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Periacetabular Osteotomy and Femoral Osteotomy

 

Periacetabular Osteotomy and Femoral Osteotomy

 

 

 

THE BERNESE PERIACETABULAR OSTEOTOMY

Developmental dysplasia of the hip (DDH) is associated with structural deformity of the acetabulum that creates mechanical dysfunction and has been recognized as a major factor in the etiology of osteoarthritis of the hip joint (1,2,3). Symptomatic acetabular dysplasia in the congruous dysplastic hip is usually treated by realignment pelvic osteotomy. Although proximal femoral osteotomies alone are utilized less for stabilizing hips with residual acetabular dysplasia (4), femoral osteotomies may be indicated in association with a pelvic osteotomy in cases of severe hip deformity (5). Several techniques of periacetabular osteotomies have been proposed to reorient the dysplastic acetabulum and normalize the mechanics of the hip. Single innominate osteotomy (6) is insufficient to restore joint stability in more complex and severe dysplasia in the adult population. Spherical and rotational acetabular osteotomies (7,8,9) are reported to provide excellent coverage of the femoral head. However, the small size of the acetabular fragment may introduce difficulty with stable fixation, delay patient ambulation, and compromise the blood supply to the acetabular fragment (10).

In 1988, Ganz et al. (11) described the polygonal-shaped Bernese periacetabular osteotomy (PAO) that has the advantages of a relatively large and yet mobile acetabular fragment. The Bernese PAO allows correction in multiple planes and rigid fixation while preserving the blood supply to the acetabulum (12), the abductor muscles (13), and the posterior column, which permits early partial weight bearing. The Bernese PAO has become the most widely used acetabular reorientation osteotomy in North America for the mature dysplastic hip (5,14,15,16,17,18,19,20).

 

Indications and Contraindications

The goals of the Bernese PAO are to reorient the dysplastic acetabulum while reducing pain and improving the function of the hip, with the long-term intention of slowing the progression or preventing symptomatic end-stage arthritis. The Bernese PAO is typically indicated for the treatment of symptomatic acetabular dysplasia in the adolescent and young adult, although it has also been applied for the treatment of severe acetabular retroversion leading to femoroacetabular impingement (FAI). The recommendation to proceed with a Bernese PAO is based on several clinical and radiographic factors. Age is a limiting factor: because the Bernese PAO crosses the posterior aspect of the triradiate cartilage, the procedure is controversial in patients with an open triradiate cartilage. Upper limit of age is controversial although older age at surgery and higher degree of secondary osteoarthritis are recognized as risk factors for PAO failure (18).

Specifically, young (younger than 40 years), healthy patients with well-preserved hip motion and a congruous hip joint should be considered for joint preservation surgery even in the presence of mild secondary osteoarthritis. Contraindications include severe femoral head subluxation with the formation of a pseudoacetabulum, complete dislocation, and end-stage osteoarthritic changes.

 

 

 

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Preoperative Preparation

Typically, patients with acetabular dysplasia present with groin pain or lateral or anterior hip pain that is

aggravated by upright activities. Physical examination should include an overall assessment of the musculoskeletal system with dedicated attention to the quality of gait, hip range of motion, muscle strength, and provocative maneuvers. Special tests include the anterior impingement test, the apprehension test, and the bicycle test. The anterior impingement test is performed with the patient supine. The hip is flexed to about 90 degrees and is adducted and internally rotated, which approximates the femoral neck and the acetabular rim leading to groin or anterior hip pain if the acetabular labrum is damaged. Pain or a sense of instability may be reproduced with the hip extended, abducted, and rotated outward (apprehension test). With the patient in lateral decubitus, abductor muscle strength can be assessed and the bicycle test reflecting abductor muscle insufficiency can be performed (Fig. 9-1).

 

 

 

FIGURE 9-1 Physical examination of the hip. A: Anterior impingement test. The anterior impingement test is performed with the patient supine. The hip is flexed to about 90 degrees and is adducted and internally rotated, which approximates the femoral neck and the acetabular rim leading to groin or anterior hip pain if the acetabular labrum is damaged. B: Apprehension test. The patient is positioned supine and pain or a sense of instability may be reproduced with the hip extended, abducted, and rotated outward. C: Bicycle test. With the patient in lateral decubitus, abductor muscle strength can be assessed and the bicycle test performed.

 

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Initial imaging evaluation includes an anteroposterior (AP) pelvic plain radiograph with the patient standing and the beam centered on the femoral heads. The acetabular coverage can be estimated by the lateral center-edge angle (LCEA) of Wiberg (21) (normal is higher than 25 degrees) and by the acetabular index of Tönnis (22) (normal is between 0 and 10 degrees) (Fig. 9-2). The Shenton line is an indicator for subluxation when there is a break greater than 5 mm. The severity of subluxation can be estimated by measuring the extrusion index.

