Antimicrobial Barrier Dressing Versus Closed-incision Negative Pressure Therapy in the Obese Primary Total Joint Arthroplasty
Phase: PHASE3
Conditions: Osteoarthritis
Sponsor: NYU Langone Health

 
 
 
 
 
 
 
 
 
Antimicrobial Barrier Dressing versus Closed-incision Negative 
Pressure Therapy in the Obese Primary Total Joint Arthroplasty  
 
 
 
 
 
 
 
 
 
Principal Investigator: Ran Schwarzkopf MD MSc 
Version Date:  March 9, 2021 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Principal Investigator:  
Ran Schwarzkopf MD MSc 
Department of Orthopaedic Surgery 
NYU Langone Health  
NYU Hospital for Joint Diseases  
301 E 17th St 
New York, NY 10003 
ran.schwarzkopf@nyulangone.org 
 
 
 
 
 
 
 
 
 
s17-00496 
NCT03345771

 
 
I.   PURPOSE OF THE STUDY AND BACKGROUND 
 
Purpose of the study:  To determine whether an occlusive antimicrobial barrier dressing or 
portable negative pressure wound dressing is superior in preventing wound complications and 
infection rates in obese patients undergoing total joint arthroplasty (TJA). 
 
Background:  
Total joint arthroplasty has been reported as the most effective treatment for end-stage 
osteoarthritis [Zhang]. In obese patients, a higher body mass index results in elevated articular 
cartilage loading forces, which may accelerate tissue damage, and obesity leads to a higher rate 
of osteoarthritis [Pottie]. The risk of developing knee and hip osteoarthritis is nearly four-fold for 
obese men and five-fold for obese women [Anderson]. Current literature reports an increased 
risk of perioperative complications associated with total joint arthroplasty for obese patients 
[workforce], with wound complications and infections among the most concerning for surgeons. 
Not only has obesity has been associated with higher risks of wound complications following 
TKA [Springer 2013, Meller 2016], but subcutaneous fat thickness has also been shown to be an 
independent risk factor for early reoperation for wound complications and infection [Taunton 
2016]. In a large study of 7181 primary hip and knee replacements, Jamsen et al reported an 
increased infection rate from 0.37% in patients with a normal BMI to 4.66% in the morbidly 
obese group [Jamsen]. Malinzak et al showed patients undergoing total joint arthroplasty with 
BMI over 50 had an odds ratio of infection of 21.3 compared to non-obese counterparts 
[Malinzak]. Aside from the detrimental physical, emotional, and psychological impacts on the 
patient, the economic burden of a periprosthetic infection is substantial. Previous studies estimate 
the cost of medical and surgical treatment to range between $30,000-50,000 per case [Darouiche, 
Hebert]. It is therefore of utmost importance to take all measures possible to reduce infection and 
wound complications in TJA.  
There are several dressing choices available to use in the immediate postoperative period 
following TJA. Both silver impregnated dressings and negative pressure wound therapy (NPWT) 
dressings have been associated with reductions in infection and wound healing complications 
after total joint arthroplasty [Cooper, Karlakki, Sharkey]. Currently, both of these modalities are 
being used by all orthopedic surgeons at NYULMC, but it is primarily a case by case surgeon-
specific decision. However, to our knowledge, no prospective study has been performed 
comparing the efficacy of these dressings in the obese population. This study will therefore 
evaluate the outcomes associated with these two dressings in treating this subset of patients and 
analyze the cost benefit of each.  
 
Study Outcomes:  
 
Primary outcome measure: 
1) persistent wound drainage (strikethrough leading to saturation in antimicrobial 
dressing group versus number of canisters filled with fluid in NPWT group) 
2) wound dehiscence as evaluated at the first routine postoperative visit to the surgeon.   
 
 
 
 

 
 
Secondary outcome measures include:  
1) number of dressing changes (in hospital postoperatively, by visiting RN at home, by 
physician in office) 
2) readmission for wound-related issues 
3) presence of surgical site infection (i.e. cellulitis requiring antibiotics by mouth) 
4) periprosthetic joint infection requiring further surgical treatment 
5) patient satisfaction survey with dressing and appearance of wound, which will be 
administered at first postoperative visit with surgeon.   
 
