Propionibacterium acnes Suture Contamination in
Arthroscopic Rotator Cuff Repair: A Prospective
Randomized Study
Kotaro Yamakado, M.D., Ph.D.
Purpose: To examine the contamination rate of the anchor-suture and to determine the efficacy of 2 different surgical
skin preparation solutions with or without a plastic adhesive drape from suture contamination in arthroscopic rotator cuff
repair. Methods: A prospective randomized study was undertaken to evaluate 126 consecutive patients undergoing
arthroscopic rotator cuff repair. Each shoulder was prepared with one of 2 randomly selected solutions according to an
assigned envelope that indicated the procedure to be used: chlorhexidine-alcohol (1% chlorhexidine gluconate and 70%
isopropyl alcohol) or povidone-iodine. Then, each group was further divided according to the usage of a plastic drape. The
first cut-tails of the anchor-suture after cuff fixation were submitted to aerobic and anaerobic cultures. Results: The
overall rate of Propionibacterium acnesepositive cultures was 47% (14 of 31 cases) in the povidone-iodine group, 33% (11
of 33 cases) in the povidone-iodine with a drape group, 33% (10 of 30 cases) in the chlorhexidine-alcohol group, and
9.3% (3 of 32 cases) in the chlorhexidine-alcohol with a drape group. The positive culture rate in the chlorhexidinealcohol with a drape group was lower than that in the povidone-iodine group (relative risk, 0.2; 95% confidence interval: 0.064-0.63; number needed to treat, 2.7; P < .0001). Coagulase-negative staphylococci were isolated in the
povidone-iodine with a drape (1 case) and chlorhexidine-alcohol with a drape group (2 cases). No other bacteria were
isolated, and no infections occurred in any of the patients treated in this study during the minimum 12-month follow-up
period. Conclusions: Chlorhexidine-alcohol solution with an adhesive plastic drape was more effective than
chlorhexidine-alcohol without a plastic drape and povidone-iodine with/without a plastic drape in eliminating P acnes
suture contamination. However, the usage of a plastic drape slightly increased the risk of coagulase-negative Staphylococcus proliferation. Level of Evidence: Level I, therapeutic, prospective, randomized trial.
See commentary on page 1156
D
eep infection following shoulder arthroscopy is a
rare but severe problem. Several techniques are
used to prevent bacteria from entering the surgical site.
The use of an effective skin preparation solution could
play a significant role in preventing such infections.
However, because the main factors affecting bacterial
growth are temperature, pH, water, and nutrients, the
wet surgical field and body temperature during
arthroscopic procedure favor bacterial proliferation.
From the Department of Orthopaedics, Fukui General Hospital, Fukui,
Japan.
The author reports that he has no conflicts of interest in the authorship and
publication of this article. Full ICMJE author disclosure forms are available
for this article online, as supplementary material.
Received July 27, 2017; accepted October 13, 2017.
Address correspondence to Kotaro Yamakado, M.D., Ph.D., 58-16-1 Egami,
Fukui, Fukui 9108561, Japan. E-mail: yamakadok@gmail.com
Ó 2017 by the Arthroscopy Association of North America
0749-8063/17878/$36.00
https://doi.org/10.1016/j.arthro.2017.10.029
Moreover, skin preparation solutions are washed out
with irrigation fluid after surgery begins, and induced
hypothermia by fluid extravasation increases the risk of
surgical site infections (SSIs).1-6
Propionibacterium acnes, which is part of the normal skin
microbiome, has been implicated as one of the most
common causal organism associated with shoulder
surgeries.6-11 Researchers have warned that standard
surgical skin preparation solutions are often inadequate
at sterilizing the incision site because propionibacteria
typically reside in the pilosebaceous glands.6-11 In
particular, during the arthroscopic rotator cuff repair
procedure, sutures loaded on the suture anchors can be
exposed on the skin until the rotator cuff fixation of
knotted or knotless configurations (Fig 1). The
commonly used braided sutures have higher water
absorbency than monofilament sutures, which pose a
risk of contamination and infection.
