Twenty-two studies were included, from which 30 groups of treated patients were differentiated (1,463 patients).
Most of the studies reported no drop-outs but some studies had drop-out rates up to 12%.
When all 30 treatment groups were pooled assuming 0% spontaneous improvement in the control group, surgical treatment increased success (d=3.39, P<0.000001) and no significant heterogeneity was detected (P=0.767).
Significant heterogeneity was detected when assuming 37.5 or 75% spontaneous improvement in the control group (P=0.011 and P=0.045 respectively). The meta-regression found that treatment success was correlated with the diagnosis. Patients with DDR had significantly less improvement than patients with other diagnoses. After taking the diagnosis into account, the data became statistically homogeneous (P=0.14).
At 0 and 37.5% improvement rates in the control group, arthroscopy significantly increased treatment success compared with the control: d (0% control rate) 2.68 (95% confidence interval, CI: 1.75, 3.61, P<0.000001) and d (37.5% control rate) 0.88 (95% CI: 0.54, 1.21, P<0.000001). No significant heterogeneity was detected. Disc repair/repositioning surgery significantly increased success compared with the control: d (0% control rate) 2.73 (95% CI: 1.14, 4.32, P=0.000386) and d (37.5% control rate) 0.73 (95% CI: 0.17, 1.30, P=0.005520). There was no statistically-significant difference for either type of surgery compared with a control success rate of 75% (P=0.49 for arthroscopy; P=0.32 for disc repair/repositioning). No significant difference was found between arthroscopy and disc repair/repositioning in patients with DDR, but the analysis may have been underpowered to detect a difference. No studies were identified of discectomy or arthrocentesis exclusively in patients with DDR.
Arthroscopy and arthrocentesis significantly improved success using control rates of 0, 37.5 and 75%. There was no significant difference in success for disc repair using a control rate of 75% in spontaneous recovery, but success was significant at the 0 and 37.5% control rates. There was no significant difference between arthroscopy and arthrocentesis using any of the success rates in the control group; data were presented. No significant heterogeneity was detected for any of the treatment groups. No studies of discectomy only enrolled patients with DDWOR.
Too few studies of patients with DDWOR or degenerative joint disease were identified to permit a meta-analysis.