Failed M6-C Artificial Disc? Signs You May Need Revision Surgery

What Does it Mean When an M6-C Disc "Fails"?

To understand why an M6-C artificial disc might fail, it helps to look at how it was built. Unlike many other discs made of solid metal or plastic, the M6-C Artificial Cervical Disc was designed as a physiologic or biomimetic disc replacement. 

The M6-C uses an ultra-high molecular weight polyethylene (UHMWPE) fiber annulus wound around a polycarbonate urethane (PCU) core. This design generates microscopic wear debris when the fibers fray under years of mechanical stress. While the PCU core is a specialized form of polyurethane, clinical data indicates it is primarily the fraying of the polyethylene fibers that triggers an aggressive immune response. 

When the body detects these fragments, it may trigger an inflammatory response. This reaction can lead to osteolysis, where the surrounding bone weakens. When the disc can no longer maintain its height or position, it is considered a clinical failure. 

Comparing a Healthy vs. Failing M6-C Disc

This table explains the difference between a disc that is working correctly and one that may require medical attention:

5 Warning Signs Your M6-C Disc May Have Issues

If you have an M6-C implant, it is important to monitor how your neck feels, even years after your procedure. While some discomfort during recovery is normal, certain symptoms can indicate that the device is no longer functioning correctly. Based on patient reports and clinical observations, here are five critical warning signs:

1. Returning Neck and Arm Pain

Many patients seek an M6-C disc replacement to find relief from chronic pain. If that same sharp, burning, or aching pain returns in your neck or radiates down into your shoulders and arms, it is a major red flag. This often happens because the disc has collapsed, allowing the surrounding bone to put pressure on the nerves once again.

2. Cervical Radiculopathy (Nerve Tingling and Weakness)

When an artificial disc fails or shifts, it can interfere with the nerve roots in the cervical spine. You might experience pins and needles, a persistent tingling sensation, or numbness that travels into your hands and fingers. In more serious cases, you might notice a loss of grip strength or find it difficult to perform fine motor tasks, like buttoning a shirt or typing.

3. Mechanical Clicking or Grinding Sensations

A notable sign of artificial disc wear or loosening is the sensation of mechanical noise. If you feel or hear a click, pop, or grinding sound when you tilt or rotate your head, the disc may have shifted from its original position (migration) or the internal core may be damaged. This crepitus suggests that the metal plates may be rubbing or that the implant is no longer stable.

4. Balance Issues and Unsteady Gait

If a failed M6-C disc moves toward the spinal canal, it can cause cervical myelopathy, which is pressure on the spinal cord itself. This is a serious symptom that often manifests as a loss of balance, tripping more frequently, or a heavy feeling in your legs. If you feel unsteady on your feet or notice a change in how you walk, you should seek a specialized spinal evaluation immediately.

5. Reduced Range of Motion and Neck Stiffness

While the M6-C was designed to provide natural movement, a failing disc often leads to increased stiffness. This can be caused by inflammation in the surrounding tissues or by Heterotopic Ossification (HO), which is when the body grows extra bone around the implant. If you find it increasingly difficult to turn your head left or right, it may be a sign that the disc is no longer moving as it should.

Can an M6-C Disc Cause Bone Loss (Osteolysis)?

One of the most significant concerns identified by global health authorities is the risk of osteolysis (bone loss) associated with the M6-C implant.

How the M6-C Causes Bone Loss

Osteolysis occurs due to a biological reaction to wear debris. The M6-C uses a UHMWPE polyethylene fiber annulus surrounding the polycarbonate urethane (PCU) core, and these fibers can experience friction over years of neck movement. As they fray and break down, they release microscopic particles into the surrounding tissue. The immune system identifies these particles as foreign objects, triggering an inflammatory response that dissolves the healthy bone intended to hold the implant in place. 

Why Osteolysis is Often a "Silent" Complication

Bone loss itself usually does not hurt. A patient can have significant hollow spaces forming in their vertebrae without feeling a thing. The pain only begins when the bone becomes so thin that it leads to subsidence (the disc sinking into the bone) or fractures. Surgeons now recommend regular imaging for M6-C patients, even if they feel fine, to ensure the bone remains dense. 

Your Options for Fixing a Failed Disc

When an M6-C disc fails, the primary goal of surgery is to decompress the nerves and restore the stability of the cervical spine. Depending on the condition of your vertebral bone and the reason for the failure, there are two primary surgical paths.

Option 1: Revision Arthroplasty (Disc-to-Disc Replacement)

In some cases, it is possible to remove the failing M6-C and replace it with a more reliable, time-tested artificial disc such as the ProDisc-C. This is known as a revision arthroplasty.

• How it works: The surgeon carefully extracts the M6-C components and prepares the bone surfaces to receive a new implant.
• The benefit: This option allows you to maintain motion in your neck, which helps protect the other discs in your spine from adjacent segment disease, which is wear and tear on the levels above or below the surgery.
• When it is possible: This is typically an option if the vertebral bone is still strong and there is minimal bone loss.

Option 2: Spinal Fusion (ACDF)

If there has been significant bone loss or if the spine has become unstable, Anterior Cervical Discectomy and Fusion (ACDF) is the most predictable and well-established solution. ACDF has long been considered the standard surgical treatment for cervical degenerative disc disease, and clinical evidence confirms it is an effective revision option when cervical disc arthroplasty has failed.

• How it works: The surgeon removes the M6-C disc and any inflammatory debris. In the empty space, a bone graft or spacer (cage) is inserted, and a small titanium plate is then screwed into the vertebrae to hold them together while they grow into one solid bone.
• The benefit: By stopping all movement at the failing level, fusion eliminates the mechanical pain caused by a loose or unstable implant, providing a very high rate of success for long-term pain relief.
• When it is necessary: This is usually required if the M6-C has caused significant damage to the bone, or if the ligaments are too weak to support a second moving disc.

