The examples and perspective in this article deal primarily with the United States and do not represent a worldwide view of the subject. (April 2014) |
Total disc replacement (TDR), or artificial disc replacement (ADR), is a type of arthroplasty in which degenerated intervertebral discs in the vertebral column are replaced with artificial disc implants in the lumbar (lower) or cervical (upper) spine. The procedure is used to treat chronic, severe low back pain and cervical pain resulting from degenerative disc disease. Disc replacement is also an alternative intervention for symptomatic disc herniation with associated arm and hand, or leg symptoms (radicular pain).
| Total disc replacement | |
|---|---|
| Other names | Artificial disc replacement, intervertebral disc arthroplasty |
| ICD-9-CM | 80.5 |
TDR has been developed as an alternative to spinal fusion, with the goal of pain reduction or elimination, while still allowing motion throughout the spine. Faster recoveries after surgery have also been widely reported by surgeons.[1] Another possible benefit is the prevention of premature breakdown in adjacent levels of the spine, a potential risk in fusion surgeries.[2] Recent studies have shown a strong correlation between providing motion in the spine and avoiding adjacent segment degeneration.[3]
Regulation
editUnited States
editMultiple artificial discs (or disc replacements) have been approved by the FDA for use in the US, although several have been discontinued by their manufacturers. The Charité, a mobile core device for use in the lumbar spine, was approved first, in 2004, but is no longer in use. prodisc, the longest continually used disc replacement device in the US, is a fixed core device manufactured by Centinel Spine and was approved in 2006 for the lumbar spine with a cervical device approved in 2007. The first cervical disc replacement available in the US was the Prestige, manufactured by Medtronic. There have been several Prestige cervical disc replacement designs manufactured by Medtronic, with the current design being the Prestige LP.
FDA approvals for devices are for one- or two-level use and at specific levels in the cervical or lumbar spine. Clinical studies are currently required to obtain FDA approval for disc replacements. These studies are comparative, noting differences between patients receiving a new device versus patients that receive spinal fusion or another previously-approved disc replacement. The below table illustrates currently-approved disc replacement devices, their approval dates, the number of approved levels for each device, and their current usage status.
| Device | Anatomy | # Levels, (indicated levels) | Approval Date | In Current Use? |
|---|---|---|---|---|
| Charité [4] | Lumbar | 1 level only (L4-S1) | 10/04 | No |
| prodisc L[5] | Lumbar | 1 or 2 level (L3-S1) | 8/06 | Yes |
| ActivL[6] | Lumbar | 1 level only (L4-S1) | 6/15 | Yes |
| Prestige[7] | Cervical | 1 level only (C3-C7) | 7/07 | No |
| prodisc C[8] | Cervical | 1 level only (C3-C7) | 12/07 | Yes |
| Bryan[9] | Cervical | 1 level only (C3-C7) | 5/09 | No |
| Secure-C[10] | Cervical | 1 level only (C3-C7) | 9/12 | Yes |
| PCM[11] | Cervical | 1 level only (C3-C7) | 10/12 | No |
| Mobi-C[12] | Cervical | 1 or 2 level (C3-C7) | 8/13 | Yes |
| Prestige LP[13] | Cervical | 1 or 2 level (C3-C7) | 7/16 | Yes |
| M6-C[14] | Cervical | 1 level only (C3-C7) | 2/19 | Yes |
| Simplify[15] | Cervical | 1 or 2 level (C3-C7) | 4/21 | Yes |
| prodisc C Vivo[16] | Cervical | 1 level (C3-C7) | 7/22 | Yes |
| prodisc C SK[16] | Cervical | 1 level (C3-C7) | 7/22 | Yes |
| prodisc C Nova[16] | Cervical | 1 level (C3-C7) | 7/22 | Yes |
While these discs have received FDA approval, reimbursement by insurance companies is not always automatic. Effective August 14, 2007, the Centers for Medicare & Medicaid Services (CMS) does not cover, on a national basis, Lumbar Artificial Disc Replacement (LADR) for patients over the age of 60. However, individual entities (Medicare Administrative Contractors, or MACs) regulate the determination of covered use of devices in patients 60 and under, and several approve the use of LADR for these patients.[1] Approval by insurance companies is generally better for cervical disc replacements, with over 90% of the US population covered by a commercial payer that reimburses for cervical disc replacements, and over 85% for lumbar disc replacements.[17]
Outside of the United States
editMany countries have their own individualized approval process for medical devices. In Europe, Regulation (EU) 2017/745 defined the Medical Device Regulation (MDR) used for reviewing, approving, and monitoring the quality of medical devices. There are a large number of total disc replacements available and approved for use in Europe, including all of those available in the US. Some other international regulatory bodies base their approvals upon regulations in third party countries, such as the EU or the US. Nearly all countries have their own approval process. The below table lists cervical disc replacement options available outside of the US.
