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The Urgent Need to Protect Implants from Bacteria: Incidence of DRIs and Occult Infections

The Urgent Need to Protect Implants from Bacteria: Incidence of DRIs and Occult Infections

Property of Orthobond Corporation 2026

Jordan Katz, Ph.D., Meredith Prysak, Ph.D.

There are over two million healthcare-associated infections (HAIs) every year which costs the U.S. healthcare system $28-45 billion annually1, of which the CDC estimates 90% of cases could be avoided through implementation of improved infection controls.2 About 50-70% of HAIs can be attributed to microbial colonization of indwelling implants.3,4 The resulting device-related infections (DRIs) create a staggering financial burden, with costs ranging from $30,000 to treat a catheter infection to over $150,000 to address an infected total joint prosthesis. The risk of patient morbidity and death with DRIs is also alarmingly high. A recent review by Kurtz et al. demonstrated that the 5-year survival rate for an infected total knee implant is lower than the 5-year survival rate for breast or prostate cancer.5

Figure 1: At left is an SEM image of a titanium screw at low magnification. At right is a higher magnification SEM image of the region highlighted in red, revealing bacterial attachment on the screw surface.

To address the DRI problem, healthcare has evolved to include pre-operative, peri-operative and post-operative infection control procedures,6 but one significant remaining gap is a strategy specifically designed to protect the surface of implantable and/or patient-contacting medical devices. Addressing this gap is particularly urgent because numerous studies have shown that when a foreign body such as an implant is present in a wound site, it takes approximately 1000x fewer bacteria to generate an infection.7-12 Once bacteria adhere to a device surface, they can further develop into a biofilm, becoming embedded within a self-produced matrix composed of polysaccharides and other cellular materials. This biofilm creates both a physical and metabolic barrier that significantly reduces antibiotic penetration and activity, making antimicrobial treatments largely ineffective at eliminating the infection.

Studies of operating room airflow handling and analysis of surgeon’s gloves, gowns and instruments demonstrate that bacteria are abundantly present in the “sterile” field of the modern operating room.13,14 A recent study of surgical lamps and instrument tables revealed a positive bacterial culture rate of up to 19%.15 Consequently, it is not surprising that analyses for the presence of bacterial DNA on implants reveals that 70-100% of explanted hardware from failed total joint replacements have some level of bacterial contamination.16 When the inherent vulnerability of an implant surface is coupled with the host’s foreign body reaction, a highly permissive environment for biofilm formation emerges. As a result, florid DRIs occur in 0.5-1.0% of hip and knee replacements, 5% of elbow arthroplasties and up to 15% of prosthetic heart valves.4 These DRIs lead to significant patient morbidity and mortality, and yet clinically diagnosed DRIs only account for a small fraction of the problem that bacterial contamination of implantable medical devices can cause.

Clinical research in a wide range of applications has now linked the presence of bacterial contamination to implant failure mechanisms previously assumed to be aseptic in etiology. In total joint arthroplasty, the leading cause of implant failures is implant loosening, a condition widely believed to be aseptically caused by micro-particulates and/or poor load transfer leading to osteolysis and micromotion. However, twenty years of scientific and clinical studies have now provided a clear link between “aseptic” loosening and chronic, low levels of bacteria on the implant surfaces.16-23 Recently, Renard and colleagues evaluated 523 total hip arthroplasty revisions presumed to be aseptic and found that the explants were culture positive in 22% of the cases.21 The Renard study is consistent with other similar studies performed over the past two decades, demonstrating that explanted “aseptic” hips and knees are culture positive in 9.5 to 29.7% of all cases. Bacterial debris activates immune cells which can lead to osteolysis and device loosening through multiple parallel but distinct immune pathways, such as direct activation of macrophages as shown in Figure 2.24,25 Thus, it is unsurprising that low level, persistent, bacterial colonization of an implant, often termed occult infection, can contribute to negative sequelae such as aseptic loosening, and ultimately lead to poor patient outcomes and failed implants. In fact, the presence of occult infection in TJA was recently shown to correlate with a significantly lower Oxford score (higher pain level) in patients prior to revision surgery.26

Figure 2: Signals from bacterial debris leading to increased osteoclastic activity.

