Surgery Section - Vertical Expandable Prosthetic Titanium Rib

IMPORTANT REMINDER

This Medical Policy has been developed through consideration of medical necessity, generally accepted standards of medical practice, and review of medical literature and government approval status.

Benefit determinations should be based in all cases on the applicable contract language. To the extent there are any conflicts between these guidelines and the contract language, the contract language will control.

The purpose of medical policy is to provide a guide to coverage. Medical Policy is not intended to dictate to providers how to practice medicine. Providers are expected to exercise their medical judgment in providing the most appropriate care.

Description

Thoracic insufficiency syndrome (TIS) is the inability of the thorax to support normal respiration or lung growth. (2) It results from serious defects affecting the ribs or chest wall such as severe scoliosis, rib fusion (which may accompany scoliosis), and various hypoplastic thorax syndromes such as Jeune’s Syndrome and Jarcho-Levin syndrome. Spine, chest, and lung growth are interdependent. While the coexistence of chest wall and spinal deformity is well documented, their effect on lung growth is not completely understood.

Progressive thoracic insufficiency syndrome includes respiratory insufficiency, loss of chest wall mobility, worsening three-dimensional thoracic deformity, and/or worsening pulmonary function tests. As a child grows, progressive thoracic deformity and rotation toward the concave side occurs with worsening respiratory compromise. This progression is often accompanied by a need for supplemental oxygen and can require mechanical ventilation. While spinal fusion is one approach to treatment, it may not be successful and also may limit growth (lengthening) of the spine.

The vertical expandable prosthetic titanium rib (VEPTR) is a curved rod placed horizontally in the chest that helps to shape the thoracic cavity. It is positioned either between ribs or between ribs and either spine or pelvis. The device is designed to be expanded every four to six months as growth occurs and also to be replaced if necessary. Some patients require multiple devices.

A VEPTR has received FDA approval under a humanitarian device exemption (HDE). (3) The FDA review indicated that the device is indicated for the treatment of Thoracic Insufficiency Syndrome (TIS) in skeletally immature patients. This review also indicated the device should not be used at an age less than 6 months.

Skeletal maturity occurs at about age 14 for girls and age 16 for boys.

Given the complexity of these procedures and patients, implantation of this device should be performed in specialized centers. Preoperative evaluation requires input from pediatric orthopaedists, pulmonologist, and thoracic surgeon. In addition, preoperative evaluation of nutritional, cardiac and pulmonary function (when possible) is required.

Policy/Criteria

Use of the Vertical Expandable Prosthetic Titanium Rib may be considered medically necessary in the treatment of progressive thoracic insufficiency syndrome due to rib and/or chest wall defects in infants/children between six months of age and skeletal maturity.

Scientific Background

Information from the FDA website reports results of an initial feasibility study involving 33 patients and a subsequent prospective study of 224 patients (214 with baseline data) at seven study sites. (3) Of these patients, 94 had rib fusion, 93 had hypoplastic thoracic syndrome, 46 had progressive scoliosis, and 14 had flail chest as a cause of their thoracic insufficiency syndrome (TIS). Three and 5-year follow-up rates for the multicenter study were approximately 95%. Of the 247 patients enrolled in either study, 12 patients died (4.8%) and 2 withdrew. None of the deaths was determined by investigators to be device-related. Since standard pulmonary function testing was not possible for most of this population, an “Assisted Ventilatory Rating” (AVR) was used to assess impact on respiratory status. The AVR ranged from “0” for unassisted breathing on room air to “4” for full-time ventilatory support. In the multi-center prospective study, the AVR outcome improved or stabilized for 93% of the patients. Data were not reported for the number of patients who were no longer ventilator-dependent.

Several studies using this device have also been reported in the literature. One study is from Campbell, the developer of the device (4) while others report its use in specialized pediatric centers (5, 6).

Campbell and colleagues reported on 27 patients who had surgery for TIS and for whom at least 2 years of follow-up data were available; this series was based on 41 patients treated between 1990 and the acceptance of the paper. (4) Entry criteria for this study were acceptance by pediatric general surgeon, pediatric pulmonologist, and pediatric orthopedist, age 6 months to skeletal maturity, progressive thoracic insufficiency syndrome, more than 10% reduction in height of the concave hemithorax, three or more anomalous vertebrae with three or more fused ribs at the apex of the deformity. Patients were followed an average of 3.2 (2–12) years. Prior to surgery, the mean yearly rate of progression was 15 degrees per year (range 2–50). Following surgery the Cobb angle (of scoliosis) improved from 74 degrees to a final value of 49 degrees. Spine growth was at the rate of 0.8 cm per year. (Normal spinal growth is 0.6 cm/year for ages 5 – 10 years.) The final FVC (forced vital capacity) was 49% of predicted in the 19 children who could complete pulmonary function tests (PFTs). Preoperatively one patient required CPAP for ventilatory support, at final follow up one patient required CPAP and one needed supplemental oxygen.

