ORTHO NEWS

In the year before total knee arthroplasty (TKA), patients incur considerable costs for nonoperative treatments and other procedures for osteoarthritis (OA) – raising questions about the value of those procedures, reports a study in The Journal of Bone & Joint Surgery. The journal is published in the Lippincott portfolio in partnership with Wolters Kluwer.

The study shows “substantial variation in the type and cost of nonoperative procedures for patients with late-stage knee OA prior to TKA,” according to the report by Eric L. Smith, MD, of New England Baptist Hospital, Boston, and colleagues.

Estimated costs of $2.4 billion over 3 years for nonoperative procedures before TKA

Using nationwide commercial insurance databases, the researchers analyzed claims for nearly 24,500 patients who underwent primary TKA in 2018 and 2019. The study examined the types and costs of nonoperative procedures in the months leading up to TKA.

Average costs for nonoperative procedures in the year before TKA were $1,355 per patient. Knee imaging studies were the most common procedure overall, performed in about 96% of patients. Intra-articular steroid injections were the most frequent treatment procedure, performed in 54%. Bracing was the least common nonoperative treatment, performed in approximately 8% of patients.

Intra-articular injection of hyaluronic acid, excluding professional administration fees, was the most costly procedure: performed in about 13% of patients, it made up 10% of total costs. By comparison, steroid injections were performed in more than half of patients, but accounted to just over 1% of costs. Physical therapy was used in about 27% of patients and accounted for about 17% of costs.

Most patients underwent at least two nonoperative treatments, while more than one-third underwent three or more. Costs increased with time between diagnosis and surgery, exceeding $2,000 in patients with a 12-month duration before undergoing TKA.

Women had higher total costs for nonoperative treatment, with the greatest differences in physical therapy and prescription of nonsteroidal anti-inflammatory drugs. Men had higher costs for opioids. Procedures and costs also varied by region, with the Northeast region having the highest average cost ($1,740).

TKA is a highly effective and cost-efficient treatment for knee OA. The researchers note that decisions about TKA can be “extremely complicated,” involving factors related to patients, providers, and insurers. For example, insurers may require some period of nonoperative treatment before authorizing coverage for TKA. With the national focus on reducing costs while delivering high-value care, the requirement of nonoperative treatment in the months before TKA warrants evaluation.

Extrapolated to the 600,000 TKAs performed each year in the United States, the total costs of nonoperative treatment are estimated at $2.4 billion over a 3-year period and are likely to increase in the future. The authors point out some limitations of their study, mainly related to the use of insurance claims data.

“For patients who eventually undergo TKA, the cost-effectiveness of these nonoperative treatments right before TKA needs to be carefully considered as the health-care system transitions toward a value-based model,” Dr. Smith and coauthors conclude. They also note that some nonoperative treatments – for example, intra-articular steroid or hyaluronic acid injections or bracing – do not have strong evidence of effectiveness. The researchers call for further studies focusing on the benefits of nonoperative treatments at different stages of knee OA.

Process to create nanostructures on implant surfaces also enhances bone cells’ attachment

WEST LAFAYETTE, Ind. – A patent-pending process developed by Purdue University engineers could improve the quality of life for the more than 6 million people who undergo orthopedic and trauma surgery annually, according to a paper published in Langmuir: The ACS Journal of Fundamental Interface Science.

Infection is a major complication when rods, plates, screws and other devices are embedded into people during procedures like joint replacement surgery and spinal fusion surgery. Most infections occur because the devices’ titanium implant surfaces have poor antibacterial and osteoinductive properties; osteoinduction is the process that prompts bone formation.

Rahim Rahimi, a Purdue University assistant professor in the School of Materials Engineering, has created a process that immobilizes silver onto the implant surfaces of titanium orthopedic devices to improve antibacterial properties and cellular integration. The process can be implemented onto many currently utilized metal implant surfaces.

The antibacterial efficacy of laser-nanotextured titanium surfaces with laser-immobilized silver was tested against both gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli) bacteria. The surfaces were observed to have efficient and stable antimicrobial properties for more than six days. The laser-nanotextured titanium surfaces also provided a 2.5-fold increase in osseointegration properties as compared to the pristine titanium implant surface.

“The first step of the two-step process creates a hierarchical nanostructure onto the titanium implant surface to enhance the bone cells’ attachment,” Rahimi said. “The second step immobilizes silver with antibacterial properties onto the titanium implant surface.

