No Evidence Supporting Newer Joint Replacement Devices

Beth Skwarecki

September 11, 2014

Recent improvements in joint replacement devices may not be worth the risk, according to a systematic review published online September 9 in the BMJ. The authors found no evidence to recommend 5 newer designs over their more established counterparts, and some of the newer devices came with a higher likelihood of revision surgery.

"[N]ew technologies are being introduced to the commercial market without sufficient high quality evidence for improved benefit over existing, well proven, and safe alternative implant solutions," write Marc J. Nieuwenhuijse, MD, PhD, from the Patient Centered Comparative Effectiveness Program and US Food and Drug Administration Medical Device Epidemiology Science and Infrastructure Center, Department of Public Health, Weill Cornell Medical College, New York, City; the Department of Orthopaedics, Leiden University Medical Center, the Netherlands; and the Office of Surveillance and Biometrics, Center for Devices and Radiological Health, US Food and Drug Administration, Silver Spring, MD, and colleagues. "[T]he status quo regarding the introduction of new device technologies is not acceptable."

In the systematic review, Dr. Nieuwenhuijse and colleagues considered 5 devices that were purported to be improvements over previous technology: ceramic-on-ceramic bearings, modular femoral necks, and uncemented monoblock (not metal-on-metal) acetabular cups in total hip replacement, and high-flexion implants and sex-specific implants in total knee replacement.

The device innovations were chosen on the basis of 3 criteria: they must have a rationale for expected superior outcomes, must have been reported with at least 90% completeness in a national orthopedic registry (to ensure the data would reflect widespread use rather than surgeries by a few "skilled enthusiasts"), and must be comparable to a traditional device for the same indication.

The researchers did not include metal-on-metal hip replacements. The US Food and Drug Administration issued cautionary guidelines about this type of replacement in 2013 after studies showed that metal debris could be released from the device and that revision surgery was more often needed with these devices than with other types of hip replacements. They also excluded highly cross-linked polyethylene hip replacements, because long-term follow-up data are not yet available, and resurfacing total hip replacements and unicompartmental knee arthroplasty for lack of a suitable reference device.

Dr. Nieuwenhuijse and colleagues identified 118 studies that included 15,384 implants in 13,164 patients. They found no evidence for clinically relevant improvement in 4 of the 5 devices, and one device, modular femoral necks, had insufficient evidence.

Revision rates were deemed comparable to those of older devices for uncemented monoblock hip replacements and for sex-specific knee replacements, but the rates were higher for the other 3 devices. The revision rate for modular femoral neck replacements was nearly doubled, with a hazard ratio of 1.92. High-flexion knee replacements had an elevated rate ranging from 1.0 to 1.76 over 56 studies, and ceramic-on-ceramic hip replacements ranged from 1.0 to 1.55 (compared with ceramic-on-polyethylene devices) in 42 studies.

Complications were comparable with those of older devices for ceramic-on-ceramic hip replacements and were not reported for the knee replacements and uncemented monoblock hip replacement. Modular femoral neck devices were associated with higher rates of dislocation and implant fracture.

Dr. Nieuwenhuijse and colleagues argue that changes to devices such as joint replacements require more oversight. At this time, as moderate-risk, class 2 medical devices, incremental changes to devices can be made through the 510(k) pathway, which requires manufacturers to demonstrate that the new product is "substantially equivalent" to the design that was previously approved.

Rather than requiring extended testing for each change in device design, which could delay important updates, Dr. Nieuwenhuijse and colleagues suggest new features should be used in smaller numbers of patients before being approved for wider use.

In an editorial, Aaron S. Kesselheim, MD, and Prashant V. Rajan, both from the Program on Regulation, Therapeutics, and Law, Division of Pharmacoepidemiology and Pharmacoeconomics, Department of Medicine, Brigham and Women’s Hospital, and Harvard Medical School, Boston, MA, suggest an approach similar to the drug facts boxes that have been tested for pharmaceuticals, summarizing crucial evidence needed for decision-making. They write that "an equivalent device facts box for hip and knee replacement devices could help correct the overestimation of benefits and underestimation of harms that many consumers would otherwise expect when learning of 'new and improved' models."

Dr. Nieuwenhuijse received a fellowship from the US Food and Drug Administration Medical Device Epidemiology Network's Science and Infrastructure Center under the International Consortium of Orthopaedic Registries initiative. One coauthor received funding from the US Food and Drug Administration for establishing the Medical Device Epidemiology Network's Science and Infrastructure Center and is the principal investigator of the International Consortium of Orthopaedic Registries contract. The authors and editorialists have disclosed no other relevant financial relationships.

BMJ. Published online September 9, 2014. Full text


Comments on Medscape are moderated and should be professional in tone and on topic. You must declare any conflicts of interest related to your comments and responses. Please see our Commenting Guide for further information. We reserve the right to remove posts at our sole discretion.