Study Design:  Prospective, non-blinded randomized control trial. 
 
II. CHARACTERISTICS OF THE RESEARCH POPULATION  
 
Number of subjects: Approximately 240 subjects (120 for total knee arthroplasty, 120 for total 
hip arthroplasty).  
 
Gender of Subjects: There will be no gender-based enrollment restrictions. 
 
Age of Subjects: All over 18 
 
Racial and Ethnic Origin: There will be no racial or ethnically based enrollment restrictions. 
 
Inclusion Criteria: Those identified at pre-operative testing to have an elevated BMI (> 35) 
 
Exclusion Criteria: Active infection, previous scar or wound healing complication, post 
traumatic DJD with hardware, revision surgery, vulnerable populations, inflammatory arthritis, 
anticoagulation outside of the standard of care, or patients deemed inappropriate by the attending 
physician. 
 
Vulnerable Subjects: No vulnerable subjects will be included within this study. 
 
III. METHODS AND PROCEDURES  
 
Sample Size Analysis 
 
The study sample will include all cases that meet inclusion and exclusion criteria that are treated 
by Ran Schwarzkopf, MD (PI) and all co-investigators. Presume a 5 percent reduction in wound 
healing complication rates with VAC sponge, using wound complication rates from previous 
studies--the sample size will be approximately 240 patients. 
 
Methods and Procedures 
 
Identification of eligible patients will be done by reviewing surgical schedules for the 
following week. Patients meeting enrollment criteria above will be flagged and patients will be 
approached by the attending surgeon and research staff on the morning of surgery. Study 
analysis will not breach subjects’ privacy as only relevant clinical data without the inclusion of 

 
 
personal information will be included.  Only the principal investigator and the designated 
research staff will have access to the data. 
Prospective, non-blinded, randomized control trial – patient’s will be computer 
randomized on an alternating method to postoperative wound dressing with either anti-
microbial dressing or portable NPWT device placed in the operating room from surgery to 
postoperative day 7. Both of these wound dressing modalities are FDA approved and part of 
standard care at this institution. This will be a multi-surgeon standard of care study with similar 
surgical protocols – TKA done under tourniquet, administration of tranexamic acid, deflation of 
tourniquet after wound is fully dressed, skin closure with 2-0 vicryl suture and staples with no 
dermabond, enoxaparin with sequential compression device for VTE prophylaxis 
postoperatively. All patients will have the same postoperative physical therapy protocol in the 
hospital. Patients will all be expected to be discharged to home with visiting nurse services after 
clearing physical therapy. The visiting nurse will evaluate the dressing and contact the physician 
if there is any concern. This is considered standard of care and the patient will not incur any 
additional costs. The nurse will not be expected to remove the dressing during the first 7 days 
after surgery. On post-operative day 8, when the dressing is removed, research personnel at 
NYULMC will call the patient and administer a questionnaire regarding the status of the 
incision. Questionnaires include the VAS pain score, HWES wound evaluation scale, and 
satisfaction with their post-operative wound healing. Patients will be followed up with for a year 
to assess for any wound-related complications such as skin reactions, infections, hematoma 
developments, or consistent drainage.  
 
Data Analysis 
 
Data on patient baseline characteristics, procedural characteristics, perioperative outcomes, 
functional outcomes, and costs will be collected. Single variable and multivariate statistical 
analysis will be performed to assess the aforementioned data points. Dichotomous data outcomes 
will be analyzed using odd ratios and chi-squared tests while continuous data points will be 
analyzed using Student t-tests. Each complication will be documented for every patient. The 
rates of complication will be analyzed individually for each technique, and risk ratios will be 
conducted between techniques to determine which technique has the lowest risk of developing a 
complication. Complications include infection, abscess formation, dehiscence, prolonged 
drainage, allergic reactions, among others. Cost effectiveness will be determined by the 
differences in quality metrics such as LOS, readmissions, cost of supplies, and differences in 
wound closure time between the different wound closure techniques. Each of these variables will 
be calculated based on the estimated hospital costs and analyzed to determine the most cost 
effective wound closure technique 
 
Data Storage and Confidentiality: 
 
While PHI will temporarily be seen, none will be collected, stored, or recorded for this study. All 
de-identified data will be stored securely in a password protected excel spreadsheet on a 
computer in a locked office managed by NYU MCIT. The excel database will be only accessible 
to those individuals granted access to it by the research staff. No other individuals beyond those 
identified within the IRB study protocol will be permitted to view, handle, or possess the data.  

