Zimmer Holdings Inc. manufactures a number of hip replacement devices and parts. The variety is intentional, designed to give orthopaedic surgeons as many options as possible when choosing the right prosthesis for a patient.
Previous hip replacement devices were limited in size and shape. Surgeons had to make the hip bone fit the implant. Some Zimmer devices use what the company calls Kinectiv Modular-Neck Technology, which has four parts instead of three, so the surgeon can choose each component of the replacement prosthesis in a size and shape that best matches the patient’s actual hip.
Some Zimmer hip products use Metasul Metal-on-Metal articulation. This type of hip joint is forged metal, instead of cast like traditional hip implants. This is supposed to make it harder and smoother, which should make it more durable.
Zimmer also sells products that use Trabecular Metal technology, which is a three-dimensional material that is supposed to simulate the body’s spongy bone. It should provide a high level of friction allowing the hip joint to quickly stabilize after being implanted. It should also allow growth into the hip implant.
Zimmer’s Hip Replacement Products
Hip replacement devices manufactured by Zimmer include femoral (neck and stem) components, acetabular (cup) components and revision surgery systems. The company believes it uses special technology to make the devices sound and also cutting-edge.
Zimmer Femoral Components
- M/L Taper Hip Prosthesis: This alloy hip stem helps to conserve bone and is available in 14 sizes.
- Fitmore Hip Stem: Designed to be used in minimally invasive procedures, providing a number of benefits, including quicker recovery time, less scarring and quicker stabilization.
- Trabecular Metal Primary Hip Prosthesis
- VerSys Epoch FullCoat Hip
Zimmer Acetabular (Cup) Components
- Continuum Acetabular system
- Trabecular Metal Modular Acetabular System
- Trilogy Acetabular System
- Durom Acetabular Component
Zimmer Revision Surgery Components
- Trabecular Metal Acetabular Revision
- ZMR Hip Systems
- Wagner SL Revision Hip
Zimmer’s Durom Acetabular Component (Durom Cup)
Zimmer’s most problematic hip product is the Durom Acetabular Component, commonly known as the Durom Cup. It is a synthetic replacement for a natural acetabulum and is made from a single piece of cobalt chromium alloy metal.
The acetabulum is the cavity at the bottom of the hipbone, one shaped like a cup. The top of the thigh bone – also referred to as the head of the thigh bone, which is shaped like a ball – fits into the acetabulum. This ball-and-socket meeting creates the hip joint.
The Durom Cup was designed to address two problems that were inherent in the function of previous hip replacement devices – durability and range of motion. Durability became an issue because doctors began performing total hip replacements on younger patients, people who planned to continue with active lifestyles. Longer-lasting synthetic devices were needed to keep up with a younger patient demographic.
The active lifestyle of these younger patients – people who desire a life of more or vigorous exercise and not just playing golf, walking or going dancing after dinner – requires hip-replacement devices with more range of motion. The prosthesis needed to do more than just accommodate walking without dislocating. While larger device heads are supposed to provide greater range of motion than smaller ones, they also cause more wear and tear on the hip replacement device.
Zimmer Holdings believed the Durom Cup solved both problems. It was intended for use with the Zimmer Metasul Metal-on-Metal Tribological Solution LDH (large diameter head), providing a total metal hip replacement device that was durable and had larger diameter heads for maximum range of motion.
But Durom Cups can slip out of place, something that can cause excruciating pain. After a brief recall and many lawsuits, surgeons seem to have moved away from the once-celebrated Durom Cup to other devices.
Problems with the Zimmer Durom Cup
In 2006, the FDA approved the Durom Cup for use in total hip replacements. Just a year later, however, problems began to surface.
In 2007, Lawrence Dorr, M.D., a nationally recognized orthopedic surgeon and a paid consultant for Zimmer, reported problems with the Durom Cup. He said that within a few months after implanting the Durom Cup in patients, the device failed and caused great pain. In some cases, he performed corrective surgery to replace the hip replacement device. He blamed the product’s “poor construction.”
Dorr in 2008 told colleagues at the American Association of Hip and Knee Surgeons about his experiences with the Durom Cup. In his letter, he detailed 10 revision surgeries out of 165 Durom Cup surgeries and made the following points:
- During the first year after surgery, revisions were required because of loose implants.
- Fixation surface wasn’t adequate.
- A circular cutting surface on the edge of the implant prevented it from seating.
Dorr later discovered other doctors had had similar experiences, but Zimmer blamed the problems on Dorr’s technique and not on its Durom Cup.
Zimmer Recalls Durom Cup
The Durom Cup was in use until 2008, when Zimmer recalled it. The FDA says the recall was because “instructions for use/surgical technique instructions were inadequate.”
Zimmer sent “Dear Surgeon” letters explaining the recall and urging orthopedic surgeons to stop implanting the device until they had received additional training.
After updating the product labeling and creating a surgical training program on its website, Zimmer returned the Durom Cup to the U.S. market despite its problems.
Zimmer Hip Replacement Lawsuits
Zimmer has received claims from patients who had the Durom Cup implanted who are now seeking reimbursement costs and compensation for pain and suffering. The company in 2008 created a $69 million fund to pay claims that met specific requirements. It was management’s estimation of Zimmer’s liability regarding revision surgeries associated with the Durom Cup.