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DePuy Hip Expert Witness: A Litigation Guide

Stephen Gomez

Written by
— Updated on February 12, 2021

DePuy Hip Expert WitnessDePuy Orthaepedics is a subsidiary of Johnson and Johnson and produces devices for total hip arthroplasty. In 2010, DePuy issued a recall of their ASR Hip Resurfacing System and their ASR XL Acetabular System 1, after evidence emerged that the device caused significant health complications. The devices, which were intended to last approximately fifteen years, had a much shorter useful life, with some studies suggesting that almost half of the procedures required revision after seven years. Furthermore, since the recalls, the FDA has received 400 complaints involving hip implant failure (coupled with the almost 900 complaints it received prior to the device recalls). Following the complaints, a number of suits were filed against DePuy, Johnson and Johnson, and other parties involved in the manufacturing process of the hip implants. In light of recent litigation, The Expert Institute assembled this litigation guide to help attorneys, the DePuy hip expert witness, investors, and the more than 93,000 patients who received a DePuy hip implant understand the issues which may arise during litigation, the basis of the claims which are most often brought against DePuy, and how a DePuy hip expert witness can be used to effectively litigate these claims.

Medical summary

Hip replacement or Total Hip Arthroplasty (THA) is a surgical procedure in which the hip joint is replaced by a prosthetic implant. Normally, a disease-free hip functions as a “ball-and-socket” joint. The femoral head (ball) articulates with the acetabulum (socket), allowing for a smooth range of motion in multiple planes. Accordingly, any disease state that affects either of these structures can cause deterioration of the joint and lead to deformity, pain, and loss of function. Specifically, a total hip replacement consists of replacing both the acetabulum (socket) and the femoral head (ball), while hemiarthroplasty generally only replaces the femoral head. Most frequently, this type of orthopedic surgery is conducted to relieve severe pain caused by degenerative osteoarthritis, or to fix severe physical joint damage resulting from a hip fracture. Currently, hip replacement is the most common orthopedic procedure performed for patients with hip pain due to a variety of conditions. Ultimately, the objective is to relieve pain, restore function, and improve quality of life. The previous methodology, conventional hip replacement, ran the potential risks of postoperative dislocation, extensive bone loss, and gross migration of the femoral prosthetic component. As a result, hip resurfacing has evolved as an alternative form of hip replacement therapy that conserves a significant portion of skeletal tissue.

Surgical procedure

depuy-hip-replacements2 The orthopedic surgeon makes an incision in the skin over the hip joint, cutting through skin, soft tissue, and muscle to provide visualization of the hip joint. The femoral head is then dislocated from the socket and removed from the end of the femur with a saw. The acetabulum (hip socket) is exposed and a reamer (advanced grater) is used to create a perfect, hemispherical bone socket that matches the external shape of the acetabular cup. Next, the acetabular cup is carefully positioned into the socket.  The cup is helped in place using a number of methods depending on surgeon preference and the patient’s overall bone quality. The methods may include cement to hold the cup in place, but most cups are designed to allow the bone to grow into the metal for a permanent bond. The next step involves the acetabular insert, made of plastic, ceramic, or metal, which is then positioned into the cup. The inside of the femur is cleared with various types of surgical instruments and, at this point, a prosthetic stem is secured to the end of the thighbone. During surgery, a trial of mobility is evaluated with a test ball to determine the range of motion and stability of the joint. A final ball is placed onto the femoral stem and the leg is again evaluated for mobility, stability, and leg length equality before the surgeon closes the incision site.

Complications of THA

By early 2010, reports in the orthopedic literature have cited problems of early failure of metal-on-metal prostheses in an increasing percentage of THA patients. Failures were linked to the release of metallic particles or metal ions from wear of the implants, causing pain and disability severe enough to require revision surgery. Design deficits of some prosthesis models, especially with heat-treated alloys and a lack of special surgical experience, accounts for most of the failures. Surgeons at leading medical centers such as the Mayo Clinic have reported reducing their use of metal-on-metal implants by 80 percent over the last few years in favor of those made from other materials (combinations of metal and plastic). The cause of these failures remains controversial and may include both design factors, technique factors, and factors related to patient immune responses (allergy type reactions). In 2012, The Lancet published a study, based on data from the National Joint Registry of England and Wales, finding that metal-on-metal hip implants failed at much greater rates than other types of hip implants and called for a ban on all metal-on-metal hips. The analysis of 402,051 hip replacements showed that 6.2% of metal-on-metal hip implants had failed within five years, compared to 1.7% of metal-on-plastic and 2.3% of ceramic-on-ceramic hip implants. Each 1mm increase in the head size of metal-on-metal hip implants was associated with a 2% increase in failure. Likewise, surgeons of the British Hip Society recommended that large head metal-on-metal implants should no longer be used.

