Hip Replacement Expert Witness: A Litigation Guide

Stephen Gomez

Written by
— Updated on February 5, 2020

hip replacement expert witnessCo-authored by Kelly Lhungay.

Stryker Orthaepedics is a medical equipment firm which develops and produces hip implants, among other medical equipment. Stryker’s Rejuvenate Modular Hip System, a hip replacement device, was first introduced in 2009. It was marketed to younger patients as a custom-made device that would fit patients better, last longer, and offer a better range of motion than competitors. The Rejuvenate system was created as an alternative to other metal-on-metal hip replacements, which had been recalled.

Patients implanted with the Stryker Rejuvenate System began to complain of similar symptoms to those of the metal-on-metal hip replacements despite the ceramic addition. [1] Now there are an increasing amount of cases against Stryker regarding claims of negligence in designing, manufacturing, and marketing the Rejuvenate devices. The Expert Institute assembled this litigation guide to help attorneys, the hip replacement expert witness, investors, and the more than 30,000 individuals who received a Stryker hip implant worldwide (20,000 in the U.S.) understand the issues which may arise during litigation, the basis of the claims which are most often brought against Stryker, and how a hip replacement expert witness can be used to effectively litigate these claims.

Medical Summary
Stryker’s Rejuvenation hip device was promoted as having a superior design. It would allow surgeons to customize the length of the implant for certain aspects of a patient’s anatomy and hip biomechanics. Unlike the single femoral component of a traditional artificial hip device, the Stryker Rejuvenate hip contains a modular neck stem. This consists of a metal neck that sits inside of a metal stem. After only a few years of the implant being used, however, there have been a number of cases of Stryker Rejuvenate hips failing and resulting in removal surgery. While hip implants are typically expected to last fifteen to twenty years, some Stryker Rejuvenate hips are failing in less than five years. [2]

Reports are appearing that Stryker hip implants pose the same risks to patients as the recalled DePuy ASR hips, despite the design differences. The Stryker products implicated in the recall also consist of metal parts; a metal neck and metal stem which may be rubbing together just as the DePuy hips did. Evidence shows that the resulting friction, combining with the corrosion and fretting of the metal neck stem, has links to the heavy development of metallosis, or metal poisoning, within the patient.  This release of metallic debris into the body may trigger an inflammatory tissue response. Thus resulting in muscle and soft tissue damage. Metallosis symptoms include limited mobility, dissolution of the bone, kidney and liver damage, heart enlargement, DNA changes, and an increased risk of bladder cancer.

Furthermore, some patients who were implanted with metal-on-metal hips have developed high levels of cobalt. The increase of which can lead to many critical health problems like hypothyroidism, cardiomyopathy, blindness, deafness, and peripheral neuropathy. Due to growing controversy surrounding metal-on-metal hip implants, the FDA formed an advisory panel to make recommendations about whether the devices should have additional warnings and guidelines for the approval of the implants. Subsequently, the number of lawsuits filed against Stryker has continued to rise. Claims that the medical device company did not provide the FDA, physicians, and patients with the necessary information about adverse effects behind the lawsuits. Following the recent recall, it is probable that Stryker will face more suits alleging that its Rejuvenate and ABG II modular hip implants caused injuries, some of which required revision surgery.

Legal Summary
In July 2012, the company announced that it would be voluntarily recalling two metal hip implant components, known as neck stems, found in its Rejuvenate and ABG II modular hip implants. Since its introduction in 2009, the Rejuvenation device has been implanted into about 20,000 patients; individuals who will now face an increased risk of complications and failures in the future. The device, which received approval through the FDA’s 501(k) pre-market notification process in October 2009, has had recent cases that highlight the dangers. On June 11, 2013, cases were consolidated in Minnesota’s MDL, after similar actions were taken in Florida and New Jersey. [3] With the growing number of cases, along with the issues litigated, the hip replacement expert witness brought in, will be critical to the resulting decisions.

