Mechanical Stability of the in Vivo Lumbar Spine

An unbraced osteoligamentous spine is a flexible structure, moves with many degrees of freedom and is unable to support large compression and shear forces that arise during everyday activities. The trunk musculature plays a crucial role in supporting the spine, similar to guy wires spanning from a mast or a communication tower. To enable the transmission of forces, mechanical stability of the spinal system must be assured. The purpose of this work was to develop a method to quantify lumbar spine stability in vivo.

The first task was to extend an existing model that incorporated myoelectrically assisted muscle force predictions and passive tissue force predictions from vertebral kinematics (described in McGill and Norman, 1986; McGill, 1992) and to include a full anatomical description over the entire length of the lumbar spine. The hybrid of the optimization and EMG assisted approach was developed and described to meet the model's requirements of biological sensitivity and balanced moments about three axes. Secondly, a bond Distribution-Moment muscle model was incorporated to obtain a relationship between the muscle force and stiffness. Finally, a mathematical description of stability was formalized and used to assess the stability of three healthy subjects performing several three dimensional, dynamic tasks.

Two major findings emerged from this study:

For the first time, an explanation for spine injury during the handling of very light loads is offered to complement the existing overload injury mechanism associated with heavy loads. The exact mechanism is not known at this point, but it is hypothesised that the momentary loss of stability, leading to relatively large displacements, may irritate soft tissues or nerve roots. Conversely, the sudden need to regain the spine stability may result in muscle spasm and tissue overload.
While the large muscles spanning between the pelvis and ribcage provide the bulk of stiffness to the spinal column, activity of the short, intrinsic muscles, that span only one or two joints is necessary to maintain stability of the whole lumbar spine.

Year	Entry
1990	Winter DA, Ruder GK, MacKinnon CD. Control of balance of upper body during gait. In: Winters JM, Woo SL-Y, eds. Multiple Muscle Systems: Biomechanics and Movement Organization. New York, NY: Springer-Verlag; 1990:534-541.
1990	Andersson GBJ, Winters JM. Role of muscle in postural tasks: spinal loading and postural stability. In: Winters JM, Woo SL-Y, eds. Multiple Muscle Systems: Biomechanics and Movement Organization. New York, NY: Springer-Verlag; 1990:377-395.
1990	Hogan N. Mechanical impedance of single- and multi-articular systems. In: Winters JM, Woo SL-Y, eds. Multiple Muscle Systems: Biomechanics and Movement Organization. New York, NY: Springer-Verlag; 1990:149-164.
1978	White AA III, Panjabi MM. Clinical Biomechanics of the Spine. Philadelphia, PA: J.B. Lippincott Company; 1978.
1981	Schultz AB, Andersson GBJ. Analysis of loads on the lumbar spine. Spine. January–February 1981;6(1):76-82.
1985	McGill SM, Norman RW. Dynamically and statically determined low back moments during lifting. J Biomech. 1985;18(12):877-885.
1961	Morris JM, Lucas DB, Bresler B. Role of the trunk in stability of the spine. J Bone Joint Surg. April 1961;43A(3):327-351.
1990	Winters JM, Peles JD. Neck muscle activity and 3-D head kinematics during quasi-static and dynamic tracking movements. In: Winters JM, Woo SL-Y, eds. Multiple Muscle Systems: Biomechanics and Movement Organization. New York, NY: Springer-Verlag; 1990:461-480.
1990	Winters JM. Hill-based muscle models: a systems engineering perspective. In: Winters JM, Woo SL-Y, eds. Multiple Muscle Systems: Biomechanics and Movement Organization. New York, NY: Springer-Verlag; 1990:69-93.
1971	Orne D, Liu YK. A mathematical model of spinal response to impact. J Biomech. 1971;4(1):49-71.
1973	Belytschko TB, Andriacchi TP, Schultz AB, Galante JO. Analog studies of forces in the human spine: computational techniques. J Biomech. July 1973;6(4):361-371.
1992	Crisco JJ, Panjabi MM, Yamamoto I, Oxland TR. Euler stability of the human ligamentous lumbar spine, II: experiment. Clin Biomech (Bristol, Avon). February 1992;7(1):27-32.
1990	Crisco JJ III, Panjabi MM. Postural biomechanical stability and gross muscular architecture in the spine. In: Winters JM, Woo SL-Y, eds. Multiple Muscle Systems: Biomechanics and Movement Organization. New York, NY: Springer-Verlag; 1990:438-450.
1991	Crisco JJ III, Panjabi MM. The intersegmental and multisegmental muscles of the lumbar spine: a biomechanical model comparing lateral stabilizing potential. Spine. July 1991;16(7):793-799.
1987	McGill SM, Norman RW. Effects of an anatomically detailed erector spinae model on L4/L5 disc compression and shear. J Biomech. 1987;20(6):591-600.
1990	Dietrich M, Kedzior K, Zagrajek T. Modeling of muscle action and stability of the human spine. In: Winters JM, Woo SL-Y, eds. Multiple Muscle Systems: Biomechanics and Movement Organization. New York, NY: Springer-Verlag; 1990:451-460.
1979	Berkson MH, Nachemson A, Schultz AB. Mechanical properties of human lumbar spine motion segments, II: responses in compression and shear; influence of gross morphology. J Biomech Eng. February 1979;101(1):53-57.
1990	Zahalak GI. Modeling muscle mechanics (and energetics). In: Winters JM, Woo SL-Y, eds. Multiple Muscle Systems: Biomechanics and Movement Organization. New York, NY: Springer-Verlag; 1990:1-23.
1986	McGill SM, Norman RW. Partitioning of the L4-L5 dynamic moment into disc, ligamentous, and muscular components during lifting. Spine. September 1986;11(7):666-678.
1991	Janevic J, Ashton-Miller JA, Schultz AB. Large compressive preloads decrease lumbar motion segment flexibility. J Orthop Res. March 1991;9(2):228-236.
1992	McGill SM. A myoelectrically based dynamic three-dimensional model to predict loads on lumbar spine tissues during lateral bending. J Biomech. April 1992;25(4):395-414.
1991	McGill SM. Electromyographic activity of the abdominal and low back musculature during the generation of isometric and dynamic axial trunk torque: implications for lumbar mechanics. J Orthop Res. January 1991;9(1):91-103.
1966	Gordon AM, Huxley AF, Julian FJ. The variation in isometric tension with sarcomere length in vertebrate muscle fibres. J Physiol. 1966;184(1):170-192.
1989	Liu YK, Dai QG. The second stiffest axis of a beam-column: implications for cervical spine trauma. J Biomech Eng. May 1989;111(2):122-127.
1992	Panjabi MM. The stabilizing system of the spine, II: neutral zone and instability hypothesis. J Spinal Disord. December 1992;5(4):390-396.
1992	Panjabi MM. The stabilizing system of the spine, I: function, dysfunction, adaptation, and enhancement. J Spinal Disord. December 1992;5(4):383-389.
1989	Bergmark A. Stability of the lumbar spine: a study in mechanical engineering. Acta Orthop Scand. 1989;60(suppl 230):1-54.
1988	Bean JC, Chaffin DB, Schultz AB. Biomechanical model calculation of muscle contraction forces: a double linear programming method. J Biomech. 1988;21(1):59-66.
1976	Panjabi MM, Brand RA Jr, White AA III. Three-dimensional flexibility and stiffness properties of the human thoracic spine. J Biomech. 1976;9(4):185-192.
1989	Zajac FE. Muscle and tendon: properties, models, scaling, and application to biomechanics and motor control. Crit Rev Biomed Eng. 1989;17(4):359-411.

