Open Reduction for the Treatment of Developmental Dysplasia of the Hip

FUNDAMENTALS

Open reduction is the recommended treatment for a dislocated hip when a concentric stable reduction cannot be achieved closed. It should be emphasized that closed reduction should not be forceful, and in order to be accepted as the treatment of choice of a dislocated hip, the following criteria should be present:

The femoral head should be covered by at least two-thirds of the acetabular labrum in the reduced position without major infolding of the labrum.
The femoral head should be deeply seated in the acetabulum and proximity to the acetabular fossa, and no more than 5 mm of medial dye pooling should be accepted.
The hip should have an ample arc of abduction and a wide safe zone (≥30°) of instability.
The hip should be immobilized in a spica cast without forceful abduction. Abduction in the cast should be less than the maximum degree of abduction (maximum abduction is 60°; ideally at 50°).
The concentric reduction achieved in the operating room should be confirmed after the application of the spica cast by advanced imaging.

If these criteria are not fulfilled, then the hip should be treated by an open reduction. Moreover, children at walking age with high hip dislocation (grade IV according to the International Hip Dysplasia Institute [IHDI] grading system¹) may benefit from an open reduction because of the pathologic anatomy of the hip. With time, several intra-articular and periarticular structures may block a concentric closed reduction. These structures, including a tight anterior medial joint capsule, a constricting iliopsoas tendon, a hypertrophic teres ligament, excessive fibrofatty pulvinar, and a tight transverse acetabular ligament, can be released during the open reduction, which would allow the femoral head to articulate deep in the acetabular fossa. Finally, an absolute indication for open reduction is the child with a high hip dislocation when femoral and often pelvic osteotomies are planned.

Open reduction of a dislocated hip may be performed through an anterior approach or various medial approaches. Although the goal for the different approaches is the same, that is, to obtain a concentric reduction of the femoral head into the acetabular cavity, the two approaches have different advantages and disadvantages. Overall, the treating pediatric orthopedic surgeon should consider the severity of the dislocation and pathology, the patient’s age, the association with other disorders, and whether previous prolonged brace treatment in a dislocated position was performed. Controversy surrounds the lower and upper age limit for open reduction. In general, medial open reduction is performed from 4 to 12 months of age and the anterior approach is carried out after 6 months of age. We recommend open reduction with femoral and pelvic osteotomies up to 8 years of age, especially in those with unilateral disease.

MEDIAL APPROACH FOR OPEN REDUCTION OF A DISLOCATED HIP

The medial approach for open reduction of the hip was originally described by Ludloff.² Since its description, several authors have described slight modifications of the medial approach including a description by Ferguson³ who used the interval between the adductor longus and the adductor brevis. We use the anteromedial approach through a medial incision with the deep dissection between the neurovascular bundle and the pectineus muscle⁴,⁵ (Figure 3.1). Although the medial approach has been used for patients up to age 3 years,
we believe the medial approach should be limited to patients younger than 12 months, especially those with bilateral dislocated hips.⁶

FIGURE 3.1. Illustration of right hemipelvis anatomy in the axial plane showing the plane of dissection of the anteromedial approach to the hip between the pectineus and the neurovascular bundle (black dashed line). Alternatively, the hip may be approached from the medial incision using the plane between the adductor brevis and the adductor magnus or between the adductor brevis and the pectineus. AL, adductor longus; IP, iliopsoas; IPR, inferior pubic ramus; IT, ischial tuberosity; OE, obturator externus; TFL, tensor fascia lata; VI, vastus intermedius; VL, vastus lateralis.

Advantages

Direct access to the blocks to concentric reduction, including the tight anteromedial joint capsule, the tight transverse acetabular ligament, a hypertrophic ligamentum teres, capsular constriction by a tight iliopsoas tendon, and removal of the fibrofatty pulvinar.
Cosmetic scar
Bilateral hip dislocations can be treated with minimal blood loss.
Easy to perform a tenodesis of the ligamentum teres to the anteromedial aspect of the acetabular rim, which may help keep the reduction stable

Disadvantages

Formal capsulorrhaphy is not possible, although some stiches can be placed in the capsule after reduction.
The medial femoral circumflex artery (MFCA) crosses the field and is at risk of damage during surgery, raising the concern of high risk of osteonecrosis of the femoral head.
It is not possible to perform secondary procedures, such as a pelvic osteotomy.

