Spine Niche! Opportunity in the Spinal Deformity Market

“Sit up straight and watch your posture!” It’s the routine command at the dinner table when parents see their children hunching over their food. Eating like a vulture may or may not contribute to spinal deformity but, going forward, spine companies should seek out niche markets. Given the myriad of start-up companies pursuing the same patients, product differentiation and solutions for specific target markets could be the key in the future.

We use the PearlDiver Patient Records Database to outline the dynamics of the spinal deformity market. We present our estimated procedure volumes for posterior fusion as a treatment for scoliosis—followed by the results of a study identifying complications associated with instrumented posterior thoracic fusion in treating scoliosis.

The Basics: Deformity Diagnoses, Curve Types, and Incidence Rates

To gain an understanding of the diagnoses trends in the deformity market, we ran an analysis over the PearlDiver Patient Records Database. As can be seen in Chart 1 below, idiopathic scoliosis (ICD-9 diagnostic code 737.30) accounts for the majority (78%) of primary diagnoses with respect to deformity. Adolescent scoliosis comprises nearly 75% of idiopathic scoliosis in the population under 65 years of age. According to an article written on Spine-Health.com (http://www.spine-health.com/conditions/scoliosis/scoliosis-%E2%80%93-what-you-need-know) by Dr. Peter Ullrich, there are three classifications of idiopathic scoliosis. These include: Infantile (from birth to 3 years), Juvenile: (from 3 to 9 years old), and Adolescent: (from 10 to 18 years old). Scoliosis and related conditions such as kyphoscoliosis comprise the majority of remaining conditions. Kyphosis, which is an exaggerated rounding of the back, comprised just 2% of the diagnoses and lordosis (excessive curvature in the lumbar region of the spine) accounted for 1%.

Chart 1: Distribution of Primary Spinal Deformity Diagnoses

Source: PearlDiver Patient Records Database (2004-June 2007)

According to the Scoliosis Research Society, scoliosis may be diagnosed when a patient has curvature upon forward bending of 10°. It has been estimated that the prevalence of AIS (adolescent idiopathic scoliosis) is about 2% – 3%. In the Spine Technology Handbook (page 146), Dr. Steven Kurtz and Dr. Avram Edidin highlighted five classical curve patterns relating to idiopathic scoliosis. These include the right thoracic (the most common), the thorocolumbar, lumbar, double primary, and double thoracic primary curve. Curves are named based on the apex of the curve being diagnosed. Cobb’s angle measures the degree of scoliosis.

According to the Scoliosis Research Society, treatment options fall into three main categories. The first is observation, which is commonly used for moderate curves under 40° – 45° when the patient is still growing. The second is bracing, which is for curves 25° – 45° in growing children. The final option is surgical treatment, which generally occurs for curves greater than 50° in adolescents and adults.

Scoliosis Demogaphics: From Adolescent to the Elderly Patient

Based on PearlDiver data, scoliosis is diagnosed nearly 70% of the time in females. Clearly, idiopathic scoliosis represents the primary market. However, opportunities exist for solutions targeting middle-aged patients and the elderly. We broke down diagnoses by age in the PearlDiver database and found that over 30% of idiopathic scoliosis diagnoses in the non-Medicare population (age<65) occur between the ages of 30 – 64.

Given the powerful demographic changes which will hit the health system at full force during the next two decades, the elderly patient is likely to play an increasing role in the deformity market. The Scoliosis Research Society suggests two reasons for the occurrence of adult scoliosis. The first is that the patient had AIS as a youth. The second is that the patient has degenerative or de novo scoliosis which can occur after the age of 40 due in part to disc and facet joint degeneration.

Based on data from the Agency for Healthcare Research and Quality, over 30% of hospital discharges related to scoliosis occur in the population over age 65, making this a formidable, yet challenging market. A challenge in developing solutions for this population is handling comorbidities such as osteoporosis during treatment. Reported statistics relating to the prevalence of adult scoliosis have varied tremendously, but we found a study presented at NASS 2007 that addressed the issue.

NASS 2007 Submission: General Session: Best Papers

In the Best Papers session at NASS, research was presented on the actual incidence of scoliosis in the adult population over 40 years of age. Prior to this research, estimates had ranged from 1.9% to 68%.

Paper Number 2: Prevalence of Scoliosis in Adults Age 40 Years and Older: A Study of 2973 Individuals

This article was submitted by Dr. Gabor Voros, Dr. Philip Neubauer, Dr. Mohammad Khoshnevisan, Dr. Richard Skolasky, Dr. John Kostuik, and Dr. Khaled Kebaish.

The purpose was to “study the prevalence of scoliosis and its relationship with age, race, and gender adult population, greater than 40 years of age.” The authors concluded that, “Our study indicates that the prevalence of lumbar scoliosis in adults is 8.85%. Increasing age was associated with increasing likelihood of scoliosis while the non-white race was associated with reduced likelihood of scoliosis.”

Deformity Related Procedure Volumes and Indications

We ran several analyses over the PearlDiver database in order to identify trends in treatment should the curvature be severe enough to warrant surgical intervention. Our first step was to find out what primary diagnoses were associated with posterior dorsal fusion.

