior position to lie directly posterior to the acetabulum.
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The surgeon then grasps the proximal thigh and pulls the thigh laterally, allowing the head of the femur to clear the acetabular lip.
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The second assistant applies longitudinal traction.
The senior author prefers to use the Rochester method, because it has proved to provide a controlled environment for single-person reduction :
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The patient is placed supine with the uninjured hip flexed to 45° and the knee flexed to 90°.
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The uninjured knee acts as a bolster for the arm that will be used as a pivot point for the reduction.
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One of the surgeon’s arms is placed underneath the injured knee, the forearm in the popliteal fossa of the injured leg, and the hand is placed on top of the uninjured knee, so that both knees and hips are now flexed.
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The surgeon then grasps the ankle of the injured leg and, through downward pressure, the surgeon is able to pivot around the stable forearm to generate traction.
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The ankle can be used to provide internal and external rotation as needed.
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Reduction is obtained by traction, internal rotation, and then external rotation once the femoral head clears the acetabular rim.
The East Baltimore lift reduction maneuver is similar to that of the Rochester method, but more appropriate for patients with contralateral leg disorder :
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The patient is placed supine and the injured hip and ipsilateral knee are placed in 90° of flexion.
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The surgeon stands on the side of the dislocation with 1 assistant facing the surgeon on the opposite side of the bed.
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The more proximal of the surgeon’s arms, with respect to the patient, is positioned under the proximal calf of the injured leg with the surgeon’s hand placed on the shoulder of the assistant across the table.
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The surgeon’s other hand is used to control rotation of the distal leg.
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The assistant then positions an arm in a similar fashion to that of the surgeon, crossing under the proximal calf with the hand resting on the surgeon’s shoulder.
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A second assistant is used for stabilizing the pelvis.
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The bed is lowered so that, as the surgeon and assistant stand from a squatted position, an anteriorly directed traction is applied to the hip.
After closed reduction of a hip in which the reduction is deemed concentric and stable, routine CT should be obtained to ensure no occult fracture is present.
Operative intervention
Approaches
Kocher-Langenbeck
Planning
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Positioning may be either lateral decubitus or prone, depending on surgeon preference.
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If in the lateral position, the injured leg may be draped free. An advantage of lateral positioning is the ability to test for hip stability following posterior repair and before wound closure.
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If in the prone position, distal femoral traction is generally placed and the leg is positioned into a traction table with the hip in extension and the knee flexed to slightly less than 90°.
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The use of a traction table may be optimal if an assistant is not available for traction.
Approach
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Incision is made along the posterior one-third of the femoral shaft to the tip of the trochanter and then curves posterosuperior at around a 45° angle to end 1 cm proximal to the posterior superior iliac spine (PSIS).
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The skin and subcutaneous fat are sharply dissected down to the tensor muscle, iliotibial band, and the gluteal fascia.
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The tensor fascia lata and iliotibial band are sharply divided in line with the fibers along the posterior aspect of the femoral shaft.
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After division of the gluteal fascia in line with the muscle fibers, gentle finger dissection can be used to split the muscle body of the gluteus maximus.
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Proximal extension is reached when the surgeon reaches the first crossing nerve fibers at approximately the halfway point between the PSIS and greater trochanter.
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The Charnley retractor is placed below this layer to optimize the view for the remainder of the procedure.
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Iatrogenic injury to the sciatic nerve can occur if the posterior retractor arm is placed too deeply.
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The bursa overlying the greater trochanter is then excised to better visualize the short external rotators.
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The sciatic nerve is then identified and protected for the remainder of the procedure.
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A Hibbs retractor should be placed around the gluteus medius tendon for protection as the leg is internally rotated to put the short external rotators on stretch.
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The piriformis tendon is identified, tagged, and divided approximately 1 to 2 cm from its attachment to the femur to decrease risk of injury to the blood supply of the femoral head.
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The sciatic nerve should be readily visible at this point and should be assessed for contusion, hemorrhage, or laceration.
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The process is then repeated with a tagging suture placed into the obturator internus tendon with division of the superior and inferior gemelli and the obturator internus, again 1 to 2 cm from their insertion.
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The gemelli and the obturator internus provide protection for the sciatic nerve because of its course along the posterior aspect of this muscle group.
