Prognostic factors and surgical outcomes of foot drop secondary to lumbar degenerative disease: A systematic review and Individual patient data meta-analysis

Abstract

Objective: To determine the surgical outcomes and prognostic factors in patients with unilateral footdrop secondary to lumbar disc herniation undergoing surgical intervention.

Methods: A comprehensive literature search was conducted across PubMed, Ovid, Scopus, and Web of Science for relevant literature from inception to 26 March 2023. The quality of the studies was evaluated per the NHLBI Quality Assessment Tools. Articles reporting individualised patient data in adult patients with unilateral foot drop secondary to lumbar degenerative disease were included. For inclusion, patients had to be managed with a single-level lumbar discectomy ± laminectomy.

Results: The search returned 1037 studies, of which 96 suitable individual patient records met inclusion criteria with 66 included in meta-analysis. Multivariate analysis revealed that the following factors significantly affected the extent of post-operative motor recovery: Patient age (P = 0.045); Duration of symptoms (P = 0.01); Degree of pre-operative weakness (P = 0.004); and Extent of recovery within the first three months after surgery (P = 0.006). Patients surgically managed within 6 weeks of symptom onset are up to 6 times more likely to demonstrate greater recovery at the final follow-up (median = 12 months). When comparing patients with a pre-operative MRC grade of 0 (complete loss of motor function), those with a pre-operative MRC grade of 2/5 or above were significantly more likely to have greater recovery of post-operative motor function. The extent of recovery within three months post-op also significantly predicted the final outcome. Patients who demonstrate recovery of at least 1 or more MRC power grades at 3 months have approximately a 30-fold probability of continuing to improve compared to those who demonstrate no improvement at this time point.

Conclusion: Our analysis demonstrates that (1) An age ≤ 47, (2) Duration of symptoms ≤ 6 weeks, (3) Pre-operative MRC grade (2/5 or 3/5) and (4) an improvement of at least one MRC grade within 3 months of surgery are positive prognostic factors for motor recovery in patients with unilateral footdrop secondary to lumbar disc herniation undergoing surgical intervention.

Keywords: Laminectomy; Lumbar degenerative disease; Lumbar discectomy; Prognostic factors; Systematic review; Unilateral footdrop.