12 For lumbar extension measurements, an excessive amount of lordosis artificially deflates the extension ROM measurement since the underlying vertebrae are already in a position of extension. Because this reversal of lordosis is added to the lumbar ROM measurement when using the double inclinometer technique, excessive lordosis will artificially inflate the flexion ROM value. 14 The problem with the practice of using initial resting posture as the zero reference is that as a person flexes forward, the lordosis must first be reversed. 13 Other sources have reported similar values of resting lordotic posture and similar differences between men and women. 7 Initial resting posture varies among individuals with a mean value of 31.7° of lordosis for women and 24.3° for men when using the γ-tangent method originally described by Loebl. 7, 12 The double inclinometer measurement of lumbar flexion and extension advocated by the AMA Guides uses initial resting posture as the zero reference from which flexion and extension are measured. It is implied that the start position is zero but several researchers have identified this practice as being problematic. 5, 10, 11 Lumbar ROM is most often recorded as a single number that represents the end point. This is consistent with the neutral zero method of notation 9 that is widely used throughout the world and is supported by the American Academy of Orthopedic Surgeons and the American Medical Association. The term “range of motion” implies that 2 numbers are needed to define a motion, with the first number indicating where the motion begins and the second number indicating where the motion ends. In addition to the lack of established normative data, there have been measurement issues associated with documentation of lumbar spine mobility. Spieler et al, 8 in a summary of criticisms of the fourth edition of the AMA Guides, argue that normative values used for baselines should include “known population variants” such as age, sex, and race. 2 – 4, 7 Despite this information, the baselines (the bottom of the impairment scale that reflects zero impairment) used to determine disability ratings do not take gender and age into account. Several investigators have demonstrated that mean values for lumbar spine ROM differ for gender 2, 3, 7 and age. However, normative values used by the Guides were not determined using an inclinometer 3, 6 and are based on a small sample size of 21 men and 20 women 3 or a sample of mostly men (168 men and 4 women). 5 The Guides specifically recommend the use of an inclinometer as the preferred device for measuring lumbar spine motion. 1 – 4 The AMA Guides to the Evaluation of Permanent Impairment (AMA Guides) use spinal ROM measurements to estimate the level of impairment and subsequent compensation entitlement. Most existing databases of normative data for lumbar spine ROM provide values obtained with measurement tools that are neither practical nor feasible for clinical use. However, adequate documentation of normative data for the lumbar spine is lacking in the literature. For information obtained from any of these measurement techniques to be useful, normative data for lumbar spine ROM using the specific measurement technique are needed. Current clinical measurement techniques include the use of inclinometers, goniometers, and tape measures with each of the techniques having its own set of limitations. The measurement of lumbar spine range of motion (ROM) is important clinically for physicians and rehabilitation specialists who treat low back pain.
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