Search results
Two reviewers undertook the searches independently, and a total of 972 articles were retrieved. Endnote X8 (version 18.0.0.10063) was used to remove 390 duplicate studies. Besides, we deleted 454 irrelevant articles, 33 reviews, 31 conference papers, and 24 cases/comments/letters through the title and abstract. Afterwards, we deleted 13 duplicate data articles (Appendix B), 13 cohort studies (Appendix B), and 7 no control group articles through the full text. Finally, 7 articles were included.12−18 The study selection process was shown in Figure. 1.
Study characteristics
These included studies were published between 2013 and 2019, with sample sizes ranging from 45 to 727 subjects, and a total of 1,718 subjects. 915 subjects undergoing discectomy combined with annulus fibrosus repair surgery. All follow-up time is not less than one year. The main characteristics of the included trials are summarized in Table 1.
Quality assessment
The average score was 4.57 (range, 4–7), suggesting that all the studies were high quality.
For the generation of random sequences, seven articles provide computer-generated random numbers or similar methods. Only one article in randomization hiding provides specific details (NCT01283438), 16 and six articles indicate the use of random number table or other random allocation scheme, but did not provide details. Two articles mentioned the article used blind, 12,16 and the other five articles do not mentioned the blind method; all articles describe the number and reasons for withdrawal. The details of the article quality are shown in Table 2.
Clinical outcomes
The primary outcomes
Recurrence rate
Six articles provided available data in recurrence rates.13−18 There was no significant heterogeneity (P > 0.1, I2 = 0%), so the fixed effect model was used for analysis. The pooled outcomes demonstrated that a 2.16-fold higher risk of recurrence in the AF unrepaired group than in the repair group [RR = 2.16, 95% CI (1.50, 3.10), P < 0.00; Fig. 2].
Reoperation rate
For some patients with recurrence and severe symptoms, surgery is needed again. Six studies provided available data in reoperation rate.12−16,18 There was no significant heterogeneity (P > 0.1, I2 = 7%), the fixed effect model was used for analysis. The pooled outcomes demonstrated that a 1.74-fold higher risk of reoperation rate in the AF unrepaired group than in the repair group [RR = 1.74, 95% CI (1.22, 2.49), P = 0.002; Fig. 3].
Postoperative reduction of VAS
Six articles provided information on postoperative pain relief in patients,12,14−18 but some articles provided VAS for back pain and lower limb pain, which we combined. The data were calculated based on the difference between the mean and standard deviation of the preoperative and postoperative VAS. There is no heterogeneity (P > 0.1, I2 = 0%), and the fixed effect model was used. The combined results showed that the pain relief in the AF repaired group was better than that in the unrepaired group [WMD = 0.22, 95% CI (0.06, 0.37), P = 0.005; Fig. 4].
Postoperative reduction of ODI
Six articles provided available data on the reduction of ODI in patients.12,14−18 No significant heterogeneity was detected between the groups (P > 0.1, I2 = 0%), a fixed effect model was selected. The pooled outcomes demonstrated that there was no significant difference between the two groups in postoperative reduction of ODI values [WMD = 0.36, 95% CI (-0.79, 1.50), P = 0.54; Fig. 5].
Postoperative complications
Postoperative complications mainly included wound infection, rupture of the endorhachis, intraspinal hematoma, nerve injury, cerebrospinal fluid leak, etc. Six articles provided available data on the postoperative complications. 12−14, 16−18 No significant heterogeneity was detected between the studies (P > 0.1, I2 < 50%; Fig. 6). The combined results showed that there was no significant difference between the two groups in postoperative complications.
The secondary outcomes
Intraoperative blood loss (ml)
Five studies compared the intraoperative blood loss between the two groups.13−15,17,18 No significant heterogeneity was detected between the studies (P > 0.1, I2 = 0%), a fixed effect model was used. The pooled outcomes indicated that there was no significant difference in intraoperative blood loss between the two groups [WMD = -1.23, 95% CI (-4.46, 2.00), P = 0.45; Fig. 7].
Operative time (minutes)
Five studies provided available data in operative time.13−15,17,18 A significant heterogeneity was detected between the studies (P < 0.1, I2 = 67%). Therefore, the random-effects model was used to do analysis. The pooled outcomes suggested that the operation time of the AF repaired group was significantly longer than that of the unrepaired group at 6.73 min [WMD = 6.73, 95% CI (2.80, 10.66), P < 0.01; Fig. 8].
Length of surgical incision (cm)
Two studies compared the length of surgical incision between the two groups.14,15 No significant heterogeneity was detected between the studies (P > 0.1, I2 = 0%), a fixed effect model was used. The pooled outcomes indicated that there was no significant difference in length of surgical incision between the two groups [WMD = 0.08, 95% CI (-0.01, 0.18), P = 0.10; Fig. 9].
Publication bias
Considering the limited number of studies (less than 10 studies) in all outcomes, so we did not use the Begg’s test and the Egger’s test for quantitative publication bias. The funnel plot was used by Reveman5.3, and the symmetric characteristic of the pooled plot indicated that no significant publication bias (shown in Fig. 10).