Clinical Scenario

A 12-week-old girl presented to clinic because the pediatrician noted that the hips were asymmetric during her well-child physical examination. She was the first-born child via a C-section owing to breech presentation, and there was no family history of developmental dysplasia of the hip (DDH). Ultrasonography of the hips revealed a severe dislocation of the left hip considered Grafgrade IV, that is, the femoral head was dislocated out of the acetabulum and was pushing against the labrum caudally. The hip was not easily reducible during the Ortolani maneuver, and she was scheduled to undergo closed versus open reduction. Preoperative radiographs obtained at 5 months of age showed dislocation of the left hip (Figure 3.2). Arthrogram of the left hip revealed excessive medial dye pooling (>5 mm) and an infolded labrum and a tight transverse acetabular ligament (Figure 3.3). The patient underwent treatment by an anteromedial open reduction.

FIGURE 3.2. Preoperative radiograph of a 5-month-old girl born breech who was found to have left irreducible hip during examination showing that the left hip was dislocated

FIGURE 3.3. Left hip arthrogram. Intraoperative fluoroscopy C-arm imaging after left hip arthrogram and attempted closed reduction. The hip was placed in flexion and maximum abduction to about 60° to 70°, but the femoral head was not well covered and the labrum was infolded (white arrow). The femoral head did not pass through the transverse acetabular ligament (yellow arrow), and it was seating laterally, creating a wide (>5 mm) pooling of the dye medially (white dashed lines). The patient was treated with open reduction through the anteromedial approach.

Surgical Technique

The medial open reduction is performed with the patient supine on the radiolucent table under general anesthesia and with assisted caudal anesthetic blockage to help with pain management postoperatively. A Foley catheter is inserted and secured in the midline to help in managing the patient and to avoid getting the cast wet during the first 24 hours after surgery. The patient is positioned with the affected hip in flexion, abduction, and external rotation, and the hemipelvis and lower extremity are prepared and draped using standard technique (Figure 3.4).

A transverse skin incision is performed from the inferior border of the abductor tendon proximally to the level of the femoral neurovascular bundle parallel to the groin crease. The subcutaneous tissue is dissected exposing the adductor compartment fascia. The fascia on top of the abductor longus tendon is opened longitudinally in line with the tendon. The adductor longus tendon is identified and dissected free (Figure 3.5). The adductor longus is released at the muscle-tendon junction and retracted distally (Figure 3.6). With retraction of the adductor longus tendon distally, the anterior branch of the obturator nerve is identified crossing on top of the adductor brevis muscle.

FIGURE 3.4. Patient positioning: intraoperative picture showing the patient is positioned with the left hip in flexion and abduction with external rotation. The entire hemipelvis and lower extremity should be draped free.

The anterior branch of the obturator nerve serves as a reference to identify the pectineus. The nerve is traced proximally where it enters the obturator foramen beneath the pectineus muscle. The neurovascular bundle is identified and dissected free at the proximal or superior border of the wound (Figure 3.7). It is our preference to dissect the neurovascular bundle at this time because it is safer to have the femoral artery, vein, and nerve protected and to identify the femoral medial circumflex artery (MFCA) early to avoid damage to the main vascular supply to the femoral head. A vessel loop may be used to protect the neurovascular bundle. The fascia on top of the pectineus is opened in the interval between pectineus, and the neurovascular bundle is dissected, being very careful to avoid damage to the MFCA that courses from superior to inferior. The hip is rotated externally to bring the lesser trochanter toward the operative field. The lesser trochanter is palpated, and the iliopsoas tendon can be identified and dissected with the help of a peanut dissector sponge (Figure 3.8). A right-angled clamp is passed underneath the iliopsoas, and the tendon is cut at the insertion on the lesser trochanter (Figure 3.9).

FIGURE 3.5. Superficial dissection: the adductor longus muscle and tendon. (A) Illustration and (B) intraoperative picture showing the adductor longus muscle and tendon should be identified after the fascia is open in line with the muscle.

FIGURE 3.6. Tenotomy of the adductor longus. (A) Illustration and (B) intraoperative picture showing that the adductor longus tendon is brought to the surface by a right-angled clamp, and a tenotomy (black dashed line) is performed at the muscle-tendon junction.