In 2004, DePuy introduced the ASR Acetabular system in the United States. The ASR system, however, was introduced in other parts of the world as early as 2003. On August 5, 2005, by way of the FDA’s 510(k) approval process, the FDA approved DePuy’s ASR Acetabular System. Normally, medical devices need to go through the premarket approval (PMA) process to ensure that they are safe. In order to market a device, manufacturers need to collect relevant data from clinical investigations, a completed application which summarizes important safety information, and an approval from the FDA that finds, “there is a reasonable assurance of the device’s safety and effectiveness.”4 Also, changes in the medical device have to be recorded with the FDA. By utilizing the 510(k) approval process, however, DePuy saved time and money. Essentially, the 510(k) process states that if a manufacturer can prove that a new device is “substantially similar” to a device already on the market, then it does not have to go through the FDA’s normal, PMA process to be approved. Also, the average cost for a successful FDA 510(k) submission can be ¼ the price of a successful PMA submission.5

Originally, the 510(k) approval process was designed to allow manufacturers to make improvements and helpful changes to their devices without having to resubmit their devices. PMA can take thousands of hours, whereas the 510(k) process may require a small fraction of that amount of time. As the process developed, manufacturers used the 510(k) process as a way to avoid the normal, stringent requirements of the FDA. Unfortunately, by avoiding the normal processes, the devices, despite being deemed “substantially similar,” were not subject to the same safety testing and scrutiny.

depuy hip implant

With the approval of the ASR Acetabular System6 (a device which featured a metal cup and a metal head), DePuy also wanted to have their ASR Hip Resurfacing device approved by the FDA. The 510(k) approval process was not available, however, because the resurfacing system was a relatively new technique. As a result, the FDA required DePuy to submit the ASR Hip Resurfacing System through the PMA process, including clinical trials, for approval.

During clinical trials for the system, a number of issues became apparent. More fractures were occurring at the femoral neck than were normally seen in other devices, and extensive wear and tear between the cup and ball caused metal shards to be released from the device (an issue that would later be revealed in the FDA-approved ASR device). Because of the complications associated with the ASR Hip Resurfacing device, DePuy withdrew their application for FDA approval but continued selling the device in other countries. Furthermore, though not approved by the FDA, physicians in the US could choose to implant the ASR Hip Resurfacing device in “off-label” use. With the lack of a national reporting database (like those in the UK or Australia), it is unknown exactly how many procedures were done in the US. One note is that, because of the lack of specific clinical trials, many physicians remained unaware of complications with the FDA-approved ASR Hip. Although complaints can be filed with the FDA, patients and doctors are not required to submit them. With the absence of clinical trials — and possibly underreported data on the error rates — many surgeons chose a device based on marketing or financial incentives.

With the setback of the ASR Hip Resurfacing Device, DePuy heavily marketed the ASR Acetabular System. Their methods, however, included paying surgeons who would use a DePuy device, which ran afoul of FDA regulations. Because of this practice, on September 27, 2007, DePuy agreed to pay more than $84 million in a civil settlement.[7]

Even with the setback, however, the ASR Hip was implanted in tens of thousands of patients. Beginning in 2006, though, a number of complaints began to be filed with the FDA over the device’s failure. Until 2010, and DePuy’s recall, complaints grew dramatically each year.

Complaints filed with FDA over DePuy hip implants

  • 2006: 12
  • 2007: 87
  • 2008: 239
  • 2009: 424
  • 2010 (recalled in August): 125

“Studies” Abroad

While complaints mounted in the United States, the international community was producing numerous studies that suggested the DePuy system was defective. As early as 2007, presentations were already being made that hinted at issues.

November 2007: At the annual fall meeting of the American Association of Hip and Knee Surgeons, British orthopaedic surgeon Dr. Antoni Nargol made a presentation on adverse findings/ failure rates in patients, in addition to concerns of metal debris from the device.

November 2007 (and 2008): In the Australian National Joint Replacement Registry’s 2007 annual report, they stated that their studies showed that patients receiving the ASR Resurfacing System were at least twice as likely to receive revision as other similar devices. The following year, the same was reported in other DePuy ASR systems. Coupled with this, in between 2007 and 2009, the British Medical Journal reported that the Australian Joint Registry warned DePuy seventeen times regarding their hip implant system.

