The titanium rib, or VEPTR (vertical expandable prosthetic titanium rib), is approved by the U.S. Food and Drug Administration (FDA) and is available for use under the Humanitarian Device Exemption regulations. One approved use is for constrictive chest wall disorders, including fused ribs and scoliosis.

Progressive thoracic congenital scoliosis in patients age 6 months to skeletal maturity

Three or more fused ribs at the apex of the concave hemithorax

Greater than 10% reduction in space available for lung (Campbell et al, 2004)

Presence of progressive thoracic insufficiency syndrome (Campbell et al, 2004)

Patients are evaluated for curve flexibility, head decompensation, truncal decompensation, and trunk rotation.

Resting respiratory rate is measured and compared with normative values. An elevated rate suggests the child has occult respiratory insufficiency. The lips are examined for cyanosis. The fingers are examined for clubbing, a sign of chronic respiratory insufficiency, and the percentile normal weight for age is determined. When the work of breathing is excessive, children are often underweight.

Thoracic function resulting from chest wall expansion is assessed by the thumb excursion test (Campbell et al, 2004).

The examiner’s hands are lightly placed on each side of the patient, around the lateral base of the thorax, with the thumbs in back pointing upward medially, equidistant from the spine (Figure 21-1). The patient breathes spontaneously, and rib cage motion carries the thumbs outward away from the spine. Greater than 1 cm of thumb motion away from the spine is normal and is graded as a +3 thumb excursion test; 0.5 to 1 cm is a +2 thumb excursion test; less than 0.5 cm motion is +1; and no thumb excursion with respiration is graded +0.

Causes of abnormal thumb excursion test include extensive fused ribs or the distortion of rib hump. Absent chest wall motion is a sign of thoracic insufficiency syndrome (TIS), because the rib cage cannot aid the diaphragm in expanding the lung during normal respiration.

Radiographs should include anteroposterior (AP) and lateral films of the entire spine, including the entire rib cage and the pelvis. These are assessed for Cobb angle, space available for the lungs, and head and truncal decompensation (Figure 21-2). Space available for the lungs is determined by the ratio of the height of the concave lung from the middle of the most proximal rib to the top of the hemidiaphragm compared with the height of the convex lung measured in the same fashion. Head decompensation is measured from the center sacral line to the middle of C7, and truncal decompensation is measured from the midthorax at T6 to the center sacral line.

Supine lateral bending radiographs are used to determine curve flexibility and apex of rib cage constriction on the concave side of the curve (Figure 21-3, arrow). In cases of thoracic kyphosis, a cross-table lateral radiograph of the spine with a bolster at the apex of the curve is included to assess for flexibility.

Cervical spine films, with flexion/extension laterals, are performed to assess for cervical spine abnormalities and instability.

Computed tomography (CT) scans of the chest and spine are performed, unenhanced, at 0.5-cm intervals from T1 to the sacrum, to assess for three-dimensional spine and rib cage abnormality. Thoracic rotation from rotation of the spine into the convex hemithorax with loss of lung volume is the angle between the sagittal plane of the spine and the sternum (Figure 21-4). To minimize radiation exposure, the scan should be performed at pediatric settings, with appropriate milliamperage and pitch angle.

Fluoroscopy of the diaphragm or ultrasonography is performed to document normal function. Dynamic lung magnetic resonance imaging (MRI), if available, also can be used to assess diaphragm function.

MRI of the entire spinal cord is performed to assess for spinal cord abnormalities.

Proximally, the common insertion of the middle and the posterior scalene muscle on the first and second ribs is identified. The brachial plexus and the artery lie immediately anterior to this (Figure 21-5). It is an important landmark, because the neurovascular bundle is just anterior. The safe zone for VEPTR proximal rib cradle attachment is posterior to the scalene muscles, extending from the second through the fourth ribs. Attachment anterior to the scalene muscles or posterior on the first rib endangers the neurovascular bundle.

Absent ribs in the exposure are identified by palpating the flail area. These are commonly associated with dysraphism of the spine, and care should be taken to avoid violating the spinal canal in the dissection. The preoperative CT scan commonly identifies bony defects in the canal. Figure 21-6 shows the CT scan of an infant with a spinal dysraphism with the meningocele extending up to the medial border of the scapula that was poorly appreciated on radiographs. In surgery, the scapula was gently retracted upward and the rhomboid muscles dissected just adjacent to the edge of the scapula so that the dura was not injured.

The patient is placed in a modified lateral decubitus position with the torso tilted slightly forward (15 degrees) (Figure 21-7).

The upper extremities are draped outside the exposure. They are positioned with the shoulders in 90 degrees of flexion, with the elbows also flexed. An axillary roll is placed, along with another soft bolster under the apex of the convex hemithorax. The extremities are immobilized by placing hand towels on the midcalf and the hips with a 2-inch cloth tape used to strap across the patient.

Central venous line, arterial pressure monitoring line, urinary catheter, and spinal cord monitoring leads are placed.

To avoid skin slough, a long curvilinear incision is made, beginning proximally between the posterior spinous process of the spine at T1 and the medial edge of the scapula, extending distally down to the tenth rib, then anteriorly in a gentle curve along the rib to the posterior axillary line (Figure 21-8).

The trapezius, latissimus dorsi, and rhomboid muscles are divided by cautery in line with the skin incision.

The scapula is gently retracted laterally.

An interval is developed by blunt dissection between the chest wall and the overlying scapula, anteriorly to the costochondral junction, and superiorly up to the first rib. The middle and posterior scalene muscle insertion on the first and second rib is identified in order to protect the neurovascular bundle just anterior to the muscle.

The separate incision for the hybrid laminar spinal hook is to be made 1 cm lateral to midline of the proximal lumbar spine posterior spinal processes.

The paraspinal muscles are reflected by cautery, laterally to medially, up to the tips of the transverse spinous processes, leaving a 1-mm thick layer of soft tissue overlying the ribs to avoid rib devascularization (Figure 21-9). The spine is not uncovered in order to avoid inadvertent fusion.