FIGURE 3.7. Identification of the femoral vessels and the medial femoral circumflex artery (MFCA). A, Illustration showing the anterior branch of the obturator nerve crossing under the pectineus. The interval between the pectineus and the neurovascular bundle (NVB) is dissected. B, Intraoperative picture showing the NVB has been fully dissected on the superior or proximal aspect of the operative field, and the MFCA is identified early to protect it during the entire procedure and avoid damage to the main vascular supply to the femoral head.

FIGURE 3.8. Exposure of the iliopsoas: intraoperative picture showing a peanut sponge is used to dissect the iliopsoas tendon at the level of the insertion on the lesser trochanter. External rotation of the hip facilitates palpation, and identification of the lesser trochanter before the iliopsoas is dissected free.

Light retraction is applied to the neurovascular bundle proximally (superior portion of the field) and on the pectineus distally to expose the hip capsule. It is important to alternate proximal and distal retraction, avoiding applying both at the same time because the MFCA crosses the operative field from superior to inferior and would be in too much traction if both retractors are pulled together. To expose the anteromedial aspect of the joint capsule, the pectineus is retracted distally, and to expose the superolateral aspect of the capsule, the neurovascular bundle is retracted proximally. It is crucial to expose the entire capsule medially and laterally to the MFCA before the capsulotomy is performed (Figure 3.10). Once the capsule is dissected free, an incision is performed in the anteromedial aspect parallel to the acetabular rim. One alternative is to perform another cut to the capsule, creating a “T”-shape capsulotomy, which, at times, improves the visualization of the acetabulum and may allow one to two stitches to be placed after reduction augmenting the stabilization of the reduction (Figure 3.11). After the joint capsule is opened, the femoral head is exposed, and the ligamentum teres is cut free from its insertion in the femoral head (Figure 3.12). The ligamentum teres is grasped with a Kocher clamp and is pulled to facilitate exposure of its insertion in the acetabular floor. The ligamentum teres, along with the acetabular transverse ligament, is incised with a knife, allowing for the acetabular introitus to increase. The acetabular cavity is cleaned from the fibrofatty tissue (pulvinar) that is removed with a pituitary rongeur (Figure 3.13). Alternatively, the ligamentum teres can be left intact in the femoral head, but only resected at its insertion at the bottom of the acetabular cavity. The hypertrophic ligament is shortened, and a suture is passed through the ligament. At the end of the procedure, the stump of the ligamentum teres is sutured to the anteromedial aspect of the capsule, acting like a tenodesis and augmenting the stability of the reduction⁷,⁸ (Figure 3.14).

FIGURE 3.9. Tenotomy of the iliopsoas tendon. (A) Illustration and (B) intraoperative picture showing the iliopsoas tendon is isolated with a right-angled clamp, and a tenotomy is performed at the insertion on the lesser trochanter. The white dashed line marks the level of the tenotomy.

Finally, the femoral head is reduced in the acetabulum under direct vision by flexion of the hip to about 90°, abduction, and by applying a gentle push through the greater trochanter. If possible, one or two 0 Vicryl stitches are placed in the capsule to improve the stability postreduction, which can also be improved by the tenodesis of the ligamentum teres. Before the wound

is closed, we inject about 1 mL of a 50% solution with ioversol and saline to confirm the reduction and to help assess the reduction while applying the spica cast (Figure 3.15). The wound is irrigated and closed in layers: the deep adductor fascia, the subcutaneous tissue, and then the skin. Steri-Strips and sterile dressings are applied, and the patient is carefully transferred into a radiolucent spica cast table.

FIGURE 3.10. Complete exposure of the hip capsule medially and laterally to the medial femoral circumflex artery (MFCA). A, Illustration showing the exposure of the hip capsule proximally and distally. The black dashed lines mark the capsulotomy. To expose the proximal aspect of the capsule, a retractor is placed under the neurovascular bundle. To expose the distal aspect, a retractor is placed under the pectineus. Note that the MFCA crosses the field from superior to inferior, and it would be submitted to excessive traction if both retractors are pulled simultaneously. Therefore, exposure of the capsule should be done in a synchronized manner: if one of the retractors is pulling, the other should be relaxed and vice versa. The MFCA should not be placed under excessive tension. (B) Intraoperative picture showing the hip capsule should be visualized both medially and laterally to the MFCA. Lateral exposure is important, especially in higher dislocations. AL, adductor longus.