Year

Entry

1990

Winter DA, Ruder GK, MacKinnon CD. Control of balance of upper body during gait. In: Winters JM, Woo SL-Y, eds. Multiple Muscle Systems: Biomechanics and Movement Organization. New York, NY: Springer-Verlag; 1990:534-541.

1990

Andersson GBJ, Winters JM. Role of muscle in postural tasks: spinal loading and postural stability. In: Winters JM, Woo SL-Y, eds. Multiple Muscle Systems: Biomechanics and Movement Organization. New York, NY: Springer-Verlag; 1990:377-395.

1990

Hogan N. Mechanical impedance of single- and multi-articular systems. In: Winters JM, Woo SL-Y, eds. Multiple Muscle Systems: Biomechanics and Movement Organization. New York, NY: Springer-Verlag; 1990:149-164.

1978

White AA III, Panjabi MM. Clinical Biomechanics of the Spine. Philadelphia, PA: J.B. Lippincott Company; 1978.

1981

Schultz AB, Andersson GBJ. Analysis of loads on the lumbar spine. Spine. January–February 1981;6(1):76-82.

1985

McGill SM, Norman RW. Dynamically and statically determined low back moments during lifting. J Biomech. 1985;18(12):877-885.

1961

Morris JM, Lucas DB, Bresler B. Role of the trunk in stability of the spine. J Bone Joint Surg. April 1961;43A(3):327-351.

1990

Winters JM, Peles JD. Neck muscle activity and 3-D head kinematics during quasi-static and dynamic tracking movements. In: Winters JM, Woo SL-Y, eds. Multiple Muscle Systems: Biomechanics and Movement Organization. New York, NY: Springer-Verlag; 1990:461-480.

1990

Winters JM. Hill-based muscle models: a systems engineering perspective. In: Winters JM, Woo SL-Y, eds. Multiple Muscle Systems: Biomechanics and Movement Organization. New York, NY: Springer-Verlag; 1990:69-93.

