Partial Anulus Replacement with Barricaid® Prosthesis
January 3, 2013
Discectomies often only result in a short-term success. An aggressive removal of the nucleus increases the risk of a collapse of the intervertebral disc. Whereas a carefully limited discectomy could lead to an increased risk of reherniation. The Barricaid® Prosthesis for anular closure closes the anular defect, thus enabling the nucleus to be largely preserved. Specialists from various disciplines, attending a symposium organised by Intrinsic Therapeutics as part of the 7th Annual Meeting of the German Spine Society, discussed to what extent Barricaid® can sustainably prevent reherniations as well as preserving the intervertebral disc height and hence the biomechanics.
In 2011, over 173,000 disc operations were performed in hospitals in Germany1Federal Statistical Office.Flat rate case–related hospital statistics (DRG statistics) operations and procedures of fully stationary patients in hospitals. Detailed description – 2011. 25th October 2012. The outcome of the discectomies are often only satisfactory in the short-term. One year after the surgery, some 25% of all patients suffer again from pain, while 15% undergo a subsequent operation within four years. The risk of a post-discectomy syndrome increases significantly if the intervertebral disc height was reduced by more than 25%. This has led today to increased numbers of limited discectomies performed, which, in turn, is associated with an increased risk of a recurring disc herniation.
Closure of the anulus defect: more nucleus – less risk of collapse
Prof. Claudius Thomé, Director of the Neurosurgical Department at Innsbruck University explained the problem: “The surgeon faces a dilemma. If he performs an aggressive nucleus removal, then - although this reduces the risk of a recurring prolapse - it will also increase the risk of a disc collapse. If he decides in favour of a limited discectomy, this will increase the probability of the nucleus extrusion recurring due to the anulus fibrosis defect.” The risk of recurrence increases with the size of the defect. If it exceeds 6 mm, the probability of another prolapse is as high as 27%. 2Carragee EJ et.al. (2003) Clinical outcomes after lumbar discectomy for sciatica: the effects of fragment type and anular competence. J Bone Joint Surg Am 85-A:102-108.. A unique implant is available in the form of the Barricaid® Prosthesis for anular closure to effectively and securely close the anular defect. Barricaid® consists of a tissue mesh that is attached to the adjacent vertebrae with a titanium bone anchor. The mechanical barrier is attached in only a few minutes directly following the limited discectomy. Active patients, in particular, with anular defects exceeding 5 mm and a pre-operative intervertebral disc height of more than 5 mm will benefit from Barricaid®. According to Thomé: “The closure of the anular defect can enable the nucleus and thus the intervertebral disc height to be preserved. The biomechanics are retained without increasing the risk of a reherniation occurring.”
In vitro stress test shows reliability: 100,000 stress cycles – no relapse
Prof. Dr. biol. hum. Hans Joachim Wilke, from the Institute for Orthopaedic Research and Biomechanics in Ulm, presented the findings of an in-vitro study, which checked the reliability of Barricaid® under the “worst case” conditions. Following provoked herniated discs, the nucleus was pressed back into the intervertebral disc and the defect closed with the prosthesis for anular closure. The specimens were then subject to a long-term stress test.
It emerged that the original intervertebral disc height, which had been significantly reduced by the prolapse, had to a large extent been restored thanks to the Barricaid® implant. “The most important result, however, was that in no case did another herniated disc occur – even after 100,000 stress cycles. The prosthesis for anular closure appears to prevent reherniations thanks to the closure of the defect“, Wilke concluded.
Clinical study: fewer relapses – even with large defects
Dr. Peter Douglas Klassen, Head of the Spinal Surgery und Neurotraumatology Department at St. Bonifatius Hospital in Lingen presented the findings of two multicentre clinical studies. As part of the single-arm, prospective studies, the results of the discectomy using the intervertebral disc partial endoprosthesis for 75 patients were evaluated and compared. Not only with the data from a control group but also with previous publications on the results of discectomies. After two years, the recurrence rate of symptomatic herniated discs in the Barricaid® group was 1.4% compared to 11.7% in the control group. Even with patients having an anulus defect of more than 6 mm, the relapse rate was only 1.5%. This is in contrast to Carragee et al., who reported a relapse rate of 27.3% with a comparable group of high-risk patients with a sole discectomy. Klassen explained that the discectomy using Barricaid® showed significantly better results (also related to the preservation of the intervertebral disc height) in comparison with the discectomy alone. In addition, the patients suffered less pain and functional restrictions.
Maintaining the intradiscal pressure may delay degeneration of the intervertebral disc
Dr. Richard Bostelmann, Head of Spinal Surgery at the University of Düsseldorf, explained why the closure of the anulus defect may have several positive effects. Assuming that a lower intradiscal pressure is associated with increased intervertebral disc degeneration, and that not only the disc prolapse but also the discectomy reduces the pressure in the intervertebral discs, Bostelmann examined whether the closure of anular defects would interrupt the degenerative cycle.Extensive stress tests on the intervertebral discs of nine human cadaveric specimens have shown that - although the intradiscal pressure is reduced following the discectomy - the closure of the anulus defect can restore the natural pressure. The findings reveal that Barricaid® may delay or even hold back invertebral disc degeneration after a discectomy and thus reduce the risk of a disc collapse and nucleus extrusion.”
Barricaid® Prosthesis for Partial Anulus Replacement is recommended for those patients at particularly high risk of a recurring herniated disc, intervertebral disc collapse, recurring sciatica as well as early stage pain in the lower back. Even before the operation, the doctor is able to determine whether Barricaid may be appropriate from the intervertebral disc height recorded on the MRI (>5 mm). The final measurement to verify this assumption takes place during the operation: if the anular defect exceeds 5 mm in size, then it may be assumed that there is an increased risk of a future herniated disc.
Lunch symposium “Closure of anulus defects with Barricaid® partial endoprosthesis". Stuttgart, 6th December 2012 – organised by: Intrinsic Therapeutics.