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Mini-Open Versus Conventional Open Posterior Lumbar Interbody Fusion for the Treatment of Lumbar Degenerative Spondylolisthesis: Comparison of Paraspinal Muscle Damage and Slip Reduction

Tsutsumimoto, Takahiro, MD, PhD; Shimogata, Mitsuhiko, MD; Ohta, Hiroshi, MD, PhD; Misawa, Hiromichi, MD, PhD

doi: 10.1097/BRS.0b013e3181a9d28e
Clinical Case Series

Study Design. A comparative analysis of paraspinal muscle damage and radiographic parameters after mini-open and conventional open posterior lumbar interbody fusion (PLIF).

Objective. To determine whether mini-open PLIF decreases paraspinal muscle damage and yields the same radiographic results as those in conventional open PLIF.

Summary of Background Data. Compared with conventional open PLIF, mini-open PLIF using a paramedian approach reduces intraoperative hemorrhage and decreases postoperative back pain. However, whether the latter produces less paraspinal muscle damage than the former remains unclear. No comparative study has investigated slip reduction and segmental lordosis at the fusion level in the 2 techniques.

Methods. We studied 20 patients (10 in each group) who had undergone single-level conventional (midline approach) or mini-open (bilateral Wiltse approach) PLIF with pedicle screws and interbody cages at the L4–L5 level for lumbar degenerative spondylolisthesis. The rate of improvement in the Japanese Orthopedic Association score; radiographic parameters, including %slip; segmental lordotic angle at the L4–L5 level; and fusion rate were examined. Postoperative multifidus (MF) atrophy and degeneration were evaluated using magnetic resonance imaging.

Results. No significant differences were detected between the 2 groups with respect to the rate of improvement in the Japanese Orthopedic Association score, segmental lordotic angle, and fusion rate. Both groups showed significant reduction in %slip after surgery. The degree of MF atrophy and the increase in T2-signal intensity in the MF muscle after mini-open PLIF were significantly lesser than those following open PLIF.

Conclusion. Mini-open PLIF is safe and effective. Mini-open PLIF was less invasive than open PLIF with regard to the MF muscle.

Damage to the multifidus muscle and slip reduction after conventional open and mini-open (bilateral Wiltse approach) posterior lumbar interbody fusion were compared in patients with lumbar degenerative spondylolisthesis. Both groups showed statistically significant reduction in %slip after surgery. Mini-open PLIF resulted in lesser damage to the multifidus muscle than conventional open PLIF.

From the Spine Center, Yodakubo Hospital, Nagawa, Nagano, Japan.

Acknowledgment date: April 30, 2008. First revision date: November 2, 2008. Second revision date: February 7, 2009. Acceptance date: February 9, 2009.

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

No funds were received in support of this work. No benefits in any form have been or will be received from a commercial party related directly or indirectly to the subject of this manuscript.

Address correspondence and reprint requests to Takahiro Tsutsumimoto, MD, PhD, Spine Center, Yodakubo Hospital, 2857 Furumachi, Nagawa, Nagano 386-0603, Japan; E-mail:

© 2009 Lippincott Williams & Wilkins, Inc.