J. Richard Bowen
DEFINITION
The labral support (shelf) procedure has been used in patients with Legg-Calvé-Perthes disease (or Perthes disease) in Waldenström's stages of necrosis or fragmentation in which the femoral head shows deformity or is at risk for deformity6 (FIG 1).
The concept of the labral support (shelf) procedure in patients with Perthes disease includes the following steps6:
Reducing the necrotic femoral head into the acetabulum
Eliminating hinge subluxation and improving femoral head coverage
Supporting the labrum and preventing deformity of the acetabulum (femoral–acetabular impingement)
Preparing for the (labral support) shelf to reabsorb after reossification of the femoral head
Stimulating overgrowth of the acetabulum and remodeling of the femoral head
ANATOMY
The posterior branch lateral femoral cutaneous nerve
The lateral femoral cutaneous nerve arises from divisions of the second and third lumbar nerves.
FIG 1 • AP radiograph of an arthrogram demonstrates a labral support (shelf) in a patient with Perthes disease. The shelf supports the labrum and enlarges the acetabulum to prevent subluxation of the femoral epiphysis.
It courses the lateral border of the psoas muscle, crosses the iliacus muscle obliquely, passes under the inguinal ligament, and divides into an anterior and posterior branch.
The posterior branch traverses beneath the sartorius muscle and exits the fascia lata about 1 to 2 cm below the anterior superior iliac spine.
The nerve supplies sensation to the skin anterolaterally from the level of the greater trochanter to the middle thigh.
The medial aspect of the bikini skin incision used in the labral support (shelf) procedure is very near the posterior branch of the lateral femoral cutaneous, which requires protection.
The labrum is located at the lateral rim of the acetabulum and has acetabular cartilage medially and fibrocartilage and fibrous tissue laterally.
The labrum growth plate contributes depth to the acetabulum and must not be damaged while performing the labral support (shelf).
In the adult, the average width of the acetabular labrum is 5.3 mm (standard deviation 2.6 mm).
The labrum is wider superiorly and anteriorly than posteriorly.
The surface area of the acetabulum without the labrum is 28.8 cm2 and with the labrum is 36.8 cm2.
PATHOGENESIS
Perthes disease is a condition of the immature hip caused by necrosis of the epiphysis and the growth plate of the proximal capital area of the femur.
The necrotic tissue is gradually resorbed and replaced by new bone.
During the process, the epiphysis may become deformed and the growth of the proximal femur retarded.
Typically, the age at onset of symptoms is between 4 and 8 years, but it has been seen in children from 2 years to maturity.
There is a male predominance of 4:1, and the condition occurs bilaterally in up to 17% of cases.
Factors with the greatest prognostic significance in Perthes disease are:
Age at onset of the disease
Degree of necrosis of the capital epiphysis
Premature capital physeal growth plate closure
Persistent stiffness of the hip, with deformity of the femoral head (impingement)
At maturity, the hip may be normal or may have one of four patterns of deformity: coxa magna, coxa brevis, coxa irregularis (impingement), and osteochondritis dissecans.
In adulthood, patients with irregular (incongruent) hips develop impingement with progressive degenerative joint disease.
About 50% of all patients with Perthes disease have severe degenerative arthritis by the sixth and seventh decades of life.14–16,22
FIG 2 • Computed tomography of the hip of a patient with Perthes disease showing necrotic bone in the epiphysis and a subchondral fracture.
NATURAL HISTORY
Waldenström described four sequential stages of Perthes disease in childhood (later modified to the following): necrosis, fragmentation (resorption), reossification, and remodeling.24,25
The stage of necrosis begins with an infarction of the capital femoral epiphysis and lasts about 6 months.
After the infarction, the child is usually asymptomatic, but a subchondral fracture subsequently develops in the necrotic bone and the hip becomes irritable (FIG 2).
A mild effusion develops and the femoral heal begins to lateralize in the acetabulum.
The hip becomes painful and adduction–flexion–external rotation contractures develop.
The first radiographic sign of removal of necrotic bone begins the fragmentation stage (resorption).
Gradually revascularization of the epiphysis begins, usually at the anterolateral area of the epiphysis.
Over the ensuing months, the necrotic bone is removed, and the epiphysis may begin to deform, subluxate, and impinge on the margin of the acetabulum (hinged subluxation).