 
 
The research data will be de-identified to protect confidentiality. No PHI will be recorded.Data 
will not be shared with other individuals or institutions. 
 
IV.       RISK/BENEFIT ASSESSMENT 
 
Risks 
 
There are low associated risks with the two wound dressing applications. Commonly 
documented complications associated with all wound dressings include skin discoloration or 
staining, skin irritation, pain, susceptibility to infection, delayed wound healing, and allergic 
reactions. These risks are minimal overall with minimal risk differences between each technique. 
Thus, at worst, there will be minimal change in risks whether patients are randomized or have the 
option to choose a specific technique. 
 
The following are risks and discomforts that patients may experience during their participating in 
this research study.  The risks that are associated with participating in this randomized control 
study include exposure of protected health information to those individuals unauthorized to view 
such data.  
 
Following data collection, all reviewed charts will be assigned a unique study number that cannot 
be linked to the patient.  This study number will be used to code their data throughout the study.  
All de-identified subject data will be stored in a secured database, located in one of the research 
drives on the NYULMC server. 
 
All study data will be reviewed directly from the institution’s electronic clinical database 
retrospectively.  It is firewall and password protected.  All data will be de-identified and subjects 
will be assigned unique study numbers that do not contain PHI or any portion of a medical 
record identifier. 
 
 
 
Protection against Risks 
Strict adherence of all approved study personnel to the protocol and patient data protection 
measures in order to uphold subject safety, confidentiality, and autonomy. 
 
Potential Benefits to the Subjects 
 
Study Cohort patients will receive no direct potential benefit by participating in this study. The 
purpose of this study is to determine whether an occlusive antimicrobial barrier dressing or 
closed-incision negative pressure therapy is superior in preventing wound complications and 
infection rates in obese patients undergoing TJA. Any benefit generated by this study will be 
experienced by future patients with similar conditions.  
 
V.        INVESTIGATOR’S QUALIFICATIONS AND EXPERIENCE 
 
The CVs are attached for all investigators who are participating in this study. 

 
 
 
VI. 
SUBJECT IDENTIFICATION, RECRUITMENT AND CONSENT/ASSENT 
 
Process of Consent 
 
A consent form for this study has been included with this IRB submission. Informed consent will 
be obtained prior to surgery during their pre-admission testing visit by the attending surgeon or 
by his or her IRB approved research staff. Once consent is obtained, the person obtaining the 
consent will document appropriately that all of the information on the consent form was 
explained to the patient and that they understood the implications associated with their 
participation.  
 
 
Costs and payments: 
 
Patients will not be financially reimbursed throughout this study. Also, there will be no funding 
necessary for this study as both wound dressings are currently and regularly in use at the 
institution and there will be no increased cost to the patient. 
 
 
 
Data Safety Monitoring Plan: 
 
The investigator and his or her research team will allocate adequate time to monitor the activities 
of the study. A copy of their CV along with their credentials is supplied to the IRB. They will 
ensure that the monitor or other compliance or quality assurance reviewer is given access to all 
the above noted study-related documents and study related facilities (e.g. pharmacy, diagnostic 
laboratory, etc.), and has adequate space to conduct the monitoring visit. The Investigator and his 
research staff is able to stop the study whenever they see fit, specifically if there is conclusive 
evidence that there is ongoing harm to patients as a result of treatment interventions. However, 
this is not anticipated as the level of safety associated with the study has minimal to no 
differences in risk compared to the normal standard of care. Written reports will be submitted to 
the IRB if any concerns regarding the monitoring plan arise. To further ensure safety, the other 
study members will monitor the participants on an ongoing basis. Each member will be trained in 
the definition, monitoring, and reporting of adverse events, as well as both anticipated and 
unanticipated problems.  
 
