Innominate Osteotomy of Salter
Innominate Osteotomy of Salter
DEFINITION
The Salter innominate osteotomy is commonly performed in conjunction with an open reduction for the dislocated hip in developmental dysplasia of the hip (DDH) after 18 months of age.
The osteotomy can also be performed to treat acetabular dysplasia in the child with a concentrically reduced hip.6
ANATOMY
The Salter innominate osteotomy rotates through the symphysis pubis to increase anterior and lateral coverage of the femoral head.
The center of the hip undergoes slight distal, posterior, and medial displacement in addition to rotation.4
A 30-degree bone wedge inserted in the osteotomy site consistently increases femoral head coverage by 25 degrees anteriorly and 15 degrees laterally.4
PATHOGENESIS
Acetabular dysplasia is caused by the following:
Lack of a reduced, spherical head within the growing acetabulum
Abnormal interstitial or appositional growth within the acetabular and triradiate cartilage Abnormal development of the secondary centers of ossification of the ilium, pubis, and ischium
In the developmentally dislocated hip, the acetabular labrum is flattened, hypertrophied, everted, and is referred to as the Limbus.
Acetabular dysplasia in the infant and young child with DDH is predominantly anterior and lateral.7
NATURAL HISTORY
The natural history of the dysplastic hip with subluxation is worse than the hip with acetabular dysplasia alone.
Patients with subluxated dysplastic hips develop pain and disability and radiographic evidence of osteoarthrosis. The age of onset of symptoms depends on the degree of subluxation, with severe subluxation
leading to symptoms in the third decade of life.10
Patients with acetabular dysplasia without subluxation develop radiographic evidence of osteoarthrosis in the sixth decade of life and some will develop pain and disability, depending on the degree of dysplasia.10
PATIENT HISTORY AND PHYSICAL FINDINGS
Patients with developmental hip dislocation may have a positive family history and are usually female and firstborn children.
There may be a history of breech presentation at birth.
Children with a dislocated hip usually meet their gross motor milestones within the appropriate timeframe. In children with bilateral dislocations, walking is frequently delayed until 16 to 18 months.
The pertinent physical examination findings in the walking child (the timeframe when this operation is typically performed) are listed in the following text.
Gluteus medius lurch: Trunk lean over the stance phase leg signifies a positive test, which is a nonspecific sign of hip pathology caused by dislocation, coxa vara, or painful hip conditions.
Trendelenburg sign: If the pelvis dips away from the affected leg during single-limb stance, the test is positive. Like the gluteus medius lurch, a positive test is a nonspecific sign of hip pathology caused by dislocation, coxa vara, or painful hip conditions.
Galeazzi sign: Knees at different levels signify a positive test, which indicates unilateral hip dislocation or congenital shortening of the femur.
Limitation of hip abduction: Normal abduction range of motion is 70 to 80 degrees tested in flexion in the newborn and infant. Asymmetric abduction suggests unilateral hip dysplasia, subluxation, or dislocation. Bilaterally decreased abduction suggests bilateral disease.
Hamstring tightness test: Normally, the hamstrings will tighten with passive knee extension, and no knee hyperextension should be possible. A positive test implies hip dislocation or flaccid paralysis of the hamstring muscles.
Inspection of inguinal skin folds: Normal inguinal skin folds are symmetric and stop short of the anal aperture posteriorly. Asymmetric skin folds are a relatively nonspecific finding in the dislocated hip.
IMAGING AND OTHER DIAGNOSTIC STUDIES
Standing anteroposterior (AP), supine frog-leg lateral, supine abduction-internal rotation view, and standing false-profile view pelvic radiographs may be used.
On the AP film, the acetabular index should be measured to diagnose acetabular dysplasia. Normal values are 35 degrees at birth, 25 degrees at 1 year of age, and 20 degrees at 2 years of age (FIG 1).8
Also on the AP film, Shenton line is inspected for discontinuity, which represents hip subluxation (see FIG 1).
Widening of the acetabular teardrop can be seen with persistent acetabular subluxation due to inadequate loading of the medial acetabular wall.
A false-profile view of the hip can identify more subtle cases of acetabular dysplasia, particularly in the walking child.
The abduction-internal rotation view demonstrates the likely position of correction following Salter innominate osteotomy.
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FIG 1 • Measurement of the acetabular index and location of Shenton line. This schematic of an AP pelvis radiograph demonstrates a dislocated right hip. Hilgenreiner line is drawn through the top of the triradiate cartilages. A second line is drawn from Hilgenreiner at the inferior edge of the ossified margin of the acetabulum to the lateral edge of the ossified margin of the acetabulum. The angle between these two lines is the acetabular index. Shenton line should be a continuous arc between the medial femoral neck and the superior aspect of the obturator foramen in the normal hip. It is discontinuous in the subluxated or dislocated hip.