During the fragmentation stage, the height of the lateral pillar of the femoral epiphysis correlates with outcome and predicts the chance of developing arthritis in adulthood (Table 1).
The first radiographic signs of new bone formation indicate the reossification stage.
About 12 to 14 months after the initial infarction, new bone begins forming in the epiphysis, usually at the anterolateral margin.
Once the anterolateral column of the epiphysis has reossified, further epiphyseal deformity does not typically occur.23
Reossification continues until the entire epiphysis is healed, which may take up to about 4 years.
The remodeling stage extends from the end of reossification until skeletal maturity.
The femoral epiphysis may improve in sphericity with continued growth.
Premature closure of the physis may cause limb shortening or deformity of the femoral neck.
Common deformities of the hip following Perthes disease include coxa magna, coxa brevis (premature physeal closure), coxa irregularis (asphericity and incongruence of the hip with acetabular–femoral impingement), and osteochondral loose bodies.8,26
Stulberg et al22 classified hips into five groups that predict development of arthritis in adulthood (Table 2).
PATIENT HISTORY AND PHYSICAL FINDINGS
Perthes disease may present in children as an acute or chronic ache, which is commonly felt in the area of the hip, thigh, or knee. There is often an associated limp and hip stiffness.
The ache is mild and usually presents immediately after getting up in the morning and after extended exercise, but it does not prevent walking.
An antalgic limp is observed in the first few weeks of the disease, and then the gait may become a stiff pattern with flexion and adduction hip contractures.
The flexion–adduction hip contracture results in an apparent limb shortening, with dipping of the pelvis and a short stride length during ambulation.
Muscle atrophy is often observed at the buttock, thigh, and knee.
Additional clinical signs include a positive Thomas test (hip flexion contracture) and a positive log-roll test (loss of internal rotation of the hip).
Growth in height is decreased during the early stages but returns to normal after healing.
IMAGING AND OTHER DIAGNOSTIC STUDIES
The diagnosis is typically confirmed by anteroposterior and frog-leg lateral radiographs.
Early in the disease (Waldenström stage of necrosis), radiographs show:
Increased inferomedial joint space
Lateral displacement of the femoral head18
Subchondral fracture21
Increased epiphyseal density
A small proximal epiphysis of the femur
During the Waldenström stage of resorption (fragmentation), there is a gradual removal of the sclerotic necrotic bone and the femoral epiphysis may deform.
As healing progresses with reossification, the epiphysis returns to a normal density and the femoral neck widens.
The proximal femoral physis may close prematurely.1
If the radiograph is not diagnostic, a bone scan or magnetic resonance imaging usually confirms the bone necrosis.
The bone scan shows a cold area in the femoral epiphysis in the early stage of necrosis.
With early revascularization (fragmentation stage of Waldenström), the scan will show the vascular ingrowth before radiographs.
Magnetic resonance imaging clearly demonstrates the necrotic epiphysis in the early stage of the disease; however, marrow edema should not be confused with the area of necrosis.
In the early stage, synovitis is observed, collapse and deformity of the cartilage of the epiphysis is usually clearly visible, and the degree of hinged subluxation (impingement) can be determined (FIG 3).17
In the fragmentation and reossification phases, vascular ingrowth is clearly visible.
Computed tomography shows bone well and is most helpful to evaluate hip incongruity during the late stages of remodeling and during young adulthood.
Skeletal hand bone age is decreased during the first year of the disease.
DIFFERENTIAL DIAGNOSIS
Toxic synovitis (irritable hip syndrome)
Infection, such as Lyme disease or tuberculosis
Avascular necrosis of known etiology such as sickle cell disease, hemoglobinopathies, Gaucher disease, trauma, and steroid bone necrosis
FIG 3 • Magnetic resonance image of the hip of a patient with Perthes disease showing lateral subluxation, synovitis, and acetabular–femoral impingement (hinged subluxation).
Arthritis, such as rheumatic fever
Multiple epiphyseal dysplasia
Tumors, such as chondroblastoma, leukemia, and lymphoma
Slipped femoral epiphysis (preslip stage)
NONOPERATIVE MANAGEMENT
Children less than 6 years of age without severe collapse of the femoral epiphysis have a good prognosis and do not require operative treatment.2
Their pain can be treated with nonnarcotic analgesic medications and crutch walking.
