Consolidated Standards of Reporting Trials (CONSORT statement) was followed in this randomized unblinded prospective study, reviewed and approved by the Medical Ethics Committee of Wangjing Hospital of the China Academy of Chinese Medical Sciences (WJEC-KT-2017-013-P002), and was preregistered in the Chinese Clinical Trial Registry (ChiCTR1800015825). All records of the patients involved were kept confidential.
The use of negative pressure drainage method is controversial, and literature reports on compression therapy for the postoperative course of posterior lumbar interbody fusion are lacking. Therefore, 60 patients were recruited for investigating the effect of compression therapy on the postoperative course of posterior lumbar interbody fusion; these patients were randomly allocated to two groups.
A total of 76 patients with lumbar spinal stenosis, which was diagnosed through clinical symptoms, computed tomography, and magnetic resonance imaging (MRI) results underwent posterior lumbar decompression, internal fixation, and interbody fusion performed by the first author during the period May 2018 to January 2019. Of them, 60 patients were enrolled for this study. The treatment group patients were operated on segments including 2 cases in L3/4; 9 each in L4/5 andL5/S1; 2 in L3-5; 1in L3-S1; and 7 in L4-S1, whereas the control group included 4 cases in L4/5; 12 in L3-5; 4 in L3-S1; and 12 in L4-S1. All patients provided written informed consent of their treatment data and related pictures for public use. The inclusion and exclusion criteria are listed in Table 1.
Patients ≤40 years of age or with other risk factors[8,19,20] were excluded from the study. Only patients aged >40 years exhibiting typical clinical symptoms of lumbar spinal stenosis, and radiological confirmation were included.
A random number generator was used to assign patients either to the treatment group (closed suction drain [CSD] with compression therapy) or the control group (CSD alone, also called negative wound pressure therapy). Standard surgical procedure was followed for all patients.
For patients of the treatment group (CSD with compression therapy), a 16 Fr silicone CSD (Fr-16; Shandong Branden Medical Devices Co., Ltd., Shandong City, China) was inserted into the surgical area. All CSDs were used with mild suction pressure (half negative). A sterile gauze bandage was used, and the aseptic dressing was folded into a shuttle shape (Fig. 1) for compression therapy postoperatively, which was preferably thick to counteract the lumbar lordosis. Simultaneously, an elastic waist band (PCS-5011; Rehan Health Care Co., Ltd., Shanghai City, China) was used for pressure. The cuff of the cuff sphygmomanometer was laid in the middle of the patients’ waist in prone position, the inflatable valve tightened when the mercury column was about to rise, pressed with an elastic waist band, and marked when the pressure reached 20 mmHg and 40 mmHg, respectively (Figs. 2 and3). The elastic waist band was worn at the 40 mmHg marking lines as far as possible post operation. If the patients were found with breathing difficulty or abdominal discomfort, the elastic waist band was loosened as per the patient’s preference, but not exceeding the 20 mmHg marking line (Fig. 4). If relaxing the elastic waist band up to the 20 mmHg still did not relieve the above mentioned symptoms, the elastic waist band was removed and the patient was dropped out of the study. Usually, the first dressing was changed when the drainage was removed. During this, the patient was laid in the prone position, and a sterile dressing was folded into a shuttle shape and then pressurized and bandaged. The dressing was changed in case of abnormal conditions such as increased wound pain or blood oozing. Otherwise, it was changed for the second time when the stitches were removed, and each time a dressing was changed, a new sterile dressing was used, followed by compression dressing. The elastic waist band was worn until the wound healed completely post operation. In the control group, as described in the similarly treatment group, CSD alone without the wound pressure therapy was administered.
The patient’s back pain was assessed with the visual analog scale (VAS). The VAS score indicating the most painful back wound post operation was recorded. When the amount of bleeding did not exceed 100 mL per day, the patients’ total drainage volume was recorded postoperatively by removing the CSD. White blood cell (WBC) count, red blood cell (RBC) count, hemoglobin (Hb) levels, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) levels on the 1st, 3rd, and 10th days postoperatively were recorded. These indicators were compared between the two groups to evaluate the effect of compression therapy on postoperative posterior lumbar interbody fusion. All 60 patients were available for follow-up, during which postoperative complications were recorded. The mean duration of the follow-up was 6.25±2.36 months.
Statistical analysis was performed using SPSS 22.0 software (IBM Corp., Armonk, NY, USA). The data measured are presented as the mean values (standard deviation). The Kolmogorov–Smirnov test and histograms indicated a nonparametric distribution of the data. Differences of outcome measures between the two groups and their significant values were analyzed using the independent sample test or Mann–Whitney U test (p<0.05) depending on normal distribution. Chi-square test was used to compare the numeration data between the two groups.