SURGICAL TECHNIQUES PEDIATRIC 2022, Dec, 23 | 12:00 am

Valgus Osteotomy for Perthes Disease

 

Chapter 78

Valgus Osteotomy for Perthes Disease

 

Ellen M. Raney

 

DEFINITION

  • Valgus osteotomy for Legg-Calvé-Perthes disease (Perthes disease) is a salvage operation. It is designed for those hips in which the primary goal of containment is no longer possible owing to hinge abduction. The following sections are focused on hips that have developed hinge abduction rather than a complete discussion of Perthes disease.

  • The valgus osteotomy relieves the hinging and improves congruency of the hip joint.

    ANATOMY

  • A femoral head with normal anatomy moves concentrically within the acetabulum. The lateral aspect of the femoral head glides under the acetabulum with abduction.

  • In severe Perthes disease with significant deformity of the femoral head, the lateral aspect of the head may impinge on the acetabulum with attempted abduction. Continued abduction creates a lateral hinge, which pulls the inferomedial portion of the head away from the acetabulum.4

    PATHOGENESIS

  • Hinge abduction is a consequence of several contributing factors.

  • Early in the process of Perthes disease there is cartilaginous overgrowth laterally and anteriorly. Later, during the healing process, this cartilage ossifies, contributing to the ridge of lateral bone.

  • Osteonecrosis of the bony epiphysis of the femoral head leads to recurrent subchondral fractures.

    • These fractures are associated with a loss of epiphyseal height and a change in shape from round to oval.

    • Fragmented portions of the epiphysis may be extruded laterally.

    • With collapse, the femoral head migrates proximally and laterally, progressively uncovering the lateral aspect of the femoral head.

  • Catterall’s description of “head at risk signs” identified four radiographic findings associated with the later development of hinge abduction.2

    • A lytic area on the lateral aspect of the epiphysis known as Gage’s sign3

    • Calcification lateral to the epiphysis

    • Lateral subluxation of the femoral head

    • A horizontal orientation of the physeal line (as opposed to the normal more medial inclination)

  • Hinge abduction is also seen in osteonecrosis of other causes but is commonly associated with Perthes disease.

    NATURAL HISTORY

  • At maturity, patients with unrelieved hinge abduction would generally be classified as Stulberg category IV (flattened femoral head with congruent acetabulum) or category V (flattened

femoral head with a round acetabulum), both of which have been found to be associated with early-onset osteoarthritis.5

  • Patients with hinge abduction often develop pain in the second decade of life.

     

    PATIENT HISTORY AND PHYSICAL FINDINGS

  • Patients typically have pain with activity that is relieved by rest.

  • The most notable physical finding is limited abduction of the hip. Often the patients are unable to abduct the hip to neutral. Attempted abduction is painful.

  • There is generally 1 to 2 cm of shortening.

  • Patients walk with an antalgic gait with the hip in adduction.

  • A positive Trendelenburg sign indicates weakness of the hip abductor mechanism, which is unable to stabilize the pelvis.

     

    IMAGING AND OTHER DIAGNOSTIC STUDIES

  • Gross hinge abduction may be visualized on plain radiographs (FIG 1A,B).

  • On arthrogram, visualization of pooling of dye medially with abduction of the hip is considered diagnostic. The arthrogram is studied in anteroposterior (AP) and lateral projections with abduction, adduction, and internal and external rotation to determine the position that maximizes congruency and relieves impingement (FIG 1C,D).

    DIFFERENTIAL DIAGNOSIS

  • Impingement from relative trochanteric overgrowth

  • Subchondral fracture

    NONOPERATIVE MANAGEMENT

  • Perthes disease often does not require any intervention.

  • Treatment strategies early in the course of the disease should focus on containment of the femoral head in the acetabulum and preservation of the range of motion.

  • Patients with hinge abduction have pain with activity.

  • If hinge abduction is seen on radiographs but the patient is symptom-free, an osteotomy would still improve the prognosis. In that scenario it would be reasonable to wait until the patient is symptomatic.

