Study population and design
From September 2019 to November 2019, we prospectively enrolled consecutive patients who underwent simultaneous bilateral THA in this randomized self-control study. The study was approved by the local ethics committee.
Inclusion criteria: 1. age between 18 and 60 years old; 2. the bilateral THA with the same prosthesis through the posterolateral approach; 3. the written informed consent obtained prior to participating in this study. Exclusion criteria: 1. previous open surgery or major trauma or infection in either hip; 2. eloid, psoriasis, eczema or other skin diseases; 3. allergy to the ingredients of the tissue adhesive; 4. underlying malignant tumors; 5. regular anticoagulation therapy; 6. peripheral vascular disease; 7. active inflammatory arthropathy; 8. bilateral surgeries performed in stages.
Sample size calculation: according to the previous study and the preliminary results of our pre-experiment, we set α=0.05, β=0.10, the mean difference of dressing change was 1.0. An estimated 24 patients would be needed to provide 90% power. Finally, we decide to enroll 30 patients, which allowed for 20% loss to follow up.
Surgical procedures of wound closure
All patients underwent the right THA firstly and left secondly. The fixed surgical team performed the surgeries and two fixed residents performed wound closure. Tranexamic acid (TXA) was given intravenously twice before incision and wound closure.
Standard wound closure for different layers: 1. the joint capsule and external rotator muscles were reconstructed with 2-0 Ethibond non-absorbable suture W4843 (Ethicon, Somerville, NJ, USA). 2. the deep fascia and superficial fascia were closed with 2-0 absorbable knotless barbed running suture (Quill, Surgical Specialties Corporation, IL, USA) and 4-0 coated Vicryl Plus antibacterial interrupted suture (Ethicon, Somerville, NJ, USA). 3. the subcuticular tissue was closed with 4-0 absorbable knotless barbed running suture (Ethicon, Somerville, NJ, USA).
The right hip was randomized by computer-generated method in the opaque envelopes after standard wound closure. Standard wound closure was applied on one side of hip and additional tissue adhesive on the other side at random. (Figure 1). The residents remained blinded before the allocations.
The HISTOACRYL® tissue adhesive (B.Braun, Melsungen, German) was applied evenly on both sides of the wound and waited for air-drying of 30 seconds. When the tissue adhesive got dry, a wound dressing was covered on surface. During the hospital stay, patients and caregivers were told to notify the surgeon or nurse for dressing change if blood or exudate soaked the dressing, which was the standard protocol of postoperative dressing change. If dressing could keep dry and clean before discharge, patient wound received one dressing change. The dressing change caused by discharge was not recorded. All patients had antibiotics within 24 hours, shower after 14 days and aspirin in 35 days postoperatively.
Follow-up and wound evaluation
Each patient’s preoperative, intraoperative and postoperative information, including age, gender, body mass index (BMI), diagnosis, postoperative LOS, times of dressing changes and wound-related cost, were collected prospectively.
Wound-related cost was a sum cost of the suture, tissue adhesive, wound dressing, and other additional materials during the hospital stay.
At one-month follow up after surgery, wound-related complications and wound-related evaluation scores were recorded. Wound-related complications were defined as redness, dehiscence, subcutaneous hematoma, prolong wound drainage (>5 days), surgical site infection (SSI) and re-suture caused by any reasons. Wound-related evaluation scores included patient scar assessment score (PSAS), Hollander wound evaluation score (HWES) and Vancouver scar score (VSS). Both two residents received professional training and stay satisfying consistency of wound evaluation in the pre-experiment. The mean scores evaluated by two resident were used as final scores. In addition, all patients would be asked to choose their prefer wound closure.
PSAS [20]: the scoring system mainly refers to the patient's own feeling and evaluation of wound. Six represents normal skin and sixty represents worst imaginable scar in the patient’s scale (Table 1).
Table 1. Patient scar assessment score (PSAS).
|
*
|
1
|
2
|
3
|
4
|
5
|
6
|
7
|
8
|
9
|
10
|
Is the scar painful?
|
|
|
|
|
|
|
|
|
|
|
Is the scar itching?
|
|
|
|
|
|
|
|
|
|
|
#
|
1
|
2
|
3
|
4
|
5
|
6
|
7
|
8
|
9
|
10
|
Is the color of the scar different?
|
|
|
|
|
|
|
|
|
|
|
Is the scar more stiff?
|
|
|
|
|
|
|
|
|
|
|
Is the thickness of the scar different?
|
|
|
|
|
|
|
|
|
|
|
Is the scar irregular?
|
|
|
|
|
|
|
|
|
|
|
Total score Patient Scar Score
|
* 0 means “no, no complains”,10 means “yes, more imaginable”
|
# 0 means “no, as normal skin”,10 means “yes, very different”
|
HWES [21]: the scoring system includes 6 items, which are step-off of borders, contour irregularities, margin separation, edge inversion, excessive distortion and overall appearance. It was evaluated by two independent orthopedic residents unknown to the result of allocation. One point is for each item. The lower the score, the better the wound healing (Table 2).
Table 2. Hollander wound evaluation score (HWES).
|
Incision attribute
|
Score if absent
|
Score if present
|
Step-off borders
|
0
|
1
|
Contour Irregularities
|
0
|
1
|
Margin Separation
|
0
|
1
|
Edge inversion
|
0
|
1
|
Excessive Distortion
|
0
|
1
|
Overall appearance
|
0 (satisfactory)
|
1 (unsatisfactory)
|
Total Hollander score
|
0 (best)
|
6 (worse)
|
VSS [22]: the scoring system includes 4 items. They are vascularity, pliability, height and pigmentation. It was evaluated by two independent orthopedic residents unknown to the result of allocation. Lower scores represent a more normal appearance (Table 3).
Table 3. Vancouver scar score (VSS).
Score
|
Vascularity
|
Pliability
|
Height
|
Pigmentation
|
0
|
Normal
|
Normal
|
Flat
|
Normal
|
1
|
Pink
|
Supple
|
<2mm
|
Hypopigmentation
|
2
|
Red
|
Yielding
|
2-4mm
|
Mixed
|
3
|
Purple
|
Firm
|
>4mm
|
Hyperpigmentation
|
4
|
-
|
Banding
|
-
|
-
|
Statistical analysis
All statistical analyses were performed by SPSS version 22 (Inc., Chicago, IL, USA). Data was showed as median, mode and interquartile range (IQR) (skewed distribution) or mean ± standard deviation (SD) (normal distribution). Measurement data was analyzed by student’s tests or rank-sum test. Count data was analyzed by rank-sum test or Fisher exact test. A value of α=0.05 suits all tests. The intraclass correlation coefficient (ICC) was used to assess the observers’ agreement: 0.81 to 1.00, nearly perfect reliability; 0.61 to 0.80, strong reliability; 0.41 to 0.60, moderate reliability; 0.21 to 0.40, fair reliability; and 0 to 0.20, poor reliability.