This article represents a “graduation” report of the first group of patients with early-onset scoliosis treated with growing rods. Treatment of early-onset scoliosis has been challenging because early fusion has often resulted in crankshaft phenomena and/or thoracic insufficiency syndrome1,2. Since the introduction of spinal instrumentation by Harrington in 1962, clinical practice with growing rods and related devices has changed as important design and technique modifications have come about in response to clinical outcome data. The authors of the study under review have done an excellent job of highlighting these concepts in their discussion3. Despite these breakthroughs, several clinical dilemmas continue to challenge spine surgeons who manage patients with early-onset scoliosis. These dilemmas were the impetus behind the investigation by Flynn and colleagues into the circumstances guiding the decision of when to end growing-rod treatment and proceed with definitive fusion.
The strengths of this paper include a group of treating surgeons who are leaders in this field, a large group of patients, follow-up until definitive fusion, and the use of a prospective database. The authors are to be congratulated for working together to gather a large group of patients who had a rare condition.
The weaknesses of this paper are mainly twofold. The first is that this is a heterogeneous group of patients with a wide variety of diagnoses; the patients mostly presented with idiopathic, congenital, neuromuscular, and syndromic causes. The second weakness is that there was no standard treatment protocol; patients were treated with one growing rod or with two, and some had an anterior fusion performed.
So what have we learned? The good news is that a moderate degree of correction (21% to 50% correction) was achieved in many patients. The bad news is that growing-rod treatment is not a panacea, as 10% to 19% of the curves were worse after treatment3.
We also have learned that lengthening over a duration of at least three to six years was accomplished in >50% of patients and that limited remaining growth, progression of deformity, and loss of fixation comprised nearly 80% of the indications for final surgery. The indication for proceeding with definitive fusion surgery often is triggered by a problem such as infection or the belief that little spinal growth is remaining3. The average patient age at final fusion was 12.4 years, which is a vast improvement when compared with the option of definitive fusion three to six years sooner.
At the time of the final fusion, the foundation sites, which are subject to bone remodeling, were often usable in the final construct, although surgeons should expect abundant scar tissue and a likelihood of the need for osteotomies (24%), anterior-based procedures (13%), and thoracoplasty (8%)3.
Because of the patient mix, the scope of applicability of this study may be somewhat limited, but it still raises many questions. When is the best time to initiate growing-rod treatment? Which group responds best to the use of growing rods? The percentage of curves that worsened is in the double digits, and this is an area of concern. Why did the curves worsen? Was the worsening caused by the size of the curves, the treatment protocol, or the underlying disease?
One needs to remember that growing-rod surgery is not the only option for children with early-onset scoliosis. A recent survey of the members of the Pediatric Orthopaedic Society of North America (POSNA) by Fletcher et al.4 highlighted the various options for treating early-onset scoliosis by revealing that equal numbers of surgeons use cast and surgical spinal-lengthening techniques. More importantly, Mehta reported that cast treatment for children who present with early-onset scoliosis at a mean age of two years and six months could reduce, but not reverse, the deformity5. Thirty-six percent of the patients in that age group required spinal fusion before the age of ten, but 64% of the patients in the age group had not undergone spinal fusion by the time of follow-up5.
We still do not know if other treatment methods, such as simply waiting for the child to mature enough to undergo definitive fusion—which may require anterior and posterior spinal fusion—are better than repeated lengthening with growing rods. Is the benefit of avoiding an anterior spinal fusion equal to several years of repeated lengthening? Some curves may become so large and stiff that anterior release, halo-gravity traction, and posterior spinal fusion with possible vertebral body resection could be required. This possibility carries substantial potential risks, whereas there were only three relatively minor neurologic complications in the present study, which makes growing rods a very attractive treatment choice.
The results of the inaugural class of graduates from growing-rod school demonstrate mostly successes but some failures. We have learned a great deal about the management of early-onset scoliosis from them and are indebted to them for helping us make considerable strides. As the famous U.S. theologian Tryon Edwards once said, “Some of the best lessons we ever learn, we learn from our mistakes and failures. The error of the past is the success and wisdom of the future.”