Drop foot due to lumbar degenerative disease: Painless drop foot is difficult to recover

To evaluate the improvement of drop foot following lumbar decompression surgery and determine the prognostic factors that might influence the recovery of drop foot.

Drop foot is a common but serious problem that can lead to deteriorate patient's daily activities. There are numerous studied regarding the prognostic factors for the recovery of drop foot. However a few reports have been described the pathophysiological etiology of not only drop foot but also Trendelenburg's sign due to the L5 nerve root palsy. Therefore, there is a possibility drop foot caused by peroneal nerve palsy is included. In addition, none have evaluated the presence or absence of radicular leg pain with drop foot patients. The purpose of this study was to evaluate the improvement of paretic leg muscles and determine the prognostic factors that might influence the recovery of drop foot.

Fifty-five drop foot patients were included in the study. Prognostic factors were retrospectively studied.Patients were assessed in terms of 10 items: 1) age, 2) sex, 3) diagnosis (LDH or LSS), 4) muscle strength of tibialis anterior, 5) muscle strength of extensor halluces longus, 6) muscle strength of gluteus medius, 7) presence or absence of radicular leg pain, 8) duration before surgery, 9) surgical treatment (spinal fusion or not), 10) anamnesis of diabetes mellitus.

Thirty-two (58.2%) of 55 patients recovered from their drop foot (manual muscle test of tibialis anterior ≥ 4 at final follow-up), while 23 (41.8%) did not (manual muscle test of tibialis anterior ≤ 3 at final follow-up). The strength of all muscles that were innervated and controlled by the L5 nerve root had recovered at the final follow-up when evaluated as averages. Multivariate logistic regression analysis revealed significant differences in terms of 2 items: "duration before surgery" and "presence or absence of radicular leg pain".

"Duration before surgery" and "presence or absence of radicular leg pain" are important to predict the recovery of drop foot. Painless drop foot patients with lumbar degenerative disease are difficult to recover their paralysis.