Zimmer Hip Replacement

Zimmer Holdings, Inc. is an Indiana base orthopedics company.  They manufacture medical products including joint and skeletal replacement systems and surgical tools as well as biologics designed to assist in joint replacement surgeries.

Zimmer has developed hip replacement devices using technology known as Kinective Modular-Neck Technology which is a modular system, allowing the surgeon to choose each component that fits best for a particular patient.

There are two major product lines in the Zimmer hip replacement arena.  The first product is forged metal which is different than traditional hip implants made of cast metal.  The Metasul metal-on-metal products are designed to be harder and smoother, offering an advantage in durability.

Zimmer also manufactures a metal type that is designed to simulate the natural sponginess of bone tissue.  Trabecular Metal technology should provide higher levels of friction that allow for more immediate hip stabilization after a replacement surgery.  It also allows for natural growth of the bone into the implant itself.

Zimmer announced acquisition of another joint replacement device company, Biomet in April of 2014 for $13.35 billion which will make Zimmer the second largest orthopedics manufacturer in the US once the sale is finalized.

Design of Zimmer Hip Replacement Products

Early hip replacement device products were a “one-size fits all” sort of system with limited options in both size and shape.  This required a great deal of work on the surgeon’s part and possible trauma to the patient as the surgeon had to make the patient’s bone fit the implants.  Zimmer hip replacement products are component based, allowing for greater flexibility in selection of the appropriate shape and size.  The systems come as four separate pieces which allow the physician to choose the correct system with the right pieces to fit the patient.

The basic design includes a femoral component to attach to the femur (large leg bone), a neck stem, a ball joint and an acetabular cup which rests in the hip bone itself to mimic the ball and socket movement of a normal hip joint.

A Zimmer total hip replacement surgery uses these metal parts to replace the ball and cup of a dysfunctional hip.  Metal-on-metal hip reconstruction was designed to result in a stronger and more flexible hip. It was also designed to increase the lifespan of a hip-replacement device as they are reportedly more durable and will last longer.

These types of hip replacement products have been marketed as ideal for “younger” patients than the traditional hip replacement products.  The Durom Cup was designed to improve durability and range of motion and was said to be ideal in the younger patient demographic for people who intended to remain active.  It was designed to be used with the Zimmer Metasul Tribological Solution Large Diameter Head (LDH) which provided maximum range of motion and durability.

Despite the supposed improvement with metal-on-metal construction and the Durom Cup range of motion solution, Zimmer hip implants have caused a number of adverse events that are attributed to this facet, causing shards of metal to be released into surrounding tissue.  The cup has also been known to slip out of place.

Zimmer’s Durom Cup system has been the main focus in issues with Zimmer Hip Replacement products and has resulted in a number of complaints to the Food and Drug Administration (FDA) and a number of lawsuits.  It was recalled in 2008 for a short period of time but was returned to the US market with the addition of a training program for surgeons.

History of Zimmer Durom Cup Hip Implant Device

The Zimmer Durom Cup hip implant was approved in 2006 and within a year problems began to appear.  In 2007, a surgeon who had previously been a consultant to the Zimmer company reported failure with the device, causing the requirement that patients have corrective surgery.

Lawrence Dorr, MD blamed the issues on poor construction of the product and issued a letter to the American Association of Hip and Knee Surgeons delineating his experience and problems with the Durom Cup.  Dr. Dorr reported that revision surgeries were required due to loose implants, inadequate surface fixation and improper seating due to design defects.

Other physicians reported similar problems but the company blamed the physician’s techniques and not the device.

The device was a subject of a recall in 2008.  The FDA reported that the voluntary recall was due to inadequate instructions for use and surgical technique.  Zimmer sent a recall notification to physicians, urging them to discontinue implanting the Durom cup until additional training was completed.

Zimmer returned the Durom Cup to the US market after the creation of a surgical training program that was made available on the Zimmer website.

In 2012, the FDA convened an advisory panel to discuss the need to monitor patients who had received metal-on-metal hip replacements due to adverse events associated with the implantation of such devices.  The Zimmer Durom hip device was implanted in nearly 13,000 patients.