Hip stiffness can be managed with physical therapy that emphasizes hip abduction, internal rotation, and extension.
Children with necrosis involving less than 50% of the femoral epiphysis often have a good prognosis and operative treatment is often not necessary.
Children over 11 years of age may be an exception in that a femoral epiphyseal deformity may develop (segmental collapse) even with less than 50% involvement.10,20,26
SURGICAL MANAGEMENT
Indications
Necrosis of over 50% of the proximal capital femoral epiphysis
Age 6 to 11 years: Younger children often heal well without operations and adolescents poorly remodel the femoral deformity.
Waldenström stages of necrosis or fragmentation. Ideally the operation should be performed before substantial deformity occurs to the capital femoral epiphysis.
Mild subluxation of the hip with hinged impingement (acetabular–femoral impingement)
Possible indications
Children over 11 years of age with mild femoral epiphyseal collapse: These older children do not have adequate remaining growth to remodel the femoral epiphysis.
Children younger than 6 years of age with marked collapse of the femoral epiphysis: Typically children below 6 years of age heal well without treatment, but in severe cases, treatment may be indicated.
Patients with collapse of the epiphysis and hinged impingement: This operation may allow remodeling, but the outcome is less predictable.
Contraindications
Subluxation that cannot be reduced into the acetabulum
Children less than 6 years of age (these patients heal well without treatment)
Necrosis less than 50% of the proximal capital femoral epiphysis (these cases typically heal well without treatment)
Children who are too old to achieve acetabular overgrowth: Children over 11 years of age may get less benefit.
Positioning
The patient is placed in the supine position with the involved hip elevated by a longitudinal roll under the shoulder and back.
The roll should not extend down to the hip area.
The entire leg and hip is prepared and draped sterile to the anterior midline, to the posterior midline, and to the inferior rib line superiorly.
Approach
The approach for the labral support procedure is between the tensor fasciae lata muscle and the sartorius and rectus femoris muscles.
The dissection continues at the level of the anterior inferior iliac spine, beneath the origin of the gluteus minimus muscle (inferior gluteal line of ilium).
The triangular interval is developed: the iliac wing medially, the hip capsule inferiorly, and the gluteus minimus laterally.
With this approach, the origins of the abductor muscles are not elevated from the iliac wing, which we believe preserves the strength of hip abduction.
The reflected tendon of the rectus muscle is retracted laterally and then used to secure the bone graft of the labral support shelf.19
TECHNIQUES
ARTHROGRAPHY
Arthrography is performed to verify reduction of the subluxation and acetabular–femoral impingement.
With the arthrographic dye in the hip joint, the degree of femoral epiphyseal deformity and subluxation is observed with the image intensifier.
The leg is then abducted and the area of hinge abduction (acetabular–femoral impingement) is observed.
In many cases, the deformed femoral head will press against the lateral margin of the labrum and block the reduction of the femoral head into the acetabulum (TECH FIG 1A–C).
The arthrographic dye will pool in the medial–inferior joint, and with additional attempted abduction of the leg, the lateral margin of the labrum will deform upward.
In these cases, an adductor muscle tenotomy is then performed through a medial adductor incision.
Afterward, the leg is again abducted to determine the correction of the hinged abduction (ie, reduction of the weight-bearing surface of the femoral epiphysis within the acetabulum).
The hip is considered to be reduced if the deformed part of the femoral head (weight-bearing area) is under the lateral margin of the acetabulum (contained within the acetabulum), the medial dye pool is reduced, and the lateral margin of the labrum is not deformed.
If the hip reduces (TECH FIG 1D), proceed to operatively produce a bony shelf as described in the following section.
If the reduction is incomplete, a capsulotomy of the inferior aspect of the hip capsule can be performed through the same incision as used for the adductor muscle tenotomy. Then the hip can again be tested to determine reduction.
If reduction is achieved, proceed to operatively produce a bony shelf as described in the following section.
If hip reduction cannot be obtained, I recommend the procedure be terminated and postoperatively the leg be placed in skin traction or a bilateral broomstick cast until a gradual hip reduction can be obtained.