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In most patients, the sciatic nerve is found anterior to the piriformis after it is released.
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The next caudal muscle is the body of the quadratus femoris, which must be left intact to prevent injury to the medial femoral circumflex artery running along its superior border.
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At this point, a sciatic nerve retractor is placed.
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By following the short external rotators, the surgeon may easily find both the greater (piriformis) and lesser (obturator internus) sciatic notches.
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Placement of the retractor in the lesser sciatic notch allows for protection of the sciatic nerve with the obturator internus muscle belly.
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A second retractor may be placed into the greater sciatic notch, but caution must be exercised to limit the risk of injury to the sciatic nerve and the superior gluteal neurovascular bundle.
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The posterior capsule and acetabular rim are now within view.
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In the setting of a posterior wall fracture, further disruption of the capsule must be avoided to prevent devascularization of the acetabular wall fragment. The labrum and capsule are typically torn and detached caudally by the injury.
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If the acetabular wall remains intact, the capsule is most likely to be torn from the dislocation. Should the capsule remain intact or require further dissection, capsulotomy must be performed at the acetabular origin to prevent injury to the vascular supply of the femoral head.
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Care must be taken to avoid injury to the labrum during release.
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Once exposed, the femoral head may require further distraction through either the fracture table or an assistant.
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Placement of a Steinmann pin into the lateral aspect of the proximal femur can help with pure lateral distraction.
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It is rare to require complete redislocation of the femoral head and, if this is the case, it is our preference to proceed with a surgical dislocation, as discussed later.
Surgical dislocation/digastric osteotomy
Planning
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Surgical dislocation as described by Ganz and colleagues provides exceptional visualization of the femoral head and acetabulum in cases in which both anterior and posterior access is required.
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The patient is positioned in the lateral decubitus position.
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A sterile bag is placed on the side opposite the surgeon in which to place the leg during dislocation.
Approach
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Incision is made along the posterior one-third of the femoral shaft to the tip of the trochanter, and it then curves posterosuperiorly at around a 45° angle to end 1 cm proximal to the PSIS.
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The skin and subcutaneous fat are sharply dissected down to the tensor muscle, iliotibial band, and the gluteal fascia.
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The tensor fascia lata and iliotibial band are sharply divided in line with the fibers along the posterior aspect of the femoral shaft.
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The leg is then internally rotated and the posterior border of the gluteus medius tendon is identified.
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A mark is then made from the posterior superior edge of the greater trochanter to the posterior border of the vastus lateralis ridge.
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An oscillating saw is then used to perform the osteotomy along this line and in a sagittal plane through the femur.
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Some surgeons prefer to drill for fixation before completion of the osteotomy.
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At the proximal aspect of the osteotomy, the exit point should be just anterior to the posteriormost insertion of the medius tendon and distally the vastus lateralis attachment should remain intact to the wafer.
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This technique allows preservation of the medial femoral circumflex artery, which becomes intracapsular at the level of the superior gemellus muscle.
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The osteotomy is correctly placed when only a small portion of the piriformis requires release from the free fragment.
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The vastus lateralis is then freed from the lateral and anterior proximal femur for mobilization of the fragment.
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The gluteus minimus tendon is separated from the piriformis and underlying capsule.
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There is a constant anastomosis between the inferior gluteal artery and the medial femoral circumflex running along the inferior border of the piriformis that is preserved and may be used to trace to the medial femoral circumflex.
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A Z-shaped capsulotomy is performed starting with an anterolateral incision in line with the neck. The capsular incision is then carried down the anterior aspect of the neck just before the vastus ridge. The posterior limb is placed immediately adjacent to the acetabular insertion.
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Once the capsulotomy is complete, the hip is dislocated through flexion and external rotation as the leg is brought into a sterile bag on the side of the table opposite the surgeon.
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By controlling the leg, the surgeon now has full access to the acetabulum and femoral head.
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After completion of operative fixation, the capsule is repaired and the osteotomy is fixed into anatomic position with two 3.5-mm cortical screws with or without washers.
Postoperative
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Active abduction should be avoided through touchdown weight bearing for the first 6 to 8 weeks, regardless of limitations based on fixation or lack thereof ( Fig. 1 ).