As complaints continued to surface, by 2010 Zimmer set aside $69 million for compensation of injuries suffered because of Zimmer hip implants.  Zimmer estimated that up to 5.7 percent of implants will require revision surgery due to Durom Cup malfunction.

As of 2014, Zimmer has already paid $400 million in settlements and expects more will be required.

Serious Adverse Events and Complications the Zimmer Hip Implant Products

There have been hundreds of hip implant recalls since the devices were introduced to the US market.  The majority of these recalls have focused on the metal-on-metal construction in the ball and socket system.

Most of the problems associated with the devices have focused on the release of metal fragments into body tissues, resulting in toxicity or poor design causing the devices to have an inadequate seating to the bone tissue making the implant unstable.

Some studies have shown that despite manufactures claims of greater safety and stability; advanced alloys are more toxic due to higher levels of metals such as chromium and cobalt.  Many patients have faces extreme pain and suffering along with revision surgery required to correct the failed procedure.

Zimmer hip implants, particularly the Zimmer Durom Cup can cause serious adverse events such as:

• Severe Pain – the most common adverse event associated with Zimmer hip replacement.  This is most often caused by the Durom Cup which fails to stay sealed and seated in place, allowing the cup to grate against the bone.
• Hip Instability – as the Durom Cup is known to inadequately seal to the hip bone, it may become loose and create instability in the patient’s hip.  This may prevent normal movement and may result in an inability to walk.  This is generally reversible with revision surgery but may cause extensive damage to surrounding tissue.
• Revision Surgery to Replace the Implant – frequently required because of severe pain and physiologic malfunction.  The implanted device will require surgical removal and replacement.  This may result in a painful recovery period that is significantly longer than the original surgery.

Other serious adverse events that may be created by Zimmer hip replacement products:

• Osteonecrosis – tissue death in areas surrounding the implant due to toxicity from metal fragments
• Metallosis – tissue toxicity caused by metal corrosion and flaking of microscopic or even some larger pieces that are deposited into body tissues.  Metallosis results from metal-on-metal contact of hip replacement parts.
• Osteonecrosis – tissue death in bone surrounding the implant due to toxicity from metal fragments. Oxygen in blood cannot reach and supply bone tissue which may also result in dissolution of the bone itself.  Osteolysis may require additional reconstructive tissue as bone tissue will most likely not grow back.
• Heterotopic ossification – bone tissue that forms outside to the skeleton into the soft tissue.  It is excruciatingly painful and may be permanently damaging.
• Periprosthetic fractures – fractures surrounding the hip implant which may require reconstructive surgery
• Pseudotumors – large collections of mass around the implant which cause inflammation, pain and restricted movement

Less serious, but still significant events that may be caused by the Zimmer hip replacement device:

• Thigh, hip or groin pain
• Movement disorder
• Loss of muscle tissue
• Zimmer Kinective Modular-Neck TechnologyLocalized hip inflammation
• Generalized body inflammation due to metal toxicity which can include rash, headache, fatigue and other symptoms

Zimmer Kinective Modular-Neck Technology

Zimmer Inc., headquartered in Warsaw Indiana, is an ISO 9001 certified company that specializes in musculoskeletal health care. It is one of the largest medical company in the world, with 8500 employees serving all over the globe for more than 80 years. Zimmer’s 2011 sales were approximately $4.5 billion.

Zimmer Hip Products

The hip products are classified according to the individual component of the hip replacement system.

Acetabular (Cup) Components

Fit into the natural acetabulum (where the head of the femur meets with the pelvis). They have ball-like socket into which the head of femur articulates to produce movements in all directions.

The acetabular components manufactured by Zimmer include:

• Continuum Acetabular system
• Trabecular Metal Modular Acetabular System
• Trilogy Acetabular System
• Durom Acetabular Component

Zimmer Revision Surgery Components

• Femoral Revision Systems
• Trabecular Metal™ Acetabular Revision System
• ZMR Hip Systems
• Wagner SL Revision Hip

Zimmer Femoral Components

Include stem, neck and femoral head. They are fixed with the superior part of femur and is designed to produce movements at the hip joint.