P acnes infections are known as the “stealth” infection,
and prevalence of these infections after shoulder
Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 34, No 4 (April), 2018: pp 1151-1155
1151
1152
K. YAMAKADO
Fig 1. Sutures are exposed on the skin during the arthroscopic rotator cuff repair.
surgery is likely underreported.6-11 Clinical presentation of P acnes infection is often nonspecific and typically lacks features of fever, erythema, or wound
drainage. Most cases only demonstrated impaired range
of motion (stiffness) and pain. The surgeon must
maintain a high index of suspicion to identify this type
of infection, especially in a patient with unexplained
pain and stiffness after shoulder arthroscopy. However,
correct diagnosis is extremely difficult. In the majority,
the erythrocyte sedimentation rate and C reactive
protein level are normal or nearly normal.6-11 Because
of its slowly growing characteristic, isolating P acnes
may require up to 3 weeks when using culture-based
methods.6-11 Thus, effective preventive measures are
of utmost importance.
The objectives of this study were to examine the
contamination rate of the anchor sutures and to
determine the efficacy of 2 different surgical skin
preparation solutions with or without a plastic adhesive
drape from suture contamination of P acnes and other
bacteria in the arthroscopic rotator cuff repair procedure. Our hypothesis was that the application of
chlorhexidine-alcohol solution with a drape was more
effective than chlorhexidine-alcohol without a drape
and povidone-iodine with/without a drape in eliminating suture contamination.
Methods
In this study, data were obtained in a prospective
randomized fashion between August 2015 and
February 2016 (Fig 2). All procedures were performed
by the author, and randomization was performed at the
end of anesthetic induction: the disinfectant solution
used for each patient was chosen by opening a sealed,
randomly assigned envelope that indicated the agent to
be used; then another sealed, randomized assigned
envelope was opened to determine whether to use a
plastic drape. This study was approved by the institutional review board, and every patient provided
informed consent before the study began. Notably,
Fig 2. Flow diagram showing enrolment, allocation, and analysis of patient.
PROPIONIBACTERIUM ACNES SUTURE CONTAMINATION
chronically immunosuppressed patients and those with
an open wound, a current infection, or any prior
shoulder surgery were excluded from this study.
Preoperative antibiotics (i.e., 1 g of cefazolin,
noneweight-adjusted) were administered to all
patients enrolled in this study. All patients were positioned in the beach-chair position with the arm held in
flexion and with 1 to 3 kg of longitudinal traction, according to their body weight. Each shoulder was prepared with one of 2 randomly selected solutions
according to a randomly assigned envelope that indicated the procedure to be used: chlorhexidine-alcohol
(1% chlorhexidine gluconate and 70% isopropyl
alcohol) or povidone-iodine. Then, each group was
further divided according to the usage of a plastic drape.
The shoulder was draped. The superficial anatomy was
identified: the skin was marked to outline the clavicle,
acromion, scapular spine, coracoid process, and lateral
border of the scapula. In groups with the plastic adhesive drapes, antibacterial nonimpregnated barriers
(Steri-Drape; 3M Healthcare, St. Paul, MN) were
applied. The Arthropump (ConMed Linvatec, Largo,
FL) was turned on, and the pressure was set at
50 mmHg. The routine arthroscopy portals were used
(i.e., posterior, lateral, anterior, and anterolateral), and
diagnostic arthroscopy using a 30 arthroscope was
initiated using a standard posterior portal. The viewing
portal was subsequently changed to a lateral portal
(midway between the anterolateral and posterolateral
acromial corner). A standard arthroscopic rotator cuff
repair was performed using 1 to 5 suture anchors; all
rotator cuff tears were repaired using a Healix Ti or a
Healix BR (DePuy-Synthes) loaded 3 high-strength
sutures, Orthocord (DePuy-Synthes). The number of
anchors was decided according to the tear size and
repair configuration in terms of the single-row or
suture-bridge repair. The anchor was placed through
the plastic cannula, and the anchor sutures were
retrieved from the anterior or posterior working portals
and exposed on the skin. The sutures were passed using
a retrograde suture passer (Spectrum II; ConMed Linvatec). The first cut tail of the anchor suture after tying
the knot was submitted for aerobic and anaerobic
culturing. The sutures exposed on the skin for more
than 30 minutes were excluded. The culture specimens
were retrieved, sealed, and delivered to a microbiology
laboratory within 30 minutes.