Advanced imaging studies (three-dimensional [3-D] computed tomography [CT] scanning of the acetabulum, magnetic resonance imaging [MRI] of the hip) may be of value in older children to assess acetabular morphology.
DIFFERENTIAL DIAGNOSIS
Congenital femoral deficiency Developmental coxa vara Legg-Calvé-Perthes disease
NONOPERATIVE MANAGEMENT
The acetabular index should be observed for improvement over 12 to 18 months after successful closed reduction in the child younger than 18 months of age.
Indications for a Salter innominate osteotomy include residual acetabular dysplasia with an increased acetabular index, widening of the acetabular teardrop, a broken Shenton line, and adductor tightness on clinical examination.
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FIG 2 • Patient positioning. The patient is placed with a gel roll longitudinally under the left hemithorax, elevating the left hemipelvis. The area of sterile preparation is from the rib cage proximally, the midline anteriorly and posteriorly, and the entire leg distally.
A child younger than 18 months old who fails closed reduction can be treated with an isolated open reduction of a dislocated hip and observed for improvement in the acetabular index into the normal range over 12 to 18 months. Salter innominate osteotomy is only indicated as per the criteria stated earlier.
SURGICAL MANAGEMENT
Indications
Age 18 months to 9 years5
Concentric hip reduction on an abduction-internal rotation radiograph (either preoperatively or intraoperatively after an open reduction)5
No or minimal osteoarthrosis of the hip
At least 100 degrees of hip flexion and 30 degrees of hip abduction Anterolateral acetabular dysplasia
Preoperative Planning
For the dislocated hip, a closed reduction is attempted.
If a gentle concentric closed reduction is achieved and the patient is older than 18 months old, a Salter innominate osteotomy including intramuscular psoas lengthening without open hip reduction can be performed.
An estimation of femoral anteversion with fluoroscopy before patient positioning is used to decide if a concurrent femoral derotational osteotomy is necessary.
We perform a judicious femoral derotational osteotomy if femoral anteversion is greater than 60 degrees if it is felt that it will enhance stability of the hip.
Positioning
The patient is placed supine on the operating table with a gel roll under the ipsilateral hemithorax (but not under the pelvis), raising the affected side into an oblique position.
The hip is prepared from the midline anterior and posterior, to the inferior rib cage proximally, and the ankle distally (FIG 2).
Approach
An anterior Smith-Petersen approach to the hip is used (FIG 3).
The oblique incision is centered 1 to 2 cm distal to the anterior superior iliac spine (ASIS).
No vertical extension is used, as it leads to a poor cosmetic result and does not enhance the exposure.
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FIG 3 • Surgical incision. A straight incision is placed obliquely over the anterior aspect of the hip and is centered 2 cm below the ASIS. Proximally, the incision lies distal to the iliac crest. Because the skin is mobile in the child, the incision can be easily moved to complete the exposure of the iliac crest and the anterior aspect of the hip without having it rest directly on the iliac crest. This also allows the incision to lie directly over the hip joint. A vertical distal limb of the incision is unnecessary for exposure and just leaves an unsightly scar.
TECHNIQUES
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Exposure of the Anterior Hip and Ilium
The exposure of the anterior hip is the same as for an open reduction of the hip in Chapter 87.
While retracting the external oblique muscle proximal and medial, the iliac apophysis is split with a no. 10 blade scalpel from the midpoint of the iliac crest to the anterior inferior iliac spine (AIIS).
The inner and outer tables of the ilium are subperiosteally dissected with a broad periosteal elevator to visualize the sciatic notch.
Sponges are used to facilitate subperiosteal dissection and to achieve hemostasis. An intramuscular psoas tendon lengthening is performed at the pelvic brim.
The rectus femoris tendon is only exposed and divided if exposure for an open reduction of the hip is required.
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Salter Innominate Osteotomy
Rang retractors are placed subperiosteally in the sciatic notch from the medial and lateral sides. The medial retractor is placed on top of the lateral retractor in the notch.
The Gigli saw is placed into a Kelly clamp and passed through the sciatic notch from medial to lateral (TECH FIG 1A).
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TECH FIG 1 • A. Gigli saw on top of Rang retractors placed subperiosteally in the sciatic notch. B. The osteotomy is created perpendicular to the plane of the ilium using the Gigli saw from the sciatic notch to the proximal edge of the AIIS. C. Location of the Salter innominate osteotomy.
