Disc Arthroplasty's Steep Learning Curve
BY ROBIN R. YOUNG CFA, JULY 12, 2004
We now have data from the early disc arthroplasty patients. The good news is that a 17 year follow-up study of 51 disc arthroplasty (non-fusion) patients was presented at the recent EuroSpine conference in Porto, Spain. The bad news is that 55% of those patients (37 segments) spontaneously fused. The worse news was that they were the happiest group in the study. Of course, these were earlier version of the SB Charite and the instrumentation has improved significantly during the term of the study. Still, the data suggests that both the technology and the surgeons employing it have been walking up a steep learning curve.
The FDA is expected to approve the SB Charite for U.S. sale in the coming six to nine months, our estimate. With that approval, the multi-billion dollar disc arthroplasty industry, which at the moment exists only in business plans at Johnson & Johnson, Synthes, Medtronic, Biomet and a score of smaller orthopedic implant manufacturers, will be launched in the United States.
So far, we estimate, as much as seven hundred and fifty million dollars has been spent by companies to purchase and develop commercial disc arthroplasty products for the U.S. market. Furthermore, these disc arthroplasty technologies represent more than just a new implant. They are a new philosophy for addressing severe back pain using the concept of motion preservation, not fusion.
It may be a clich' to say it, but the stakes are very high. With FDA approval, salesmen will make the calls. Surgeons will explain the notion of non-fusion to their patients. JNJ will ship the redesigned instrument sets. Hundreds of rank and file surgeons will make their first cuts and begin the complex process of implanting thousands of SB Charite discs. What happens next will set the stage for this nascent industry segment.
Like scores of surgeons and a handful of industry analysts, we also looked back at two decades of European disc arthroplasty experience to understand what will happen in the US. The European experience is instructive.
- The learning curve for surgeons is steep. It is very surgeon specific and requires significant attention to detail.
- When performed well, the average operative time is 90 minutes with minimal blood loss.
- Patient selection is critical. Best patients are young, active, motivated with chronic discogenic low back pain at either L4-L5 or L5-S1 levels.
- The least suitable patients are those with severe stenosis, degenerative spondylolisthesis, severe facet joint arthropathy, significant scarring from prior surgeries or significant scoliotic deformity.
- The majority of disc implant related complications are related to poor positioning.
- This is a procedure that experienced surgeons use on about 4% of patients.
A follow up study conducted by Dr. Theirry David of the Polyclinique de Bois-Bernard is interesting. Dr. David has used the SB Charite for 14 years in approximately 350 procedures. He presented the results of his first 147 Charite patients (treated between 1989 and 1997) at the Second Annual Argos North American conference last October. Of his 147 patients, 120 reported good function (82%) at an average follow-up period of 10 years. Thirteen patients required secondary fusion procedures. Seven had no mobility in the disc due to periprosthetic ossification.
Dr. David's experience is amazingly similar to the recently reported American IDE study led by the Texas Back Institute for Johnson and Johnson.
| Dr. David's 10-year rate of 'good function':
| 82%
|
| U.S. study: % of Patients who would have the Charite again:
| 82%
|
| U.S. study: % of satisfied BAK patients:
| 81%
|
| U.S. study: Excluded training patients from results.
|
|
The U.S. study also reported that 88% of the patients expressed satisfaction with the SB Charite at 24 months. 82% said they would choose the Charite again.
Not included in those U.S. study results were the complication rates in the first 71 cases. The vast preponderance of major complications occurred in these 'training patients.' Most surgeons using the Charite experience learning curve related problems in the first five discal arthroplasties. Until those are under their belt, outcomes are worse than fusion.
So, if 500 surgeons use the Charite on 2,500 patients (the first five), how many implant related complications will there be? Considering how surgeon specific this procedure is, potentially, they could number in the hundreds.