How common are these cases?
The exact numbers regarding the amount of Stryker hip implant failures are unknown. In initial communications on this issue, Stryker cited the revision surgery rates as “less than one percent,” and continued to use that figure until May 2012, when the description changed to “extremely low” complication rates. [5] Dr. Robert Zann is an orthopedic surgeon who has implanted about 400 Rejuvenate hips over two years. He says that he has already had to perform revision surgery on at least 100 patients and estimates that he will have to remove another 100 in the coming months and years. This estimation leaves the failure rate of Stryker Rejuvenate and ABG II hip prosthesis at about 50%, which makes this one of the more serious medical device failures in recent history. [6]

Stryker’s response…
As a response to the concerns about the high rate of Rejuvenate failure, Stryker placed the blame on physicians and patients, claiming that doctors implanted the devices incorrectly or patients did not correctly rehabilitate after surgery. In April 2012, Stryker officials blamed patients’ prior illness. They stated in a Product Correction Bulletin that, “Factors such as diabetes and infection may play a role in potential corrosion of an implant as these conditions may affect the pH of the tissue surrounding the implant.” [4]

Harm indicative of breach/viable cause of action in Stryker cases

Pain/Difficulty Walking:
The most likely issue after a hip replacement, many patients experience mobility problems following hip surgery. The recovery time after a total hip replacement varies considering age, weight, height, and a myriad of physical factors. However, patients are generally discharged a few days after the procedure. While the artificial implant may cause some inflammation, the associated pain tends to taper off after the first few weeks of surgery. If such a tapering does not occur, it may be indicative of an issue.

Metal Poisoning (Metallosis):
Metallosis is a condition involving deposition and build-up of metal debris in the body’s tissues. This condition has been hypothesized to occur when metallic components in medical implants, specifically joint replacements, abrade because of friction. It has been observed in approximately 5% of metal joint implant patients over the last few years. If metallosis occurs, it may involve severe inflammatory processes at the hip and knee joints, the shoulder, wrist, or elbow joints. Also, metal debris that finds its way into the bloodstream may cause confusion, gastrointestinal distress, and emotional disturbances.

Bone Deterioration:
Hip implant surgery may cause serious bone deterioration in a number of ways. One of the most significant is osteolysis, which occurs when the body reabsorbs bone as an autoimmune response. Osteolysis has been noted as a side effect of many total hip replacement systems. Put simply, the more debris that is released into the body, the more common osteolysis becomes. Metal-on-metal hip implants were thought to have less likelihood of debris because they were made of harder materials. The design of metal-on-metal devices, however, caused significant friction. This has caused a great deal of metal debris, raising the risk of osteolysis.

The recent report on the cause of pseudotumor formation in patients with metal-on-metal hip replacements was originally thought to be of unknown etiology. It is postulated that there is an association between elevated levels of serum metal ions and pseudotumor formation. Dutch researchers suggest that pseudotumors may be ten times more likely in patients after metal-on-metal hip resurfacing and total hip replacement (THR). In a multivariate analysis, serum cobalt ion levels above 5 µg/mL were the only significant predictive factor for pseudotumors. Patients with elevated cobalt levels were four times more likely to develop pseudotumors than those with lower levels. Even after adjusting for age, gender, surgical characteristics, allergy, and other factors they were still more likely.

Avascular necrosis is defined as cellular death of bone components due to an interruption in blood supply. It may be due to the patient’s preexisting hip disease. Or it could be due to a severe inflammatory response from the implant itself. As necrosis sets in, the bone structures collapse, resulting in further bone destruction, pain, and total loss of joint function. When end-stage AVN occurs in the hip, and collapse of the femoral head has occurred, the only reasonable consideration for pain relief and return to function is to perform a revision hip replacement procedure.