Care is taken to push and not pull the Gigli saw through the sciatic notch, as pulling will cause engagement of the saw, and thus preventing its smooth passage.
The operating room table is lowered, and with hands as wide as possible, the Gigli saw is used to make the osteotomy, exiting just above the AIIS (TECH FIG 1B,C).
It is critical to make the cut perpendicular to the ilium and not the long axis of the patient.
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Harvesting Bone Graft
The triangular-shaped iliac crest bone graft is grasped with a Kocher clamp and removed with an oscillating saw from lateral to medial, from the AIIS to the iliac tubercle (TECH FIG 2A,B).
The resultant graft is a 30-degree tricortical bone wedge.
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TECH FIG 2 • A. An oscillating saw is used to cut the iliac crest bone graft from the AIIS to the midpoint of the iliac crest. B. The iliac crest graft is removed with Kocher clamp.
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Placing the Graft
A pointed towel clamp is used to hinge the distal fragment in line with the ilium rotating anterolaterally. The distal fragment is pulled anteriorly to prevent posterior displacement, and the posterior part of the osteotomy is kept apposed (TECH FIG 3A).
If done as an isolated procedure, opening the osteotomy site can be facilitated by placing the leg in the figure-4 position.
The graft is placed in the osteotomy gap concave side medial, with the medial cortex flush with the medial cortex of the proximal and distal fragments (TECH FIG 3B).
The graft is secured with two 2.8- or 3.2-mm threaded Steinmann pins placed from proximal across the graft into the medial and posterior portion of the distal fragment up to the triradiate cartilage (TECH FIG 3C).
Estimating Steinmann pin length: The Steinmann pin can be held along the medial surface of the osteotomy and graft to estimate the depth of pin insertion (TECH FIG 3D).
The acetabulum is palpated (if done with an open reduction) or the hip taken through full range of motion (if done as an isolated procedure) to ensure pins are extra-articular.
An intraoperative obturator oblique radiograph is taken with the pins in place to ensure they do not enter the triradiate cartilage or the hip joint (TECH FIG 3E,F).
Any prominent graft is trimmed anteriorly.
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TECH FIG 3 • A. Hinging open the osteotomy. A towel clamp is used to grasp the distal osteotomy fragment only. The proximal fragment is merely stabilized and the distal fragment is pulled in an anterolateral direction in line with the ilium. A spade-shaped elevator may be used to assist with hinging of the osteotomy. B. The graft is placed in the osteotomy site biased toward the medial cortex of the ilium. The medial cortex of the proximal fragment, graft, and distal fragment are flush with each other. The proximal, and particularly the distal, osteotomy fragments are wider than the graft, meaning that the lateral cortex of the graft is significantly more medial than the lateral cortices of the proximal and distal fragments. The posterior aspect of the osteotomy should remain closed to allow correct angulation. The graft need not be pushed fully to the apex of the osteotomy, as this may prevent angular correction by the osteotomy and instead just lengthen the ilium. C. Two threaded Steinmann pins are drilled from the proximal fragment across the posterior half of the graft to the distal fragment. The pins are placed just deep to the medial cortices. The surgeon is looking from proximal lateral to distal medial along the Steinmann pin path in this figure. (continued)
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TECH FIG 3 • (continued) D. Estimating Steinmann pin length. The Steinmann pin can be held along the medial surface of the osteotomy and graft to estimate the depth of pin insertion. E. Intraoperative obturator oblique pelvic radiograph shows the Steinmann pins holding the graft in place and stopping short of the triradiate cartilage. F. Reconstructed 3-D CT image to show exact position of graft, with optimally hinged osteotomy with desirable minimal anterior translation of distal fragment.
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Wound Closure
The iliac apophysis is approximated with a pointed towel clip and closed with absorbable suture in a figure-8 fashion (TECH FIG 4).
The first loop of the figure 8 is circumferential around the entire apophysis, and the second loop captures only the superficial half of the apophysis.
The pins are cut above the apophysis, coming to lie in the subcutaneous fat, for easy future removal.
The common head of the rectus femoris tendon is repaired to its insertion if it was divided to facilitate an open reduction.
Subcutaneous tissue and skin are closed in the standard fashion.
TECH FIG 4 • The iliac apophysis is approximated with a pointed towel clip and closed with absorbable suture in a figure 8 fashion. Note final position of the two Steinmann pins.
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PEARLS AND PITFALLS
Indications
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The osteotomy should be performed only for anterior and lateral acetabular
deficiency in the concentrically reduced hip.
