Final Fusion After Growing-Rod Treatment for Early Onset Scoliosis: Is It Really Final?

Poe-Kochert, Connie RN, CNP; Shannon, Claire MD; Pawelek, Jeff B. BS; Thompson, George H. MD; Hardesty, Christina K. MD; Marks, David S. FRCS; Akbarnia, Behrooz A. MD; McCarthy, Richard E. MD; Emans, John B. MD

Journal of Bone & Joint Surgery - American Volume:
doi: 10.2106/JBJS.15.01334
Scientific Articles
Abstract

Background: Final fusion is thought to be the end point for patients with early onset scoliosis following treatment with the use of growing rods. But is it? The purpose of this study was to determine the incidence and cause of any reoperation after final fusion.

Methods: A multicenter database of patients with early onset scoliosis was retrospectively analyzed to identify patients treated with growing rods with a minimum of 2 years of follow-up after final fusion. All reoperations were recorded. Reoperation was defined as a return to the operating room for any complication related to the final fusion surgery or etiology of the spinal deformity.

Results: One hundred (84%) of 119 patients met the inclusion criteria: for 38 of the patients, the etiology of scoliosis was neuromuscular; for 31, syndromic; for 22, idiopathic; and for 9, congenital. The mean age at final fusion was 12.2 years (range, 8.5 to 18.7 years). The mean follow-up after final fusion was 4.3 years (range, 2 to 11.2 years). Twenty (20%) of the patients had 30 complications requiring reoperation (57 procedures). There was a mean of 1.5 complications per patient after final fusion. Eight patients with neuromuscular scoliosis, 8 with syndromic, 4 with idiopathic, and no patient with congenital scoliosis required reoperation. Nine (9%) of the patients experienced infection (33 reoperation procedures); 6 (6%) had instrumentation failure (8 procedures); 5 (5%) had painful or prominent instrumentation (6 procedures); 3 (3%) each had coronal deformity (3 procedures), pseudarthrosis (3 procedures), or sagittal deformity (3 procedures); and 1 (1%) had progressive crankshaft chest wall deformity requiring a thoracoplasty (1 procedure).

Conclusions: A higher-than-anticipated percentage of patients treated with growing rods required unplanned reoperation following final fusion. Long-term follow-up after final fusion is necessary to determine true final results. Patients and parents need to be counseled regarding the possibility of further surgery after final fusion.

Level of Evidence: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Author Information

1Rainbow Babies and Children’s Hospital, University Hospitals Case Medical Center, Cleveland, Ohio

2Growing Spine Foundation, San Diego, California

3Royal Orthopaedic Hospital, Birmingham, United Kingdom

4Arkansas Children’s Hospital, Little Rock, Arkansas

5Boston Children’s Hospital, Boston, Massachusetts

E-mail address for G.H. Thompson: ght@po.cwru.edu

Article Outline

Early onset scoliosis is defined as scoliosis occurring in patients who are <10 years of age, regardless of the etiology1. The term early onset scoliosis is important when considering the developmental stage of not only the skeleton but the pulmonary system as well. Thoracic height increases most rapidly between birth and 5 years of age; as a result of early scoliotic progression, these children are at increased risk for pulmonary insufficiency2,3. Many children with early onset scoliosis also have syndromic or neuromuscular conditions with additional anomalies that can further exacerbate their complications from cardiopulmonary decline4.

Surgical treatment with the use of growing rods is the most common technique in the management of progressive early onset scoliosis5-9. The use of fusionless surgical techniques allows the spine to continue to grow in length and maximize thoracic volumes, while attempting to maintain or improve the coronal and sagittal alignment. This concept was first introduced by Harrington in 196210. Today, there are numerous techniques available to achieve these same goals. Skaggs et al. classified these into 3 categories: distraction-based systems, such as single or dual growing rods, the vertical expandable prosthetic titanium rib (VEPTR) device, and remotely expandable devices; compression-based systems with vertebral tethers or staples; and guided growth systems including the Shilla procedure and Luque trolley11. Regardless of the technique employed, the common end goal is a posterior spinal fusion and segmental spinal instrumentation once the patient reaches adequate maturity. This is known as the final fusion. For patients, their families, and the medical team alike, this is often a much-anticipated and celebrated event marking the end of many years of repeated surgical interventions and potential risks for complications.