The "Bertagnoli Method" for M6-C Revision Surgery

Revision surgery is significantly more complex than a first-time disc replacement. Because the M6-C artificial disc has titanium-coated plates with fixation fins designed to integrate into your bone, removing it requires a surgeon with extreme precision and specialized experience. The Bertagnoli Method focuses on preserving as much natural bone as possible while ensuring the source of the pain is completely removed.

World-Class Experience in Complex Re-Do Surgeries

With over 35 years of experience and more than 10,000 artificial disc replacement procedures performed, Dr. Bertagnoli is a global pioneer in motion-preservation spine surgery. Many surgeons are hesitant to perform revisions on the M6-C due to its unique design. Dr. Bertagnoli's deep understanding of spinal biomechanics and his history of co-developing the ProDisc artificial disc technology allows him to handle re-do cases that others may find too high-risk.

The Delicate Process of Safe Device Removal

One of the biggest challenges in M6-C revision is the explanation (removal) process. The M6-C features low-profile fixation fins and a specialized surface that bonds tightly to the vertebrae.

• Precision extraction: Dr. Bertagnoli uses specialized micro-surgical tools to carefully separate the metal plates from the bone without causing additional damage.
• Bone preservation: The goal is to leave the vertebral surfaces smooth and intact. This is critical because if too much bone is lost during removal, it may be impossible to place a new artificial disc, making fusion necessary instead.

Cleaning the Debris Field and Reducing Inflammation

As documented in FDA adverse event reports and medical literature, a failing M6-C often leaves behind microscopic particles of polyethylene wear debris. This debris can cause a localized inflammatory reaction (granuloma) that continues to affect the bone even after the disc is removed.

• Meticulous debridement: Part of the Bertagnoli Method involves a thorough cleaning of the surgical site. The team carefully removes any inflamed tissue and debris to ensure the environment is healthy for the new implant or fusion to heal properly.

Global Care for International Patients

Patients from all over the world travel to the Pro-Spine clinic for revision of failing implants. We understand that traveling for a second surgery is stressful.

• Remote MRI reviews: Our team provides expert secondary opinions via remote image reviews, helping you understand if your M6-C is failing before you ever board a plane.
• Comprehensive support: From logistical planning to post-operative rehabilitation, the clinic is designed to support international patients through every step of their revision journey.

What to Expect During Recovery After M6-C Revision

Recovery from revision surgery is highly specialized. Because Dr. Bertagnoli uses minimally invasive techniques, the goal is a rapid return to function while ensuring the new implant or fusion stabilizes correctly.

Your Hospital Stay

Most patients stay in the hospital for 2 to 4 days. During this time, the focus is on monitoring breathing, swallowing, and neurological health. Early walking is encouraged to promote circulation and speed up the healing process.

Pain Management

Managing inflammation is the priority, especially since removing a failed M6-C involves cleaning out wear debris. The team uses a combination of targeted anti-inflammatories and localized pain relief to keep you comfortable without heavy sedation.

Recovery Timeline

While every patient is unique, this general timeline is based on standard clinical protocols for cervical revisions:

• Week 1: Rest and limited activity. A soft collar is often used for support.
• Weeks 2 to 4: Return to light desk work. Driving is usually permitted once you have a safe range of motion and are off pain medications.
• Weeks 6 to 12: Physical therapy begins to restore neck strength and flexibility.
• 3 to 6 months: Return to most physical activities. High-impact sports require specific clearance via follow-up imaging (X-ray or CT) to confirm the bone has healed around the new site.

Conclusion

If you are struggling with a failed M6-C artificial disc, remember that you are not alone. Complications like core collapse or osteolysis are serious but they are treatable. You do not have to live with mystery pain or the uncertainty of a failing implant.

The key to a successful recovery is early detection and specialized care. Using the Bertagnoli Method, our team focuses on the safe removal of failing hardware and the precise restoration of your spinal health. Whether through a revision to a new disc or a stable fusion, there is a clear path to meaningful improvement.

Expert help is available to guide you through this journey.

FAQ

Q: Why was the M6-C artificial disc discontinued, and does this mean my implant is faulty?

A: The manufacturer (Orthofix) discontinued the M6-C in February 2025. In January 2026, the UK Medicines and Healthcare products Regulatory Agency (MHRA) issued a safety alert with new monitoring requirements for all patients implanted with the M6-C, citing reports of osteolysis and a delay by the manufacturer in communicating this risk to patients and healthcare providers. The design's polyethylene fiber annulus is prone to premature wear, which can cause mechanical failure or inflammatory bone loss. This does not mean every implant will fail, but all patients should undergo the regular monitoring imaging that is now recommended.

Q: Why is M6-C revision surgery considered more complex than the initial implantation?

A: Revision is complex because the fixation fins integrate deeply with the vertebrae. Removing them without damaging the bone requires specialized experience. Surgeons must also navigate scar tissue and thoroughly clean out microscopic polyethylene wear debris that causes local inflammation. 

Q: Are multi-level M6-C implants at a higher risk of failure than single-level replacements?

A: Multi-level M6-C implants often face higher mechanical stress because they must coordinate movement across several spinal segments. Clinical data suggests that multi-level constructs may experience faster core degradation or subsidence if spinal alignment is not perfect, as the cumulative wear debris can trigger a more significant biological response. 

Q: If my M6-C disc has failed, is a second artificial disc (Revision ADR) still an option for me?

A: A second artificial disc is often possible if your vertebral bone remains strong and healthy. However, if significant osteolysis or bone loss has occurred, revision to a spinal fusion (ACDF) may be necessary to ensure long-term stability and prevent further nerve compression.