The surgical repair of an aged or injured natural hip joint by adding an artificial joint, or implant — date back three centuries. Reasons for these implants are the same now as then: a fracture or similar injury to the hip, arthritis or a wearing down of the joint over time. The goal is to reduce pain and increase mobility.
Although there are varied designs and models of hips built by several manufacturers, there are three basic components of an artificial hip — a stem that is inserted into the femur (thighbone); a ball that attaches to the top of the femur; and a cup that attaches to the pelvis.
METAL-ON-METAL HIP REPLACEMENT
Patients can undertake one of three types of surgeries — partial hip replacement, total hip replacement or hip resurfacing. Modern implants, increasingly popular since the 1970s, are made from a combination of materials, including plastics, ceramics and metals. Many of the most recent devices were metal-on-metal designs, created with the hope that hip replacements would last longer to give younger, active patients more pain-free mobility for more years.
However, metal-on-metal hip implants produced one significant complication: metal ions can rub off of the devices and enter a recipient’s bloodstream, creating a metal poisoning known as metallosis. Other complications with these implants and others include a loosening of the implant, joint dislocation and, in one case, a squeaky hip.
These complications may lead recipients to pursue corrective actions that are both physical and financial. Many people with problematic artificial hips opt for revision surgery, a corrective procedure that gives them a new hip implant. Many of those same patients — and others — opt for legal action by suing device manufacturers, claiming the companies knew their hip systems were defective.
All hip replacement systems must be approved by the U.S. Food and Drug Administration (FDA) before being used in the United States. Device companies use the FDA’s 510(k) program to gain approval. The program allows the companies to streamline the approval process instead of making them undergo much more rigorous testing. Some of the largest device manufacturers are DePuy Orthopaedics, Zimmer Holdings and Stryker Orthopaedics. All three companies are facing issues with faulty hip devices.
HAVE YOU RECEIVED ANY OF THE FOLLOWING HIP REPLACEMENTS
A number of brands of Hip Implants have failed to work properly, causing a number of painful complications, which in some cases has required further surgery. The metal-on-metal Hip Replacement Systems have had a particularly high failure rate, with the metal parts rubbing together, creating metal debris and failure of the implant.
Some of these Hip Implants and their manufacturers are:
- Biomet Regenerex® RingLoc®+ Modular Acetabular System
- Stryker Hip Implants
- Birmingham Hip Replacement
- Birmingham Hip Resurfacing (BHR) system
- Metal on Metal Hip Implants
- Wright Medical Hip Implants
- Wright Conserve Plus
- DePuy ASR™ XL Acetabular System
- DePuy ASR™ Hip Resurfacing System
- DePuy Pinnacle® Acetabular Cup System
- Zimmer Durom Cup
- Johnson & Johnson
- Zimmer Nexgen
- Dynasty Hip Implant
COMPLICATIONS AND IMPLANT FAILURE
As with any surgery, complications can arise following hip replacement procedures. Some problems can be detected immediately, while others may not surface for years. Serious situations may require patients to undergo a second surgery, called revision surgery.
Some of the complications associated with hip replacements are tied to the materials used in the implants. Metal-on-metal implants can lead to metallosis, which is a serious condition that occurs when metallic debris builds up in the soft tissue of the body. Osteolysis, another serious complication that can occur following hip replacement surgery, is the loss of bone around the implant as the body works to “clean up” foreign particles that are produced by the device during normal movement. This can lead to loosening and failure of the implant.
Other serious complications include:
- Implant dislocation
- Avascular necrosis (bone death)
- Loosening of the implant
- Heterotopic Ossification
Rare condition that is caused by the buildup of metallic debris in the soft tissue of the body — in this case the soft tissue surrounding the hip joint. It is more often seen in hip resurfacing patients than in total hip replacement patients. Primarily this is due to two issues. First, most hip resurfacing implants are used in younger, more active recipients — who tend to place a higher level of wear and tear on the implant than older recipients. Second, hip resurfacing implants tend to have a larger femoral ball than total hip replacement implants. Because the femoral ball is larger, there tends to be more abrasive wear within the joint, which produces more metallic debris. However, metallosis can occur in metal-on-metal total hip replacements. This usually requires the failure of the articular interface, which is a plastic insert that separates the metal femoral component from the metal acetabular cup.