There have been numerous studies on the heterogeneous nature of patients with early onset scoliosis and the varied medical complications associated with their individual diagnoses. These patients are at increased risk for surgical complications on the basis of these factors4,6,12,13. The nature of growing-rod surgery necessitates repeated surgical interventions for scheduled lengthenings6,14. Bess et al. showed a 20% complication rate per procedure, with 58% of all patients in their series having a minimum of 1 complication15.

Given the high rates of complications for growing-rod surgery in the treatment of early onset scoliosis and in the setting of the highly anticipated final fusion in these patients, it seems pertinent to investigate whether this is truly the “final” procedure. In this study, we sought to determine the incidence of reoperation and to define the causes of unplanned repeat surgical procedures in patients who had undergone a final fusion after growing-rod treatment for early onset scoliosis.

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Materials and Methods

We performed a retrospective review using data from an international, multicenter database of patients with early onset scoliosis. All participating centers obtained institutional review board approval prior to the initiation of the study. All patients who had undergone growing-rod surgery with a minimum follow-up of 2 years after final fusion were identified. Reoperation, for the purpose of this study, was defined as a return to the operating room for intervention due to any complication of the final fusion or etiology of the spinal deformity. The number of reoperations and the underlying etiology were recorded for each patient.

All causes of reoperation were divided into categories: implant infection, failure of instrumentation, painful or prominent instrumentation, coronal or sagittal deformity, pseudarthrosis, neurologic conditions, and thoracoplasty. We did not attempt during this initial review to determine the current results of those patients requiring reoperation or to identify specific risk factors.

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Results

The study period was 1987 through 2009. The database at the time of query (June 2013) included 595 patients who had undergone surgery with use of traditional growing rods; there were no VEPTRs, remotely expandable devices, tethers, staples, or guided growth systems used. There were 119 potential patients from 13 centers who were due for 2-year follow-up after final fusion. A total of 100 (84%) of these patients were seen at or after their 2-year postoperative period and thus were included in the analysis. The 19 patients who were excluded did not have a 2-year follow-up for various reasons, including relocation or failure to return. Among the 100 study patients, the etiology was classified as neuromuscular for 38 patients, syndromic for 31 patients, idiopathic for 22 patients, and congenital for 9 patients. The patients with neuromuscular and syndromic scoliosis had a wide variety of other diagnoses. Among the patients with neuromuscular scoliosis were 9 patients with myelodysplasia; 7 with cerebral palsy; 5 each with spinal muscular atrophy and muscular dystrophy; 2 each with spinal cord infarction and unclassified muscle disorders; and 1 each with 8 other neuromuscular disorders. Among the patients with syndromic scoliosis were 7 with Marfan syndrome; 5 with chromosomal abnormalities; 4 with neurofibromatosis; 3 with arthrogryposis; 2 each with spondyloepiphyseal dysplasia, VATER (vertebral defects, imperforate anus, tracheoesophageal fistula, and radial and renal dysplasia) syndrome, and Prader-Willi syndrome; and 1 patient each with 6 other syndromic disorders. In the idiopathic group, there were 10 patients with infantile and 12 with juvenile scoliosis. Among those with congenital scoliosis, the scoliosis was classified as unspecified in 5, mixed in 3, and thoracogenic in 1 patient. The mean age of the patients at the time of the initial growing-rod surgery was 7.0 years (range, 2.0 to 14.4 years), and the mean age at the time of final fusion was 12.2 years (range, 8.5 to 18.7 years). The mean follow-up period after final fusion was 4.3 years (range, 2 to 11.2 years). There were 58 female and 42 male patients.

