Hip replacements often use a variety of exotic metal alloys or ceramics to recreate the ball-in-socket mechanism of the human hip. A total hip replacement will typically consist of four parts:

• The socket (or acetabular component).
• The ball (or femoral head) that goes into the socket.
• A liner for the socket that is in direct contact with the ball.
• A stem for the ball (also known as a femoral stem) that connects the ball to the thigh bone (femur).

The liner is placed into the socket and the socket is placed into the pelvis. The ball attaches to the stem and the stem attaches to the femur. The result is a total artificial ball-in-socket hip replacement.

Sometimes, these hip replacements don’t work as expected. One such example comes from Zimmer US, Inc. and related companies (which we’ll collectively refer to as “Zimmer”). Many patients have reported problems with a particular set of Zimmer femoral head and stems.

What’s Wrong with Zimmer’s Artificial Hips?

At issue are two femoral stems: the M/L Taper Hip Prosthesis and the M/L Taper Hip Prosthesis with Kinectiv Technology. When either of these components is paired with the Zimmer VerSys Hip System Femoral Head, many artificial hip recipients have reported a variety of problems, such as:

• Metallosis (elevated metal levels in the body)
• Osteolysis (destruction of bone tissue)
• Pseudotumor formation

Often, any of these problems require revision surgery, which is surgery to replace the failed implant. It’s believed that many of these hips are failing due to corrosion, trunnionosis and the release of tiny bits of metal at the point where the femoral head connects with the femoral stem.

Have Patients with Failed Zimmer M/L Hip Replacements Taken Legal Action?

Yes. There have been hundreds of plaintiffs who have filed suit against Zimmer alleging defectively designed and manufactured hip components, Zimmer’s failure to warn patients and doctors about the risks of using the hip replacement and that Zimmer did not properly test the artificial hip components.

With so many lawsuits consisting of similar injuries and allegations, along with a single (or small number) of defendants, our court system has a special system in place to consolidate the cases for pre-trial matters. This consolidation is called multi-district litigation, or MDL.

The purpose of MDL is to handle much of the pre-trial matters, such as discovery, in a single court with a single judge. With a single judge handling these pre-trial matters, the cases can be processed more efficiently, as the judge’s decisions will apply to all cases at the same time.

The ultimate goal is to reach a comprehensive settlement that resolves all of the cases fairly. One way to do with is by having several bellwether trials. These sample cases are supposed to be representative of most of the cases in the MDL. Therefore, how they turn out can serve as a signal of what the plaintiffs and defendants can expect if their respective cases go to trial.

How these bellwether cases turn out will shape how settlement negotiations will go. As you can imagine, the better they go for the plaintiffs, the more negotiating leverage plaintiffs will have during settlement talks.

Right now, the Zimmer lawsuits involving the M/L Taper Hip Prosthesis, the M/L Taper Hip Prosthesis with Kinectiv Technology and the VerSys Hip System Femoral Head are in MDL in the US District Court for the Southern District of New York before Judge Paul A. Crotty.

Zimmer MDL’s Current Status

The Zimmer MDL is in the discovery phase, with the first bellwether trial scheduled for January 25, 2021. But if this date is pushed back, don’t be surprised. It was originally scheduled for September 14, 2020, then pushed back to October 19, 2020 and now has this date in early 2021.

All of this to say, there’s a lot of discovery and pre-trial motions to complete before a single trial takes place. As new developments arise in this case, I’ll post an update in this blog. Until then, there’s a long grind of pre-trial matters to get through.

Call me to discuss further: (919) 830-5602.

The vast majority of artificial hip failures over the past decade involved metal-on-metal (MoM) hip components. These medical devices were meant to revolutionize the artificial hip market. Specifically, the all-metal hip components were intended to last a long time, and much longer than older generation artificial hips using materials like ceramics and plastics, which had a tendency to wear down and “fail” after twelve or fifteen years. Beyond that, the metal-on-metal artificial hips were touted to withstand the rigors of active, athletic patients. It sounded like a terrific advancement in the development of artificial hips. The problem is, the metal-on-metal design did not work, in many cases because the metal acetabular cup and the metal femoral head would grind together day after day, month after month, releasing harmful metal debris (metallosis) into the patient’s body. Far too many people were forced to get revision surgeries a few years after the implant surgery to remove the metal hips.

