Assessing abilities and capacities in range of motion
- 1. Validity in Assessing Abilities and Capacities in Range of Motion
- 2. - Goniometric measurements are used by occupational therapists to quantify baseline limitations of motion, decide on appropriate therapeutic interventions, and document the effective-ness of these intervention. - The universal goniometer (i.e, full-circle manual goniometer) remains the most versatile and widely used instrument in clinical practice. - Clinical Measurement of Range of Motion Review of Goniometry Emphasizing Reliability and Validity. - Reliability in goniometry simply means the consistency or the repeatability of the ROM measurements, that is, whether the application of the instrument and the procedures produce the same measurements consistently under the same conditions.
- 3. - The reliability of the measurements expresses their reproducibility or stability only in relation to the time intervals reported. - The most accurate evaluation of the reliability of the instrument and procedures is determined when short time intervals separate tests, the classic "test-retest" design. - These results will be more reliable than the results of with long time intervals between tests because the accuracy of the measurements is increased with few uncontrolled variables - Estimating ROM by visual inspection is unreliable when precision and accuracy are needed and measurements with the goniometer are more reliable estimates of ROM
- 4. - If the goniometer is reliable, then the reliability of ROM measurements depends primarily on the standardization of procedures. - Accurate reproducibility depends on careful measurement technique - The reliability of goniometry is affected by many factors Improper alignment of the goniometer, misidentification of bony landmarks, and variations in manual force, all contributed to goniometric error - The application of the goniometers should depend on the ease of operation and on the adaptability of the instrument to the particular clinical problem (edema, joint enlargements, joint deformities).
- 5. - The reliability of ROM measurements also may be influenced by changes in ROM that result from repeated testing trials - The average of several measurements of elbow flexion and wrist extension is more reliable than one measurement. - Recording the average of several measurements may increase the reliability of some ROM measurements - Post treatment increases in some measurements may be a normal function of increased compliance of tissues from repeated testing over time - The reliability of measuring ROM of the extremities is affected by the complexity of the actions measured and by the inherent structural and functional differences of the action.
- 6. - The reliability of goniometric measurements varies in different joints. - Reliability of measuring ROM is specific to the action measured and to regional structure and function - Measurements of the elbow, generally considered a simple hinge joint, show less day-to-day variation in ROM than measurements of the wrist, the movement of which is affected by multiple joints and numerous muscles crossing these joints. - ROM measurements of movements that are influenced by movement of adjacent joints or by multiple joint muscles might be expected to be less reliable than the ROM measurements of simple hinge joints, strict standardization of procedures should increase reliability
- 7. - Complex movements can be measured reliably when the measurement procedures are controlled strictly - Measuring complex actions reliably may be more difficult than measuring simple actions because of the greater potential for error resulting from large fluctuations within the same individual or because of systematic changes over time. - Passive ROM is more difficult to measure reliably than active ROM - Passive movements are extremely difficult to reproduce, because the stretching of soft tissues at the limits of motion depends on the force applied to the limb, which must, therefore, be carefully controlled - The range of passive forearm movement is nonlinearly dependent on the external torque applied, and the variability of the passive movement increased with decreasing external torque.
- 8. - The force exerted by the therapist during the passive movement may be the variable that caused the goniometric discrepancy - The reliability of ROM measurements may be influenced directly by the type of patient problem - The validity of a measurement "constitutes the degree to which an instrument measures what it is purported to measure; the extent to which it fulfills its purpose.“ - In goniometry, we must be confident that the goniometer and measurement procedures are accurate and that we understand the meaning of the measurement results. - We must show that the measurement procedures are consistent with our interpretation of the results
- 9. - The primary purpose of goniometry is to measure ROM of the musculoskeletal system of the human body. To fulfill this purpose, the goniometer was designed as a modification of the protractor, a device known to represent accurately the degree intervals of a circle - The accuracy and, therefore, the validity of goniometers are in question, the degree units can be compared simultaneously against known angles. - A strong relationship establishes concurrent validity, a type of criterion-related validity. This comparison can detect any systematic errors resulting from faulty construction so that proper adjustments can be made. - Although small errors in the construction of goniometers may exist, the instruments generally are accepted as valid clinical tools
- 10. - The measurements obtained are limited to degree units of a circle and, as a result, we accept that the movements we measure have fixed axes of motion about which movement occurs what isn’t true because of other motions within joints, such as articular sliding and rotation, the axes of motion are not fixed. - Another limitation of goniometric measurements is that they are recorded in degree units and, therefore, only ROM can be measured. This limitation is not a problem if the results are interpreted within this restriction, but Occupational therapists inadvertently may reach beyond this restriction and invalidly expand the meaning of the results.
