© 2024 HMP Global. All Rights Reserved.

A substantial number of antibiotics used to treat wounds in both the hospital and outpatient setting are often not indicated, prescribed inappropriately, and used in excess. The Centers for Disease Control and Prevention in fact reported that across all pathologies, 1 in 3 antibiotic prescriptions may be unnecessary.¹ The associated reasons are many. Often, I find that patients with wounds have other significant medical issues, and as a result, undergo initial evaluation and treatment by physicians. However, many such practitioners are unfamiliar or uncomfortable with wound debridement, one of the first and arguably the most important step in wound management. As a result, antibiotic prescription may take place without a true understanding of wound pathophysiology, diagnosis, or the concept of wound biofilm. Often, if no improvement is noted, they may renew or change the antibiotic in hopes of a clinical improvement without considering a different treatment approach.  

Bacterial resistance or other antibiotic side effects, such as an allergic reaction or the development of C. difficile infection, may not be in the thought process, nor whether or not the antibiotic treatment is actually beneficial. Additionally, in my observation, the use and understanding of appropriate dressings is often lacking. Just as important, dealing with the patient's comorbidities and their impact on wound healing must be addressed. This article will specifically focus on treating postoperative wound infections associated with prosthetic joint replacement surgery and will examine an alternative, nonoperative, treatment approach.

Important Aspects of Prosthetic Joint Infections

The clinical presentation of an infected prosthetic joint can vary from incisional erythema, pain, suture line ischemia, localized tissue edema, and a fluctuant mass. Increased wound drainage, with wound dehiscence often follows, revealing a seroma or underlying hematoma. Joint pain with decreased range of motion may be present along with leukocytosis, fever, chills and tachycardia.²

Possible etiologies of this complication include:

·       wound seromas;

·       hematomas;

·       wound dehiscence;

·       surgical site inoculation from skin bacteria;

·       hematological spread from unrelated sources such as dental, respiratory, urinary or other skin wounds;

·       postoperative direct local trauma from a fall; or

·       a medical device pressure injury from a supportive brace.

Additionally, patient comorbidities that can affect wound closure include advanced age, poor tissue quality, obesity, poor nutrition, and immunosuppressive medication.³  

Early identification relies on a high index of suspicion, diagnostic studies, and astute physical examination. Plain X-rays and or an ultrasound of the surgical site may identify deep, abnormal tissue edema, an early sign of joint infection. This finding is supported by elevated blood work, including CBC, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) and, a synovial fluid aspiration. New biomarkers such as alpha defensin, an antimicrobial peptide secreted by neutrophils in response to a pathogen, and leukocyte esterase, an enzyme produced by activated neutrophils may assist in a more accurate diagnosis.⁴ Wound drainage should be cultured.  Staphylococcus aureus is common, being present in 50% of the cases, with 20% showing polymicrobial organisms and 30% of the cultures may exhibit no growth which does not rule out an infection.⁵

Addressing PJI

When suspecting a wound complication, early return to the operating room is vital for surgical site exploration, cultured and debridement.  I’ve seen some delay this intervention, with the hope of improvement using antibiotic therapy alone.  Unfortunately, in my observation, this sets up a difficult management situation, allowing the surgical incision pathology to progress. A seroma or hematoma, left untreated, I find rarely resolves and often requires aggressive treatment. Evacuation, debridement and removal of devitalized tissue is indicated along with joint aspiration and deep tissue culture to isolate the pathogen. The presence of a sinus tract, palpable bone or prosthesis is consistent with biofilm involvement of the joint. In my experience, a highly absorptive, medicated foam should be used, avoiding wet-to-dry dressings which are no longer considered standard of care. I also feel that negative-pressure wound therapy should be considered, with the understanding that this may not be the sole definitive approach.

Wound bacteria will eventually adhere to the prosthesis, undergo genetic modification, and as a means of survival form a polysaccharide, protective envelope, in which the bacteria functions in an anaerobic state.  The biofilm forms an encompassing barrier protecting the bacteria from the host’s inflammatory response and impedes antibiotic penetration enabling bacterial antibiotic tolerance and resistance.  Biofilm eradication by antibiotics alone has proved ineffective.⁵ Additionally, it should be noted that the majority of antibiotics function by interfering with cell wall synthesis and blocking messenger RNA. These mechanisms of action only function on actively dividing bacteria. Bacteria residing within the biofilm are quiescent, therefore the only effective way to eradicate bacterial biofilm is to remove the hardware.⁵

To achieve a definitive cure of an infected prosthetic joint, I’ve observed general agreement that one must remove the involved prosthesis. A 1- or 2-stage treatment approach exists. The 2-stage procedure involves prosthesis removal, surgical site debridement, and temporary spacer insertion. The patient is placed on the appropriate antibiotic, based on intraoperative cultures, and the surgeon inserts a new prosthetic joint at a later time. In the past, the 2-stage procedure was considered the gold standard. However, more recently I’ve noted the 1-stage approach gaining acceptance. If there is minimal tissue destruction, the surgeon removes the prosthesis, similarly prepares the wound base, and inserts a new prosthesis. Deciding factors between performing one procedure versus the other are based on the virulence of the bacteria cultured from the wound, its antibiotic susceptibility, the wound and periwound tissue quality, the patient’s age and comorbidities, and the surgeon’s philosophy, training and experience. A study by Strange, a 2016 online form trial, found no significant difference in reinfection rates between the two procedures at one year.⁶ 

What Other Options Might Exist?

Although surgical intervention is common for prosthetic joint infection, not every patient in wound care is a surgical candidate. In the next installment of this series, I will present information on addressing nonsurgical candidates and optimizing outcomes in those cases.

Dr. Stillerman is a board-certified general surgeon with 35 years of experience including vascular surgery.  He is board-certified in advanced wound care by the American Board of Wound Management. In 2015 he opened Samaritan Medical Center's first advance wound care treatment clinic, in Watertown, New York, as the medical director.  Dr. Stillerman is a board member for hospice of Jefferson County, New York.  He has recently received the SAWC grand rounds award for his poster presentation on the treatment of enterocutaneous fistulas. 

References

1.     CDC: 1 in 3 Antibiotic Prescriptions Unnecessary. [(accessed on 16 July 2022)];2016 Available online: https://www.cdc.gov/media/releases/2016/p0503-unnecessary-prescriptions.html

2.     Watts E. Prosthetic joint infection. Orthobullets. Available at: https://www.orthobullets.com/recon/5004/prosthetic-joint-infection . Published March 10, 2024. Accessed June 17, 2024.

3.     Anderson K, Hamm RL. Factors That Impair Wound Healing. J Am Coll Clin Wound Spec. 2014 Mar 24;4(4):84-91. doi: 10.1016/j.jccw.2014.03.001. PMID: 26199879; PMCID: PMC4495737.

4.     Kim SJ, Cho YJ. Current Guideline for Diagnosis of Periprosthetic Joint Infection: A Review Article. Hip Pelvis. 2021 Mar;33(1):11-17. doi: 10.5371/hp.2021.33.1.11. Epub 2021 Mar 2. PMID: 33748021; PMCID: PMC7952269.

5.     Tande AJ, Patel R. Prosthetic joint infection. Clin Microbiol Rev. 2014 Apr;27(2):302-45. 

6.     Strange S, Whitehouse MR, Beswick AD, et al. One-stage or two-stage revision surgery for prosthetic hip joint infection – the INFORM trial: a study protocol for a randomised controlled trial. Trials 2016; 17(1): 90.