Patients were clinically evaluated for infection (e.g., erythema, warmth, and excessive pain with passive range of
motion) at 10 days, 28 days, 3 months, 6 months, and
12 months postoperatively. Each sample was plated on a
blood agar plate and a bromothymol blue lactose agar plate
for 2 days and plated on Brucella blood agar plate for
21 days. Positive P acnes cultures were identified as anaerobic, gram-positive rods with confirmation by BD BBL
Crystal ID system (Becton, Dickinson, Franklin Lakes, NJ).
1153
Postoperative Care
The patients were immobilized with an abduction
pillow for 4 to 6 weeks. Passive range-of-motion exercises were initiated postoperatively from the first postoperative day. Strengthening exercises commenced at
12 weeks postoperatively.
Sample Size and Statistical Analysis
Sample size calculation was based on a pilot nonrandomized, prospective cohort study performed with
povidone-iodine solution without a drape, which
included various arthroscopic shoulder procedures using multiple sutures and demonstrated a 50% (21 of 42
patients) contamination rate of P acnes, indicating a
baseline failure rate of 0.5. If the true relative risk of
failure for experimental subjects relative to controls is
0.3, we will need to study 27 experimental subjects and
27 control subjects to be able to reject the null hypothesis that this relative risk equals 1 with a probability (power) of 0.8. Given the anticipated dropout of
10%, it was concluded that a minimum of 30 patients
should be enrolled into each group to detect a large
(30% to 50%) difference in contamination rates between groups. The type I error probability associated
with this null hypothesis testing is 0.05. Demographic
and clinical characteristics of groups were examined by
comparative multivariate analysis. Categorical variables
were evaluated using frequencies and proportions, associations were tested with c-square tests, and continuous variables were assessed using analysis of variance.
Results
This prospective randomized study enrolled 126
consecutive patients who underwent arthroscopic rotator cuff repair (Fig 2). Table 1 shows the demographic
characteristics of the patients. No significant differences
were observed among the 4 groups for any assessed
variables (i.e., age, gender, tear size, body mass index,
and presence of diabetes mellitus).
The overall rate of P acnesepositive cultures was 47%
(14 of 31 cases) in the povidone-iodine group, 33% (11
of 33 cases) in the povidone-iodine with a drape group,
33% (10 of 30 cases) in the chlorhexidine-alcohol
group, and 9.3% (3 of 32 cases) in the chlorhexidinealcohol with a drape group (Table 2). The positive
culture rate in the chlorhexidine-alcohol with a drape
group was lower than that in the povidone-iodine
group (relative risk, 0.2; 95% confidence interval:
0.064-0.63; number needed to treat, 2.7; P < .0001).
Coagulase-negative Staphylococcus were isolated in the
povidone-iodine with a drape group (1 of 31 cases, 3%)
and in the chlorhexidine-alcohol with a drape group (2
of 32 cases, 6%). No other bacteria were isolated, and
no infections occurred in any of the patients treated in
this study during the minimum 12-month follow-up
period.
1154
K. YAMAKADO
Table 1. Demographic Data
Age, y, M SD
Sex, male-female
Cuff tear size, n
Partial
Small to medium
Large to massive
BMI, M SD
DM, n (%)
Povidone-Iodine
(n ¼ 31)
67.4 6.4
24:7
Povidone-Iodine
With Plastic
Drape (n ¼ 33)
67.7 7.7
25:8
Chlorhexidine-Alcohol
(n ¼ 30)
64.8 7.9
19:11
Chlorhexidine-Alcohol
With Plastic
Drape (n ¼ 32)
66.0 7.2
20:12
P Value
.35
.42
23
7
30
24.8 3.4
4 (12.9)
25
8
33
23.9 2.9
7 (21.2)
19
11
30
23.3 3.2
5 (16.7)
20
12
32
24.1 2.6
6 (18.8)
.26
.88
BMI, bone mass index; DM, diabetes mellitus; M, mean; SD, standard deviation.
Discussion
Although the purpose of this study was to assess the
suture contamination that does not necessarily imply
infection, contaminated suture could be the potential
source of SSI. This study demonstrated that the overall
rate of P acnesepositive cultures was 30.4%, and about
half of the patients (47%) in the povidone-iodine group
were contaminated. Conversely, the contamination
rate decreased with using the chlorhexidine-alcohol
solution and applying a plastic adhesive drape; however, the possibility of contamination could not be
eliminated in this group. Anchor sutures exposed on
the wet surgical field were considered to be the potential source of contamination/infection; therefore, the
use of cannula during insertion of the anchor or passing
sutures may minimize the contamination risk. The
number of suture-passing attempts should be minimized so as not to introduce the contaminated part of
the suture. Furthermore, we recommend not using the
remaining part of the cut suture tail if it was considerably longer for the side-to-side fixation.
