Each month during the coming year, OrthoBuzz will bring you a current commentary on a “classic” article from The Journal of Bone & Joint Surgery. These articles have been selected by the Editor-in-Chief and Deputy Editors of The Journal because of their long-standing significance to the orthopaedic community and the many citations they receive in the literature. Our OrthoBuzz commentators will highlight the impact that these JBJS articles have had on the practice of orthopaedics. Please feel free to join the conversation about these classics by clicking on the “Leave a Comment” button in the box to the left.
The JBJS Classic Treatment of Scoliosis: Correction and Internal Fixation by Spinal Instrumentation by Paul R. Harrington describes 15 years of investigation, beginning in 1947, soon after Dr. Harrington completed his residency in Kansas City and headed an Army orthopaedic unit during World War II. The importance of this paper can’t be overstated. With this description of instrumentation that improved deformity outcomes, Harrington ushered in modern spine surgery. It was also one of the rare early examples of orthopaedic clinical science funded by a national grant.
The need for this daring, revolutionary instrumented approach was the polio epidemic, which left Dr. Harrington caring for many patients with severe, collapsing curves that threatened their health. Polio patients comprised 75% of the first series described in this paper.
This comprehensive study combines theory, basic science, surgical techniques, and outcomes. With it, Harrington started the still-continuing dialogue about indications for scoliosis surgery with the comment that “clinical indications for therapy are still being worked out.” As a partial answer to the indications quandary, he introduced the Harrington factor—the number of degrees of primary curve divided by the number of vertebrae in the primary curve. This calculation continues to be used (renamed) in some current research into risks of curve correction, while debate continues about other indications such as progression, pain, and pulmonary issues.
The technique of spinal instrumentation is extensively described in this landmark article. Noteworthy is Harrington’s gradual embrace of the need for fusion and well-molded body cast immobilization, both of which he credits with improved results. (Initially Harrington had hoped to avoid fusion in many cases.) Although “instrumentation” today is nearly synonymous with “fusion,” some of our most promising ideas in deformity correction now involve instrumentation without fusion.
Also impressive is the respect with which Harrington treated the spinal cord and dura. He describes careful insertion of the hooks and recommends against downward hooks above L2, where the conus ends. This paper reminds us that we should always pursue the lowest-risk approach to instrumentation that will serve our patients. Dr. Harrington was also cognizant of the importance of blood loss, and meticulously measured it by stage of surgery. He showed that most blood loss occurred during subperiosteal dissection, a fact that we still recognize today.
Harrington’s description of selective thoracic fusion was illustrated radiographically in Figure 7, which shows a dramatic result where a 55° unfused lumbar curve declined to 18° after correction of a larger thoracic curve. This concept was further developed by Moe, King, Lenke and others, but the idea of spontaneous correction of lumbar curves started with the power of Harrington’s instrumentation.
The benefits of our more “modern” instrumentation are evident when reading the recommended aftercare in Harrington’s paper: a 16-day hospital stay, 8 weeks of bed rest, and a Risser localizer cast for 3 to 5 months, only to find out whether the patient might need reoperation for instrumentation problems or pseudarthrosis.
A modern journal editor might have expended some red ink on Dr. Harrington’s paper. The organization was less formal than many scientific papers today, but this may reflect the multiple simultaneous investigations and changes that took place during this decade-plus of revolutionary work. Dr. Harrington emphasizes that the results improved with each iteration of the procedure and device, which underwent more than three dozen design modifications.
Details on the curve sizes were not given, but we now recognize that curve size does not correlate linearly with clinical parameters. While Harrington does not describe the contributions of others who may have been involved in this work, neither does he use the eponymous term (“Harrington instrumentation”) that others attached to his spinal fixation device. While remarkable in its prescience, this paper did not anticipate the problems of distraction instrumentation in the lumbar spine, later characterized as Flatback Syndrome. It also did not elaborate on the need for differing mechanics in kyphoscoliosis or Scheuermann kyphosis.
Nevertheless, in this single article, Dr. Harrington laid the groundwork for three major themes that orthopaedists have further developed:
- The safety and benefits of metal fixation in spine surgery
- The use of growth guidance in patients < 10 years old
- The idea of selective thoracic fusion for double curves
Each of these ideas has generated hundreds of additional studies and papers to get us to modern practice. Just as current hip arthroplasty techniques represent incremental improvements on the monumental contribution of Charnley, current techniques in scoliosis surgery, especially of the thoracic spine, are but stepwise improvements on Harrington’s classic work.
Paul Sponseller, MD, JBJS Deputy Editor for Pediatrics
Marc Asher, MD, Professor Emeritus, Department of Orthopaedic Surgery, University of Kansas Medical Center
Orthopaedic surgical procedures to correct axial and appendicular skeletal deformities are usually dependent upon fixation devices, either external or internal or both. These devices are often developed through close collaboration with engineers who are generally employed by major manufacturing companies. After the devices successfully clear rigorous bench, in-vitro, and in-vivo testing, the standard initial presentation of clinical results is a case series.
All too often the initial report of results comes from a co-developer of the device, with inherent selection and detection bias that constitute what most readers would consider a conflict of interest. McCarthy and McCullough’s case series on five-year results with Shilla growth guidance in 33 children with early-onset scoliosis in the October 7, 2015 JBJS is an exception to that rule. The authors report every conceivable major and minor adverse event without holding back any negative information. They categorize complications as infection secondary to wound breakdown, spinal alignment issues, and implant issues. The overall complication rate was 73%, a rate that is not surprising given the fact that the device under study is designed to maintain correction of spinal deformity in growing children.
Thankfully, the authors reported no neurologic complications. Also on the positive side, they found that spinal curves averaging 69° preoperatively averaged 38.4° at the most recent follow-up or prior to definitive spinal instrumentation. McCarthy and McCullough also calculated a 73% reduction in the number of surgical procedures among their cohort, relative to what would be necessary to treat the same population with distraction methods every six months.
I applaud the authors for comprehensively reporting the results of correction of spinal deformity in this difficult clinical situation with high accuracy and strict definitions of major and minor events. This is how we will make advances in correcting deformity for skeletally mature and immature patients—with innovation, incremental improvement, and the widespread sharing of adverse events with the orthopaedic community. Armed with the information from this study, we must now see what the number and severity of complications look like when the broader community of orthopaedic surgeons applies these devices.
Marc Swiontkowski, MD