 

Acetabular retroversion is identified by the

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crossover sign (23) and by the projection of the ischial spine into the pelvis (24). The false-profile view assesses the anterior coverage of the femoral head by measuring the anterior center-edge angle (ACEA; normal is higher than 20 degrees) (25). A lateral radiograph of the proximal femur gives information about the sphericity of the femoral head and the head-neck offset that can be quantitatively evaluated by the alpha angle and the headneck offset ratio (26). Functional radiographs with the hip in abduction/internal rotation assess the congruency of the hip. Diagnosis of acetabular dysplasia by definition involves relative undercoverage of the femoral head, as measured by any of the following parameters (22,25,26):

 

 

 

FIGURE 9-2 Radiographic assessment of the dysplastic hip. A: The lateral center-edge angle (LCEA) of Wiberg is the angle formed by a perpendicular line to the line connecting the center of the two femoral heads and a line connecting the center of the femoral head to the most lateral aspect of the ossified sourcil. Normal value is higher than 25 degrees. B: The Tönnis acetabular inclination angle is measured by the angle formed by a line

drawn through the inferior aspect of the acetabular sourcil that is parallel to the line connecting the inferior aspect of the tear drop and a line connecting the lateral and medial aspects of the acetabular sourcil. Normal values are between 0 and 10 degrees. Note the abnormal high Tönnis angle on the right hip. The Shenton line is broken on the right hip, which denotes hip subluxation. C: The femoral head extrusion index is a percentage that is calculated by dividing the horizontal distance of the portion of the femoral head that is lateral to the edge of the acetabulum (A) by the horizontal width of the femoral head (A+B) and multiplied by 100. D: A vertical line through the center of the femoral head and a line through the center of the femoral head to the most anterior point of the acetabulum form the anterior center-edge angle on a false-profile radiograph. Measurements of less than 20 degrees indicate structural instability.

 

 

Lateral center-edge angle less than 20 degrees

 

Tönnis acetabular inclination greater than 10 degrees

 

 

Percent coverage less than 80%/extrusion index greater than 20% Anterior center-edge angle less than 20 degrees

When performing the Bernese PAO, there is a fine balance between undercorrection and overcorrection and the potential for causing secondary FAI. Achievement of optimal acetabular correction following a Bernese PAO is important for long-term clinical success (18). When planning for the radiographic correction of acetabular dysplasia, we recommend the LCEA between 25 and 40 degrees, ACEA between 18 and 38 degrees, Tönnis angle between 0 and 10 degrees, medial offset distance less than 10 mm, postoperative extrusion index less than or equal to 20% and no retroversion sign. It should be noted that optimal correction varies according to the underlying pathomorphology of the hip.

Advanced imaging techniques such as computed tomography (CT) scan and magnetic resonance (MR) imaging play a role in both understanding the biomechanical environment of the hip and estimating the prognosis after surgical intervention. Secondary damage to the labrum and articular cartilage may compromise the results of the Bernese PAO; therefore, appropriate imaging is recommended as part of the preoperative planning. The delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC) technique of the dysplastic hip has been shown to correlate well with success or failure of PAO (27).

 

Technique

We currently prefer epidural and/or general anesthesia for patients undergoing the Bernese PAO. Prophylactic antibiotics are administered, continuous electromyography peripheral nerve monitoring is optional, and a Cell Saver (Haemonetics, Braintree, MA) is used for blood transfusion. Intraoperative fluoroscopy is recommended to evaluate the osteotomy cuts and assists in the acetabular positioning and fixation. The patient is positioned supine on a radiolucent table. The entire lower extremity and the hemipelvis are prepared and draped, and nerve-monitoring leads are placed. The original technique described by Ganz et al. (11) utilized an iliofemoral approach involving extensive abductor dissection and transection of both the indirect and direct heads of the rectus femoris tendon. Since the original description, there have been several reports describing different approaches to perform the Bernese PAO. These include a direct anterior approach without abductor dissection

(13) and (more recently) a rectus femoris preserving approach (28) that minimize the morbidity and improve recovery. We typically perform a modified Smith-Petersen approach preserving the abductors. The rectus femoris tendon is preserved in cases where there is more than 90 degrees of flexion and more than 20 degrees of internal rotation preoperatively with no proximal femur head-neck deformity and no full-thickness labral tear on preoperative MRI or in cases where a hip arthroscopy is performed in combination with the Bernese PAO. The incision begins proximally and extends just lateral to the iliac crest and the anterior superior iliac spine (ASIS) curving distally and laterally to about 10 cm (Fig. 9-3). The aponeurosis of the external oblique muscle is