Recently, significant evidence has demonstrated that occult infections also play a role in the failure of other orthopedic devices, such as instrumented spine fusions. Spine fusion has created significant benefit for patients, although these procedures are not without risk and have been associated with failure rates of up to 40%.27 Historically, the majority of failed spine fusion surgeries have been linked to chronic pain of unclear etiology, commonly termed “aseptic” due to the lack of systemic signs of infection. Recent studies, however, have now linked the presence of low levels of bacterial contamination to this reported chronic pain and implant loosening (Table I).28-36 Steinhaus et al. retrospectively examined data from routine microbiology cultures taken from spinal implants in 112 patients undergoing revision due to chronic pain. The results of their study, performed between 2008 and 2013, indicated the presence of bacteria in 40.2% of cases that had been presumed to be aseptic.30 Separately, in a prospective observational study, Callanan et al., evaluated whether the rate of occult infection among failed spine fusion cases was higher than the widely reported incidence of infection.33 They removed instrumentation from 50 consecutive spine fusion patients experiencing severe pain from no clear etiology (i.e. without any signs of systemic infection) and cultured for the presence of bacteria. 38% of patients were culture-positive, and polymicrobial infections were found in 26% of the culture-positive patients.

Table I: Contamination rate of explanted pedicle screws

Clinical Study Contamination Rate Patients Cultured
Leitner et al. 2018 29.1% 110
Steinhaus et al. 2018 40.2% 112
Prinz et al. 2019 40.7% 54
Pumberger et al. 2019 45.2% 166
Callanan et al. 2019 38% 50
Garcia-Perez et al. 2021 29% 38
Burkard et al. 2021 10.2% 128
Yaagoubi et al. 2024 56% 36
TOTAL 34.2% 694

Clinical evidence linking bacterial contamination to “aseptic” device failures is not limited to orthopedics and spine. In breast implants, the predominant cause of device failure and retrieval is capsular contracture, a painful and disfiguring condition which affects 15% of women following aesthetic procedures and approximately 50% of all women following reconstructive surgery post-mastectomy.37 Capsular contracture was previously thought to be caused by an adverse cellular reaction to the implant surface, but studies have now implicated the presence of bacteria as causal in at least a substantial subset of these cases. In one of the first such studies, Virden and colleagues isolated bacteria from 56% of implants recovered from contracted capsules, versus 18% recovered without the presence of capsular contraction. Additionally, the presence of bacteria was correlated to pain in 91% of cases.38 Numerous other studies have also associated the presence of bacterial contamination with capsular contracture, with contamination rates as high as 89.5%.39,40 Interestingly, bacterial contamination is not merely associated with the incidence of capsular contracture, but also with its severity, as measured by the Baker Scale. Rieger et al. demonstrated that the degree of capsular contracture is directly related to the percentage of contaminated implants, increasing from an 18% contamination rate at Baker grade I to 60% for Baker grade IV.41 This study also observed that the contamination rate for implants needing early (< 3 months) surgical revision was higher than those that didn’t require it: 87% vs 41%. Hu et al. demonstrated a direct relationship between the magnitude of contamination on a given implant with the severity of contracture by relating Baker grade to both colony forming units (CFU) of culturable bacteria and qPCR. The calculated number of bacteria increased by nearly 1 log between Baker grades I and IV.42

Clearly, reducing or eliminating bacterial contamination on the implant surface is an important goal, distinct from current anti-infective procedures and protocols. In other indications, new evidence is also demonstrating the ubiquitousness of the harmful effects of bacteria seeding on medical implants, while underscoring the potential benefits of delaying or eliminating the formation of bacterial biofilms. A recent dental implant study of nearly 1000 patients by Tabrizi et al. showed that earlier infections were correlated to a significantly higher implant failure rate than late infections.43 Similarly, a recent review of cardiac implants infections concluded that DRIs occurring within the first year following implantation or revision are generally due to bacterial contamination at the time of surgery.44 These recent reports demonstrate the importance of delaying or eliminating bacterial contamination at the time of surgery to allow for optimal integration of the device with host tissue. This concept, known as “the race to the surface” points to the importance of antimicrobial surface technologies: if bacteria “win” the race (i.e. are present on the surface before mammalian cells have a chance to seed), this can lead to poor, and in some cases devastating, patient outcomes.

In response to this need, Orthobond Corporation has developed a covalent, non-eluting surface that has rapid, broad-spectrum antibacterial activity (Ostaguard). Recently, Orthobond received the first-ever FDA approvals for this surface modification on permanent implants with separate approvals in spine stabilization and limb salvage. Hundreds of patients have now received Ostaguard treated devices and Orthobond is rapidly expanding into new markets. Other emerging technologies designed to actively reduce bacterial contamination on implant surfaces face a difficult path to market due to fears of prophylactic antibiotic use driving the continued emergence of antibiotic-resistant bacteria. Through decades of research and development, the Ostaguard surface is the only technology that has successfully overcome these obstacles.

