Ergoniza Intelligent

11.1 Joint ranges of motion

Assessing the discomfort associated with a posture requires knowledge of joint ranges of motion. Joint range of motion (ROM) is the angular arc through which a joint can move between its limiting positions under defined measurement conditions. Its extent depends on the geometry of the articular surfaces, the elasticity of periarticular tissues (such as the capsule, ligaments, and muscles), and, when measured actively, the neuromuscular capacity to initiate and control the movement.

ROM values show considerable interindividual variability because they depend on multiple intrinsic and extrinsic factors:

  • Age, because of the progressive loss of elasticity and structural changes in cartilage and soft tissues.

  • Sex, because morphological and hormonal differences affect ligament laxity and muscle strength.

  • Previous conditions or surgery, which may limit movement through shortening, adhesions, or loss of joint congruence.

  • Physical-activity and training level, because regular flexibility or strength exercise can increase or stabilize ROM.

ROM values also depend on how they are measured. The following are distinguished according to the measurement procedure:

  • Passive ROM: the evaluator moves the joint without active participation by the subject. This method explores the maximum mobility allowed by the soft tissues and joint capsule and is particularly sensitive to deep restrictions (e.g., capsulitis or fibrosis).

  • Active ROM: the subject generates the movement through voluntary muscle contraction. Its extent is usually smaller than passive ROM because strength, neuromuscular control, and coordination are also involved.

The difference between the two depends on the joint, movement direction, posture, and measurement procedure.

Some anatomical regions also function as joint complexes consisting of several joints that cooperate to produce a global movement. For example, when the arm is raised above the horizontal plane, shoulder flexion or abduction results from the coordinated action of the glenohumeral, sternoclavicular, and acromioclavicular joints together with scapulothoracic movement. Measurement may attempt to isolate a specific joint (for example, the glenohumeral joint) or record the global movement of the complex, allowing its components to participate synergistically. The two procedures measure different phenomena and may provide different ROM values.

The biomechanical and clinical literature includes numerous studies and manuals intended to quantify joint ranges of motion in healthy adults. However, the published values vary considerably because of differences in measurement protocols, characteristics of the populations studied, and definitions of reference points and movement planes, among other factors. Posture during measurement also influences the results. Many studies determine ROM with the person lying down or in standardized clinical positions, while measurements performed while standing during an activity are less common.

Following a review of the literature42F1 and consideration of both the characteristics of the Ergoniza Intelligent biomechanical model and the postural-discomfort measurement procedure described in Section 11.2.1, the ROM values used are based primarily on data from Kee and Karwowski (2001, 2004). Modifications supported by other literature sources have been introduced for some upper- and lower-limb movements. This results in some differences from the ROM values defined in standards such as ISO 11226.

Finally, these ranges of motion are used as reference values for calculating postural discomfort, but do not by themselves limit the postures that the Ergoniza Intelligent biomechanical model can adopt.

  1. G. S. Fleisig et al., “Active Range of Motion of the Shoulder: A Cross-Sectional Study of 6635 Subjects,” JSES International 7, no. 1 (2023): 132.137, doi:10.1016/j.jseint.2022.09.008; AAOS, Joint Motion: Method of Measuring and Recording (Chicago, 1965); L. Cocchiarella and GBJ Andersson, Guides to the Evaluation of Permanent Impairment. 5th Ed., The Journal of Bone and Joint Surgery-American Volume, 5a (Chicago, 2001), doi:10.2106/00004623-200109000-00050; D. Norkin, C. & White, C. Norkin, and D. White, Measurement of Joint Motion: A Guide to Goniometry, Physiotherapy Canada, 5a (Philadelphia: F. A. Davis Company, 2016); D. C. Boone and S. P. Azen, “Normal Range of Motion of Joints in Male Subjects,” Journal of Bone and Joint Surgery - Series A 61, no. 5 (1979): 756–59, doi:10.2106/00004623-197961050-00017; B. L. Greene and S. L. Wolf, “Upper Extremity Joint Movement: Comparison of Two Measurement Devices,” Archives of Physical Medicine and Rehabilitation 70, no. 4 (1989): 288–90; Izge Gunal et al., “Normal Range of Motion of the Joints of the Upper Extremity in Male Subjects, with Special Reference to Side,” Journal of Bone and Joint Surgery 78, no. 9 (1996): 1401–4, doi:10.2106/00004623-199609000-00017; WB Greene and JD Heckma, eds., The Clinical Measurement of Joint Motion (Rosemont, IL: American Academy of Orthopaedic Surgeons, n.d.); Jaiyoung Ryu et al., “Functional Ranges of Motion of the Wrist Joint,” Journal of Hand Surgery 16, no. 3 (1991): 409–19, doi:10.1016/0363-5023(91)90006-W; S. Svenningsen et al., “Hip Motion Related to Age and Sex,” Acta Orthopaedica Scan 60, no. 1 (1989): 97–100, doi:10.3109/17453678909150103; K. E. Roach and T. P. Miles, “Normal Hip and Knee Active Range of Motion: The Relationship to Age,” Physical Therapy 71, no. 9 (1991): 656–65, doi:10.1093/ptj/71.9.656; C. A. Lantz, J. Chen, and D. Buch, “Clinical Validity and Stability of Active and Passive Cervical Range of Motion with Regard to Total and Unilateral Uniplanar Motion,” Spine 124, no. 11 (1999): 1082–89, doi:10.1097/00007632-199906010-00007; J. W. Youdas, J. R. Carey, and T. R. Garrett, “Reliability of Measurements of Cervical Spine Range of Motion - Comparison of Three Methods,” Physical Therapy 71, no. 2 (1991): 98–104, doi:10.1093/ptj/71.2.98; M. Tousignant et al., “Criterion Validity Study of the Cervical Range of Motion (CROM) Device for Rotational Range of Motion on Healthy Adults,” Journal of Orthopaedic and Sports Physical Therapy 36, no. 4 (2006): 242–48, doi:10.2519/jospt.2006.36.4.242.↩︎

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