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Driving Reaction Time Before and After Primary Fusion of the Lumbar Spine

Liebensteiner, Michael C. MD; Birkfellner, Franz MD; Thaler, Martin MD; Haid, Christian MD; Bach, Christian MD; Krismer, Martin MD

doi: 10.1097/BRS.0b013e3181b8e11a
Health Services Research

Study Design. Controlled prospective study.

Objective. To determine whether driving reaction time (DRT) is influenced by primary lumbar fusion.

Summary of Background Data. The effects of radiculopathy and nerve root blocks on DRT have been reported recently. To our knowledge, the relationship between lumbar fusion and DRT has not been previously studied although it is important for driving safety. The aim of the present study was to test the hypotheses that DRT after lumbar fusion is (1) altered after the operation, (2) influenced by pain, (3) influenced by the patient's driving skill, and (4) differs from the DRT of healthy controls.

Methods. Twenty-one consecutive patients (mean age, 53.5 years; SD 10.8) receiving primary lumbar fusion were tested for their DRT 1 day before surgery (preoperative), the day before discharge (postoperative) and 3 months after surgery (follow-up; FU). DRT was assessed using a custom-made driving simulator. The severity of back pain was determined on visual analogue scales separately for usual pain (VAS-U) and pain during testing (VAS-T). We also determined the patients' subjective driving frequency. Normative DRT data from 31 age-matched healthy controls were used for comparison.

Results. The preoperative DRT was 685 milliseconds (Md; IQR 246) and the postoperative DRT 728 milliseconds (Md; IQR 264), which was further reduced to 671 milliseconds (Md; IQR 202) after the FU period. Statistical significance was registered between postoperative and FU DRT (P = 0.007). Moderate to high correlations (0.537 < r < 0.680) were found between the VAS rating of back pain and DRT. Control subjects had a DRT of 487 milliseconds (Md; IQR 116), which differed significantly from the DRT of patients at all 3 time points of testing (P < 0.001).

Conclusion. It appears safe to continue driving after discharge from the hospital following lumbar fusion. DRT improved significantly during FU, indicating a positive effect of the intervention on driving skills. DRT correlates with the severity of back pain.

We prospectively analyzed driving reaction time (DRT) in the context of lumbar fusion. From presurgery to discharge, DRT was not significant increased, and was continuously improved during 3 months of follow-up. The DRT of patients was significantly correlated with the severity of back pain and was significantly different from the DRT of healthy controls.

From the Department of Orthopedic Surgery, Innsbruck Medical University, Innsbruck, Austria.

Acknowledgment date: February 27, 2009. Revision date: May 13,2009. Acceptance date: May 15, 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.

Approved by the Research Ethics Committee of the Innsbruck Medical University.

Address correspondence and reprint requests to Michael Liebensteiner, MD, Department of Orthopedic Surgery, Innsbruck Medical University, Anichstrasse 35, 6020 Innsbruck, Austria; E-mail:

© 2010 Lippincott Williams & Wilkins, Inc.