    SURGICAL MANAGEMENT

  • The valgus osteotomy is considered a salvage operation for late cases in which the femoral head has developed a lateral ridge that can no longer be brought under the acetabulum.

    Preoperative Planning

  • The arthrogram is reviewed. Extension, flexion, or rotation may be required in addition to valgus to fully relieve impingement and maximize congruency.

 

1583

 

 

 

 

 

 

 

 

 

 

 

 

A B C

 

FIG 1 • A. Radiograph demonstrates a lateral prominence of the femoral head impinging on the acetabulum. B. Lateral radiograph demonstrates anterior impingement. In a different patient.

(C) Arthrograms show hinge abduction with medial dye pool and

D improved congruency in adduction (D).

 

 

  • Preoperative templating is essential.

  • The template is rotated into abduction to check for lateral impingement.

    • The amount of valgus required to allow at least 10 degrees of abduction without lateral impingement is measured. Usually about 20 degrees of correction is required.

    • The oblique limb of the osteotomy should be just below the lesser trochanter.

    • Placing the transverse limb distally will bring the completed osteotomy parallel to the ground when the patient is standing.

  • Fixation should also be drawn on the template.

    • I prefer a 120-degree blade plate with a lateral stepoff, which provides medialization of the distal fragment (FIG 2).

    • The placement of the blade plate, rather than the saw cuts, will dictate the final position of the osteotomy.

  • To calculate the angle for insertion of the blade plate relative to the femoral shaft, the angle of the planned correction is subtracted from 120 degrees.

    • Example: For a desired 20 degrees of valgus correction, the blade is inserted at 100 degrees from the shaft. With the blade at 100 degrees, the shaft must come into 20 degrees of valgus to accommodate a 120-degree fixed-angle blade plate.

    • The blade plate should occupy 50% to 75% of the width of the femoral neck on the lateral projection for optimum strength.

       

      Positioning

  • The patient is placed supine on a radiolucent surgical table with a soft bump under the affected hip.

  • The surgeon should check that sufficient AP and lateral radiographs can be obtained.

    Approach

  • The lateral approach to the hip is used.

     

     

     

     

    FIG 2 • Two 120-degree blade plates with offset. The cannulated blade plate (left) was contoured to reach 120 degrees.

     

    TECHNIQUES

     

    EXPOSURE

    Gluteus medius

    Greater trochanter

    Incision

     

     

    • The fascia lata is split in line with the fibers over the pal-pated lateral border of the femur.

    • The vastus lateralis is elevated from the intermuscular sep-tum. Perforating vessels are identified and cauterized.

    • Proximally, the fascia of the vastus lateralis is opened anteriorly with the electrocautery along the vastus ridge, creating an L shape (TECH FIG 1).

    • The femur is exposed subperiosteally. The exposure should be extended sufficiently distal to allow removal of the previously measured segment of bone and the application of a plate.

       

      TECH FIG 1 • Line of incision in vastus lateralis.

       

      VALGUS OSTEOTOMY OF THE FEMUR USING A CANNULATED BLADE PLATE

      Guidewire Placement

    • If using a cannulated blade plate (Smith and Nephew, Memphis, TN), a guidewire is inserted in the proposed location for the blade.

    • To insert the wire at the proposed angle, a premeasured triangle equal to the supplement of the desired angle of insertion is held against the lateral aspect of the femur.

      • To use the previous example, 180 — 100 = 80 degrees (TECH FIG 2A).

    • In the lateral plane, the wire should parallel the proposed track of the blade plate (ie, centered in the femoral neck) (TECH FIG 2B).

    • The length of the inserted guidewire is measured.

    • The guidewire is inserted further than the templated blade plate depth.

      Chisel Insertion

  • The chisel is inserted parallel to the guidewire in the AP and lateral planes (TECH FIG 3A).

    • For pure valgus, the chisel is perpendicular to the lateral shaft of the femur (TECH FIG 3B).

  • To add extension or flexion, the chisel is rotated posteriorly or anteriorly from perpendicular, respectively. The desired amount of flexion or extension should be marked on the bone (TECH FIG 3C).