Please address questions to Jordan Katz at katzj@orthobond.com or visit www.orthobond.com

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References

  1. Stone, P.W., Economic burden of healthcare-associated infections: an American perspective. Expert Rev Pharmacoecon Outcomes Res, 2009. 9(5): p. 417-22. ↩
  2. https://www.cdc.gov/. Current HAI Progress Report. 2024. ↩
  3. <Darouiche inf surg implants NEJM 350 2004.pdf>. ↩
  4. VanEpps, J.S. and J.G. Younger, Implantable Device-Related Infection. Shock, 2016. 46(6): p. 597-608. ↩ ↩
  5. Kurtz, S.M., et al., Are We Winning or Losing the Battle With Periprosthetic Joint Infection: Trends in Periprosthetic Joint Infection and Mortality Risk for the Medicare Population. J Arthroplasty, 2018. 33(10): p. 3238-3245. ↩
  6. Parvizi, J., et al., Introduction: Proceedings of International Consensus on Orthopedic Infections. J Arthroplasty, 2019. 34(2S): p. S1-S2. ↩
  7. Elek, S.D. and P.E. Conen, The virulence of Staphylococcus pyogenes for man; a study of the problems of wound infection. Br J Exp Pathol, 1957. 38(6): p. 573-86. ↩
  8. James, R.C. and C.J. Macleod, Induction of staphylococcal infections in mice with small inocula introduced on sutures. Br J Exp Pathol, 1961. 42: p. 266-77.
  9. Widmer, A.F., et al., Correlation between in vivo and in vitro efficacy of antimicrobial agents against foreign body infections. J Infect Dis, 1990. 162(1): p. 96-102.
  10. Zimmerli, W., et al., Pathogenesis of foreign body infection: description and characteristics of an animal model. J Infect Dis, 1982. 146(4): p. 487-97.
  11. Poelstra, K.A., et al., A novel spinal implant infection model in rabbits. Spine (Phila Pa 1976), 2000. 25(4): p. 406-10.
  12. Poelstra, K.A., et al., Prophylactic treatment of gram-positive and gram-negative abdominal implant infections using locally delivered polyclonal antibodies. J Biomed Mater Res, 2002. 60(1): p. 206-15. ↩
  13. Beldame, J., et al., Surgical glove bacterial contamination and perforation during total hip arthroplasty implantation: when gloves should be changed. Orthop Traumatol Surg Res, 2012. 98(4): p. 432-40. ↩
  14. Pasquarella, C., et al., A mobile laminar airflow unit to reduce air bacterial contamination at surgical area in a conventionally ventilated operating theatre. J Hosp Infect, 2007. 66(4): p. 313-9. ↩
  15. Ion, N.C.I., et al., Key factors influencing orthopaedic operating room contamination: Impact of human activity and Staphylococcus epidermidis prevalence. J Exp Orthop, 2025. 12(3): p. e70321. ↩
  16. <tunney et al., 1999., J Clin Microbiology., Detection of prosthetic hip infection.pdf>. ↩ ↩
  17. Dempsey, K.E., et al., Identification of bacteria on the surface of clinically infected and non-infected prosthetic hip joints removed during revision arthroplasties by 16S rRNA gene sequencing and by microbiological culture. Arthritis Res Ther, 2007. 9(3): p. R46.
  18. Moojen, D.J., et al., Incidence of low-grade infection in aseptic loosening of total hip arthroplasty. Acta Orthop, 2010. 81(6): p. 667-73.
  19. Kempthorne, J.T., et al., Occult Infection in Aseptic Joint Loosening and the Diagnostic Role of Implant Sonication. Biomed Res Int, 2015. 2015: p. 946215.
  20. Fernandez-Sampedro, M., et al., 26Postoperative diagnosis and outcome in patients with revision arthroplasty for aseptic loosening. BMC Infect Dis, 2015. 15: p. 232.
  21. Renard, G., et al., Periprosthetic joint infection in aseptic total hip arthroplasty revision. Int Orthop, 2020. 44(4): p. 735-741. ↩
  22. Jacobs, A.M.E., et al., The unsuspected prosthetic joint infection : incidence and consequences of positive intra-operative cultures in presumed aseptic knee and hip revisions. Bone Joint J, 2017. 99-B(11): p. 1482-1489.
  23. Bereza, P.L., et al., Identification of Asymptomatic Prosthetic Joint Infection: Microbiologic and Operative Treatment Outcomes. Surg Infect (Larchmt), 2017. 18(5): p. 582-587. ↩