 

reflected medially off the iliac crest. The sartorius and inguinal ligament insertion are detached by a wafer osteotomy of the ASIS. Distally, the tensor fasciae latae compartment is entered, and the sartorius is identified. The lateral femoral cutaneous nerve is not exposed and is protected within the sartorius fascia. The dissection is extended deep onto the origin of the rectus femoris. The indirect head of the rectus femoris is identified and released leaving a stump of tendon for later repair. The direct head of the rectus is released from the anterior inferior iliac spine exposing the underneath iliocapsularis muscle. The rectus tendon and muscle then are elevated distally and medially together with the iliocapsularis muscle from the joint capsule. The iliocapsularis muscle fibers are reflected off the anterior hip capsule, and the interval between the anterior hip capsule and the iliopsoas tendon is developed. A pair of Metzenbaum scissors is inserted into the interval that is enlarged. Blunt dissection

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using a noncutting Lane retractor or a hip skid allows for palpation of the infracotyloid groove of the ischium. The anterior inferior aspect of the joint should not be entered.

 

 

 

FIGURE 9-3 Drawing of the modified Smith-Petersen approach. A: The incision begins proximally and extends just lateral to the iliac crest and the anterior superior iliac spine (ASIS) curving distally and laterally to about 10 cm. Deep dissection is through the fascia envelope of the tensor fascia latae to preserve the lateral femoral cutaneous nerve. B: After the rectus femoris has been released, the iliocapsularis is elevated from the hip capsule, and the interval between the capsule and the psoas tendon is developed. A pair of scissors is placed in the depth of the interval, and the infracotyloid groove of the ischium can be palpated. (From Clohisy JC, Barrett SE, Gordon JE, et al. Periacetabular osteotomy in the treatment of severe acetabular dysplasia. Surgical technique. J Bone Joint Surg Am 88(Suppl 1 Pt 1): 65-83, 2006. Review.)

 

At this time, the incomplete ischial osteotomy can be performed with a special curved chisel positioned in the infracotyloid groove. The position of the chisel should be about 5 to 10 mm from the teardrop image and should be confirmed in both AP fluoroscopy imaging and a 55-degree oblique view. The ischial osteotomy aims toward the ischial spine as visualized on the 55-degree oblique fluoroscopy C-arm image. The chisel is first inserted along the medial cortex and is advanced to the level of a trajectory bisecting the posterior column (approximately

1 cm anterior to the posterior cortex of the posterior column). The chisel is then introduced in the center of the ischium, and finally, the lateral aspect of the ischium is cut. The lateral cut is only 15 mm deep because of the narrowing of the posterior column laterally and the proximity of the sciatic nerve (Fig. 9-4). Positioning the lower extremity in abduction can minimize risk of sciatic nerve damage.

 

Once the first incomplete ischial cut is performed, attention is then turned proximally for preparation of the superior pubic ramus osteotomy. Retracting the iliopsoas and the femoral neurovascular bundle medially exposes the superior pubic ramus. Hip flexion and adduction facilitate exposure and subperiosteal dissection of the superior pubic ramus. A narrow Homan retractor is then advanced onto the superior pubic ramus, medial to the iliopectineal eminence. The superior pubic ramus osteotomy can be performed with a small oscillating saw to the deep cortex and completed with an angled osteotome. An alternative is to perform the osteotomy using a Gigli saw technique (Fig. 9-5). The pubic osteotomy is angled away from the joint and is oriented from anterolateral to posteromedial. Mobility between the two fragments of the pubic ramus should be confirmed, and the periosteum should be released completely to facilitate later mobilization of the fragment.

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FIGURE 9-4 First osteotomy of the Bernese PAO: incomplete ischial cut. This cut is made in three passes: first medial, then central and lateral. The position of the osteotomy is confirmed in the AP fluoroscopy imaging: medial (A), then central (B), and finally lateral (C). D: The depth of the osteotomy is confirmed on a 55-degree oblique fluoroscopy imaging. The lateral pass should be shorter than the medial and central pass to avoid injury to the sciatic nerve.

 

 

 

FIGURE 9-5 Second osteotomy of the Bernese PAO: the superior pubic ramus osteotomy. The ramus is cut perpendicular to its long axis when viewed superiorly and oblique from proximal-lateral to distal-medial when viewed from the front. A: The osteotomy can be performed with an oscillating saw. B: As an alternative technique, a Gigli saw can be used.

