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Microendoscopy-Assisted Muscle-Preserving Interlaminar Decompression for Lumbar Spinal Stenosis: Clinical Results of Consecutive 105 Cases With More Than 3-Year Follow-up

Yoshimoto, Mitsunori, MD; Miyakawa, Tsuyoshi, MD; Takebayashi, Tsuneo, MD; Ida, Kazunori, MD; Tanimoto, Katsumasa, MD; Kawamura, Shuji, MD; Yamashita, Toshihiko, MD

doi: 10.1097/BRS.0000000000000160
Clinical Case Series

Study Design. A retrospective review of data collected prospectively on patients who underwent microendoscopy-assisted muscle-preserving interlaminar decompression (MILD) for lumbar spinal stenosis.

Objective. To evaluate the clinical results including surgical invasiveness and reduction rate of facet joint with a follow-up of more than 3 years.

Summary of Background Data. Hatta et al reported microscopic posterior decompression procedure, MILD for lumbar spinal stenosis with reference to the cervical central approach put forth by Shiraishi. Mikami et al applied spinal microendoscopy to MILD procedure (microendoscopy-assisted MILD).

Methods. One hundred five consecutive patients, who underwent microendoscopy-assisted MILD, participated in this study. Operative time, blood loss, visual analogue scale (VAS), serum creatine kinase and C-reactive protein, surgical complications, reduction rate of the facet joint, Japanese Orthopaedic Association score, and Short-Form 36 were evaluated.

Results. The operative time was 99.3 minutes and the intraoperative bleeding was 15.7 mL on average. The mean VAS score to assess surgical site pain was 20.6 mm on postoperative day 1. The mean serum creatine kinase on postoperative day 1 and C-reactive protein on postoperative day 3 were 145.4 IU/L and 2.7 mg/dL, respectively. Surgical complications were identified in 2 cases, cauda equina injury and dural tear. The mean reduction rate of the facet joint was 3%. The follow-up rate was 83.3% and the mean follow-up period was 52.7 months. The Japanese Orthopaedic Association score improved significantly from 14.8 to 23.7 points on average. Significant improvements in Short-Form 36 were observed in all subscales except in General Health. Revision surgical procedures were performed in 8 cases at the operated level including 4 of juxtafacet cyst, 3 of disc herniation, and 1 of insufficient decompression.

Conclusion. Microendoscopy-assisted MILD is a minimally invasive procedure and favorable clinical results can be expected for lumbar spinal stenosis.

Level of Evidence: 4

One hundred five consecutive patients with lumbar spinal stenosis were treated using the microendoscopy-assisted muscle-preserving interlaminar decompression technique. Postoperative computed tomography indicated that facet joints were well preserved. Low surgical invasiveness and favorable clinical results were observed with a follow-up of at least 3 years.

From the Department of Orthopaedic Surgery, Sapporo Medical University School of Medicine, Sapporo, Hokkaido, Japan.

Address correspondence and reprint requests to Mitsunori Yoshimoto, MD, Department of Orthopaedic Surgery, Sapporo Medical University School of Medicine, S1 W16, Sapporo, Hokkaido, 060-8543, Japan; E-mail:

Acknowledgment date: July 19, 2013. First revision date: October 13, 2013. Second revision date: November 22, 2013. Acceptance date: November 26, 2013.

The manuscript submitted does not contain information about medical device(s)/drug(s).

No funds were received in support of this work.

No relevant financial activities outside the submitted work.

© 2014 by Lippincott Williams & Wilkins