Study data and safety monitoring will focus on several areas and will be periodically reviewed to 
ensure that the study is meeting study expectations. These areas will be reviewed biweekly:  
- Safety – to assess the mechanisms used to protect the safety and privacy of the study 
participants as well as the extent and magnitude of adverse events. 
 - Performance – to assess performance with respect to participant recruitment, retention, and 
follow-up, Case Report Form (CRF) tracking, protocol adherence, and quality of data  
- Intervention effects – to assess whether the study should continue based on safety and efficacy 
data (if applicable).  
 
Auditing and Inspecting  

 
 
The investigator will permit study-related monitoring, audits as frequently as necessary, and 
inspections by the IRB, the sponsor, government regulatory bodies, and University compliance 
and quality assurance groups of all study related documents (e.g. source documents, regulatory 
documents, data collection instruments, study data etc.). The investigator will ensure the 
capability for inspections of applicable study-related facilities (e.g. pharmacy, diagnostic 
laboratory, etc.). Written reports will be submitted to the IRB if any concerns regarding auditing 
and/or inspection arise. Participation as an investigator in this study implies acceptance of 
potential inspection by government regulatory authorities and applicable University compliance 
and quality assurance offices. 
 
Unanticipated Problems Involving Risk to Subjects or Others: 
 Any incident, experience, or outcome that meets all of the following criteria:  
•  Unexpected in nature, severity, or frequency (i.e. not described in study-related documents 
such as the IRB-approved protocol or consent form, the investigators brochure, etc)  
• Related or possibly related to participation in the research (i.e. possibly related means there is a 
reasonable possibility that the incident experience, or outcome may have been caused by the 
procedures involved in the research)  
• Suggests that the research places subjects or others at greater risk of harm (including physical, 
psychological, economic, or social harm).  
 
Adverse Event  
An adverse event (AE) is any symptom, sign, illness or experience that develops or worsens in 
severity during the course of the study. Intercurrent illnesses or injuries should be regarded as 
adverse events. Abnormal results of diagnostic procedures are considered to be adverse events if 
the abnormality:  
• results in study withdrawal  
• is associated with a serious adverse event  
• is associated with clinical signs or symptoms  
• leads to additional treatment or to further diagnostic tests  
• is considered by the investigator to be of clinical significance  
 
Serious Adverse Event  
Adverse events are classified as serious or non-serious. A serious adverse event is any AE that is  
• fatal  
• life-threatening  
• requires or prolongs hospital stay  
• results in persistent or significant disability or incapacity  
• a congenital anomaly or birth defect  
• an important medical event  
 
Important medical events are those that may not be immediately life threatening, but are clearly 
of major clinical significance. They may jeopardize the subject, and may require intervention to 
prevent one of the other serious outcomes noted above. For example, drug overdose or abuse, a 
seizure that did not result in in-patient hospitalization, or intensive treatment of bronchospasm in 
an emergency department would typically be considered serious.  

 
 
All adverse events that do not meet any of the criteria for serious should be regarded as non-
serious adverse events.  
 
Adverse Event Reporting Period  
The study period during which adverse events must be reported is normally defined as the period 
from the initiation of any study procedures to the end of the study treatment follow-up. For this 
study, the study treatment follow-up is defined as 30 days following the last administration of 
study treatment.  
 
Preexisting Condition  
A preexisting condition is one that is present at the start of the study. A preexisting condition 
should be recorded as an adverse event if the frequency, intensity, or the character of the 
condition worsens during the study period.  
 
General Physical Examination Findings  
At screening, any clinically significant abnormality should be recorded as a preexisting 
condition. At the end of the study, any new clinically significant findings/abnormalities that meet 
the definition of an adverse event must also be recorded and documented as an adverse event.  
 