“The technology allows us to not only immobilize antibacterial silver compounds onto the surface of the titanium implants but also provide a unique surface nanotexturing that allows better settle attachment mineralization.

“These unique characteristics will allow improving implant outcomes, including less risk of infection and fewer complications like device failure.”

Rahimi said the traditional method to address infections caused by implanted orthopedic devices often utilizes antibiotics or other surface modifications that have their own associated complications.

“Long-term antibacterial protection is not possible with these traditional drug coatings because a large portion of the loaded drug is released in a short time,” Rahimi said. “There also is often a mixture of microbes that are found in implant-associated infection; it is essential to choose a bactericidal agent that covers a broad spectrum.”

Rahimi disclosed the innovation to the Purdue Research Foundation Office of Technology Commercialization, which has applied for a patent on the intellectual property. Industry partners seeking to further develop this innovation should contact Patrick Finnerty, pwfinnerty@prf.org, about reference number 2022-RAHI-69768.

Rahimi said the next steps to develop the laser process to texturize and immobilize silver onto orthopedic devices are to implement it onto standard orthopedic fixtures, validate the technology to get approval from the U.S. Food and Drug Administration, and license it to companies working in the orthopedic sector.

Rahimi’s research was funded by Purdue’s School of Materials Engineering.

About Purdue University

Purdue University is a top public research institution developing practical solutions to today’s toughest challenges. Ranked in each of the last five years as one of the 10 Most Innovative universities in the United States by U.S. News & World Report, Purdue delivers world-changing research and out-of-this-world discovery. Committed to hands-on and online, real-world learning, Purdue offers a transformative education to all. Committed to affordability and accessibility, Purdue has frozen tuition and most fees at 2012-13 levels, enabling more students than ever to graduate debt-free. See how Purdue never stops in the persistent pursuit of the next giant leap at https://stories.purdue.edu.

About Purdue Research Foundation Office of Technology Commercialization

The Purdue Research Foundation Office of Technology Commercialization operates one of the most comprehensive technology transfer programs among leading research universities in the U.S. Services provided by this office support the economic development initiatives of Purdue University and benefit the university’s academic activities through commercializing, licensing and protecting Purdue intellectual property. In fiscal year 2021, the office reported 159 deals finalized with 236 technologies signed, 394 disclosures received and 187 issued U.S. patents. The office is managed by the Purdue Research Foundation, which received the 2019 Innovation and Economic Prosperity Universities Award for Place from the Association of Public and Land-grant Universities. In 2020, IPWatchdog Institute ranked Purdue third nationally in startup creation and in the top 20 for patents. The Purdue Research Foundation is a private, nonprofit foundation created to advance the mission of Purdue University. Contact otcip@prf.org for more information.

Writer: Steve Martin, sgmartin@prf.org

Source: Rahim Rahimi, rrahimi@purdue.edu

ABSTRACT

Laser-Assisted Nanotexturing and Silver Immobilization on Titanium Implant Surfaces to Enhance Bone Cell Mineralization and Antimicrobial Properties

Vidhya Selvamani, Sachin Kadian, David A. Detwiler, Amin Zareei, Ian Woodhouse, Zhimin Qi, Samuel Peana, Alejandro M. Alcaraz, Haiyan Wang, Rahim Rahimi

Despite the great advancement and wide use of Titanium (Ti) and Ti-based alloys in different orthopedic implants, device-related infections remain the major complication in modern orthopedic and trauma surgery. Most of these infections are often caused by both poor antibacterial and osteoinductive properties of the implant surface. Here, we have demonstrated a facile two-step laser nanotexturing and immobilization of silver onto the titanium implants to improve both cellular integration and antibacterial properties of Ti surfaces. The required threshold laser processing power for effective nanotexturing and osseointegration was systematically determined by the level of osteoblast cells mineralized on the laser nanotextured Ti (LN-Ti) surfaces using a Neodymium-doped yttrium aluminum garnet laser (Nd-YAG, wavelength of 1.06 μm). Laser processing powers above 24 W resulted in the formation of hierarchical nanoporous structures (average pore 190 nm) on the Ti surface with a 2.5-fold increase in osseointegration as compared to the pristine Ti surface. Immobilization of silver nanoparticles onto the LN-Ti surface was conducted by dip coating in an aqueous silver ionic solution and subsequently converted to silver nanoparticles (AgNPs) by using a low power laser-assisted photocatalytic reduction process. Structural and surface morphology analysis via XRD and SEM revealed a uniform distribution of Ag and the formation of an AgTi-alloy interface on the Ti surface. The antibacterial efficacy of the LN-Ti with laser immobilized silver (LN-Ti/LI-Ag) was tested against both gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli) bacteria. The LN-Ti/LI-Ag surface was observed to have efficient and stable antimicrobial properties for over 6 days. In addition, it was found that the LN-Ti/LI-Ag maintained a cytocompatibility and bone cell mineralization property similar to the LN-Ti surface. The differential toxicity of the LN-Ti/LI-Ag between bacterial and cellular species qualifies this approach as a promising candidate for novel rapid surface modification of biomedical metal implants.