Early 2008: At a British Orthopaedic Association Conference, Dr. David Langton made a presentation on problems associated with the shallowness of the acetabular cup, causing increased wear in the device.9

January 2009: Dr. Nargol, Dr. Langton, and Tom Joyce, an engineer from Newcastle University, came to the conclusion that ASR’s shallow cup was the main issue with the device.

Late 2009: DePuy voluntarily withdrew the ASR system from the Australian market, citing decreased demand for the device.

Early 2010: DePuy announced a worldwide phase-out of the ASR system because of decreased demand.

March 2010: DePuy sent an alert letter to doctors including information on the studies and data from the Australian Joint Registry.

August 2010: DePuy issued a worldwide recall of both the ASR Systems because of “New, unpublished 2010 data from National Joint Registry of England and Wales revealing revision rates more than twice what is expected after five years in both ASR products.”

Litigating a DePuy Claim

As cases continue to be filed, there are over a thousand cases to be litigated against DePuy. Cases of this nature are difficult because they involve the actions of the physician, in addition to the actions of DePuy. Also, with the sheer magnitude of cases coming in, consolidation has occurred, with many cases being consolidated in MDL courts.

With this being the process, the first cases were critical as bellwether cases. The issues were presented, a DePuy hip expert witness was brought in, and items were disputed, thus highlighting the different elements that will likely be determinative in subsequent litigation.

And So It Begins

The first of the cases to go to trial was Kransky v. DePuy10. The case alleged that DePuy did not adequately test the device, intentionally disregarded physician complaints on the device’s shortcomings, and did not properly warn patients of the risks. The jury ruled in favor of the plaintiff, awarding Kransky $8.3 million in damages. The specific breakdown was ~$300,000 for Kransky’s medical expenses and $8 million for pain and emotional suffering. In terms of claims, the jury specifically stated that the design of the ASR hip caused his injuries and that DePuy failed to warn of the risks associated with the hip implant. Notably, however, the jury declined to award punitive damages, though some jurors clearly thought they should be awarded.11

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In the case, the plaintiff used over eighteen DePuy hip expert witnesses to help illustrate the specific harms that were caused by the hip. This included multiple orthopedic surgeons, biomedical engineers, employees of DePuy, and specific practitioners. With the multitude of medical specialties represented, Kransky was able to present a full picture of the effects of the implant. This was essential, as he had a number of pre-existing conditions including diabetes, cancer, kidney disease, and vascular disease. Taking this into account, the jury awarded no damages for negligence (most likely due to difficulties involving causation) and limited the award to the design of the device and DePuy’s failure to warn.

DePuy strikes back

The second case, however, would have a very different outcome. In Strum v. DePuy, the jury ruled in favor of the defendants.  According to Bloomberg, a large part of Strum’s case involved the damage due to the metal ions, which had allegedly poisoned her tissue and sent metal ions into her blood. The defense, however, had argued that Strum simply was hyper-sensitive to the implant and that this was illustrated by the fact that she experienced little pain relief when the implant was replaced with a different device.

The relative health of Strum (as compared with the numerous conditions that Kransky had) is interesting, as the causal link between the alleged breach and harm should have been easier to establish. Furthermore, documents introduced during the trial stated that company officials knew that the design of the device was flawed long before they recalled it, and they never shared their knowledge with doctors or patients.12 Analysts suggested that the attorneys representing Strum, however, did not paint a full picture linking harm to these issues. As Charles Adeyanju, a juror, said, “there were a lot of unanswered questions…It just wasn’t substantial enough.”

Ultimately, the Strum decision (and its deviation from Kransky) put the emphasis on subsequent cases to establish a consistent trend by which future cases will be litigated. As such, it is critical to understand the elements of a DePuy case and fully demonstrate the symptoms an injured patient may suffer from, and clearly communicate this information with the assistance of well-qualified DePuy hip expert witnesses.

Indications Of A Breach / Viable Causes Of Action


Pain/ Difficulty Walking

The recovery time after a total hip replacement13 varies based on a number of factors (age, weight, height, etc.), but patients are generally discharged a few days post-surgery. While the artificial implant causes a slight inflammatory response, the associated pain tends to taper off significantly after the first few weeks of surgery. If such a tapering does not occur, it may be indicative of a serious issue and greater complications to follow.