This is achieved by the patient's legs being progressively abducted in the ensuing postoperative days until complete reduction is accomplished.
The patient then returns to the operating room for continuation of the labral support shelf procedure.
TECH FIG 1 • A–C. Arthrograms of the hip of a patient with Perthes disease in which the leg is progressively abducted. The abnormal femoral head deforms the labrum with progressive abduction of the leg. D. AP radiograph of the hip of a patient with Perthes disease in which the femoral epiphysis is contained within the acetabulum as the leg is placed in abduction.
INCISION AND SUPERFICIAL DISSECTION
The incision starts at a point 1 cm inferior to the anterior superior iliac crest and extends laterally along the skin lines of Langer for about 3 cm (TECH FIG 2).
The dissection continues with a Cobb periosteal elevator between the tensor fasciae lata muscle and the sartorius and rectus femoris muscles.
The superior origins of the abductor muscles are not elevated from the outer wall of the iliac crest. I believe that maintaining the abductor muscles attached to the outer wall of the iliac wing improves postoperative hip abduction power.
With the periosteal elevator, a subperiosteal plane along the outer iliac wing about 3 cm wide is then developed beneath the gluteus medius and minimus muscles just above the hip. The image intensifier is useful to direct the periosteal elevator at a level of about 1 cm above the lateral margin of the acetabulum.
TECH FIG 2 • The bikini skin incision.
DEEP DISSECTION
An arthroscope is helpful for visualization during the remainder of the procedure.
The subperiosteal plane is developed further along the outer iliac wing over the hip capsule from the anterior inferior iliac spine toward the sciatic notch.
Caution is taken not to injure the labral growth cartilage of the acetabular margin.
The tendon of the reflected head of the rectus femoris, which is adherent to the hip capsule, is retracted laterally and preserved to be used later to support the bony shelf.
The capsule is exposed with a periosteal elevator: anteriorly to the level of the anterior iliac spine, posteriorly to the sciatic notch, and laterally about 2 cm.
While exposing the capsule, do not injure the lateral growth plate of the acetabulum. (The capsule may be thickened, but it is never thinned.)
TROUGH CREATION AND GRAFT COLLECTION
The level for the buttress shelf along the ilium is identified as about 3 mm above the labral growth plate of the acetabular rim. This corresponds to the superomedial margin of the hip capsule insertion into the ilium, a position that is verified with fluoroscopy by a metal marker (TECH FIG 3A).
A trough is then developed at this level, as described by Staheli,19 by making a series of 1-cm-deep holes at the edge of the acetabulum using a 5/32-inch drill (TECH FIG 3B).
The holes should be directed upwardly about 20 degrees and extended posteriorly and anteriorly sufficiently to provide the needed coverage.
Care must be taken not to damage the cartilaginous margin of the acetabular growth plate.
An osteotome, narrow rongeur, or power burr (or a combination) is used to connect the holes to make a trough that is about 1 cm deep and angled cephalad about 15 degrees. The floor of the trough is the subchondral bone of the acetabulum and should be level with the capsule (TECH FIG 3C).
Autogenous bone graft is obtained from the previously exposed outer wall of the iliac wing, which is just superior to the trough and beneath the gluteus medius muscle.
The graft is typically about 1 × 1 × 1.5 cm and is cut into three longitudinal strips.
TECH FIG 3 • A. Intraoperative AP fluoroscopy image with the level of the labral support (shelf) identified with a medal marker. The proper level is just above the cartilaginous labral growth area. (continued)
TECH FIG 3 • (continued) B. To begin creation of the trough, a line of upwardly inclined, 1-cm-deep holes is made where the rectus femoris tendon (now reflected) attaches to the acetabular margin. C. The holes are connected using a burr, osteotome, or narrow rongeur to create a slightly angled 1-cm-deep trough. An osteotome is then used to collect strips of cancellous and corticocancellous bone for the outer wall of the iliac wing.
CREATION OF THE SHELF
Several absorbable sutures (usually three) are placed through the outer fibers of the hip capsule to be used later to secure the pieces of bone graft to the capsule.
The leg is then placed in about 45 degrees of abduction and the deformed femoral head is again reduced into the acetabulum (contained), and this position is verified by the image intensifier. Caution: The femoral head must be contained within the acetabulum with no hinged subluxation, no deformity of the lateral labrum, and no impingement.
