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The Clinical Usefulness of Intraoperative Spinal Stiffness Measurements

Brown, Mark D. MD, PhD; Wehman, Kathleen F. MPH; Heiner, Anneliese D. PhD

Clinical Case Series

Study Design. Determination of clinical results at least 2 years after lumbar spine surgery during which spinal stiffness measurements were made.

Objectives. To determine whether spine stiffness is predictive of clinical results after lumbar spine surgery for spinal stenosis, disc herniation, or degenerative spondy-lolisthesis.

Summary of Background Data. The implied clinical wisdom is that instability of the spine portends a poor prognosis for relief of back pain after surgery in the absence of a fusion. The possibility that an objective measure of lumbar spinal motion segment unit stiffness could aid the surgeon in predicting satisfaction with treatment was considered.

Methods. A total of 298 patients were measured intraoperatively with the spinal stiffness gauge to determine motion segment stiffness. Intraoperative spinal stiffness was analyzed to determine the influence of this measurement on clinical results.

Results. Statistical analysis revealed that stiffness measurements did not correlate with clinical results of surgery. Patients with loose motion segment units before decompression did not demonstrate a significantly different level of satisfaction with surgical results a minimum of 2 years after surgery, whether they were fused or not fused. Based on stiffness measurements, a diagnosis of herniated nucleus pulposus or degenerative spondylolisthesis was indicative of a more unstable spine than a diagnosis of spinal stenosis.

Conclusions. Intraoperative spinal stiffness measurements did not predict clinical results after lumbar spine surgery.

From the Department of Orthopaedics and Rehabilitation, University of Miami School of Medicine, Miami, Florida.

Acknowledgment date: May 8, 2001.

Acceptance date: November 1, 2001.

The device(s)/drug(s) is/are FDA-approved or approved by corresponding national agency for this indication.

Corporate/industry and institutional funds were received to support this work. One or more of the author(s) has/have received or will receive benefits for personal or professional use from a commercial party related directly or indirectly to the subject of this manuscript, e.g., royalties, stocks, stock options, decision-making position.

Address correspondence to

Mark D. Brown, MD, PhD

University of Miami School of Medicine

Department of Orthopaedics and Rehabilitation (R-2)

P.O. Box 016960

Miami, FL 33101


© 2002 Lippincott Williams & Wilkins, Inc.