 

 

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The ilium and the posterior column are stripped subperiosteally in anticipation of the supra-acetabular and

posterior column osteotomies. A radiolucent retractor is placed along the inner aspect of the quadrilateral surface

toward the ischial spine. In preparation for the supra-acetabular and posterior column cut, a straight chisel is placed approximately 1 cm superior and lateral to the pelvic brim. Using fluoroscopy C-arm imaging, the trajectory of the posterior column cut is planned, and a target hole is marked with a drill or a high-speed burr to mark the intersection of the iliac supra-acetabular and posterior column cuts. A small subperiosteal window is developed just distal to the ASIS at the lateral aspect of the ilium to protect the abductor muscles. The supra-acetabular cut is performed from just proximal to the osteotomy of the ASIS directly toward the sciatic notch with an oscillating saw, first along the medial cortex (Fig. 9-6). The hip is abducted, and the outer iliac cut is made with the saw.

The posterior column is exposed with a radiolucent bent retractor, and the posterior column cut is made with the goal of bisecting the posterior column between the articular surface anteriorly and the posterior cortex. This cut is made at an approximate angle of 120 degrees to the supra-acetabular cut (Fig. 9-7). A straight osteotome is used to make a first pass along the medial cortex. The orientation of this cut is monitored with fluoroscopy, and the cut is then completed typically extending to about 5 cm down the posterior column. Three passes are made: one medial, one central, and one lateral. The lateral pass of the osteotome is only extended for 4 cm because of thinning of the posterior column distally and the proximity of the sciatic nerve. A Schanz pin is placed into the acetabular fragment in the supra-acetabular region. A lamina spreader is placed in the corner of the iliac and posterior column cuts, and the mobility of the fragment is tested. Typically, the corner between the supra-acetabular and posterior column cut requires completion of the osteotomy using an angled osteotome. The acetabular fragment should be free to be mobilized and positioned at this time. If this is not the case, we first inspect the periosteum around the superior pubic ramus and the ramus osteotomy is displaced. Then, the posterior cortex at the 120-degree corner and the posterior column lateral cortex are tested as potential sites of incomplete osteotomies.

 

 

 

FIGURE 9-6 Third osteotomy of the Bernese PAO: the iliac supra-acetabular cut. A: In preparation to the iliac cut, a small window is created in the lateral ilium, and a straight narrow Homan retractor is placed to protect the abductor muscles. The Homan retractor marks the level of the cut in the AP fluoroscopy view—typically about 3 cm above the joint. B: The end-point of the iliac supra-acetabular osteotomy is marked with a highspeed burr and corresponds to the corner of the starting point of the posterior column osteotomy. C: The iliac osteotomy is performed from the ASIS toward the superior aspect of the sciatic notch and stops about 1 cm above the iliopectineal line anterior to the notch, at the level of the high-speed burr mark.

 

 

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FIGURE 9-7 The fourth osteotomy of the Bernese PAO: the posterior column osteotomy. A: The posterior column cut is performed in three passes. Initially, a straight chisel is inserted with its blade outside the medial cortex to assure that only the medial cortex is cut. B: The straight chisel is advanced toward the ischial spine, directed about 120 degrees from the iliac cut. The orientation of the posterior column cut is monitored with a 55-degree oblique fluoroscopy C-arm view. The cut should split the posterior column in half, leaving at least 1 cm of bone anteriorly to avoid penetrating the joint. C: The posterior wall cut aims toward the end of the first incomplete ischial cut. D: The posteroinferior corner between the first cut and the posterior column cut can be completely freed by using an angled chisel.

 

The acetabulum is repositioned to optimize the surgical correction (Fig. 9-8). The superior pubic ramus should be completely displaced superiorly by anterolateral mobilization of the acetabular fragment to correct lateral coverage. The acetabulum is repositioned with internal rotation (to avoid retroversion) and forward tilt extension (to improve anterior coverage) and medially translated. It is important to assure that there is bone-to-bone contact with the overlying ilium. The acetabular fragment is provisionally fixed with three 2.4-mm Kirschner wires. The position of the acetabular reduction

 

 

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is assessed intraoperatively by obtaining a fluoroscopy image of the entire pelvis centered over the symphysis pubis. The fluoroscopy C-arm is angled to accomplish a correct pelvic tilt with the relation of the sacrococcygeal joint and the symphysis pubis being similar to the preoperative AP radiograph. In the AP pelvis image, the position of the acetabular fragment is established by assessing the following:

 

 

 

FIGURE 9-8 Repositioning the acetabular fragment. A: A Schanz pin is inserted into the supra-acetabular area and serves as a guide to the reorientation of the acetabular fragment. B: A schematic drawing of the left hemipelvis after PAO. C: The fragment is initially brought up toward the ceiling and pulled down (forward tilt extension) to increase anterior coverage. D: The fragment is then rotated laterally (adduction) and distally to increase lateral coverage (curved black arrow). Note that with this maneuver, there is a superior displacement of the superior pubic ramus (blue arrow). Finally, the fragment is translated medially (red arrow) and internally rotated in the sagittal axis to correct the acetabular version to neutral.

