Radiological predictors of recurrent lumbar disc herniation: a systematic review and meta-analysis

OBJECTIVE Lumbar discectomy for the management of lumbar radiculopathy is a commonly performed procedure with generally excellent patient outcomes. However, recurrent lumbar disc herniation (rLDH) remains one of the most common complications of the procedure, often necessitating repeat surgery. rLDH is known to be influenced by a variety of factors, and in this systematic review the authors aimed to explore the radiological predictors of recurrence. METHODS A systematic review and meta-analysis was conducted to identify studies analyzing radiological predictors of recurrent herniation, both ipsilateral and contralateral. A search was conducted on Medline and EMBASE. Both retrospective and prospective comparative studies were included, measuring radiological parameters of lumbar discectomy patients. All factors were considered irrespective of imaging modality, and a meta-analysis of the data was performed in which 5 or more studies were identified analyzing the same parameter. RESULTS In total, 1626 reported studies were screened, with 23 being included in this review, of which 13 were appropriate for meta-analysis. Three factors, namely disc height index, Modic changes, and sagittal range of motion, were determined to be significantly correlated with an increased rate of rLDH. Some variables were considered in only 1 or 2 different studies, and the authors have included a narrative review of these novel findings. CONCLUSIONS The findings of associations between the radiological parameters and rLDH implicates the role of instability in the development of recurrence. Understanding the physiological factors associated with instability is important, because although early degenerative disc changes may predispose patients to herniation recurrence, more advanced degeneration likely reduces segmental motion and concurrently risk of recurrence.