Twenty (20%) of the 100 study patients had 30 complications (mean, 1.5 complications per patient) that required a total of 57 reoperations. These occurred in 8 patients with neuromuscular scoliosis (40% of those requiring reoperation), 8 patients with syndromic scoliosis (40%), 4 patients with idiopathic scoliosis (20%), and no patient with congenital scoliosis (Table I). The mean time to the first reoperation after the final fusion procedure was 2.0 years (range, 11 days to 7.4 years). The mean number of reoperations per patient was 2.9 (range, 1 to 19 procedures). Eleven (26%) of the 42 male patients required reoperation (5 neuromuscular, 5 syndromic, and 1 idiopathic). Nine (16%) of the 58 female patients required reoperation (3 neuromuscular, 3 syndromic, and 3 idiopathic).

Of the patients requiring reoperation (Table II), 9 patients (9% of the total number of patients) required reoperation for infection and underwent a total of 33 procedures: 23 surgical site debridements due to deep infection, 2 irrigation and debridement procedures for superficial skin breakdown, 1 flap for skin breakdown, and 7 instrumentation removals. One patient had 17 debridements followed by instrumentation removal. Reinstrumentation was later successful for this patient. Six (6%) of the patients underwent 8 reoperations due to instrumentation failure: 5 rod fractures and 3 distal hook or screw pullouts. Five (5%) of the patients had painful or prominent hardware (6 procedures). Three (3%) of the patients had reoperation for coronal deformity (3 procedures); 3, for pseudarthrosis (3 procedures); and 3, for sagittal deformity (3 procedures). One (1%) of the patients with a progressive crankshaft chest wall underwent a thoracoplasty. The patient requiring a thoracoplasty had juvenile idiopathic scoliosis and underwent final fusion at 12.6 years of age; at 1.8 years postoperatively, the patient experienced crankshaft phenomena, pain, and an increasing rib hump.

Seven (12%) of the 57 reoperations occurred within the first 3 months after undergoing final fusion (early complications). Fifty (88%) of the reoperations took place more than 3 months after final fusion surgery (late complications) (Table III). The early complications occurred in 3 (15%) of the 20 patients who required reoperations and consisted of 5 operations for infection and 2 operations for failure of instrumentation. The late complications occurred in 17 (85%) of the 20 patients who required reoperations. These included 28 operations for infection; 6 operations each for failure of instrumentation and painful/prominent instrumentation; 3 operations each for coronal deformity, sagittal deformity, and pseudarthrosis; and 1 for thoracoplasty (Table IV).

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Discussion

A higher-than-anticipated number of patients with early onset scoliosis who underwent growing-rod treatment required reoperation after final fusion. This information is very disconcerting, not only for the surgical and medical providers who care for these patients but also for the patients and their families. The “final fusion” is regarded as the end of a long road of repeated surgical procedures that is frequently fraught with complications. As a result of these difficult challenges endured by the patients and their families, the implied conclusiveness of the final fusion is a typically celebrated event for all involved. This study, however, clearly showed that consideration must be given to the fact that this may not be a “final” event for up to 20% of patients treated with growing rods. A substantial number of patients with a wide variety of diagnoses required further unplanned surgery and the associated risks of a return trip to the operating room. Morbidity and mortality rates have been reported to be as high as 84% and 18%, respectively, for all patients undergoing scoliosis surgery in the early onset scoliosis population16. In patients undergoing growing-rod treatment specifically, studies have shown up to a 20% complication rate per procedure, with 58% of all patients in 1 series having at least 1 complication13,15. Furthermore, after 15 procedures, no patient in another study was complication-free according to a Kaplan-Meier analysis5.