 

 

Lateral center-edge angle: the goal is to be between 25 and 40 degrees.

 

Acetabular inclination: the Tönnis angle is between 0 and 10 degrees.

 

 

Medial translation of the hip-joint center: the goal is to have the extrusion index less than 20%. Position of the teardrop: it should be elevated.

 

Version: the goal is to avoid retroversion (no crossover sign) or excessive anteversion.

A 65-degree oblique view is obtained with the C-arm and the anterior coverage of the femoral head is assessed. The goal is to have the ACEA between 18 and 38 degrees. If necessary, the acetabulum is repositioned to achieve optimal correction. The acetabulum is then fixed with three or four 4.5-mm cortical screws. If needed, a screw can also be placed from the anterior acetabular fragment into the ilium. Once definitive fixation is achieved, fluoroscopic images are then made again to confirm the acetabular reduction and to test for joint range of motion. At least 90 degrees of hip flexion and 20 degrees internal rotation should be obtained, and if this is not the case, then the fragment should be repositioned, or more commonly, the hip joint should be assessed by an anterior arthrotomy to evaluate for FAI. The arthrotomy allows for visualization of the acetabular labrum and the femoral head-neck junction. Unstable labral tears are repaired with suture anchors. Surgical repair is not performed for stable labral tears. An osteochondroplasty of the femoral headneck junction is then performed with a high-speed burr. After the osteochondroplasty, hip motion is checked to confirm that there is no anterior impingement. In cases of severe femoral deformity, an intertrochanteric femoral osteotomy may be necessary as determined preoperatively. The anterior hip capsule is approximated with absorbable suture. The rectus tendon origin is repaired with nonabsorbable suture. The site of the ASIS osteotomy is repaired with nonabsorbable suture through drill holes in the ilium.

The remainder of the superficial wound is closed in a routine fashion.

 

Pearls and Pitfalls

Incomplete Ischial Cut

 

 

Enlarge the interval between the hip capsule and psoas tendon with a noncutting instrument. Careful placement of the chisel and position confirmed with fluoroscopy C-arm .

 

Three passes are made: first medial, then central to about 2 to 2.5 cm aiming toward the ischial spine. The most lateral pass should not exceed 1.5 cm to avoid injury to the sciatic nerve.

 

During the most lateral, the lower extremity should be in abduction and slight external rotation to avoid tension of the sciatic nerve.

 

Superior Pubic Ramus Cut

 

 

Complete subperiosteal exposure is recommended to avoid damage of the obturator neurovascular bundle. Avoid excessive tension while retracting the psoas tendon and femoral neurovascular bundle.

 

 

The cut is medial to the iliopectineal eminence to avoid creating an intra-articular osteotomy. Make sure the periosteum is released after the cut to facilitate fragment mobilization.

 

Supra-acetabular Iliac Cut

 

Start at the level of the ASIS aiming toward the top of the sciatic notch. This higher location allows better bone for fixation and protects the blood supply to the fragment.

 

Two passes with the oscillating saw are recommended: first, the medial cortex is cut with the lower extremity flexed and adducted. To complete the lateral cortex cut, the lower extremity should be abducted.

 

Mark the corner between the supra-acetabular cut and the posterior column cut with a high-speed burr.

 

Posterior Column Cut

 

Fluoroscopy C-arm guidance is recommended. The cut should split the posterior column in half (anterior to posterior).

 

Three passes are recommended with the chisel: medial, central, and lateral cortex. Avoid extending the lateral pass over 4 cm because the posterior column narrows distally. The lateral pass should be performed with the leg in abduction.

 

Before attempting to mobilize the fragment, make sure the corner between the supra-acetabular cut and the posterior column cut is free.

 

 

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Fragment Positioning

 

Avoid acetabular retroversion (crossover sign).

 

 

Acetabular sourcil should be horizontal with LCEA 25 to 40 degrees. Medialization of the joint

 

Reassure hip motion is greater than 90 degrees of flexion and 20 degrees of internal rotation. If impingement is suspected, an arthrotomy is warranted for labral inspection and osteochondroplasty of the femoral headneck junction.