| Device | Manufacturer | Earliest Usage |
|---|---|---|
| Prestige-ST | Medtronic Inc | 2003 |
| prodisc C | Centinel Spine | 2002 |
| prodisc C Nova | Centinel Spine | 2009 |
| prodisc C Vivo | Centinel Spine | 2009 |
| Bryan | Medtronic Inc | 2000 |
| Secure-C | Globus Medical Inc | 2006 |
| PCM | NuVasive (Medtronic Inc) | 2002 |
| Mobi-C | ZimmerBiomet | 2004 |
| Prestige-LP | Medtronic Inc | 2004 |
| Rotaio | SIGNUS Medizintechnik GmbH | 2011 |
| Baguera-C | Spineart Geneva SA | 2007 |
| Granvia-C | Medicrea International | 2010 |
| Freedom-C | Axiomed Spine Corp | 2012 |
| Discover | Centinel Spine | 2006 |
| CP ESP | FH Orthopedics | 2012 |
| Simplify | Simplify | 2015 |
| Discocerv | Alphatec Spine Inc | 2006 |
| NuNec | RTI Surgical, Inc | 2012 |
| Tri-Lobe | Dymicron | 2014 |
| NEOphytos | Artworld Medical | Unknown |
| Activ-C | Aesculap AG | 2007 |
| Rhine | K2M | 2016 |
| Cadisc-C | Ranier Technology Ltd | 2012 |
| Almas | NovaSpine | 2012 |
| D6 | TrueMotion Spine Inc | Unknown |
| ACDG5 | MAXXSPINE Ltd | 2009 |
History
editThe first artificial disc was implanted in 1959, with Swedish surgeon Ulf Fernström publishing a description of his experience implanting a stainless-steel ball bearing into an intervertebral disc space after discectomy in 1966. Fernström balls, used in approximately 250 patients, created segmental hypermobility and demonstrated a marked tendency to settle into the vertebral endplates. Reports suggest that function, while initially good, degenerated over time.
During the 1970s, a new concept was introduced: achieving mobility through articulation between the concave and convex surfaces of a multi-component device. Designs patented at that time combined metal, ceramic, or other types of elastic bearings with components made of silicone composites, rubber, polyurethane, plastics, or fluid-filled membranes. Some designs incorporated balloons, cages, pegs, wire screens, hinged plates, or springs. Springs proved to be particularly impractical because they could not withstand biomechanical fatigue tests of stress and strain.[18]
The first design with wide clinical adoption was the Charité disc replacement, designed by East German scientists: two-time Olympic champion in women's artistic gymnastics Karin Büttner-Janz and Kurt Schellnack, a doctor, engineer, and professor—both of whom were affiliated with the Charité Center for Musculoskeletal Surgery at the Medical University of Berlin[2]. First implanted in 1984, the disc had a biconvex polyethylene nucleus within a radiopaque metal ring that interfaced with two cobalt-chromium-molybdenum alloy endplates, which were coated with calcium phosphate. Approved for use in the United States in 2004, after a 4-year clinical trial, Charité was removed from the market by 2012.