Zimmer is manufacturing following femoral components:

• M/L Taper Hip Prosthesis: It is available in 14 different sizes.
• Fitmore Hip Stem: Its slim and sleek design is meant for minimally invasive surgery.
• Trabecular Metal Primary Hip Prosthesis
• VerSys Epoch FullCoat Hip

Companies using modular-neck technology

The modular-neck technology is employed by many companies and marketed under different names as follows:

• Stryker Rejuvenate
• Wright ProFemur
• Stryker ABG II
• Smith & Nephew Short Modular Femoral Hip System
• Apex Modular Hip System
• Zimmer M/L Taper Prosthesis with Kinectiv Modular Neck

Zimmer Kinectiv Modular-Neck Technology

This technique allows the surgeon to address length, version and offset independently. The M/L Taper with Kinectiv Technology is dotted and porous with different necks that can meet the anatomical variations of the patients. The wide range of neck sizes enables the surgeon options to deal with the anatomical differences between male and female patients. Proper offset and leg-length restoration improve the total hip replacement function and lower the risk of dislocation.

The Modular Neck

Enables the surgeon to do a minimally invasive surgery. The modular neck requires less retraction of the muscles and it easily fits into the space. Different sizes are easily available. Moreover, the ante version and retroversion of the neck is necessary is some patients with a different anatomy.

The Femoral Stem

With Kinectiv Technology is shorter than conventional stems, providing greater bone conservation compared to other hip replacement systems.

The Femoral Heads

Of +0 sizes can be used because Kinectiv technology allows the surgeon to correct the length independent of the size of the femur head. This helps in proper stabilization of the femoral head and normal movements of the hip joint.

Problems with Modular-neck Technology

The corrosion is more at the location where the modular metal neck snaps into the body of the femoral stem.

Similar to metal-on-metal hip implants, the modular-neck hip implants can corrode, slough off debris into the body and produce the following complications:

Pain

It is very common complication and is usually associated with signs of inflammation i.e. redness, tenderness, swelling, warmth etc.

Metallosis

Increased levels of metal debris and plasma concentration of metals due to metal on metal friction. There is an increased risk for metallosis the longer the implant has been in use. Metallosis can cause serious complications including sever pain, inflammation, grey discoloration surrounding the implant site and nervous system issues.

Dislocation or Loosening

Premature wearing of the articular surfaces result in the loosening of the implant. This can potentially lead to joint dislocation and other issues.

Fractures

In older ages, the bone becomes too weak to support the metal implant and fractures. This complication is more common in post-menopausal females.

Revision surgery After Device Failure

There are multiple problems than can lead to a revision surgery. Mechanical failure, infection and recurrent hip dislocation all can prompt a doctor to consider a revision surgery. Often the revision surgery is more dangerous than the initial surgery and can further damage the area of the implant.

Zimmer Hip Replacement Lawsuits

Newer models of hip replacement devices were designed to last over 20 years and were marketed to a younger demographic of hip replacement patients who needed to be able to remain active.  Despite supposed design improvements, Zimmer hip replacement side effects were brought to the medical community’s attention by Doctor Larry Dorr in April of 2008. This was less than two years after the device had been introduced.

Dr. Dorr reported that 14 out of 165 replacement surgeries required revision surgery to replace malfunctioning implants.  The hip replacement parts designed by Zimmer have been shown to fail within a few years.  Zimmer itself has estimated that nearly six percent of implants would require revision surgery.

Zimmer claims in defense, that failure of the Durom Cup was due to improper techniques on the part of the surgeons.  However the number of hip replacement side effects appears to be too high and too widespread to support that claim.

Multiple lawsuits have been filed against Zimmer Holdings, Inc. with regards to the Durom Cup hip replacement.  A multidistrict litigation (MDL) has consolidated federal lawsuits against Zimmer involving the Durom Cup in the US District Court for the District of New Jersey.  The MDL will be overseen by Judge Susan D. Wigenton.  The MDL originally included 240 cases, however many of those cases have been settled by Zimmer who has paid nearly $400 million in settlements.

Lawsuits have also been filed at the state level in several locations.  Additional lawsuits are expected to follow and Zimmer expects to pay at least another $200 million, despite the original estimate of $69 million required.

In 2015, after the completion of the acquisition of Biomet, Zimmer will be the second largest orthopedics manufacturer in the US.

Notwithstanding claims relating to this product, the drug/medical device remains approved by the U.S. FDA.