OrthoBuzz occasionally receives posts from guest bloggers. In response to a recent “safety communication” from the FDA, the following commentary comes from Ariel Palanca, MD; Adam Bitterman, DO: and Christopher Gross, MD.
During the past decade, total ankle replacement (TAR) has been challenging the gold standard of ankle fusion for treatment of end-stage ankle arthritis. Improvements in TAR component design and refined surgical techniques have led to more predictable and reproducible outcomes.
On March 15, 2021, however, the US Food and Drug Administration (FDA) released a Safety Communication about the Scandinavian Total Ankle Replacement (STAR Ankle), a product line that DJO Surgical acquired from Stryker in November 2020. The FDA’s statement cites a “higher than expected” rate of fracture of the device’s mobile-bearing polyethylene component. The communication goes on to suggest that patients younger than 55 years old and those with an active lifestyle may have a higher risk of component fracture than older, more sedentary patients.
The STAR Ankle received premarket approval from the FDA in 2009, and the FDA is compiling data from 2 post-approval trials of the device. In August 2019, Stryker issued a safety notification regarding the higher-than-expected fracture risk for STAR polyethylene implanted before August 2014. The recent FDA safety notification states there may also be a high risk of fracture for STAR polyethylene components implanted after August 2014, although the agency’s notification acknowledges that “the long-term fracture rate is not known in devices manufactured after the 2014 packaging change.”
The “packaging change” mentioned above refers to the August 2014 changeover when STAR polyethylene started to be packaged in a foil pouch, which virtually eliminates oxidation of the polyethylene and should therefore reduce fracture rates. Additionally, many peer-reviewed journal articles have reported lower STAR-component fracture rates than those found in the post-approval trials at equal or longer follow-ups.
It’s also important to note that the 8-year follow-up FDA study that revealed a 13.8% cumulative polyethylene-fracture rate only included 87 of the 606 STAR patients in the clinical trial. Patients with complications are often more likely to follow up than those with no complications, creating a potential negative bias.
Still, to err on the side of caution, the FDA suggests that surgeons who treat and follow patients with a STAR implant closely monitor them–especially younger, more active patients–for potential component fractures until more post-approval data is analyzed to further clarify any risk.
Ariel Palanca, MD is an orthopaedic foot and ankle surgeon at Arch Health Medical Group in Escondido, California. Adam Bitterman, DO (@DrAdamBitterman) is a foot and ankle specialist, an assistant professor of orthopaedic surgery at Zucker School of Medicine at Hofstra/Northwell, and a member of the JBJS Social Media Advisory Board. Christopher Gross, MD is an orthopaedic surgeon specializing in foot and ankle disorders at the Medical University of South Carolina in Charleston and a member of the JBJS Social Media Advisory Board.
There are 15 references to JBJS studies in the recently published 149-page white paper on “Biological Responses to Metal Implants,” from the FDA’s Center for Devices and Radiological Health. Most of those references are made in Section 7.5.1 (pp. 54-57), which focuses on orthopaedic devices.
The plethora of JBJS references is not surprising, but we were happy also to see that a JBJS “Case Connections” article was cited twice in the white paper. While most of the section on orthopaedic devices discussed metal-on-metal (MoM) hip problems, the FDA noted that adverse biological responses to metals in orthopaedics sometimes occur in the upper extremity. It did so by citing “Adverse Local Tissue Reactions in the Upper Extremity,” which appeared in the May 24, 2017 issue of JBJS Case Connector. The FDA white paper cautioned that metal wear debris-related adverse reactions have occurred with shoulder suture anchors (five cases of which are described in the “Case Connections” article) and with intramedullary humeral nailing (one case of which is described in the “Case Connections” article).
Among the take-home points made by co-authors Thomas Bauer and Allan Harper in the cited “Case Connections” article is this: “Patients with shoulder suture anchors who develop delayed-onset pain and/or stiffness, osteolysis, chondrolysis, or early arthropathy should be evaluated and consideration should be given to the removal of loose or prominent anchors to lessen the risk of articular damage.”
The US FDA has approved the Synovasure Alpha Defensin Lateral Flow Test Kit for helping detect periprosthetic joint infection (PJI) in the synovial fluid of patients being evaluated for revision joint replacement.
Alpha defensins are proteins released by neutrophils in early response to infection. OrthoBuzz previously summarized a 2018 JBJS study that found this rapid alpha defensin test to have 96.9% overall accuracy.
In the FDA news release about the approval, Tim Stenzel, MD, director of the FDA’s Office of In Vitro Diagnostics and Radiological Health, said the test provides health care professionals with additional information that “could potentially reduce patient risk by avoiding unnecessary revision operations for replacement joints.”
In a Commentary on the 2018 JBJS study, Garth Ehrlich, PhD and Michael Palmer, MD said the device is a “substantive advance,” but not “a panacea.” For one thing, metallosis would still need to be ruled out with MRI, because that noninfectious etiology triggers a false-positive result with this rapid test. Synovasure is also likely to miss detection of slow-growing, chronic bacterial pathogens such as Proprionibacterium acnes, the commentators said.
The Synovasure test kit received approval through the FDA’s de novo premarket pathway, which is reserved for “low- to moderate-risk devices of a new type,” according to the agency.
We have entered an era where total ankle arthroplasty (TAA) is accepted as a rational approach for patients with degenerative arthritis of the ankle. TAA results have been shown to be an improvement over arthrodesis in some recent comparative trials.