The second disc replacement to achieve wide clinical use was the prodisc total disc replacement; it continues to have worldwide use today. Designed by French orthopedic spine surgeon Thiery Marnay, M.D., in the late 1980s, early implantations of the prodisc device began in 1990, with a 7-11 year follow-up published in 2005. After implementing design changes to the bone-facing endplate, and after a clinical study in the United States, the new design was made available worldwide. In October 2001, as part of the FDA trial, Jack Zigler, M.D., a spine surgeon at Texas Back Institute in Plano, Texas, performed the first prodisc L artificial disc replacement in the United States.
Research
editThe US FDA requires manufacturers to conduct clinical studies to assess the safety and efficacy of disc replacements before obtaining approval to market the devices in the United States. Other devices can be approved for use with simpler non-clinical reviews. As a result, disc replacements have the highest level of clinical evidence of any spine devices. However, since this research is funded by industry, some controversy over data bias produced by the clinical studies exists [see Controversy].
Level 1 and level 1a studies (the highest quality levels: see Hierarchy of Evidence) have shown safety and efficacy for both lumbar and cervical discs, and have become the de facto standard of care for appropriate patients outside of the United States.[19][20] All prospective, randomized clinical studies that have been run in the United States have shown lumbar and cervical disc replacements to provide faster recovery, better long-term patient satisfaction, and fewer incidents of adjacent segment degeneration than comparative spinal fusion options.[19][20]
A few non-industry funded studies also exist. In addition to the previously mentioned 7-11 year followup study on prodisc conducted by Thiery Marnay, M.D.,[21] a Norwegian study published in The Spine Journal in 2017 compared total disc replacement and multidisciplinary rehabilitation with an eight-year follow up. The study was randomized, controlled, multi-center and not funded by industry. 77 patients randomized to surgery and 74 patients randomized to rehabilitation responded at eight-year follow-up. The study found a statistically significant benefit in favor of surgery.[22]
Controversy
editThe AAOS states that disc replacement requires a high level of technical skill for accurate placement and has a significant level of risk if revision surgery is needed.[23]
Members of AAOS and the American Association of Neurological Surgeons joined together as the Association for Ethics in Spine Surgery, formed to raise awareness of the ties between physicians and device manufacturers.[24]
Aetna rescinded its positive coverage for single level lumbar ADR after merger with Coventry in 2013.[25] There is currently (in 2022) a class-action lawsuit against Aetna Life Insurance for denying patients seeking lumbar disc replacement surgery in the United States alleging that patients are being harmed by denials since Aetna has declared them 'experimental or investigational’.[26]
Despite published meta-analyses (the highest-level clinical evidence) that have illustrated that total disc replacement seems to be superior to fusion in most clinical parameters, new studies have identified concerns regarding long-term durability of some of these devices. One such recent study identifies a large “midterm failure rate” related to the M6-C. It recommends that “patients implanted with the M6-C prosthesis should be contacted, informed, and clinically and radiologically assessed”.[27] Unfortunately, catastrophic failure of the M6-C prosthesis has also been reported.[28]
References
edit- ^ "Recovery After Cervical Total Disc Replacement: Covered by the rediscover Patient Education Team with Kevin Rutz, MD | rediscover".
- ^ Hilibrand, A. S.; Carlson, G. D.; Palumbo, M. A.; Jones, P. K.; Bohlman, H. H. (1999). "Radiculopathy and myelopathy at segments adjacent to the site of a previous anterior cervical arthrodesis". The Journal of Bone and Joint Surgery. American Volume. 81 (4): 519–528. doi:10.2106/00004623-199904000-00009. PMID 10225797.
- ^ Spivak, J. M.; Zigler, J. E.; Philipp, T.; Janssen, M.; Darden, B.; Radcliff, K. (2022). "Segmental Motion of Cervical Arthroplasty Leads to Decreased Adjacent-Level Degeneration: Analysis of the 7-Year Postoperative Results of a Multicenter Randomized Controlled Trial". International Journal of Spine Surgery. 16 (1): 186–193. doi:10.14444/8187. PMC 9519082. PMID 35177528. S2CID 246944150.
