More than 1,000 patients have filed Medtronic Infuse bone graft lawsuits alleging the medical implant can be dangerous and cause crippling side effects.

Medtronic’s Infuse bone graft system is designed to improve spinal fusion surgery, a procedure intended to help people with damage to their spinal discs. Spinal discs are cushions of connective tissue between the individual backbones, or vertebrae. As some people age, wear and tear to these discs causes them to fail, leading to back pain and damage to the spine. In traditional spinal fusions, surgeons harvest bone from elsewhere in the body and graft it to the spine. Once in place, the bone tissue joins the two bones into a single bone and supports them, reducing the pressure on the damaged disc. Infuse was supposed to be a better way of doing this.

The Infuse system consists of two parts: a metallic cage and bioengineered gel. The cage supports the two bones of the spine and the gel encourages bone to grow. The big benefit of the Infuse system is that the gel is made of a small tissue sample from the patient combined with synthetic proteins and other compounds. This means that spinal fusions with Infuse don’t require a second procedure to harvest redundant bone from elsewhere in the body.

In Infuse bone graft lawsuits, the procedure has been linked to a number of very serious complications. Many of these involve the overgrowth of bone. This alleged overgrowth of bone can damage and compress nerves in the spine. In some cases, surgeons have been unable to fix the problem. In many cases spinal surgery can cause more harm than good. The spine is rich in delicate, non-healing spinal tissue wrapped in nerve-dense muscles and connective tissues. Additionally, it has been alleged that Medtronic promoted Infuse for “off-label” purposes. Off-label purposes are those other than what has been approved by the U.S. Food and Drug Administration. If true, this can have legal implications.

Medtronic has already made major settlements over Infuse lawsuits. The week of May 12, Medtronic agreed to $22 million in settlements spread across nearly 1,000 lawsuits. Though Medtronic has denied any wrongdoing, the company told shareholders that it has put aside an additional $140 million for the 3,800 anticipated claims.

The individual Medtronic Infuse bone graft lawsuits could be combined into a single legal proceeding called multidistrict litigation, or MDL. MDLs are a type of group lawsuit, similar to class action lawsuits. In both class action lawsuits and MDLs, a group of plaintiffs allege that they have suffered similar harm at the hands of the same defendant. The main difference is that class action lawsuits start out as group lawsuits, while MDLs start as dozens, hundreds, or even thousands of individual lawsuits which are later coordinated into one proceeding.