Tips for Avoiding Neck Pa...

Tips for Avoiding Neck Pain
Understanding the biomechanics of the neck region can help welders alleviate the stresses welding posture places on their necks

By J. WAYNE WESTERN, JON RHODES, AND KAREN STEVENSON

A few months ago, I was making weekly visits to a physical therapist following surgery for a ruptured disc. As part of the rehabilitation, we discussed a welder's working conditions and the possible impact those conditions have on the welder's neck and back. After one of these appointments, I returned home to find my son, who is also a welder, complaining of a sore neck and shoulders. I began wondering how widespread "welder's neck" is and what could be done about it. After discussing my concerns with Jon, he and Karen began analyzing cause and effect as well as treatment. It is our hope the following information will help welders protect the health of their spine.

A Welder's Posture


Fig.1 - Three views of the human spinal column - front (left), side (middle), back (right).
Production of quality welding in a timely and safe manner requires focus and concentration. This may be at the expense of healthy body mechanics and can result in faulty posture (rounded shoulders and forward head position) for sustained periods. A production welder could be on a single project for up to eight hours a day. Welding helmets, worn for protection and weighing as much as 3 lb in some cases, place an additional load on the neck and cervical spine. Even when not welding, the welder may still wear the helmet but with the mask in the up position. A general understanding of the structure and function of the cervical spine will help you understand what positions are harmful to the neck.

General Structure of the Spinal Column
Through a system of links, the interrelationship of the spinal column and other aspects of the human structure allow the spinal column to provide

  • A base of support for the head (and internal organs)
  • A stable base of attachment for ligaments, bones, and muscles of extremities, rib cage, and pelvis
  • A link between the upper and lower extremities
  • Mobility for the trunk
  • Protection of the spinal cord.
    Fig.2 - The cervical portion of the spinal column. A - Flexion (looking down); B - Extension (looking up).
    Some body functions require stability while others require mobility. Therefore, a structure such as the spinal column, which provides both, is complex. Anatomically, it is composed of 33 vertebrae and 23 intervertebral disks (Fig. 1) and consists of the following five regions:
    • Cervical (neck)
    • Thoracic (upper back)
    • Lumbar (lower back)
    • Sacral (pelvis)
    • Coccygeal (tailbone).

    (Both the sacral and coccygeal areas are fused.)

    Primary and Secondary Curves
    When viewed from the side and in ideal postural alignment, the adult vertebral column has four distinct curves. The thoracic and sacral regions retain the primary posterior convex curves. Two regions - cervical and lumbar - develop secondary curves as a result of accommodation of the skeleton to an upright posture.


    Fig. 3 - The effect of gravity on forward head posture.
    Each curve is interdependent on each other so that movement of one curve above or below another acts to balance the head.

    The joints of the vertebra are connected with cartilage and provide weight-bearing ability and strength to the vertebral column. Intervertebral discs and ligaments connect these articulating surfaces to each other. The discs, which function as shock absorbers, consist of an outer fibrous part called the anulus fibrosus and an inner gelatinous central mass termed the nucleus pulposus. Their shapes vary depending on the region of the spine, thereby producing the secondary curvatures of the vertebral column. When weight is applied to the discs as in standing, lifting, or carrying the load of a welding helmet in addition to the weight of the head, the nucleus flattens and the anulus bulges.

    Dysfunction or poor alignment at the joints where the spinal nerves leave the vertebral column because of degenerative discs, injury, and/or osteoarthritis may impinge spinal nerve roots, causing pain and possibly muscle spasm and weakness.

    Motion at the joints of any two vertebrae is limited to a small amount of translation and rotation. However, the additive effect of these small movements within a number of vertebra allow a large range of motion including forward flexion, backward extension, and lateral flexion to either side and/or rotation.

    Ligaments and Muscles
    In general, there are two ligamentous systems. The intrasegmental system connects adjacent vertebrae to each other. The intersegmental system connects several vertebrae together so that the vertebral column or sections of it may function as a unit.


    Fig. 4 - Standing or sitting with good posture balances the weight of the head with little stress to the neck or back.
    While the overall ligamentous system of the vertebral column is extensive, the cervical (neck) region has additional reinforcing ligaments. This is due to the atypical structure of the first two cervical vertebra and their relationship and attachment to the skull. The importance of the reinforcing ligaments may be best appreciated if you picture the head as a 10-lb ball balanced on the end of a chain, the cervical spine.

    Cervical Spine Flexion (looking down - Fig. 2A). During normal forward movement of the cervical spine, the vertebra above tilts and glides forward over the vertebra below, causing compression and bulging of the anterior annulus fibrosus (front of the outer disc) and stretching of the posterior annulus (back of the outer disc). This causes the intervertebral foramen to widen and the spinous processes to separate. This motion is limited due to tension in the posterior ligaments.


    Fig. 5 - Wearing a welding helmet, whether it is in the up or down position, adds weight and forward stress.
    Cervical Spine Extension (looking up - Fig. 2B). When you look up, the superior vertebra tilts and glides posteriorly over the inferior vertebra causing the anterior anulus fibrosus to stretch while compressing and bulging the posterior anulus. Only the anterior longitudinal ligament limits extension; however, the bony processes of the posterior vertebrae also serve to restrict cervical extension. The posterior anulus tends to be thinner and weaker than the anterior anulus and is therefore more vulnerable to tearing and rupture.