- ^ "Premarket Approval (PMA)".
- ^ "Premarket Approval (PMA)".
- ^ "Premarket Approval (PMA)".
- ^ "Premarket Approval (PMA)".
- ^ "Premarket Approval (PMA)".
- ^ "Premarket Approval (PMA)".
- ^ "Premarket Approval (PMA)".
- ^ "Premarket Approval (PMA)".
- ^ "Premarket Approval (PMA)".
- ^ "Premarket Approval (PMA)".
- ^ "Premarket Approval (PMA)".
- ^ "Premarket Approval (PMA)".
- ^ a b c "Premarket Approval (PMA)". 13 July 2022.
- ^ "Major Commercial Third Party Payer in Utah and Idaho Significantly Expands Patient Access to Centinel Spine's prodisc® L for One- and Two-level Lumbar Total Disc Replacement".
- ^ Marnay T, 1993, SPINE System Vertebral Osteosythesis, First Edition, Sauramps Medical
- ^ a b Bai, D. Y.; Liang, L.; Zhang, B. B.; Zhu, T.; Zhang, H. J.; Yuan, Z. G.; Chen, Y. F. (2019). "Total disc replacement versus fusion for lumbar degenerative diseases - a meta-analysis of randomized controlled trials". Medicine. 98 (29): e16460. doi:10.1097/MD.0000000000016460. PMC 6709089. PMID 31335704.
- ^ a b Zhai, S.; Li, A.; Li, X.; Wu, X. (2020). "Total disc replacement compared with fusion for cervical degenerative disc disease: A systematic review of overlapping meta-analyses". Medicine. 99 (19): e20143. doi:10.1097/MD.0000000000020143. PMC 7220152. PMID 32384498.
- ^ Tropiano, P.; Huang, R. C.; Girardi, F. P.; Cammisa Jr, F. P.; Marnay, T. (2005). "Lumbar total disc replacement. Seven to eleven-year follow-up". The Journal of Bone and Joint Surgery. American Volume. 87 (3): 490–496. doi:10.2106/JBJS.C.01345. PMID 15741612.
- ^ Furunes, Håvard; Storheim, Kjersti; Brox, Jens Ivar; Johnsen, Lars Gunnar; Skouen, Jan Sture; Franssen, Eric; Solberg, Tore K.; Sandvik, Leiv; Hellum, Christian (October 2017). "Total disc replacement versus multidisciplinary rehabilitation in patients with chronic low back pain and degenerative discs: 8-year follow-up of a randomized controlled multicenter trial". The Spine Journal. 17 (10): 1480–1488. doi:10.1016/j.spinee.2017.05.011. hdl:10852/66181. PMID 28583869.
- ^ "WebMD article, Spinal Fusion (Arthrodesis)".
- ^ "About AME | Association for Medical Ethics".
- ^ Sandhu, F. A.; Dowlati, E.; Garica, R. (2020). "Lumbar Arthroplasty: Past, Present, and Future". Neurosurgery. 86 (2): 155–169. doi:10.1093/neuros/nyz439. PMID 31724719.
- ^ "Lumbar disc replacement coverage case against Aetna to move forward".
- ^ Scott-Young, M.; Rathbone, E.; Grierson, L. (2022). "Midterm osteolysis-induced aseptic failure of the M6-C™ cervical total disc replacement secondary to polyethylene wear debris". European Spine Journal. 31 (5): 1273–1282. doi:10.1007/s00586-021-07094-7. PMID 35020078. S2CID 245856451.
- ^ Carrera, Diego A.; Ricks, Christian B. (2022-03-14). "Catastrophic delayed cervical arthroplasty failure: illustrative case". Journal of Neurosurgery: Case Lessons. 3 (11): CASE21731. doi:10.3171/CASE21731. ISSN 2694-1902. PMC 9379625. PMID 36209405.