 

Postoperative Management

If an epidural catheter is used, it can be kept in place to assist with postoperative pain management for 24 to 48 hours. Alternatively, the patient can be mobilized within 12 to 24 hours. Physical therapy is started after the catheter is removed. We allow weight bearing for about 20% to 30% body weight with the use of a pair of crutches for the initial 4 to 8 weeks. A continuous passive motion machine is used for the first 4 weeks postoperatively. Thrombosis prophylaxis is achieved by using compressive devices as well as low weight subcutaneous heparin or aspirin for the first 4 weeks after surgery. The patient is seen in clinic at 2, 6, and 12 weeks postoperatively. After 12 weeks, complete healing of the osteotomies is expected, and the rehabilitation is advanced toward endurance and strength training.

 

Results and Complications

We recently performed a systematic review of the literature (29), and we report that radiographic correction was consistent and improvement in hip function and pain was noted in all studies evaluated. Clinical failure was associated with moderate to severe preoperative osteoarthritis, and conversion to total hip replacement was reported in 0% to 17% of cases. Major complications were noted in 6% to 37% of the cases. Our data indicate that the Bernese PAO provides pain relief and improved hip function in most patients over short- to midterm follow-up. The longest follow-up data available come from the Swiss group. Steppacher and colleagues (18) reported on a minimum of 19 years (mean, 20.4 years; range 19 to 23 years) follow-up of 58 patients (68 hips) operated at a mean age of 29 years old (range, 13 to 56 years). They identified age at surgery, preoperative clinical scores, anterior impingement, limp, osteoarthritis grade, and postoperative extrusion index as predictors of poor outcome. Sixty percent of the hips were preserved at 20 years.

In the systematic review of the literature, major complications were noted in 6% to 37% of the cases. Most common complications included symptomatic heterotopic ossification, wound hematoma, nerve palsies, intra-articular osteotomies, loss of fixation, and inadequate reduction/positioning of the osteotomy. We

 

acknowledged that the long learning curve associated with the Bernese PAO and the rate of complications

should decrease with increased experience.

 

 

FEMORAL INTERTROCHANTERIC OSTEOTOMY

Proximal intertrochanteric femoral osteotomy (ITO) can be applied to produce different corrective angulations in the coronal and sagittal planes. A valgus-producing ITO adducts the proximal segment and results in relative lengthening of the lower extremity. A varus-producing ITO abducts the proximal segment and inherently shortens the length of the femur (30). Limiting the magnitude of the angular correction and avoiding the use of bone wedge resections can minimize the shortening effect. Correction in the sagittal plane is typically performed in flexion or extension.

 

Indications for ITO

 

Valgus ITO

 

 

Nonunion of femoral neck fracture

 

 

Osteonecrosis of the femoral head (small lesion located laterally and superiorly) Hinge abduction after Legg-Calvé-Perthes disease

 

Minimum of 15 degrees of passive hip adduction is necessary.

 

Varus ITO

 

 

Correction of coxa valga associated with DDH

 

 

 

Treatment of early fragmentation stage of Legg-Calvé-Perthes disease Osteonecrosis of the femoral head (medial or central located small lesions) 15 degrees of passive hip abduction is a prerequisite.

 

Flexion ITO

 

 

Deformity secondary to slipped capital femoral epiphysis (SCFE) leading to FAI

 

Proximal intertrochanteric femoral osteotomies in general are recommended in symptomatic young patients who have preserved range of motion of the hip, improved congruency on functional radiographs, and absence of signs of advanced osteoarthritis. Contraindications to ITO include

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inflammatory arthritis, severe osteoporosis, active infection, and severe stiffness. Incongruency of the hip is a contraindication for varus, but not a contraindication for a salvage valgus osteotomy. The Bernese PAO has supplanted ITO as the procedure of choice for adults with symptomatic hip dysplasia. Occasionally, however, in severe cases of dysplasia of the acetabulum and femoral deformity, an ITO may be useful as an adjunct to the Bernese PAO.

 

Preoperative Preparation

Patient selection includes the assessment of the position of comfort, the limb length, and the rotational profile. Comfort in adduction favors a valgus osteotomy, while comfort in abduction is a favorable selection factor for a varus ITO. If the ipsilateral lower extremity is shorter, we favor a technique that does not include resection of a bone wedge. Hip external rotation and internal rotation should be assessed with the patient lying supine with the hip flexed to 90 degrees and also with the patient lying prone. Calculation of femoral version angle can be

estimated by clinical examination using the Craig test or by additional advanced imaging including MRI and CT scans. Plain radiographic images should include standing AP pelvis, lateral view of the femur and functional views (abduction view for varus osteotomy and an adduction view for valgus osteotomy), and frog lateral of the hip. Concentric reduction must be confirmed on the appropriate adduction or abduction view prior to consideration for reconstructive varus osteotomy surgery. Congruency is not a prerequisite for salvage valgus osteotomy. In this circumstance, relief of impingement in adduction or improvement of congruency, along with improved patient comfort, is the important consideration.