Newswise — Cementless knee replacement, an alternative approach to the traditional surgery in which bone cement is used, is gaining interest among orthopedic surgeons. Using a novel MRI technique, researchers at Hospital for Special Surgery (HSS) found that a cementless implant demonstrated excellent biologic fixation, and even improved fixation of implant components in some areas in the joint, compared to the standard cemented implant.

HSS hip and knee surgeon Geoffrey Westrich, MD, and colleagues in the HSS Radiology Department used an advanced imaging technique known as “multi-acquisition variable-resonance image combination selective MRI” to assess fixation in patients who had a cementless knee replacement compared to those whose implant was affixed with bone cement.

“The purpose of our study was to quantify and compare the fixation of uncemented versus cemented knee replacement components,” said Dr. Westrich, lead investigator. “At an average patient follow-up of 16 months, our study demonstrated robust fixation of the cementless knee replacement components, with results comparable to the cemented total knee replacements. And while there was no clinically significant difference regarding overall fixation in the knee, there were some component areas in which cementless fixation appeared to be superior.” The study was published in the October edition of the journal Arthroplasty Today.  

The HSS researchers performed MRIs in 20 patients who had a cementless knee replacement. A matched control group of 20 patients with a cemented knee replacement was also evaluated. The images were reviewed by a fellowship-trained musculoskeletal radiologist specializing in the interpretation of joint replacement MRI, including more than 20 years of experience in assessing bony fixation of knee replacement components.

In a traditional knee replacement, implant components are secured in the joint using bone cement. It’s a tried-and-true technique that has worked well for decades. But eventually, over time, the cement may start to loosen from the bone and/or the implant. This loosening is the leading cause of revision surgery, in which a patient needs a second knee replacement.

“With the cementless prosthesis, the components are press fit into place for biologic fixation, which basically means that the bone will grow into the implant,” explains Dr. Westrich, who believes a well-designed cementless implant will make loosening over time less likely. This could enable a total knee replacement to last much longer, a particular concern for younger patients.

“Overall, traditional knee replacement offers excellent outcomes and longevity,” he says. “However, younger patients generally put more demands on their joint, causing more wear and tear and potential loosening. The cemented knee implant used in a traditional joint replacement usually lasts 15 to 20 years.”

Cementless implants have been used successfully in total hip replacement surgery for many years. It has been much more challenging to develop a cementless prosthesis that would work well in the knee because of its particular anatomy, Dr. Westrich explains.

“Early generation cementless implants had numerous design flaws resulting in loosening and poor survivorship compared to cemented knee replacements,” he says. “More contemporary cementless knee components such as those used in our study utilize highly porous surfaces to promote biologic fixation of the prosthesis. This should improve outcomes.”

Candidates for the cementless procedure are generally patients under age 70 with good bone quality to promote biologic fixation. In addition to younger patients, Dr. Westrich notes that the cementless implant may prove to be a good option for very overweight patients who tend to put more stress on their joint replacement.

“While our study found that early fixation of cementless total knee components are comparable, if not superior, to cemented total knee replacement, further study with a larger number of patients over a lengthier time period is needed to assess long-term durability and fixation.”

Disclosure: Research support received from Stryker Corporation. 

Knee osteoarthritis is a major public health problem that primarily
affects the elderly. Almost 10 percent of the United States population
suffers from symptomatic knee osteoarthritis by the age of 60. In fact,
OA is prevalent worldwide, especially with an increasingly aging
society. It is one of the leading causes of pain and dysfunction in the
joints among the aging population. Despite this, there are no approved
interventions that ameliorate structural progression of this disorder. Continue reading on digital