FIGURE 3.11. Capsulotomy. Intraoperative picture showing the capsulotomy is drawn with a marking pen. The medial femoral circumflex artery (MFCA) is protected by a vessel loop. The typical capsulotomy for the medial approach is performed parallel to the acetabular margin (white dashed line). Alternatively, a second cut is added to capsulotomy perpendicular to the first one and in line with the femoral neck axis (black dashed line).

FIGURE 3.12. Ligamentum teres release. Illustration showing that with the hip in external rotation, the femoral head becomes visible in the operative field, and the ligamentum teres is grasped and pulled out. The ligamentum teres is sharply incised from the insertion in the femoral head. A Kocher clamp is used to grasp the ligament toward its insertion (not shown). The ligament is sharply incised at its insertion along with incision of the transverse acetabular ligament.

FIGURE 3.13. Preparation of the acetabular cavity: illustration showing a pituitary rongeur is used to clean the fibrofatty pulvinar from the acetabulum. Removal of the pulvinar should be performed with caution to avoid damage to the articular surface.

FIGURE 3.14. Illustration showing the steps for the ligamentum teres tenodesis technique. Instead of resecting the ligamentum from the femoral head, the insertion at the transverse acetabular ligament is incised. After the femoral head is reduced in the acetabular cavity, the remaining ligamentum is shortened and sutured back in the acetabular ligament area. Theoretically, this technique augments stability of the hip in the immediate postoperative period. Reproduced with permission from Bache et al.⁷

Spica cast application following a medial open reduction: a spica cast will be applied with the hips in 100° to 110° of flexion and 45° of abduction (<60° of abduction is highly recommended). Excessive internal rotation should be avoided; however, slight internal rotation may increase the stability of the hip. Fluoroscopy imaging is obtained through the radiolucent spica cast table after application of the cotton Webril and after the cast is applied. We strongly recommend obtaining a C-arm fluoroscopy during application of the cast because this is often the most critical time when the hip may dislocate. Another important detail while applying the cast is to keep the patient under general anesthesia to avoid any abrupt moving of the hip and knees. After the spica cast is applied, a magnetic resonance imaging (MRI) is obtained to confirm the concentric reduction of the hip. MRI protocol following open reduction does not require the patient to be under full general anesthesia. Often, with the spica cast in place and using rapid MRI sequences, a good detailed examination is possible. The patient is admitted to the orthopedic floor for pain management and spica cast education and is typically discharged the next day following surgery.

FIGURE 3.15. Postoperative imaging. A, Intraoperative fluoroscopy C-arm imaging obtained just before the spica cast is applied showing the left hip is concentrically reduced and there is minimal dye pooling medially. The arthrogram is performed before the wound is completely closed and helps guiding the application of the cast. B, Postoperative magnetic resonance imaging after anteromedial open reduction and application of spica casting confirming concentric reduction of the hip.

ANTERIOR APPROACH FOR OPEN REDUCTION OF A DISLOCATED HIP

The anterior approach may also leave a cosmetic scar if the modified anterior bikini-type incision is used. Through the anterior approach, a capsulorrhaphy can be performed. Another advantage is that when necessary, a pelvic osteotomy can be performed in the same setting. A potential disadvantage is a relatively higher blood loss compared to the medial approach, which leads to most surgeons avoiding this approach for bilateral open reductions. Bilateral hip dislocations treated through the anterior approach are typically staged 4 to 6 weeks apart. Open reduction of the hip using the anterior approach may be performed in patients older than 6 months. During the first year of life, both medial and anterior open reductions can be used, and the choice should be based on surgeon’s experience and comfort with each approach. In general, after 12 months of age, our preference is to use the anterior approach. One relative indication is a hip previously treated by a Pavlik harness with persistent dislocation and deformity of the posterolateral acetabulum—the so-called Pavlik harness disease. In such hips, the dissection of the superior and lateral aspects of the capsule and a formal capsulorrhaphy are crucial to keep a concentric and stable reduction.

SURGICAL TECHNIQUE

Surgery is performed with the patient under general anesthesia with either a single-shot caudal blockade or a lumbar plexus catheter to help with postoperative pain when an osteotomy is planned. The patient is positioned supine with a radiolucent bump under the ipsilateral shoulder and flank. The bump should not be directly under the buttock because this may raise the gluteal musculature, making the approach dissection of the posterior lateral aspect of the capsule more laborious. The entire hemipelvis up to the level of the rib cage is prepared and draped free, including the lower extremity (Figure 3.17). Careful preparation of the groin is important because the adductor longus tendon is often released in combination with the open reduction.

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