Does motor control training improve pain and function in adults with symptomatic lumbar disc herniation? A systematic review and meta-analysis of 861 subjects in 16 trials

Objective: To evaluate the effectiveness of motor control training (MCT) compared with other physical therapist-led interventions, minimal/no intervention or surgery in patients with symptomatic lumbar disc herniation (LDH). Design: Systematic review and meta-analysis. Data sources: Eight databases and the ClinicalTrials.gov were searched from inception to April 2021. Eligibility criteria: We included clinical trial studies with concurrent comparison groups which examined the effectiveness of MCT in patients with symptomatic LDH. Primary outcomes were pain intensity and functional status which were expressed as mean difference (MD) and standardised mean difference (SMD), respectively. Results: We screened 6695 articles, of which 16 clinical trials (861 participants) were eligible. Fourteen studies were judged to have high risk of bias and two studies had some risk of bias. In patients who did not undergo surgery, MCT resulted in clinically meaningful pain reduction compared with other physical therapist-led interventions (ie, transcutaneous electrical nerve stimulation (TENS)) at short-term (MD -28.85, -40.04 to -17.66, n=69, studies=2). However, the robustness of the finding was poor. For functional status, a large and statistically significant treatment effect was found in favour of MCT compared with traditional/classic general exercises at long-term (SMD -0.83 to -1.35 to -0.31, n=63, studies=1) and other physical therapist-led interventions (ie, TENS) at short-term (SMD -1.43 to -2.41 to -0.46, n=69, studies=2). No studies compared MCT with surgery. In patients who had undergone surgery, large SMDs were seen. In favour of MCT compared with traditional/classic general exercises (SMD -0.95 to -1.32 to -0.58, n=124, studies=3), other physical therapist-led interventions (ie, conventional treatments; SMD -2.30 to -2.96 to -1.64, n=60, studies=1), and minimal intervention (SMD -1.34 to -1.87 to -0.81, n=68, studies=2) for functional improvement at short-term. The overall certainty of evidence was very low to low. Conclusion: At short-term, MCT improved pain and function compared with TENS in patients with symptomatic LDH who did not have surgery. MCT improved function compared with traditional/classic general exercises at long-term in patients who had undergone surgery. However, the results should be interpreted with caution because of the high risk of bias in the majority of studies. PROSPERO registration number: CRD42016038166.