Here Comes Orthofix’s M6 Cervical Disc

After 45,000 implants outside the United States and 16 years of hard work, the elegantly designed M6 Artificial Cervical disc has been approved for sale in the U.S. The study that supported the FDA approval reported that patients who’d received the M6 experienced statistically significant pain relief which was higher than that reported by study patients receiving the standard anterior cervical disc fusion (ACDF).

The M6 Cervical Disc Implant

The M6 is a one-of-a-kind motion preserving spinal disc implant.

It is the only artificial disc with an artificial nucleus (made from polycarbonate urethane) and a virtual annulus (made from polyethylene). It is also the only motion preserving disc implant whose original design objective was to mimic as closely as possible the “natural” movement—in all planes and all axis—of the native spine disc.

Here is how the engineers who created the M6 accomplished that design objective.

	Artificial Nucleus At its core, the M6 is a viscoelastic polymer which was designed to simulate a native nucleus This viscoelastic polymer moves in a way which allows physiologic axial compression It is held between endplates and within a fiber annulus matrix The designers also shaped it so that it could enable physiologic Center Of Rotation
	Artificial Annulus At the core of the M6 implant is an ultra-high molecular polyethylene (UHWMPE) fiber artificial annulus This artificial annulus was designed to simulate and perform like a natural annulus Spinal Kinetics (the company Orthofix purchased) designed M6 to provide controlled physiologic motion in all planes and axes Finally, in a manner which is similar to a native annulus, the engineers at Spinal Kinetics designed into the implant a robust fiber matrix with multiple layers
	Sheath Next, M6’s engineers designed a sheath to surround the artificial annulus which would act to minimize tissue in-growth and debris migration The sheath is flexible and lets the disc to move in all axis and planes—a full range of motion, in other words
	Fixation Finally, the implants end plates are made from titanium and used a tri-fin design to keep the implant firmly in place The company also used a titanium plasma spray (TPS) to coat each endplate surface And, it’s a low-profile implant—only 2mm tall

The M6 Clinical Study

The M6 received CE mark approval for sale in Europe in 2006 and, prior to receiving FDA approval in February 2019, had been implanted in more than 45,000 patients. So, even before this study’s outcomes were available to physicians in the U.S., there was a significant amount of clinical information about this disc.

The U.S. Investigational Device Exemption (IDE) study stood, in many respects, on the shoulders of the international investigators who have been using M6 since 2005.

The U.S. IDE study for M6 was a prospective, concurrently controlled, multi-center study. Among the sites that participated were Hospital for Special Surgery, Indiana Spine Group, Midwest Orthopaedics at Rush, Carolina Neurosurgery and Spine, Texas Back Institute, Stanford University Hospital and the Desert Institute for Spine Care in Phoenix.

The main objective of the study was to evaluate the safety and effectiveness of the M6-C artificial cervical disc at 24 months post-surgery. The control in the study was anterior cervical discectomy and fusion (ACDF).

Investigators enrolled patients with degenerative cervical radiculopathy which was confirmed clinically and radiographically, at one vertebral level from C3 to C7. A total of 258 subjects were enrolled at 13 sites.

The first patient was enrolled in May 2014.

Here is a summary of the results.

• Pain
  • 91% of the M6 patients reported arm pain relief that qualified as clinically meaningful
  • Versus 78% of the control arm patients (ACDF) reported clinically meaningful arm pain relief
  • 91% of the M6 patients reported neck pain relief that was clinically meaningful
  • Versus 80% of the ACDF patients reported neck pain relief that was clinically meaningful
• Pain Medication Use
  • Before surgery more than 81% of the patients were taking pain medication
  • After M6 Cervical disc, 14% of the patients continued taking some type of pain medication
  • After ACDF, 38% continued taking some type of pain medication

In earlier M6 studies, the length of stay for patients receiving M6 averaged four hours.