Metal Poisoning (Metallosis)

Metallosis is a medical condition involving deposition and build-up of metal debris in the soft tissues of the body. Metallosis has been hypothesized to occur when metallic components in medical implants, specifically joint replacements, abrade against one another. Metallosis has also been observed in patients sensitive to the implant or in the absence of a malpositioned prosthesis. Metallosis 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. Furthermore, metal debris that finds its way into the bloodstream may cause the patient to present with confusion, gastrointestinal distress, and severe 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 part of an autoimmune response. Osteolysis has been noted as a side effect of many total hip replacement systems; 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 are made of harder materials, but the poor design of many metal-on-metal devices causes significant friction and a great deal of metal debris, raising the risk of osteolysis.


The cause of recently reported pseudotumor formation in patients with metal-on-metal hip replacements was originally thought to be of unknown etiology. It has been 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, after adjusting for age, gender, surgical characteristics, allergy, and other factors.


Avascular necrosis is defined as the cellular death of bone components due to an interruption in blood supply, which may be due to the patient’s preexisting hip disease or 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.

Best Experts For A DePuy Case

Orthopedic Surgeon:

An orthopedic surgeon is extensively educated in the preservation, investigation, and restoration of the form and function of the extremities, spine, and associated skeletal structures through surgical intervention. This specialist is involved in the care of patients whose musculoskeletal problems may include congenital deformities, trauma, tumors, or metabolic disturbances to the musculoskeletal system. Orthopedic physicians are intimately involved in all phases of patient care in regards to repairing and reconstructing skeletal injuries, specifically that of the hip joint. An orthopedist is the ideal medical professional needed to speak on products that are 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 such as implants, prostheses, and hardware that is used to help improve 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, failure modes, effects analysis, and clinically relevant design safety protocols, including device performance requirements during medical device litigation reviews. Additionally, these experts can provide insight into the principles of engineering mechanics to explain the basic biological processes and mechanisms related to the structure, function, and injury threshold of body tissue, with emphasis on bone and other skeletal tissues that would be relevant to DePuy litigation.

Medical Toxicologist:

Medical Toxicology is a medical subspecialty focusing on the diagnosis, management, and prevention of poisoning and other adverse health effects due to medicinal, occupational, and environmental toxins. Medical toxicologists are involved in the comprehensive, high-level care of people and patients who come into contact with drugs, substances or other agents that pose a threat to their well-being. The expertise of a medical toxicologist may be called upon in case proceedings to specifically address the implications surrounding the blood poisoning and metal toxicity which patients may experience, resulting from DePuy implants.

Medical Device Design Expert:

Medical device design physicists effectively manage a cross-functional team comprised of quality control, manufacturing, marketing, clinical, and regulatory personnel to bring novel medical devices into production. This type of professional would be very familiar with the engineering laboratory equipment, testing methodologies and standards of care in delivering high-end medical device products. Expert 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. Experts who have designed hip devices and have experience taking such medical products to market can contribute a great depth of knowledge from a business and product safety standpoint.

Expert to speak on pre-existing conditions:

In many cases involving DePuy hip implant complications, the patient who received the hip implant had suffered from a host of other issues, independent of their hip, which caused related and unrelated problems. It is critical to bring in experts who are familiar with the other issues afflicting the patient to determine if the harm is caused by previous issues, or by the DePuy hip implant. For example, in Kransky, the defense brought in a nephrologist in efforts to show that the plaintiff’s diabetes contributed to the harm associated with the hip.

[1] http://www.soactivesofast.com/default.aspx?pageid=1528

[2] http://www.drugwatch.com/hip-replacement/

[3] How the ASR XL Acetabular System is Constructed

[4] Reigel, 552 US at 318.

[5] http://www.biorunup.com/categories/faqs: A recent report on medical device development in the US estimates an average of $24 million is spent for each successful FDA 510(k) submission while PMA submissions can cost as much as $94 million, based on a survey of 204 medical technology companies.

[6] How the ASR XL Acetabular System Became “Substantially Equivalent”

[7] DePuy Hip Recall Leads to $922M Set-Aside for Settlements, Litigation Costs

[8] DePuy ASR Timeline – www.moriarty.com

[9] http://www.bmj.com/

[10] Kransky v. DePuy, BC456086, California Superior Court, Los Angeles County (Los Angeles).

[11] Bloomberg: J&J Must Pay $8.3 Million Over Defective Hip, Jury Says

[12] NY Times: J&J Must Pay $8.3 Million Over Defective Hip, Jury Says

[13] http://faultyimplants.blogspot.com/