Preoperative planning using drawings of the radiographs or using dedicated corrective software is mandatory to determine the location of the osteotomy and the entry point and direction of the implant for fixation. The patient's femoral neck shaft angle is measured, and the difference to the corrective neck shaft angle is determined. This difference will dictate the angle and position of insertion of the fixation implant. Next, the appropriate fixation implant is chosen. The most commonly used implants are the blade plate and the dynamic hip screw (DHS) system. Most recently, fixed-angled locking plates also have become commercially available. For femoral neck nonunions, the vertical nonunion angle is calculated, and the amount of valgus to make the nonunion more horizontal is calculated. A valgus correction of between 20 and 40 degrees is preferred (Fig. 9-9).

 

 

 

FIGURE 9-9 Valgus ITO for a nonunion of a femoral neck fracture in an 18-year-old male. A: AP radiograph of the proximal femur at 13 months after a closed reduction and percutaneous fixation of a displaced femoral neck fracture. Note the migration of the cannulated screws and lucency at the nonunion site. B: Preoperative planning for a valgus ITO. The green line is the axis of the femur and the red line the axis of the nonunion. There is a 50-degree angulation measured by the Pawels method.

 

 

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FIGURE 9-9 (Continued) C: The goal of the valgus ITO is to place the fracture line at an angle 20 to 30 degrees off horizontal. In this case, the planned correction is to resect 30-degree lateral-based wedge (yellow) to allow for a residual fracture angle of 20 degrees. The blue line represents the entry point of the DHS screw that should be about 2 cm proximal to the osteotomy to avoid fracture of the lateral cortex. D: Intraoperative fluoroscopy imaging showing the fracture/nonunion lined placed more horizontally. Note the lateral translation of the diaphysis that allows for keeping the lower extremity mechanical axis neutral. E: Final AP radiograph of the proximal femur 1 year after the osteotomy. The fracture nonunion and the intertrochanteric osteotomy are healed, and the patient is asymptomatic.

 

 

 

Technique

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The patient is positioned supine on the edge of a radiolucent table with a bump under the ipsilateral shoulder

(31). The entire lower extremity is draped free, with easy access to the opposite leg taken into account in case the limb length needs to be assessed during surgery. A lateral incision measuring about 20 cm in length is performed starting about 2 cm proximal to the tip of the greater trochanter and extending distally in line with the

femoral shaft. After subcutaneous tissue dissection, the fascia lata is exposed and opened in line with the skin incision. The vastus lateralis is detached sharply at its origin in an L shape, elevated from the lateral femur, and retracted anteriorly exposing the lateral aspect of the femur (Fig. 9-10).

Using fluoroscopy, the starting point for the blade plate should be identified and marked. The angle of insertion of the guided K-wire is based on preoperative planning. The position of the K-wire is confirmed on the AP and lateral fluoroscopy imaging. An additional K-wire is placed along the femoral neck to indicate the anteversion of the neck. This second wire should be placed proximal to and in parallel with the first wire to act as a guide for both the seating chisel and the definitive plate. Using the parallel guide, an anterior and a posterior hole is created to facilitate insertion of the chisel. The chisel should seat anteriorly in the greater trochanter in line with the axis of the femoral neck to avoid penetrating the posterior cortex and injuring the medial femoral circumflex artery (Fig. 9-11). It is important to determine at this time whether flexion or extension of the osteotomy is needed. If flexion is desired, the chisel is rotated aligning the blade plate anteriorly to the diaphysis. Using the remaining proximal wire as a guide, the seating chisel is inserted under fluoroscopic guidance. Once the chisel has been inserted to the final planned depth, the chisel is partially backed out (approximately 15 mm) before making the osteotomy cut.

 

The osteotomy is marked at a minimum distance of 15 mm from the plate insertion site. A new K-wire is drilled across the femur at the proposed site of the osteotomy perpendicular to the axis of the femur with positioning confirmed by fluoroscopy. Prior to performing the bone cut, rotation control should be marked. One could use the proximal K-wire as a guide and introduce a distal K-wire above the knee for establishing the desired rotational change. Another way to control rotation is to place marks on the anterolateral surface, above and below the osteotomy site. The femur

 

 

is cut just distal to the K-wire with care to cut the anterior cortex first to avoid damage to the medial femoral

P.129 P.130

circumflex artery that runs approximately 15 mm proximal to the lesser trochanter, close to the bone. The wedge

can be taken from the distal segment accordingly to the preoperative planning. Mobility of the fragments should be confirmed so that an adequate correction can be achieved.

