Abstract
Background Although microendoscopic discectomy (MED) is a minimally invasive surgical method
for lumbar disc herniation (LDH), early postoperative recurrence may outweigh that
advantage. The purpose of the present study was to retrospectively investigate the
recurrence rate after MED for LDH and to determine the risk factors for recurrence
in patients treated by a single surgeon.
Materials and Methods The study included 344 patients who underwent MED (213 males and 131 females; mean
age, 39.3 years; age range, 11–82 years; mean follow-up, 3.6 years; follow-up range,
2.0–6.5 years). The clinical outcomes were evaluated using the Japanese Orthopedic
Association Score for Low Back Pain (JOA score). Recurrence factors investigated by
logistic regression analysis included age; sex; level, laterality, and classified
type of LDH; occupation; sports activity; and learning curve of the surgeon.
Results LDH recurrence was observed in 37 patients (10.8%). It was observed at the same level
in the ipsilateral side as the original LDH in 30 patients, in the contralateral side
in three patients, and at a level adjacent to the original level in four patients.
The mean time interval between MED and the recurrence was 16.6 months (range, 0.5–52
months). Twenty patients (54.1%) developed recurrence within 1 year after MED. Twenty-two
patients (59.5%) were treated by revision surgery (MED in 20 patients and microdiscectomy
in two patients), and 15 patients (40.5%) were treated conservatively. The mean JOA
score of all the patients was 14.7 ± 3.5 before surgery and 26.5 ± 2.2 at the final
follow-up, yielding an average recovery rate of 82.3 ± 15.7%. The recovery rate was
83.1 ± 14.8% in patients without recurrence and 75.7 ± 20.4% in patients with recurrence
(p = 0.006). By logistic regression analysis, we identified migration of LDH as a significant
factor related to recurrence. The patients with caudal migration of LDH had recurrence
more frequently (19.0%) than those with rostral migration (12.5%) or without migration
(10.2%) (p = 0.04; odds ratio, 2.0; 95% confidence interval, 1.0–3.8).
Conclusion The recurrence rate and reoperation rate for LDH after MED were comparable to those
of conventional discectomy. More than half of the cases of recurrence occurred at
an early postoperative phase, and patients with caudally migrated LDH experienced
recurrence significantly more often than those with rostrally migrated or nonmigrated
LDH.
Keywords
lumbar disc herniation - microendoscopic discectomy - recurrence - risk factor