For a wider perspective on this topic, we reviewed reoperation rates for pediatric and adolescent scoliosis surgery other than growing-rod treatment. In 2012, Ramo and Richards reported a 7.5% revision rate in a consecutive series of 452 pediatric patients ≥9 years of age at a single institution17. The original published revision rate from the same institution using previous-generation spinal instrumentation was 12.9%. The lower rate of revision surgery was attributed to a diminished occurrence of infection and pseudarthrosis. In a case-matched study comparing adolescent idiopathic scoliosis (AIS) and Marfan syndrome, Gjolaj et al. found that the patients with Marfan syndrome had a significantly higher rate of reoperation: 9 (27%) of 34 required surgical revision in contrast with no patient with AIS18. Additionally, Yagi et al. reviewed 638 cases of pediatric spinal deformity that included idiopathic, congenital, and neuromuscular etiologies19. They found that 50 (7.8%) of the patients required revision after at least 3 years of follow-up; the most common cause was pseudarthrosis.

A major weakness of the current study is that we did not investigate the risk factors that may have led to reoperation. The population of patients with early onset scoliosis has been shown to have notable complication rates due to their age, underlying diagnoses, cardiopulmonary compromise, and repeated interventions13,14,16. These factors may play a role in the reoperation rate because of their poorer overall health status than that of unaffected children. It can also be hypothesized that prior infection, poor soft tissue from repeated surgical intervention and impaired nutrition, decreased bone quality, and continued overall growth would all contribute to possible unplanned surgical intervention after final fusion in the early onset scoliosis population.

Another weakness of this study is that we did not evaluate outcome measures for the patients who underwent reoperation. Multiple studies have looked at validated outcomes scores for patients who have undergone repetitive surgical interventions for early onset scoliosis20-23. Psychological dysfunction and lower quality-of-life scores have been shown repeatedly in this patient population20,21. Parental anxiety has also been repeatedly shown to affect children’s outcomes in surgical settings, particularly in the treatment of scoliosis23. This anxiety is reported to be related to a lack of knowledge about the treatment received by their child. Education is an extremely important part of the early onset scoliosis treatment algorithm, ensuring that families, caregivers, and patients, if possible, understand the plan of care, especially the potential issues surrounding “final fusion.”

Additionally, we are unable to state that this is the “true” final rate of reoperation, since some of our patients developed problems years after their supposed “final” fusion. Further diligent follow-up and data collection will be required to determine the final end point. We are currently planning a larger, more detailed study to address these concerns and to determine specific risk factors.

The database used in this study is a multicenter catalog of patients with early onset scoliosis and their treatments, but it does not provide a true incidence of early onset scoliosis or the number of patients treated with growing rods in the U.S. and abroad. As more centers and patients are added to the database, the larger sample size will provide stronger data with regard to final fusion reoperations and their causes. In the same vein, the relatively new advent of growth-friendly surgery means that many of the patients included in this study had relatively short follow-up after their final fusion. Going forward, long-term follow-up data may reveal even more patients who ultimately require surgical intervention after final fusion.

Caution must be taken to counsel parents that the “final fusion” may not be the last surgical procedure necessary to completely and permanently correct the spinal deformity. Given the duration of time to reoperation in this study (up to 7.4 years, with a mean of 2.0 years) and the predominance of late complications (occurring >3 months after final fusion), follow-up of patients treated with growing rods should be continued for a minimum of 2 years, but arguably much longer, following final fusion surgery.

Additional investigation is needed to better establish the risk factors and to determine better methods for preventing the need for reoperation after final fusion.

NOTE: The authors thank the members of the Growing Spine Study Group and their contributions to the patient population needed for this investigation.

Disclosure: Funding for this study was provided by the Growing Spine Foundation. On the Disclosure of Potential Conflicts of Interest forms, which are provided with the online version of the article, one or more of the authors checked “yes” to indicate that the author had a relevant financial relationship in the biomedical arena outside the submitted work and “yes” to indicate that the author had other relationships or activities that could be perceived to influence, or have the potential to influence, what was written in this work.

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