Metal debris from metal-on-metal hip implants can cause grey discoloration of the tissue surrounding the implant, usually indicating that the tissue is oxygen-starved and dying. The effects of metallosis can be particularly acute in implant recipients who have a condition known as metal sensitivity. In patients who have metal sensitivity, metallosis can lead to metal poisoning. The full impact of metallosis is not fully known. However, it has been linked to several hip replacement complications, including:
- Severe joint pain
- Implant failure
- Implant loosening
- Local tissue necrosis (tissue around the implant dies)
- Deterioration of the bone around the implant
- Formation of cysts or pseudotumors
If metal ions spread from the surrounding tissues into the blood and blood ion levels become too elevated, it can cause a host of other physical conditions such as mental cognitive problems, emotional imbalance, severe headaches and problems with the nervous system.
Osteolysis, or periprosthetic osteolysis, is the loss of bone around the hip replacement. It is the body’s attempt to clean up particle debris, plastic or metal, produced by the implant. Osteolysis is the most common long-term hip replacement complication. It has also been named as the cause of nearly 75 percent of all hip implant failures.
Osteolysis occurs when the body recognizes the implant debris as foreign and reacts to remove the particles. The body releases enzymes, cytokines and other cellular reactions into the area, all in an attempt to either expel or dissolve the particulates, which causes a chronic inflammatory condition.
The body’s autoimmune reaction also releases cells called macrophages, which in turn release bone reabsorption stimulators. Since hip implants continuously release particle debris, the body’s autoimmune response is continuous as well. Since the bone in the area is only stimulated to reabsorb bone and not produce it, eventually, the bone around the implant will degrade to the point that the prosthesis will loosen and eventually fail.
Other Complications & Implant Failure
Although metallosis and osteolysis are two of the more dangerous complications associated with hip implants, there are other serious complications to be aware of. Although hip arthroplasty is performed more than 450,000 times a year in the United States, and is considered by many to be routine surgery, the associated complications can be very dangerous and even deadly.
A 2003 study published in the Iowa Orthopedic Journal reviewed the results of nearly 5,000 hip arthroplasty surgeries. It found that the mortality rate for patients having the surgery for the first time was nearly 1 percent. For patients undergoing a revision surgery, the mortality rate skyrocketed to 2.5 percent. Researchers also found that the most important determining factor of mortality was age. Patients older than 70 were three times more likely to die from the surgery than younger patients.
The natural hip is held in place by a ligament that connects the ball to the socket. It is also held in place by thick, dense tissue that surrounds the joint. During hip replacement surgery, this tissue is removed and dislocation can occur. Proper placement of the implant during surgery is vital to it remaining in place postoperatively.
Although dislocation is not very common, it occurs following 1 percent to 5 percent of initial surgeries. Following revision surgery, the risk for dislocation rises as high as 20 percent. Dislocation leading to implant failure is most likely to occur within the first few months after surgery.
Heterotopic ossification is the process of bone forming outside of the skeleton, meaning soft tissue is calcified. Typically, it occurs in areas of the body where severe trauma has occurred. In the case of hip arthroplasty, the muscles around the hip joint calcify and become stiff.
Heterotopic ossification is considered one of the most common hip replacement complications, occurring in nearly 50 percent of patients. However, only about 10 percent of those suffer any side effects from the condition, including tenderness, swelling and a decreased range of motion. The condition can be treated with low-dose radiation and anti-inflammatory drugs. In severe cases, surgery is required to remove the calcified tissue.
