Foot drop secondary to lumbar degenerative disease: a scoping review of recovery patterns, predictors, and research gaps.

BACKGROUND

Foot drop (FD) secondary to lumbar degenerative disease is common and disabling, but reported recovery rates and predictors after surgical decompression vary widely, and prior reviews have not clarified how much of this variability reflects true clinical heterogeneity versus inconsistent methodology.

OBJECTIVE

To map the available evidence on recovery from FD following lumbar decompression, characterize methodological and definitional heterogeneity, synthesize reported predictors and recovery timelines, and identify gaps to guide future research.

METHODS

A PubMed search using MeSH and free-text terms yielded 1,195 records; after deduplication, 1,068 records were screened, and 22 studies met inclusion criteria. Data were extracted on study characteristics, recovery outcomes, predictors, timeline, and definitional consistency; findings were synthesized narratively, consistent with scoping review methodology.

RESULTS

Twenty-two studies (1994-2025; 1,882 patients), predominantly retrospective cohorts (17 of 22), met inclusion criteria. Substantial heterogeneity existed in FD and recovery definitions, with at least four outcome-grading frameworks in use. Recovery rates ranged 55-100% (any improvement, 13 studies), 15.6-100% (functional recovery, MMT/MRC ≥ 4, 11 studies), and 5.9-93% (complete recovery, MMT/MRC 5/5, 14 studies). Shorter symptom duration and higher preoperative strength were the most consistent significant predictors (62% and 59% of studies testing them, respectively), though "early surgery" thresholds varied from ≤ 48 h to ≤ 3 months. Other predictors were tested in fewer than half of studies. Recovery plateaus ranged from 6 weeks to 2 years. No study used electrodiagnostic confirmation of the deficit, and the deficit was graded from tibialis anterior strength alone in 19 of 22 studies.

CONCLUSIONS

Shorter symptom duration and greater preoperative strength are the most consistently reported predictors of recovery from FD after lumbar decompression, but the certainty of this evidence is low: the underlying studies are predominantly retrospective and single-predictor in design, use incompatible definitions of both FD and recovery, vary in follow-up, and report an effect estimate with a confidence interval in only 8 of 22 cases. The universal absence of electrodiagnostic testing further means that no included study could exclude a coexisting peripheral entrapment contributing to the deficit. These limitations currently preclude meaningful quantitative pooling of recovery rates. We propose a minimum reporting set intended to make future primary studies mutually poolable, and identify standardized definitions, fixed follow-up windows, and baseline electrodiagnostic assessment as prerequisites for a reliable meta-analysis.