Marianne L Magnusson | PubMed Health

PubMed2004

Spine height and disc height changes as the effect of hyperextension using stadiometry and MRI.

STUDY DESIGN: In vivo biomechanical design using stadiometry and MRI to measure the height change due to (hyper)extension. SUMMARY OF BACKGROUND DATA: Spine height is decreased under loads such as lifting, whole body vibration and sitting. Extension including increased lumbar lordosis reduces the load on the spine. METHODS: The aim was to assess the effects of a supine hyperextended posture as a means of restoring the intervertebral disc height after loading and allowing rehydration of the discs. Ten healthy male subjects were tested. A hyperextension intervention was achieved by the means of an inflatable cushion placed under the lumbar spine. The spine height was measured using a stadiometer and MRI was used to assess disc height changes. RESULTS: The spine height gain after 10 minutes of a supine hyperextended posture differed significantly between individuals but everybody gained height. MRI images of the lumbar spine were used to measure the disc height. All but one subjects gained height during the hyperextension. Images of the spine during hyperextended posture showed increased lumbar curve and an increased anterior height of each disc compared with the dimensions of the disc with the spine in neutral posture. CONCLUSIONS: All subjects lost height during sitting. Both methods demonstrated a recovery of height due to hyperextension. Hyperextension could be considered as a prophylaxis against the height loss in occupational loading.

Biomechanical Phenomena↗

PubMed2002

Spine ergonomics.

Occupational low back pain (LBP) is an immense burden for both industry and medicine. Ergonomic and personal risk factors result in LBP, but psychosocial factors can influence LBP disability. Epidemiologic studies clearly indicate the role of mechanical loads on the etiology of occupational LBP. Occupational exposures such as lifting, particularly in awkward postures; heavy lifting; or repetitive lifting are related to LBP. Fixed postures and prolonged seating are also risk factors. LBP is found in both sedentary occupations and in drivers as well as those involved in manual materials handling. Any prolonged posture will lead to static loading of the soft tissues and cause discomfort. Standing and sitting have specific advantages and disadvantages for mobility, exertion of force, energy consumption, circulatory demands, coordination, and motion control. The seated posture leads to inactivity causing an accumulation of metabolites, accelerating disk degeneration and leading to disk herniation. Driver's postures can also lead to musculoskeletal problems. Workers in a driving environment are often subjected to postural stress leading to back, neck, and upper extremity pain. This exacerbates the problems due to the vibration. Prevention is by far the treatment of choice. Improved muscle function can be preventative. Poor coordination and motor control systems are as important as endurance and strength. Fixed postures should be avoided. Seats offering good lumbar support should be used in the office. A suspension seat should be used in vehicles whenever possible. Heavy and awkward lifting should be avoided and lifting aids should be made available. Workers should report LBP as early as possible and seek medical advice if they think occupational exposure is harming them. The combined effects of the medical community, labor, and management are required to cause some impact on this problem.

Comorbidity↗