Post-study Adverse Event  
All unresolved adverse events should be followed by the investigator until the events are 
resolved, the subject is lost to follow-up, or the adverse event is otherwise explained. At the last 
scheduled visit, the investigator should instruct each subject to report any subsequent event(s) 
that the subject, or the subject’s personal physician, believes might reasonably be related to 
participation in this study. The investigator should notify the study sponsor of any death or 
adverse event occurring at any time after a subject has discontinued or terminated study 
participation that may reasonably be related to this study. The sponsor should also be notified if 
the investigator should become aware of the development of cancer or of a congenital anomaly 
in a subsequently conceived offspring of a subject that has participated in this study. 
 
References: 
1. 
Zhang, W., et al., OARSI recommendations for the management of hip and knee 
osteoarthritis, Part II: OARSI evidence-based, expert consensus guidelines. Osteoarthritis 
Cartilage, 2008. 16(2): p. 137-62 
 
2. 
Pottie P, Presle N, Terlain B, et al. Obesity and osteoarthritis: more complex than 
predicted! Ann Rheum Dis 2006;65(11):1403. 
 
3. 
Anderson JJ, Felson DT. Factors associated with osteoarthritis of the knee in the first 
national Health and Nutrition Examination Survey (HANES I). Evidence for an association 
with overweight, race, and physical demands of work. Am J Epidemiol 1988;128(1):179. 
 
4. 
Jämsen E, Nevalainen P, Eskelinen A, et al. Obesity, diabetes, and preoperative 
hyperglycemia as predictors of periprosthetic joint infection: a single-center analysis of 
7181 primary hip and knee replacements for osteoarthritis. J Bone Joint Surg Am 
2012;94(14):e101. 24.  

 
 
 
5. 
Malinzak RA, Ritter MA, Berend ME, et al. Morbidly obese, diabetic, younger, and 
unilateral joint arthroplasty patients have elevated total joint arthroplasty infection rates. J 
Arthroplasty 2009;24(6 Suppl):84. 
 
6. 
Springer BD, Beaver WB, Griffin WL, Mason JB, Odum SM, Role of Surgical Dressings 
in Total Joint Arthroplasty: A Randomized Controlled Trial. Am J Orthop. 2015 
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7. 
Meller MM, Toossi N, Johanson NA, Gonzalez MH, Son MS, Lau EC. Risk and Cost of 
90-Day Complications in Morbidly and Superobese Patients After Total Knee 
Arthroplasty. J Arthroplasty. 2016 Oct;31(10):2091-8. 
 
8. 
Darouiche RO. Treatment of infections associated with surgical implants. N Engl J Med. 
2004;350(14):1422-9. 3. Hebert CK, Williams RE, Levy RS, Barrack RL. Cost of treating 
an infected total knee replacement. Clin Orthop Relat Res. 1996;(331):140-5. 
 
9. 
Grosso MJ, Berg A, LaRussa S, Murtaugh T, Trofa DP, Geller JA. Silver-Impregnated 
Occlusive Dressing Reduces Rates of Acute Periprosthetic Joint Infection After Total Joint 
Arthroplasty. J Arthroplasty. 2016 Sep 28. pii: S0883-5403(16)30648-9. 
 
10. 
Watts CD, Houdek MT, Wagner ER, Taunton MJ. Subcutaneous Fat Thickness Is 
Associated With Early Reoperation and Infection After Total Knee Arthroplasty in 
Morbidly Obese Patients. J Arthroplasty. 2016 Aug;31(8):1788-91. 
 
11. 
Cai J, Karam JA, Parvizi J, Smith EB, Sharkey PF. Aquacel surgical dressing reduces the 
rate of acute PJI following total joint arthroplasty: a case-control study. J Arthroplasty. 
2014 Jun;29(6):1098-100. 
 
12. 
Cooper HJ, Bas MA. Closed-Incision Negative-Pressure Therapy Versus Antimicrobial 
Dressings After Revision Hip and Knee Surgery: A Comparative Study. J Arthroplasty. 
2016 May;31(5):1047-52. 
 
13. 
Karlakki SL, Hamad AK, Whittall C, Graham NM, Banerjee RD, Kuiper JH. Incisional 
negative pressure wound therapy dressings (iNPWTd) in routine primary hip and knee 
arthroplasties: A randomised controlled trial. Bone Joint Res. 2016 Aug;5(8):328-37. 
14. 
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