 

 

 

FIGURE 9-10 Surgical approach to a femoral intertrochanteric osteotomy. A: A longitudinal 20-cm incision is performed starting 2 cm proximally to the greater trochanter and extending distally in line with the femoral shaft. B: Anatomy of the lateral approach to the proximal femur. C: The vastus lateralis is detached sharply at its origin in an L shape, elevated from the lateral femur, and retracted anteriorly exposing the lateral aspect the femur. (From Wiesel SW. Operative techniques in orthopaedic surgery. Philadelphia, PA: LWW, 2010.)

 

 

 

FIGURE 9-11 Placing the seating chisel and performing a varus osteotomy. A: The axis of the femoral neck (blue line) is not in line with the axis of the greater trochanter (red line); rather, there is a 25-degree angulation. The chisel should seat anteriorly in the greater trochanter in line with the axis of the femoral neck to avoid penetrating the posterior cortex and injuring the medial femoral circumflex artery. B: The chisel is inserted using the proximal K-wire as a reference as well as a K-wire placed in front of the neck to serve as an orientation to the anteversion. C: The femoral osteotomy is performed using an oscillating saw to cut the anterior cortex. Note the two K-wires placed anterior to posterior to serve as a guide to control rotation. D: The bone cut is complete using an osteotome as a lever. In this case, a single osteotomy is performed without resection of a bone wedge. This is a preferred technique when shortening of the lower extremity is to be avoided. E: The end of the plate is then reduced to the lateral cortex using a bone clamp. Interfragmentary compression is advised, and we recommend the use of the gliding holes to achieve compression. Schematic drawing on the left and intraoperative picture on the right-hand side. F: Final aspect of the osteotomy. (Parts B, C, D, E left panel, F from Wiesel SW. Operative techniques in orthopaedic surgery. Philadelphia, PA: LWW, 2010.)

 

The seating chisel is removed and the blade plate inserted initially by hand for the first 2 cm, using the proximal K-wire as a guide. Finally, the plate can be impacted into position to the planned depth. The end of the plate is then reduced to the lateral cortex using a bone clamp. Interfragmentary compression is advised, and we

recommend the use of the gliding holes to achieve compression. After the fragments alignment is checked on fluoroscopy and rotation is determined to be satisfactory, the plate is fixed to the bone in a standard fashion. Range of motion of the hip should be checked, and the wound is closed in an anatomic fashion.

 

Pearls and Pitfalls

 

Appropriate patient selection includes assessment of range of motion of the hip.

 

Preoperative planning is essential. Determine the amount of correction, position, and angulation of the implant and the osteotomy. Avoid improvisation.

 

The chisel of a blade plate should seat anteriorly in the greater trochanter in line with the axis of the femoral neck to avoid penetrating the posterior cortex and injury to the medial femoral circumflex artery.

 

Allow a minimum of 15 mm between the implant and the osteotomy to avoid fracture of the lateral cortex.

 

Protect the posterior aspect of the femur while performing the osteotomy to avoid damage to the medial circumflex artery (which runs close to the bone about 15 mm proximal to the lesser trochanter) and injury to the sciatic nerve.

 

Postoperative Management

 

We typically allow 10 to 15 kg of weight bearing with crutch assistance for 8 weeks after surgery when a crutch on the opposite side may be recommended for an additional 4 weeks.

 

Results and Complications

Valgus ITO has a high rate of femoral neck nonunion healing with fracture consolidation (32). Varus osteotomy for the treatment of symptomatic hip dysplasia has been declining in popularity with the success of the Bernese PAO. Proximal femoral osteotomies alone may be insufficient for stabilizing hips with residual acetabular dysplasia (4). Morscher reported on 179 cases performed with lateral joint space narrowing, sclerosis, and congruency in abduction (15). He also reported using valgus osteotomies in an additional 84 cases with pronounced head deformity and congruency in adduction. Good to excellent results were reported in 88% in the total study at final follow-up (33).

Although rare, complications following ITO include: Nonunion

Malunion—malrotation, especially external rotation of the distal fragment

Limb length inequality Osteonecrosis of the femoral head

Fracture of the bone bridge between the plate and the osteotomy Symptomatic implant requiring removal

Deep venous thrombosis and pulmonary embolism Nerve injury

 

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