- 11. - Many factors may affect the outcome of ROM measurements— edema, pain, adhesions, strength deficits, and muscle hypertrophy— but ROM measurements are never measures of factors other than ROM. - The validity of ROM measurements is very specific. In the extremities, ROM is recorded in degrees, whereas the factors that may affect ROM must be measured by different methods with equally different measurement units
- 12. Examination of the Straight Leg Raise Test - The meaning of ROM measurements and invalidly interpret the results can be found by examining the SLR test - The maximal angle of SLR in relation to the horizontal plane has been used historically to provide information about hamstring muscle length (HML) and hamstring muscle flexibility (HMF) - Some study results have indicated that during SLR the pelvis moves in conjunction with the lower limbs; thus, the origin of the hamstring muscles is not fixed. - The reports also indicated that SLR may be confounded by pain from nerve root irritation and by the position of the ankle and stretching structures other than the hamstring muscles (e.g, sciatic nerve, enveloping deep fascia of the lower limb)
- 13. Examination of the Straight Leg Raise Test (2) - These findings do not mean that the SLR test is invalid for measuring the maximal angle of SLR in relation to the horizontal plane, but that these results are limited to this interpretation alone. - Hamstring muscle length may affect the maximal angle of SLR, but the SLR test does not measure HML directly - If the results of SLR were compared with the results of linear measurements of HML and if the two measurements were strongly related, then that the angle of SLR indirectly represents HML— concurrent validity would be demonstrated.
- 14. - Examination of the Straight Leg Raise Test (3) - Individuals with a small SLR angle are considered to have poor Hamstring muscle length, and those with a large SLR angle are believed to have good Hamstring muscle length. - Using the test to indicate the flexibility of the muscles may be incorrect and, therefore, invalid
- 15. - Passive flexibility, or extensibility, of skeletal muscles is a physiological property and is defined by the length-tension relationship of the tissues. - This relationship can be represented as "stiffness"—the ratio of the change in passive muscle tension (ΔP) to the change in muscle length (ΔL) (ΔP/ΔL)—or as "compliance"—the ratio of the change in muscle length (ΔL) to the change in passive muscle tension (ΔP) (ΔL/ΔP). - Problem results primarily from interpreting the results incorrectly in relation to the measurement procedures. - The content validity of the test (i.e. how well the test reflects what is being measured), which basically is judgmental, is not established.
- 16. - Accurate judgment of the content validity of ROM measurements may vary depending on the complexity of the test - We must ask ourselves, Are we measuring what we say we are measuring? - Occupational therapists judge the validity of most ROM measurements based on their anatomical knowledge and their applied skills of visual inspection, palpation of bony landmarks, and accurate alignment of the goniometer. - Generally, the accurate application of knowledge and skills, combined with interpreting the results as measurements of ROM only, provide sufficient evidence to ensure content validity
- 17. - The reliability and the validity of even simple measurements, however, may be decreased because of patient differences that we cannot control. Obesity and variations in bony structures can make accurate visual inspection and bony palpation very difficult. - The reliability of lower extremity ROM measurements is less than the reliability of upper extremity ROM measurements is because of greater difficulty accurately locating bony landmarks and aligning the goniometer with the landmarks of the lower extremity. - Factors such as the size and the weight of the extremity measured also will affect the clinician's ability to manipulate the part and thus the reliability and the validity of the measurements
- 18. - Comparing the results of goniometric measurements with those taken from photographs is one method that can be used to demonstrate validity - If still photography is used, the photographic procedures must be standardized to ensure their validity. Variations in the position of the camera in relation to the subject and the type of lens used (i.e., 35 mm vs 50 mm) are only two of many potential sources of error. - Still photography also requires marking anatomical landmarks with skin marks, and movement of the bones under the skin may cause additional error
- 19. - When active and passive unilateral and bilateral hip flexion with knee flexion was examined by cinematography, the displacement of skin marks placed over bony landmarks indicated that the hip flexion movement is composed of two movements: 1) flexion of the thigh on the pelvis and 2) pelvic rotation. - The implication of these results is that the traditional method of measuring hip flexion probably includes movement of both the femur and the pelvis, just as shoulder abduction incorporates movement of both the humerus and the scapula. - ROM measurements of the hip flexion movement takes on new and more valid meaning.
- 20. - The application of cinematography and other forms of motion analysis (e.g., electromyography, electro-goniometry, videotape recording) have the potential to add substantially to our understanding of ROM measurements. - These techniques may be particularly helpful for studying the relationship of goniometric measurements to the functional ROM needed for patients to perform various activities of daily living - Cinematography is limited by procedural problems, such as the positions of the camera and the subject and documenting movement with skin marks over bony landmarks that may move under the skin.
- 21. - The most powerful method by which the validity of ROM measurements can be studied is radiography - Radiography is an imaging technique using X-rays to view the internal form of an object. To create the image, a beam of X-rays, a form of electromagnetic radiation, are produced by an X-ray generator and are projected toward the object - Measurements of total shoulder abduction are valid only for the combined movements of the scapula on the thorax and the humerus on the scapula measured in radiography - Radiography also have contributed to our knowledge of the complex movements that occur at the shoulder. What showed that medial rotation of the humerus, not lateral rotation as generally believed, accompanies active and passive shoulder flexion