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The surgeon should avoid performing the osteotomy in conditions with known posterior hip dysplasia, such as myelomeningocele or cerebral palsy.
Iliac
exposure
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Retracting the external oblique muscle away from the iliac apophysis avoids
unnecessary bleeding when cutting it.
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Raytec sponges placed subperiosteally on the inner and outer tables of the ilium aid in dissection and decrease bleeding.
Performing ▪ The AIIS needs to be fully exposed to determine the proper osteotomy exit position.
the ▪ The osteotomy is perpendicular to the ilium not the long axis of the patient. osteotomy
Opening
the osteotomy
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The osteotomy should be hinged open, pulling the distal fragment anterior and
keeping the posterior cortex of the osteotomy opposed.
Fixation
problems
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It is imperative to use intraoperative fluoroscopy to optimize pin position.
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Intra-articular pin placement should be ruled out by direct palpation if concomitant hip open reduction is being performed or by placing the hip through a full range of motion and feeling and listening for crepitus.
POSTOPERATIVE CARE
The patient is placed in a single-leg hip spica cast with the affected hip in the position of maximal hip stability at 30 degrees of flexion, 20 degrees of abduction, and 20 degrees of internal rotation (FIG 4).
When performed as an isolated procedure or with concomitant open reduction, young children should be immobilized in a single-leg spica cast for about 6 weeks, when early radiographic evidence of healing is evident. No supplementary bracing is typically required.
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FIG 4 • The patient is placed in a single-leg hip spica cast with the affected hip in the position of maximal hip stability at 30 degrees of flexion, 20 degrees of abduction, and 20 degrees of internal rotation.
Children older than the age of 7 years who are reliable may be allowed to use crutches and perform touchdown weight bearing on the affected side without the use of a single-leg spica cast.
OUTCOMES
Patients who have undergone an open reduction and Salter innominate osteotomy for late presenting developmentally dislocated hips have good to excellent functional and radiographic outcomes scores at
older than 45 years after the index procedure.9
Functional outcomes are best when the acetabular dysplasia is initially corrected to near-normal radiographic values.1, 3
COMPLICATIONS
Neurovascular injury to structures in the sciatic notch
Lateral femoral cutaneous nerve injury during surgical exposure
Inadequate correction of acetabular dysplasia due to inadequate patient selection preoperatively or inadequate acetabular rotation intraoperatively2
Injury to the femoral nerve due to prolonged retraction of the psoas muscle or incorrect identification of
the psoas tendon during intramuscular tenotomy
Pin penetration into the hip joint or triradiate cartilage Migration of the graft due to inadequate fixation2 Avascular necrosis of the femoral epiphysis2
Growth arrest of the triradiate cartilage
ACKNOWLEDGMENT
We thank Richard E. Bowen and Norman Y. Otsuka who wrote this chapter in the first edition.
REFERENCES
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Barrett WP, Staheli LT, Chew DE. The effectiveness of the Salter innominate osteotomy in the treatment of congenital dislocation of the hip. J Bone Joint Surg Am 1984;68(1):79-87.
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Gür E, Sarlak O. The complications of Salter innominate osteotomy in the treatment of congenital dislocation of the hip. Acta Orthop Belg 1990;56:257-261.
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Macnicol MF, Bertol P. The Salter innominate osteotomy: should it be combined with concurrent open reduction? J Pediatr Orthop B 2005;14:415-421.
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Rab GT. Biomechanical aspects of Salter osteotomy. Clin Orthop Relat Res 1978;(132):82-87.
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Salter RB. Innominate osteotomy in treatment of congenital dislocation of the hip. J Bone Joint Surg Br 1961;43-B(3):518-539.
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Salter RB. Role of innominate osteotomy in the treatment of congenital dislocation and subluxation of the hip in the older child. J Bone Joint Surg Am 1966;48:1413-1439.
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Sarban S, Ozturk A, Tabur H, et al. Anteversion of the acetabulum and femoral neck in early walking age patients with developmental dysplasia of the hip. J Pediatr Orthop B 2005;14:410-414.
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Scoles PV, Boyd A, Jones PK. Roentgenographic parameters of the normal infant hip. J Pediatr Orthop 1987;7:656-663.
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Thomas SR, Wedge JH, Salter RB. Outcome at forty-five years after open reduction and innominate osteotomy for late-presenting developmental dislocation of the hip. J Bone Joint Surg Am 2007;89(11):2341-2350.
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Weinstein SL. Natural history of congenital hip dislocation (CDH) and hip dysplasia. Clin Orthop Relat Res 1987;(225):62-76.