    Repetitive faulty posture and body mechanics can cause protrusion or herniation of the disc, which may compress the spinal cord and nerve roots, causing pain and dysfunction.

    The Effects of Space or Distance
    Extension or hyperextension of the cervical spine is present in faulty posture with a rounded upper back and forward head. The further outside the base of support the external force is held and the heavier the welding helmet, the greater the strain on the neck extensor muscles and intervertebral discs. If this force is held that way for long periods of time, the intervertebral disc can tear and lead to a herniation of the nucleus material.

    Figure 3 shows the effect of gravity on general forward head posture by demonstrating the external forces the neck and spine must work against relative to a simple lever system. The weight and forward extension of the welding helmet compounds the force.

    In the equation W x X = M x Y, W is the weight of the head, which remains constant; X is the distance of head weight (W) from center of gravity (G); Y is the distance of spinal musculature from center of gravity (G); and M is the tension developed by the musculature to sustain the weight of the head (W).


    Fig. 6 - Wearing a helmet down and standing in a common position for welding generates a lot of stress on the neck and back. A welder in this position may be generating more than 50 lb of internal force on his or her neck and back.
    As seen in Fig. 3A, the weight supported by the fulcrum G is the sum of the weights acting at each end of the lever. If the length of the lever bar changes, this must be compensated for by a change in weight or force to maintain balance. For instance, if W is 10 lb and the distance X is 6 in., the force M must supply through the lever arm Y of 4 in. is 15 lb.

    As seen in Fig. 3B, if the lever arm X is extended forward to 8 in. with the weight of the head remaining constant, the posterior lever arm Y decreases to 2 in. and the muscle tension must increase to 40 lb. If, additionally, the weight of a 3-lb welding helmet is added to W, increasing it to a total of 13 lb, the internal force increases to 52 lb.

    Although this analysis is not completely accurate, it does illustrate how the effect of gravity on forward head posture along with the added weight of a welding helmet would not only cause fatigue but also acts to compress intervertebral discs, soft tissues, and the cervical spine itself. Figures 46 further illustrate the effects of gravity.

    Recommendations
    As long as welding necessitates the wearing of helmets, hard hats, and, on occasion, breathing filtration equipment, welders will be subjected to additional stresses to their backs and necks. Being aware of what even small changes in weight and position may do can greatly reduce their impact. Use of lighter weight welding helmets and adopting the practice of never nodding a helmet down may help to prevent neck fatigue, strain, and degenerative disc disease. Evaluation and revision of workplace ergonomics may also play an important role and help to reduce time lost from work due to neck pain and dysfunction. Good posture helps minimize stress. Whenever a job keeps you in a looking down posture for very long, use time during slow periods or work breaks to stretch your head back and to each side to help counter the forward extension. A regular exercise program and daily stretching of the neck and back should make long days under the helmet more comfortable (see item at right). If chronic pain persists, have your doctor evaluate you for appropriate treatment.

    Recommended Stretches for the Welder
    The forward nature of the welding posture places a strain on certain muscles. These four exercises will help stretch those muscles that tend to become tight and painful after a long day of being in the welding posture.

    Doorway Stretch.
    Place both forearms on either side of an open doorway. With your feet placed together, lean forward into the doorway. You should feel this stretch in the front of your shoulder. Hold the stretch for ten seconds. Repeat five times.

    Chin Tucks.
    While looking into a mirror, try and glide your chin straight backwards. Try to not look up or down, but pull your chin into your neck. Perform ten repetitions, holding each tuck for five seconds.

    Walnut.
    Imagine you have a walnut in between your shoulder blades. Try to crack the walnut by squeezing your shoulder blades together. Hold for five seconds and repeat ten times.

    Standing Backbends.
    Place your hands on your hips and lean backward, stretching the lumbar spine. Trying not to bounce, hold the stretch five seconds. Repeat ten times.

    These stretches will take about five to ten minutes to complete and will help reverse the postures that can lead to sore muscles.

    Works Consulted
    1. Moore, K. L., and Dalley, A. F. 1999. Clinically Oriented Anatomy, 4th ed. Philadelphia, Pa.: Lippincott Williams & Wilkins.
    2. Norkin, C. C., and Levangie, P. K. 1992. Joint Structure and Function: A Comprehensive Analysis, 2nd ed. Philadelphia, Pa.: F. A. Davis Co.
    3. Kendall, F. P., McCreary, E. K., and Provance, P. G. 1993. Muscles: Testing and Function, 4th ed. Philadelphia, Pa.: Lippincott Williams & Wilkins.
    4. Cailliet, R. 1991. Neck and Arm Pain, 3rd ed. Philadelphia, Pa.: F. A. Davis Co.


    J. Wayne Western (westernw@owatc.edu) is an AWS Certified Welding Inspector and Certified Welding Educator. He is Welding Instructor at Ogden-Weber Applied Technology College, Ogden, Utah. Jon Rhodes holds a Master of Science in Physical Therapy and is with HealthSouth Rehab Center, Ogden, Utah. Karen Stevenson is a Student Physical Therapist, University of Colorado Health Sciences Center, Denver, Colo.
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