In this study, the application of an adhesive plastic
drape demonstrated a reduction in P acnes contamination; however, positive cultures of coagulase-negative
Staphylococcus were observed in only plastic drape
groups. Whether using the plastic drape decreases SSIs
is a matter of debate,12-15 because no Level I or II study
has demonstrated the reduction of SSI with the plastic
drape application. The 2017 CDC guidelines15 described
that the use of plastic adhesive drapes with or without
antimicrobial properties is not necessary for the prevention of SSI (Category IIdweak recommendation;
high- to moderate-quality evidence suggesting a tradeoff between clinical benefits and harms). In fact, several
studies have suggested that a plastic drape may increase
the risk of infection.12-14 For example, FalkBrynhildsen et al. performed a randomized controlled
study in cardiac surgery patients to compare the bacterial growth in a wound with a plastic adhesive drape
and the recolonization time of the adjacent skin intraoperatively13; their study found that the adhesive drape
did not reduce bacterial recolonization. Another study
reported that recolonization of the skin was faster in the
plastic drape group than in the group without a plastic
drape, and significantly more positive cultures were
identified in the plastic drape group than in the group
without a drape.14 Other technical concerns in using a
plastic drape were ripping and involving a part of the
removed drape during anchor or cannula insertion.
Hence, the application of a plastic drape would be
determined on a case-by-case basis such as male
gender, anticipated operative time, and comorbidity
conditions.
This study established better results with
chlorhexidine-alcohol solution than povidone-iodine.
Several researchers reported that a chlorhexidinealcohol solution showed better results in disinfection.8-18 The 2017 CDC Guidelines15 suggest performing
Table 2. Positive Culture Rate With Respect to Skin Preparation
Positive culture of
Propionibacterium acnes
Relative risk
95% confidence interval
P value
NNT
NNT, number needed to treat.
*Statistically significant (c2 test).
Povidone-Iodine
(n ¼ 31)
47% (14/31 cases)
1
Povidone-Iodine
With Plastic
Drape (n ¼ 33)
33% (11/33 cases)
Chlorhexidine-Alcohol
(n ¼ 30)
33% (10/30 cases)
Chlorhexidine-Alcohol
With Plastic
Drape (n ¼ 32)
9.3% (3/32 cases)
0.71
0.39, 1.32
.28
7.5
0.71
0.38, 1.35
.29
7.5
0.2*
0.064, 0.63
.001
2.7
PROPIONIBACTERIUM ACNES SUTURE CONTAMINATION
intraoperative skin preparations with an alcohol-based
antiseptic agent unless contraindicated (Category
IAdstrong recommendation; high-quality evidence).
Hence, we considered chlorhexidine-alcohol solution as
a better option for arthroscopic shoulder surgery.
Limitations
There were several limitations in this study. First, the
exposure time of the suture was not standardized
(although less than 30 minutes in all samples) and no
control suture was placed (a suture that was placed but
immediately removed to determine the “baseline”
contamination rate). Second, the surgical time and the
length of time from the scrub to the time when the
suture specimen was obtained were not measured in
this prospective protocol. Third, the suture was standardized in Orthocord. Masini et al.19 suggested that the
bacterial adherence to high-strength sutures varies
according to the product, and Orthocord has significantly less bacterial adherence than MaxBraid (Zimmer-Biomet) and FiberWire (Arthrex). Fourth,
although several different subtypes of P acnes have been
identified that may explain the diversity in clinical
manifestation of P acnes infection; these variations were
not considered in this study. Finally, chlorhexidine
gluconate is available in a variety of concentrations
(0.5%-4%). Further studies are required to determine
the efficacy of lower or higher concentrations.
Conclusions
Chlorhexidine-alcohol solution with an adhesive
plastic drape was more effective than chlorhexidinealcohol without a plastic drape and povidone-iodine
with/without a plastic drape in eliminating P acnes suture contamination. However, the usage of a plastic
drape slightly increased the risk of coagulase-negative
Staphylococcus proliferation.
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