That was not always the case, however. In the 1980s, the orthopaedic community attacked ankle joint replacement with gusto, and numerous prosthetic designs were introduced with great enthusiasm based on short-term cohort studies. Unfortunately, the concept of TAA was all but buried as disappointing longer-term results with those older prosthetic designs appeared in the scientific literature. It took a full decade for new designs to appear and be subjected to longer-term follow-up studies before surgeons could gain ready access to more reliable instrumentation and prostheses. The producers of these implants behaved responsibly in this regard, facilitated by an FDA approval process that had increased in rigor.
In the December 21, 2016 issue of The Journal, Hofmann et al. publish their medium-term results with one prosthetic design that was FDA-approved in 2006. Implant survival among 81 consecutive TAAs was 97.5% at a mean follow-up of 5.2 years. There were only 4 cases of aseptic loosening and no deep infections in the cohort. Total range of motion increased from 35.5° preoperatively to 39.9° postoperatively.
The fact that a high percentage (44%) of ankles underwent a concomitant procedure at the time of TAA attests to the need for careful preoperative planning for alignment of the ankle joint and the need for thorough assessment of the hindfoot. The fact that a substantial percentage (21%) of ankles underwent another procedure after the TAA attests to the need for thoughtful benefit-risk conversations with patients prior to TAA.
I think the TAA concept and procedure are here to stay, but we still have much work to do in fine-tuning prosthetic designs and instrumentation and enhancing surgeon education for more reliable outcomes.
Marc Swiontkowski, MD
The July 6, 2016, edition of The Journal of Bone & Joint Surgery features a large case-cohort study that may help older patients and clinicians decide whether to use bone morphogenetic protein (BMP) as an adjunct to lumbar arthrodesis. Among Medicare patients aged 65 years and older, Beachler et al. found that BMP use was not associated with the following:
- Overall cancer risk
- Increased risk of individual cancer types
- Increased risk of cancer in people who had cancer prior to undergoing lumbar arthrodesis
- Increased mortality after a cancer diagnosis
BMP was used in 30.7% of >3,600 lumbar-arthrodesis patients analyzed, and the lack of association between BMP use and cancer held whether patients received the growth factor as part of an FDA-approved anterior lumbar interbody fusion or as an off-label application.
In an accompanying commentary, Singh et al. laud the authors for designing a study that was not only well-powered but also analyzed risk among those with a medical history of cancer. The commentators emphasize, however, that the median follow-up in this study was 2.4 years, leading them to wonder “whether this time frame is sufficient to evaluate the impact of BMPs on carcinogenesis.”
Until a large, prospective, randomized trial on this subject is conducted, Singh et al. say, “the decision to use BMPs should be made on the basis of sound clinical judgment by the treating physician after a full disclosure of the potential risks to the patient.”
BMJ recently published two studies of interest to orthopaedists:
- After analyzing data from more than 200 cardiovascular, orthopaedic, and neurologic devices approved in both the US and European Union (EU), Hwang et al. found that those approved in the EU first were nearly three times as likely to trigger a safety alert or experience a recall than those first approved in the US. Finding further that trial results were published for fewer than half of approved devices considered “major innovations,” the authors call for “greater regulatory transparency” so physicians and patients can make better-informed decisions. Interestingly, Figure 2 in this study showed that the FDA approval time for orthopaedic devices was faster than ortho-device approval times in the EU. However, a JBJS study earlier this year found that devices approved via the FDA’s “quick” 510(k) process were 11.5 times more likely to be recalled than those cleared through the longer and more stringent FDA pathway.
- In the second BMJ article, a registry-based case-control study, Abrahamsen et al. found that the long-term use of the bisphosphonate alendronate does not increase the risk for atypical femoral fractures (either subtrochanteric or femoral shaft), while protecting against hip fractures. After applying some sophisticated statistical analyses, the authors estimated that 38 patients with ≥5 years of alendronate adherence would need to be treated for an additional 5 years to prevent one hip fracture, while 1449 similar patients would need to be treated to cause an atypical femoral fracture. Click here for more OrthoBuzz coverage of the relationship between bisphosphonates and atypical femoral fractures.
Most orthopaedic devices are cleared through the FDA’s 510(k) process. But an analysis in the March 16, 2016 JBJS by Day et al. revealed that 510(k)-cleared devices were 11.5 times more likely to be recalled than devices cleared through the more stringent Premarket Approval (PMA) process.
The authors encourage orthopaedic surgeons who are thinking about using a new device in patients to consider how the device was approved. “If the device was approved by the 510(k) pathway, then it may have been approved without additional clinical studies confirming efficacy or safety,” they caution.
The pie chart above shows that from November 2002 to December 2012, 41% of all recalled devices from the 20 companies with the highest number of recalls were of orthopaedic origin.
In late April, the FDA issued a safety announcement cautioning that corticosteroids delivered by epidural injection to treat back and neck pain may cause “rare but serious adverse events”–including vision loss, stroke, paralysis, and death. The agency is requiring an additional label warning to increase awareness of the risks, which were confirmed after the FDA reviewed cases from its Adverse Event Reporting System. Although anesthesiologists, physiatrists, and specialists other than orthopaedic surgeons often administer such injections, orthopaedists should note that as far as the FDA is concerned, the safety and efficacy of epidural steroid injections for neck and back pain have not been established. The FDA said it plans to convene an advisory committee later this year to “discuss the benefits and risks of epidural corticosteroid injections and to determine if further FDA actions are needed.”