With an incidence rate of about 1 percent, infections following hip surgery are not common. If the infection is caught within four weeks after surgery, doctors may re-open the wound to clean it and inject antibiotics. If that does not work or if the infection is not discovered until later, the implant may need to be removed and later re-implanted after the infection has been eradicated. To avoid scar tissue and bone degeneration, re-implantation needs to occur within three months.
Infection is one of the most feared postoperative complications. In the most extreme cases, where the infection cannot be controlled, the entire hip and leg may have to be amputated. It is exceptionally rare for a patient to have to undergo a transpelvectomy, or hip-disarticulation — in which the entire leg, including the hip joint, are removed and replaced with a prosthetic limb.
Avascular Necrosis (Osteonecrosis)
Avascular necrosis is bone death caused by lack of blood and can lead to implant failure. It is more often associated with hip resurfacing than total hip replacement. With hip resurfacing, the metal cap that covers the femoral ball can reduce the amount of blood reaching the ball. If the bone is deprived of blood for an extended period of time, it will collapse, which will destroy the bone and use of the joint will be lost. In extreme cases, the implant will have to be replaced. Since the femoral ball is no longer usable, a total hip replacement is required.
Implant components can loosen over time, which is considered the most serious long-term complication because it is the strongest indicator that a revision surgery will be required. A component could loosen because it is worn out or because the cement fails to hold it in place. However, loosening of a hip implant could also point to a more serious condition like osteolysis or metallosis. If loosening is suspected, doctors will use a series of X-rays, taken over a period of time, to detect movement in the components and to determine if any corrective actions are necessary.
Periprosthetic fractures are bone breaks that occur around the implant and could cause the implant to fail. These fractures typically occur because the bone around the implant has been weakened by osteoporosis, medications, pressure from the implant or stress placed on the implant. Periprosthetic fractures occur around hip implants following a little more than 1 percent of first surgeries and 4 percent of revision surgeries.
DEPUY HIP IMPLANTS APPROVED WITHOUT CLINICAL TRIALS
The DePuy ASR devices, manufactured by Johnson & Johnson subsidiary DePuy Orthopedics, were some of the first replacement hips to cause problems and spark lawsuits around the world. The products were approved without having to conduct clinical trials, receiving 510(k) clearance from the FDA in 2005.
FDA RECEIVES 400 COMPLAINTS ABOUT ASR DEVICES
By 2008, the FDA had received 400 complaints relating to patients who had an ASR device implanted. In the same year, a report found that 13% of patients who received an ASR hip replacement required a second hip replacement surgery. Evidence of genetic damage was also found in patients who had a DePuy ASR hip implant implanted.
DEPUY ANNOUNCES WORLDWIDE RECALL
Despite the ASR devices being voluntarily recalled from the Australian market by DePuy in 2009 (due to data from the Australian Medical Device Registry showing a higher than expected failure rate of the hip replacement devices), the worldwide recall didn’t come until August 2010. The company claimed the Australia recall was due to poor sales. By the time the DePuy ASR hip recall took place, 93,000 DePuy hip replacement surgeries had been performed worldwide.
Subsequent lawsuits relating to the recall of the DePuy ASR devices claim that DePuy Orthopedics knew the replacement hips were defective for many years. This is largely due to the Australian recall and the fact that in 2006, DePuy sent a letter to medical professionals warning them that the DePuy ASR replacement hips had a high rate of failure in patients of small stature, women and people with weak bones.
Johnson & Johnson to Pay $4 Billion Plus
J&J will pay out more than $4 billion in settlements to resolve 7,500 plus product liability lawsuits related to injuries from DePuy hip implants. Victims of the defective hip implant units involved in the settlement are expected to receive an average of $300,000 each in compensation.
The settlement does not prevent other victims of failed hip implants from seeking compensation. Currently J&J faces over 10,000 additional lawsuits due to failed DePuy implants in courts across the country.