     

    A

     

    A B

    Center shaft

    of femor Angle of desired extension

     

     

    B

    TECH FIG 2 • A. Example of guidewire insertion for desired 20-degree correction. The wire is inserted at a 100-degree angle from the shaft, and an 80-degree triangle is held against the shaft to visualize the angle. B. Guidewire inserted at midpoint (AP plane).

     

    C

     

    TECH FIG 3 • A. Chisel inserted along guidewire. B. Chisel inserted perpendicular to shaft for pure valgus. C. Chisel directed posterior from axis of shaft to add extension.

     

     

     

    TECHNIQUES

     

    • The chisel is frequently backed up during insertion to prevent incarceration.

    • The path of the chisel is checked periodically with fluoroscopy.

    • The chisel is backed up to loosen it before making the osteotomy. The surgeon should verify it has backed up by checking the depth measurement.

      Making the Osteotomy

    • The proximal limb of the osteotomy should be planned as far distally from the base of the chisel as possible without interfering with the bend of the plate or the most proximal screw hole for plates without offset. This distance is usually just under 10 mm but should be checked for each plate, as systems vary (TECH FIG 4A).

    • A precut template wedge (a sterilized piece of a soda can works well) is used to mark the angle of the osteotomy.

    • The length of lateral cortex to be removed is also measured on the preoperative radiographs, but the measurement should be verified intraoperatively.

    • A longitudinal mark for rotation is made along the femur before making any cuts. The mark should be long

      enough not to be excised by the osteotomy. The mark should be well anterior to the plate so it will still be visible while the plate is being applied.

  • The proximal cut is parallel to the chisel in the lateral plane. This holds true whether the goal is pure valgus or valgus with extension–flexion. The distal cut is perpendicular to the shaft of the femur (TECH FIG 4B,C).

    Blade Plate Placement

  • When the chisel is removed, it should be exchanged for the blade plate quickly as the proper orientation is easily lost.

  • The blade plate should be inserted by hand initially to prevent deviation from the desired path.

  • The distal portion of the femur is reduced to the side plate and secured with a bone-reduction clamp.

  • Rotation is confirmed using the previously placed orientation line.

  • The side plate is secured to the femur using standard technique with the initial screws inserted in compression.

     

    B

    C

     

     

    A

     

    TECH FIG 4 • A. Angle of limbs of osteotomy in AP plane. The distal cut is transverse. B. In pure valgus, the osteotomy cuts are parallel in the lateral plane. C. For added extension, cuts are convergent anteriorly. Note proximal limb parallel to chisel in lateral plane.

     

    VALGUS OSTEOTOMY OF THE FEMUR USING A NONCANNULATED BLADE PLATE

    • The technique using a noncannulated blade plate is the same with the exceptions that follow.

    • With a solid blade plate, the guidewire should be inserted parallel to the proposed course of the chisel (TECH FIG 5A).

      • The wire should be far enough away so that it does not interfere with the chisel but should be close enough to follow easily.

    • This technique requires more frequent fluoroscopic images during chisel insertion to be sure the guidewire is being followed in both the AP and lateral planes. When

      A

      TECH FIG 5 • A. Solid system insert chisel parallel to guidewire.

      (continued)

       

       

       

       

       

      Center of femoral shaft

      Amount of extension

       

       

      TECHNIQUES

       

      Center of femoral shaft

       

      B C

       

      TECH FIG 5 • (continued) B. Guide arm of chisel is parallel to the femoral shaft for pure valgus. C. Guide arm of chisel parallel to femoral shaft for pure valgus.

       

      adding flexion or extension, at least one system (Synthes, Warsaw, IN) has a guide arm for the chisel that may be aimed posteriorly for extension or anteriorly for flexion (TECH FIG 5B,C).

      • The guide arm is not sufficiently rigid to maintain the correct amount of valgus but is quite useful to visualize the flexion–extension plane. The desired amount of flexion or extension should be marked on the bone.

      • The solid blade plates are sharper and more easily deviate from the desired path when exchanging the chisel

      for the blade plate. The guidewire must be followed carefully.