  24. Greenfield, E.M., et al., Bacterial pathogen-associated molecular patterns stimulate biological activity of orthopaedic wear particles by activating cognate Toll-like receptors. J Biol Chem, 2010. 285(42): p. 32378-84. ↩
  25. Chakravarti, A., et al., Surface RANKL of Toll-like receptor 4-stimulated human neutrophils activates osteoclastic bone resorption. Blood, 2009. 114(8): p. 1633-44. ↩
  26. Hadjimichael, A.C., et al., Sonication of revised hip and knee prostheses detects occult infections, improves clinical outcomes and prevents re - revisions. A case series study. Infect Prev Pract, 2022. 4(3): p. 100232. ↩
  27. Thomson, S., Failed back surgery syndrome - definition, epidemiology and demographics. Br J Pain, 2013. 7(1): p. 56-9. ↩
  28. Hu, X. and I.H. Lieberman, Revision spine surgery in patients without clinical signs of infection: How often are there occult infections in removed hardware? Eur Spine J, 2018. 27(10): p. 2491-2495. ↩
  29. Leitner, L., et al., Pedicle screw loosening is correlated to chronic subclinical deep implant infection: a retrospective database analysis. Eur Spine J, 2018. 27(10): p. 2529-2535.
  30. Steinhaus, M.E., et al., Risk Factors for Positive Cultures in Presumed Aseptic Revision Spine Surgery. Spine (Phila Pa 1976), 2019. 44(3): p. 177-184. ↩
  31. Prinz, V., et al., High frequency of low-virulent microorganisms detected by sonication of pedicle screws: a potential cause for implant failure. J Neurosurg Spine, 2019. 31(3): p. 424-429.
  32. Pumberger, M., et al., Unexpected positive cultures in presumed aseptic revision spine surgery using sonication. Bone Joint J, 2019. 101-B(5): p. 621-624.
  33. Callanan, T.C., et al., Prevalence of Occult Infections in Posterior Instrumented Spinal Fusion. Clin Spine Surg, 2021. 34(1): p. 25-31. ↩
  34. Garcia-Perez, D., et al., Implant Microbial Colonization Detected by Sonication as a Cause for Spinal Device Failure: A Prospective Study. Spine (Phila Pa 1976), 2021. 46(21): p. 1485-1494.
  35. Burkhard, M.D., et al., Occult infection in pseudarthrosis revision after spinal fusion. Spine J, 2021. 21(3): p. 370-376.
  36. El Yaagoubi, Y., et al., Value of (18) F-FDG PET/CT to Identify Occult Infection in Presumed Aseptic Pseudarthrosis after Spinal Fusion: Correlation with Intraoperative Cultures. World J Nucl Med, 2024. 23(1): p. 17-24. ↩
  37. Vinsensia, M., et al., Incidence and Risk Assessment of Capsular Contracture in Breast Cancer Patients following Post-Mastectomy Radiotherapy and Implant-Based Reconstruction. Cancers (Basel), 2024. 16(2). ↩
  38. Virden, C.P., et al., Subclinical infection of the silicone breast implant surface as a possible cause of capsular contracture. Aesthetic Plast Surg, 1992. 16(2): p. 173-9. ↩
  39. Virden, C.P., et al., Subclinical Infection of the Silicone Breast Implant Surface as a Possible Cause of Capsular Contracture. Aesthetic Plast Surg, 2020. 44(4): p. 1141-1147. ↩
  40. Dobke, M.K., et al., Characterization of microbial presence at the surface of silicone mammary implants. Ann Plast Surg, 1995. 34(6): p. 563-9; disscusion 570-1. ↩
  41. Rieger, U.M., et al., Bacterial biofilms and capsular contracture in patients with breast implants. Br J Surg, 2013. 100(6): p. 768-74. ↩
  42. Hu, H., et al., Bacterial Biofilm Infection Detected in Breast Implant-Associated Anaplastic Large-Cell Lymphoma. Plast Reconstr Surg, 2016. 137(6): p. 1659-1669. ↩
  43. Tabrizi, R., et al., Dental Implant Survival after Postoperative Infection. J Maxillofac Oral Surg, 2022. 21(3): p. 796-801. ↩
  44. Doring, M., S. Richter, and G. Hindricks, The Diagnosis and Treatment of Pacemaker-Associated Infection. Dtsch Arztebl Int, 2018. 115(26): p. 445-452. ↩

Property of Orthobond Corporation 2026

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