Emans and colleagues reported results on patients with TIS who underwent the procedure at Children’s Hospital in Boston from 1999 to 2005. (5) Thirty one patients with fused ribs and TIS were treated, 4 patients had prior spinal arthrodesis with continued progression of deformity. Before surgery, all patients showed progressive spinal deformity, progressive chest deformity, or progressive hemithoracic constriction. The mean age was 4.2 years and mean follow-up was 2.6 years (range 0.5 to 5.4). A 3-member team selected patients for surgery; cardiac function was also evaluated preoperatively. Surgery was performed using the Campbell technique for VEPTR. Device lengthening was planned for every 4 to 6 months, but often was longer due to intercurrent illness or difficulty with travel. The mean number of device lengthenings was 3.5 (range 0-10). Six patients had device exchanges for growth. In 30 patients, the spinal deformity was controlled and growth continued (1.2 cm/yr) in the thoracic spine during treatment at rates similar to normal children. In this study the final FVC was 73.5% of predicted. Pre-procedure, 2 patients were on ventilators and 3 required oxygen; at final follow-up one patient required oxygen. Lung volume (measured by CT scan in cubic-cm) in the operated lung increased from 157 pre-operatively to 326 at the final follow-up visit.

Motoyama and colleagues from Children’s Hospital in Pittsburgh reported on follow up of 10 patients with thoracic insufficiency with follow-up as long as 33 months. (6) Using a special portable pulmonary function testing device, they reported on lung function in 10 children who had placement of VEPTR. In this population, the median age was 4.3 years (range 1.8–9.8 years) at first test and they followed patients an average of 22 months (range 7–33 months) At baseline, forced vital capacity (FVC) showed a moderate-to-severe decrease (69% of predicted), indicating the presence of significant restrictive lung defect. FVC increased significantly over time, with an average rate of 26.8% per year, the rate of increase similar to that of healthy children of comparative ages. In terms of percent-predicted values, FVC did not change significantly between the baseline and last test (70.3%), indicating that in most children studied, lung growth kept up with body growth.

The complications that occur with this device need to be considered by practitioners and families as they are discussing this procedure. Information on complications is summarized using data from the FDA review and the papers by Campbell and Emans. (3, 4,5) About 25% of patients will experience device migration, including rib erosion. However, there does not seem to be significant long-term consequences from this. Approximately 10% of patients had infection-related complications. Brachial plexus injury or thoracic outlet syndrome occurred in 1% to 7% of these series. Skin sloughing was reported in 4 patients (15%) in the study published by Campbell.

Summary

There are no comparative trials describing the use of this device. Thoracic insufficiency occurs in a limited patient population; for example, the Boston Center reported results on 31 children treated from 1999 to 2005. The natural history of progressive TIS is worsening pulmonary function and worsening pulmonary insufficiency.

Results from the series reported at different specialty centers demonstrate improvement and/or stabilization in key measures with use of this device in progressive TIS. This improvement is noted in measures related to thoracic structure (e.g., Cobb angle for those with scoliosis), growth of the thoracic spine and lung volumes, and stable or improved ventilatory status. While pulmonary function testing is very difficult in these patients, one study does demonstrate an age-specific increase in FVC and the studies report a final FVC in the range of 50–70% of predicted.

Given the usual disease course of worsening thoracic volume and ventilatory status, the stabilization/improvement in these measures would be highly unlikely in the absence of the intervention. Taken together, these various outcome measures demonstrate the positive impact of this procedure.

Thus, this intervention may be considered medically necessary in children with progressive thoracic insufficiency syndrome due to rib and/or chest wall defects. Given the complexity of this procedure and the patient population, use of this device should be performed in specialized centers. Preoperative evaluation requires input from pediatric orthopedist, pulmonologist, and thoracic surgeon. In addition, preoperative evaluation of nutritional, cardiac and pulmonary function (when possible) is required.

An updated search of the MEDLINE database through April 2008 returned one new case series of 22 patients, the results of which do not alter the conclusions reached above.

References

1. BlueCross BlueShield Association Medical Policy Reference Manual, Policy No. 7.01.110
2. Campbell RM Jr, Smith MD, Mayes TC et al. The characteristics of thoracic insufficiency syndrome associated with fused ribs and congenital scoliosis. J Bone Joint Surg Am 2003:85-A:399-408
3. http://www.fda.gov/cdrh/ode/H030009sum.html (Verified 9/22/08)
4. Campbell RM Jr, Smith MD, Mayes TC et al. The effects of opening wedge thoracostomy on thoracic insufficiency syndrome associated with fused ribs and congenital scoliosis. J Bone Joint Surg Am 2004;86-A(8):1659-74
5. Emans JB, Caubet JF, Ordonez CL et al. The treatment of spine and chest wall deformities with fused ribs by expansion thoracostomy and insertion of vertical expandable prosthetic titanium rib: growth of thoracic spine and improvement of lung volumes. Spine 2005;30(17 suppl):S58-68
6. Motoyama EK, Deeney VF, Fine GF et al. Effects on lung function of multiple expansion thoracoplasty in children with thoracic insufficiency syndrome: a longitudinal study. Spine 2006;31(3):284-90
7. Waldhausen JH, Redding GJ, Song KM. Vertical expandable prosthetic titanium rib for thoracic insufficiency syndrome: a new method to treat an old problem. J Pediatr Surg 2007;42(1):76-80

Cross References

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