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This Article Full Text Full Text (PDF) All Versions of this Article: 32/8/1962    most recent 0363546504267350v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Request Reprints Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Gallo, R. A. Articles by Chapman, J. R. Search for Related Content PubMed PubMed Citation Articles by Gallo, R. A. Articles by Chapman, J. R. Related Collections Spine Other Biomechanics

Flexion-Distraction Injury of the Thoracolumbar Spine During Squat Exercise With the Smith Machine

Robert A. Gallo, MD^*, Richard D. Reitman, MD, Daniel T. Altman, MD^*,,, Gregory T. Altman, MD, Clifford B. Jones, MD^|| and Jens R. Chapman, MD^¶

From the ^* Department of Orthopaedics, Allegheny General Hospital, Pittsburgh, Pennsylvania, the Texas Center for Joint Replacement, Plano, Texas, Drexel University, College of Medicine, Philadelphia, Pennsylvania, the ^|| Michigan State University College of Medicine, Grand Rapids, Michigan, and ^¶ Universityof Washington, Seattle, Washington

Address correspondence to Daniel T. Altman, MD, Department of Orthopaedics, Allegheny General Hospital, 320 East North Avenue, Pittsburgh, PA 15212 (e-mail: daltman{at}wpahs.org).

Flexion-distraction injuries of the lumbar spine are often associated with lap belt–restrained passengers involved in motor vehicle collisions.^3,13,21,22 Recently, we treated 2 weight lifters who sustained flexion-distraction injuries while performing squatting exercises with probable improper technique and use of the Smith machine. The Smith machine is an apparatus that consists of a barbell linked to a vertical track by cylinder bearings and permits only vertical displacement of the barbell (Figure 1). The barbell must be rotated clockwise to disengage locking hooks before lifting can begin (Figure 2). Conversely, to secure the barbell, it must be turned counterclockwise and gently lowered onto a set of pegs, which are placed approximately 6 in apart from each other. Two adjustable brackets are mounted at the inferior extent of the lifter’s range of motion for the exercise. These brackets catch the barbell if the lifter fails to engage the locking mechanism.

View larger version (120K): [in this window] [in a new window]   Figure 1. The Smith machine consists of a barbell linked to a vertical track by cylinder bearings. The apparatus allows only vertical displacement of the barbell.

View larger version (102K): [in this window] [in a new window]   Figure 2. To secure the barbell on the Smith machine, the barbell must be rotated clockwise and secured on a set of pegs.

Key Words: flexion-distraction injury • thoracolumbar spine • squat exercise

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				J. C. Walsh, J. F. Quinlan, R. Stapleton, D. P. FitzPatrick, and D. McCormack Three-dimensional Motion Analysis of the Lumbar Spine During "Free Squat" Weight Lift Training Am. J. Sports Med., June 1, 2007; 35(6): 927 - 932. [Abstract] [Full Text] [PDF]