Kidney Damage:
Heavy metals are metals that enter the bloodstream. In this case the metals enter due to hip implants, and are at least five times denser than water. Subsequently, the body cannot metabolize them. Heavy metals have no function or nutritive value in the body and are toxic. It is extremely difficult for patients’ kidneys to filter out these toxins. It is especially hard if the patient already has other health concerns.

Hip Replacement Expert Witness needed in a Stryker case

Orthopedic Surgeon:
An orthopedic surgeon is extensively educated in the preservation, investigation, and restoration of the form and function of the extremities, spine. They also know about skeletal structures through surgical intervention. Orthopedic physicians are a part of most aspects of a patient’s care in regards to repairing and reconstructing skeletal injuries (including a hip joint). An orthopedist is the ideal medical professional to speak on products used in the medical reconstruction of damaged or diseased joints.

Biomechanical Engineer:
Biomedical engineers can serve in a variety of roles, most of which involve the invention and development of medical devices. These can include implants and hardware that improves a patient’s health and quality of life. These engineers can draw on a strong knowledge base to speak on the processes of design control. They can also use their knowledge of failure modes, effects analysis, and clinically relevant design safety protocols. For example, device performance requirements during medical device litigation reviews.

The hip replacement expert witness provide insight into the principles of engineering mechanics. They can explain the basic biological processes and mechanisms as they relate to the structure, function, and injury threshold of body tissue. Their insight has emphasis on bone and other skeletal tissues that would be relevant to Stryker litigation. More specifically, experts in tribology are knowledgeable about friction and its consequences regarding sliding mechanical components. Tribologists can use their knowledge of biomechanics to explain the wear and failure of orthopedic joint prostheses. A hip replacement expert witness in this field will be able to analyze the stresses around the sliding of ceramics and metals against metals.


Medical Toxicologist:
Medical toxicology is a medical subspecialty focusing on the diagnosis, management, and prevention of poisoning and other adverse health effects. Specifically those due to medicinal, occupational, and environmental toxins. They are involved in the comprehensive, high-level care of people and patients who come into contact with drugs. Medical toxicologists also take care of those who come into contact with other substances or potentially harmful agents. The expertise of a medical toxicologist may be called upon in case proceedings. They will specifically address the implications surrounding the blood poisoning and metal toxicity. Patients may experience these results from Stryker implants.

Medical Device Design Expert:
Medical device design experts effectively manage a cross-functional team comprised of quality control, manufacturing, marketing, clinical, and regulatory personnel. They also bring medical devices into production. This type of professional would be very familiar with the engineering laboratory equipment. They would also know testing methodologies and the standards of care in delivering high-end medical device products. Hip replacement expert witness testimony from a medical device design expert who has worked on product development, manufacturing, and regulatory compliance would be instrumental in litigation surrounding product liability. A hip replacement expert witness who has designed hip devices and has experience taking such medical products to market can contribute a great depth of knowledge from a business and product safety standpoint.


– See more at: http://www.youhavealawyer.com/blog/2013/06/11/stryker-rejuvenate-hip-failures/#sthash.re2XKADX.dpuf
[1] http://www.lawyersandsettlements.com/lawsuit/stryker-orthopedics-rejuvenate-modular-hip-system.html?utm_expid=3607522-2&utm_referrer=https%3A%2F%2Fwww.google.com%2F#.Udrbt_mTzQg
[2] id.
[3] http://www.prweb.com/releases/2013/6/prweb10815392.htm
[4] http://www.lawyersandsettlements.com/lawsuit/stryker-orthopedics-rejuvenate-modular-hip-system.html?utm_expid=3607522-2&utm_referrer=https%3A%2F%2Fwww.google.com%2F#.Udrbt_mTzQg
[5] http://www.strykerhipreplacement.com/questions-about-stryker-hip-replacements.html
[6] http://www.palmbeachpost.com/news/lifestyles/health/boynton-beach-orthopedic-surgeon-removes-recalled-/nW74k/