  • Radiographs are obtained before final seating to ensure the guidewire is being followed.

    • The surgeon should not attempt to move the leg into position for a lateral radiograph until the blade plate is inserted far enough to be secure. Performing this maneuver before there is adequate purchase will cause the blade plate to break out of the hole.

       

      PEARLS AND PITFALLS

      Chisel incarceration

       

      Loss of guidewire, cannulated system

       

      Loss of guidewire, noncannulated system

      Chisel insertion measurement

      • This can be prevented by frequently backing the chisel out.

      • The surgeon should be sure it really backs up. Check the markings. It is easy to be deceived.

      • This happens when the chisel is inserted past the end of the guidewire.

      • The surgeon should check with a radiograph while removing the chisel to verify the guidewire is staying in place.

      • This occurs when the chisel is inserted too close to the guidewire, destabilizing it.

         

      • The surgeon should verify before insertion whether the system being used puts the numbers above or below the hashmark (FIG 3).

      FIG 3 • The surgeon should be clear about the marks on the measurement instrument being used. In this example, the surgeon should know which line indicates 40 mm.

      30

      40

      50

      Osteotomy reduction, blade plate manipulation

      • The distal femur should be brought to the blade plate as much as possible. Excessive torque on the blade plate should be avoided.

      • The blade may break out of the proximal fragment, especially if insufficient distance was maintained between the bottom of the chisel and the osteotomy.

       

       

       

      POSTOPERATIVE CARE

    • Patients are allowed to bear weight as tolerated with crutches. Patients who are expected to be noncompliant with crutches and activity limitations are placed in a single-leg spica cast.

    • Elective hardware removal is controversial. I prefer hardware removal 1 to 2 years postoperatively or after bony union is obtained in patients in whom the likelihood of future surgery, including joint arthroplasty, is high.

      OUTCOMES

      • Three recent publications1,4,6 reported subjectively satisfactory results (by varying standards) in 66% to 94% of patients at 5 to 10 years of follow-up. Average Iowa hip scores ranged from 86 to 93. Further hip surgery had been performed on 10% to 20% of patients.

      • Two of the three recent articles noted no significant changes in the Sharp angle and percent coverage.1,4 One study noted a

       

      significant difference in the percent coverage and superior joint space.6

  • Bankes et al1 reported two factors associated with favorable remodeling, both concerning the timing of surgery: when the osteotomies were carried out during the healing phase of Perthes disease, and when they were carried out in patients with open triradiate cartilages.

    COMPLICATIONS

  • Nonunion is rare with the osteotomy in the immediate sub-trochanteric region. If the osteotomy is created more distally in the diaphyseal bone, nonunion may occur.

  • Hardware failure most commonly occurs via the blade plate breaking out of the proximal fragment, when too small of a bone bridge was preserved.

  • Valgus osteotomy for Perthes disease is a salvage procedure. The desired outcome is to relieve pain and delay the progression of osteoarthritis. It is important to communicate

preoperatively that the progression of osteoarthritis is not prevented.

 

REFERENCES

  1. Bankes MJ, Catterall A, Hashemi-Nejad A. Valgus extension osteotomy for ‘hinge abduction’ in Perthes’ disease: results at maturity and factors influencing the radiological outcome. J Bone Joint Surg Br 2000;82B:548–554.

  2. Catterall A. Legg-Calve-Perthes disease. AAOS Instr Course Lect 1989;38:297–303.

  3. Gage HC. A possible early sign of Perthes’ disease. Br J Radiol 1933;6:295–297.

  4. Raney EM, Grogan DP, Hurley ME, et al. The role of proximal femoral valgus osteotomy in Legg-Calve-Perthes disease. Orthopedics 2002;25:513–517.

  5. Stulberg SD, Cooperman DR, Wallensten R. The natural history of Legg-Calve-Perthes disease. J Bone Joint Surg Am 1981;63:1095–1108.

  6. Yoo WJ, Choi IH, Chung CY, et al. Valgus femoral osteotomy for hinge abduction in Perthes’ disease: decision-making and outcomes. J Bone Joint Surg Br 2004;86:726–730.