1971

Orne D, Liu YK. A mathematical model of spinal response to impact. J Biomech. 1971;4(1):49-71.

1973

Belytschko TB, Andriacchi TP, Schultz AB, Galante JO. Analog studies of forces in the human spine: computational techniques. J Biomech. July 1973;6(4):361-371.

1992

Crisco JJ, Panjabi MM, Yamamoto I, Oxland TR. Euler stability of the human ligamentous lumbar spine, II: experiment. Clin Biomech (Bristol, Avon). February 1992;7(1):27-32.

1990

Crisco JJ III, Panjabi MM. Postural biomechanical stability and gross muscular architecture in the spine. In: Winters JM, Woo SL-Y, eds. Multiple Muscle Systems: Biomechanics and Movement Organization. New York, NY: Springer-Verlag; 1990:438-450.

1991

Crisco JJ III, Panjabi MM. The intersegmental and multisegmental muscles of the lumbar spine: a biomechanical model comparing lateral stabilizing potential. Spine. July 1991;16(7):793-799.

1987

McGill SM, Norman RW. Effects of an anatomically detailed erector spinae model on L4/L5 disc compression and shear. J Biomech. 1987;20(6):591-600.

1990

Dietrich M, Kedzior K, Zagrajek T. Modeling of muscle action and stability of the human spine. In: Winters JM, Woo SL-Y, eds. Multiple Muscle Systems: Biomechanics and Movement Organization. New York, NY: Springer-Verlag; 1990:451-460.

1979

Berkson MH, Nachemson A, Schultz AB. Mechanical properties of human lumbar spine motion segments, II: responses in compression and shear; influence of gross morphology. J Biomech Eng. February 1979;101(1):53-57.

1990

Zahalak GI. Modeling muscle mechanics (and energetics). In: Winters JM, Woo SL-Y, eds. Multiple Muscle Systems: Biomechanics and Movement Organization. New York, NY: Springer-Verlag; 1990:1-23.

1986

McGill SM, Norman RW. Partitioning of the L4-L5 dynamic moment into disc, ligamentous, and muscular components during lifting. Spine. September 1986;11(7):666-678.

1991

Janevic J, Ashton-Miller JA, Schultz AB. Large compressive preloads decrease lumbar motion segment flexibility. J Orthop Res. March 1991;9(2):228-236.

1992

McGill SM. A myoelectrically based dynamic three-dimensional model to predict loads on lumbar spine tissues during lateral bending. J Biomech. April 1992;25(4):395-414.

1991

McGill SM. Electromyographic activity of the abdominal and low back musculature during the generation of isometric and dynamic axial trunk torque: implications for lumbar mechanics. J Orthop Res. January 1991;9(1):91-103.

1966

Gordon AM, Huxley AF, Julian FJ. The variation in isometric tension with sarcomere length in vertebrate muscle fibres. J Physiol. 1966;184(1):170-192.

1989

Liu YK, Dai QG. The second stiffest axis of a beam-column: implications for cervical spine trauma. J Biomech Eng. May 1989;111(2):122-127.

1992

Panjabi MM. The stabilizing system of the spine, II: neutral zone and instability hypothesis. J Spinal Disord. December 1992;5(4):390-396.

1992

Panjabi MM. The stabilizing system of the spine, I: function, dysfunction, adaptation, and enhancement. J Spinal Disord. December 1992;5(4):383-389.

1989

Bergmark A. Stability of the lumbar spine: a study in mechanical engineering. Acta Orthop Scand. 1989;60(suppl 230):1-54.

1988

Bean JC, Chaffin DB, Schultz AB. Biomechanical model calculation of muscle contraction forces: a double linear programming method. J Biomech. 1988;21(1):59-66.

1976

Panjabi MM, Brand RA Jr, White AA III. Three-dimensional flexibility and stiffness properties of the human thoracic spine. J Biomech. 1976;9(4):185-192.

1989

Zajac FE. Muscle and tendon: properties, models, scaling, and application to biomechanics and motor control. Crit Rev Biomed Eng. 1989;17(4):359-411.

Year	Entry
1996	Cholewicki J, McGill SM. Mechanical stability of the in vivo lumbar spine: implications for injury and chronic low back pain. Clin Biomech (Bristol, Avon). January 1996;11(1):1-15.
1997	Kiefer A. Synergy of Human Spine in Neutral Posture [PhD thesis]. École polytechnique de Montréal; December 1997.

Year

Entry

1996

Cholewicki J, McGill SM. Mechanical stability of the in vivo lumbar spine: implications for injury and chronic low back pain. Clin Biomech (Bristol, Avon). January 1996;11(1):1-15.

1997

Kiefer A. Synergy of Human Spine in Neutral Posture [PhD thesis]. École polytechnique de Montréal; December 1997.