With respect to inpatient surgical treatment of a primary diagnosis of idiopathic scoliosis, here is the procedure breakdown:

1. Posterior dorsal fusion: 65%
2. Anterior dorsal fusion: 13%
3. Posterior lumbar fusion: 11%

With respect to a primary diagnosis of progressive infantile scoliosis:

1. Posterior dorsal fusion: 75%
2. Anterior dorsal fusion: 14%
3. Posterior lumbar fusion: 7%

Based on the diagnosis-procedure analyses above, we see that posterior dorsal/thoracic fusion is most often used when surgical intervention is necessary. Chart 2 below looks at primary diagnoses associated with the posterior dorsal fusion (ICD-9 procedure code 81.05) in general. Idiopathic scoliosis is the primary diagnosis 44.6% of the time. Following other various deformity diagnoses, thoracic and lumbar fractures account for the second most common reason for undergoing this surgery.

Based on PearlDiver data, we estimate that there are over 30,000 posterior dorsal fusions annually, and over 20,000 of them are posterior dorsal/thoracic fusions performed in response to spinal deformity diagnoses. Here is our breakdown of posterior dorsal fusion procedures by common primary diagnoses:

1. Scoliosis (idiopathic): 16,000 – 17,000 procedures
2. Thoracic vertebral fracture: 2,400 procedures
3. Lumbar vertebral fractures: 1,500 procedures

Chart 2: Primary Diagnoses Associated With Posterior Dorsal Fusion
Source: PearlDiver Patient Records Database (2004-June 2007)

Instrumentation Usage

Based on our analyses, posterior fusion with instrumentation is still the standard of care when surgically treating scoliosis. Dr. Paul Harrington began this trend with the implantation of “Harrington rods.” Today, more advanced pedicle-based constructs are available in addition to the rods.

Posterior dorsal fusion is the most expensive fusion surgery on average in the PearlDiver database. Part of this can be attributable to the longer lengths of stay—7 – 9 days average—associated with the surgery. Some charges surpassed $160,000.

Another reason for the expensive nature of the operation is the long instrumentation often used in deformity correction. We used CPT codes to analyze instrumentation usage in posterior dorsal fusions. We first analyzed the vertebral levels over which instrumentation was implanted in general when posterior dorsal fusion (ICD-9 procedure code 81.05) was performed. We found that in posterior dorsal fusion, instrumentation spanning 7 to 12 vertebral levels was employed most often—over 47% of the time. Instrumentation spanning 13 or more levels was implanted in 18.4% of the surgeries. Three to six levels of instrumentation was implanted 16.9% of the time. We ran this analysis sequentially from 2004 through the first two quarters of 2007 and found that these percentages did not vary significantly over the period, suggesting little change in treatment patterns.

With respect to posterior dorsal/thoracic fusions where patients had a primary diagnosis involving scoliosis, 56.4% of patients had instrumentation spanning 7 to 12 vertebral levels, which is higher than the 47% seen when dorsal/thoracic fusion is analyzed without the constraint of specific associated diagnoses. Instrumentation spanning 13 or more levels was seen in over 27% of patients undergoing the surgery for spinal curvature.

Based on PearlDiver data, we found that 74% of instrumented posterior dorsal fusions, with scoliosis as a primary diagnosis, involved instrumentation spanning seven or more vertebral levels. Given our estimation of 15,000 – 17,000 annual posterior dorsal fusions for idiopathic scoliosis, it can be estimated that 11,100 involve constructs spanning seven or more levels indicated for scoliosis.

Complication Rates in Instrumented Posterior Dorsal/Thoracic Fusion for Spinal Curvature

Given the prevalence of posterior dorsal fusion as a primary surgical treatment for idiopathic scoliosis, we wanted to analyze complications associated with the surgery. We chose several common complications such as hematoma, postoperative infection, inflammatory response, device related complications, and respiratory failure, commonly seen in scoliosis patients. We then compared complications between surgeries where instrumentation spanning 7 to 12 vertebral levels was implanted versus 13 or more levels. With respect to 7 to 12 level instrumentation, we analyzed 914 patients and 444 patients who had instrumentation spanning 13 or more levels.

As can be seen in Chart 3 below, patients who had instrumentation spanning 13 or more vertebral levels implanted displayed higher complication rates in most of the categories we analyzed. Overall, complications regarding the device were quite low.

Respiratory failure/distress is a common diagnosis seen in patients who suffer from scoliosis. Scoliosis can produce pressure on the chest and cause respiratory muscle weakness, which can lead to respiratory failure. We found a high instance of respiratory distress in patients who underwent surgery for scoliosis. Respiratory distress was seen in 26% of patients implanted with instrumentation spanning 13 or more vertebral levels, and in 13% of patients with instrumentation spanning 7 to 12 levels.

Chart 3: Complications following Instrumented Posterior Thoracolumbar Fusion in Treating Scoliosis
Source: PearlDiver Patient Records Database

Spine Niche!