It turned out to be a disaster for thousands of patients and for several large medical device manufacturers. Depuy and Zimmer, to name just two companies, faced thousands of lawsuits from people injured by the metal-on-metal artificial hips. Many of those cases are resolved or resolving, but many more await settlement or jury trials.

The LFIT V40 Is a Metal-on-Polyethylene Artificial Hip

The Stryker LFIT V40 Hip is not a metal-on-metal artificial hip. The LFIT V40 system includes a metal acetabular cup, a polyethylene (or plastic) liner, a cobalt-chromium femoral head, and a titanium femoral stem. The exploded-view diagram at top right gives you an idea of how the Stryker LFIT V40 hip is assembled. Stryker avoided the problematic construction of direct metal-on-metal components.

So far so good, right? Well, unfortunately, no. Soon after being released into the market, the Stryker LFIT V40 began to fail, at an unusually high rate. And patients who received the Stryker LFIT V40 were suffering from similar symptoms as those who received metal-on-metal hips. Even, oddly, diagnoses of metallosis. It was an unexpected result. So what happened?

Something called a taper lock failure. Let’s take a closer look:

The LFIT V40 Taper Lock Failure

The failure of the Stryker LFIT V40 concerns the junction of the neck of the femoral stem and the femoral head or ball. In the illustration above, the neck is that small metal rod that extends out from the femoral stem. The neck connects and attaches to the femoral head (the ball), thus connecting the leg bone to the hip bone. This connection was intended to be permanently secured through a taper lock system, holding the stem securely to the ball.

But as it turned out, in many cases once in the body the V40 femoral head began to corrode, which means to slowly disintegrate and lose metal. The corrosion occurred at the site of the connection to the neck (the taper lock). This corrosion in the head would progress slowly, but over time the corrosion would cause the taper lock to become compromised and loosen. Eventually, the neck would corrode as well, and once the neck began to corrode the breakdown of the artificial hip would advance more quickly. According to one study from 2016, the loosening would cause fretting and micromotion at the taper lock site, and this movement or friction would cause metals to be released into body. Thus, the Stryker metal-on-polyethylene (MoP) artificial hip resulted in patients suffering from metallosis, just like so many other patients who received metal-on-metal artificial hips.

The corrosion in the LFIT V40 can be slow. This means that the average patient may not know the Stryker hip is failing and releasing cobalt and chromium into the body. It can take years for the loosening to cause problems that are recognizable to the patient. At that point, the neck may have begun to corrode, and when that happens the femoral stem may need to be removed and replaced. This can be a very difficult surgery. The femoral stem is implanted down the center of the femur bone, and when it sets it is usually there permanently. Removing the femoral stem is invasive and problematic and painful.

So How Can You Salvage the Femoral Stem?

You must remove the failing V40 femoral head as soon as possible. This means artificial hip revision surgery. If you remove the head at the beginning of the period of corrosion, and the femoral neck is not corroding, you should be able to revise your artificial hip without the difficult work of removing the femoral stem. But either way, you will have to undergo revision surgery, which is no fun at all. My thought would be: check with your surgeon and confirm the exact components you have in your body. If the doctor reports that you have the Stryker LFIT V40, you need to have a lengthy discussion about removing the v40 femoral head, even if you are not currently having symptoms.

I wrote more about the Stryker LFIT V40 artificial hip here. If you would like to read more on the study identifying failures of the Stryker LFIT V40 taper lock, google Trunnion Corrosion Causing Filure in Metal-on-Polyethylene Total Hip Arthroplasty with Monolithic Femoral Components in Reconstructive Review (April 2016).

Note: I am not a doctor, and this is not medical advice. The diagram at the top is for illustrative purposes only and is not intended to depict the specific Stryker LFIT V40 artificial hip.