The leg is held in abduction of 45 degrees, flexion of 15 degrees, and neutral rotation through the remainder of the procedure (and as the spica cast is applied).
Autogenous bone graft is placed over the capsule, with the strips of bone inserted medially in the trough and laterally under the reflected head of the rectus femoris tendon, and the sutures are tied around the strips of graft to hold them snugly to the capsule (TECH FIG 4A).
The reflected head of the rectus femoris tendon is placed over the lateral aspect of the graft to add additional support.
About 30 to 60 mL of donor allograft bone may be added above the labral support (shelf) to create a buttress for additional support (TECH FIG 4B).
The graft will appear extensive when visualized by the image intensifier.
The purpose of the shelf is to support the labrum and prevent the hip from anterolateral subluxation during reossification of the lateral column of the femoral epiphysis.
Remember: The shelf is expected to resorb in about 3 years because it is not expected to be weight bearing but only to act as a buttress with support of the acetabular labrum.
The leg is held in abduction (as described earlier) with the femoral head in the reduced position as the incision is closed in layers.
The patient is placed in a one-and-one-half hip spica cast with the involved leg in abduction of 45 degrees, flexion of 15 degrees, and neutral rotation.
TECH FIG 4 • A. Two layers of autogenous bone graft strips are placed over the capsule, one with the strips inserted lengthwise and the other with the pieces laid side by side widthwise. The strips of bone are inserted medially in the trough and laterally under the reflected head of the rectus femoris tendon. Strong, nonabsorbable sutures are used to anchor the graft into the capsule, and additional morselized bone graft is placed on top of the created shelf. B. AP arthrogram of the hip of a patient with Perthes disease in whom the femoral epiphysis and labrum is supported by a labral support (shelf) procedure.
POSTOPERATIVE CARE
The cast, subsequent abduction contracture, and an abduction hip pillow at night offer initial containment. Later the labral support (shelf) acts as a buttress for the labrum to prevent resubluxation and hinging of the hip until the lateral column of femoral epiphysis reossifies.
The cast is maintained for 6 weeks and the child is allowed to walk in the cast as soon as postoperative pain resolves.
When the cast is removed, the patient is allowed to walk with “toe touch” crutch weight bearing for an additional 4 weeks and then allowed full ambulation without support.
An abduction contracture of the hip is expected to persist additionally for about 6 weeks after cast removal.
During the month after cast removal, an abduction hip pillow is used at night.
Exercises of the hip are encouraged to maintain flexion, extension, and abduction; adduction is not encouraged for at least 6 to 8 weeks after the cast is removed.
Abduction exercises of the hip to maintain at least 45 degrees abduction are continued until reossification of the lateral column of the femoral head.
OUTCOMES
Domzalski et al6 reported the results of 49 consecutive patients treated by the labral support (shelf) procedure for Perthes disease.
The procedure has a combined effect to prevent subluxation, to stimulate additional growth of the lateral rim of the acetabulum in a vertical dimension, and to provide temporary osseous containment until the shelf resorbs with time in a manner that is beneficial for preventing impingement of the femoral neck and greater trochanter on the shelf (FIG 4).
Willett et al27 reported the results of 20 children treated by a lateral shelf acetabuloplasty and recommended its use in children over 8 years of age with Perthes disease of Catterall groups II, III, and IV.
Van der Heyden and van Tongerloo28 reported on 25 patients with Perthes disease who were treated by a shelf procedure and had good or excellent results.
Other authors have also reported encouraging results with similar labral support (shelf) procedures,5,7,10–13,20,26 but to my knowledge there has been no controlled, prospective, and randomized study comparing this procedure to other methods of treatment.
FIG 4 • AP radiographs of the hip of a patient with Perthes disease in whom the deformed femoral head was treated by a labral support (shelf) procedure. There is remodeling of the femoral epiphysis, widening of the acetabulum, and resolution of the shelf.
COMPLICATIONS
Infection
Injury of the labral growth cartilage, which prevents growth stimulation of the acetabulum
Displacement of the labral support (shelf) bone graft
Improper placement of the labral support (shelf)
Neurovascular injury
Cast problems
REFERENCES
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