Explain and recommend various instruments and methods of measurement.
Perform and interpret objective measurements of girth and joint motion.
Discuss the reliability and validity of the various instruments used to measure girth and joint motion.
Take appropriate actions to improve the reliability of girth and joint motion measurements.
Measurement has long been used to chart progress during the rehabilitation process. Therefore, it is important for all clinicians to be competent in performing and interpreting objective measurements of girth and joint motion. This chapter addresses the reliability and validity of these measurements, methods of ensuring reliable measurements, and various techniques for performing girth and joint motion assessments.
In the clinical setting, objective measurements must be obtained when decision making is necessary for a therapeutic exercise program. A flexible tape measure can be used to measure the girth of a limb and is probably the most common clinical method for documenting muscle bulk and swelling. Girth assessment with the use of a tape measure is also referred to as girth measurement, circumferential measurement, and anthropometric measurement. Not only is this assessment technique used before a weight-training program is implemented to assess its impact on muscle hypertrophy, it is also used to assess muscle atrophy or joint swelling after injury or surgery and to determine the subsequent effect of a rehabilitation program on muscle hypertrophy and joint swelling. Girth measurements have been reported in the literature for documenting the effects of a rehabilitation program on muscle atrophy or hypertrophy and joint swelling after injury, surgery, or implementation of a rehabilitation program.
The increase or decrease in girth measurement is thought to indicate a direct relationship between an increase or decrease in muscle strength. For example, as a muscle atrophies, the loss of strength is directly related to muscle size because the muscle fibers themselves are reduced in size; the outcome, therefore, is a reduction in strength. However, some evidence does support the absence of a direct relationship between girth measurement and muscle size.
Most of the variability in obtaining girth measurements arises from the use of different anatomic landmarks, tension placed on the tape measure by the clinician, and contraction of the muscle. The tension placed on the tape measure by a clinician when assessing girth does not appear to be as big an issue as was thought previously. Box 5-1 lists recommendations to improve intraclinician and interclinician reliability during girth assessments.
The clinician should attempt to place the same amount of tension on the tape measure with each measurement.
All clinicians should use the same anatomic landmarks when determining the site for girth measurements.
If possible, the clinician should take the girth measurement with the muscle contracted.
When possible, the same clinician should take all the measurements to improve reliability.
Several investigators have assessed the reliability of lower extremity girth measurements in young healthy patients. The data suggest that these measurements are reliable and can be reproduced with a high degree of accuracy, particularly when the same clinician takes the measurements. Measurements taken by different clinicians are not as reliable when a standard tape measure is used. In addition, many times clinicians use a healthy extremity to determine the amount of atrophy that may have occurred as a result of trauma. Healthy right and left lower extremities appear to have similar circumferences, which should not vary more than 1.5 cm between the right and left sides. Furthermore, comparisons between a standard flexible tape measure and a Lufkin tape measure with a Gulick spring-loaded end indicate that both intraclinician and interclinician reliability is better with the Gulick spring-loaded end than with a standard tape measure for lower extremity measurements in healthy subjects.
Although girth measurements appear to be reproducible, the validity of measurement of thigh bulk has been questioned. Stokes and Young were concerned that the tape measure was not sensitive and accurate enough for measuring selective wasting of the quadriceps. Doxey reported that detection of changes in muscle bulk in nonsurgical subjects probably requires more sensitive methods than girth measurements, such as ultrasonography or computed tomography. Moreover, a small decrease (1%) in thigh measurement may be an indicator of a significant reduction (13%) in muscle bulk. Research using ultrasonography and computed tomography has shown that muscle fiber atrophy is not adequately reflected by circumference measurements. Rather, extremity fat can mask such muscle atrophy. Thus, caution should be exercised when interpreting the results of girth measurements with regard to muscle strength and progression of individuals through a plan of care. In a rehabilitation setting, the clinician should keep accurate records of not only girth measurements but also the anatomic landmarks used so that consistency is maintained.
Goniometry is the use of instruments to measure the range of motion of body joints. All clinicians should be able to competently perform and interpret objective measurements of joint motion. Initial range-of-motion measurements provide a basis for developing a treatment or therapeutic exercise plan, and repeated measurements throughout the course of rehabilitation help determine whether improvement has been made and the goals achieved.
The literature on goniometry is extensive and describes many aspects of goniometric measuring. Gifford, in 1914, was probably the first to have reported on goniometric devices in the United States. Historically, various instruments and methods of measurement have been described and recommended. The most common methods of measuring range of motion involve the use of a universal goniometer, an inclinometer, or a tape measure ( Box 5-2 ). Special devices are also available for measuring specific joint motion, such as cervical and back motion, temporomandibular joint motion, and ankle motion.
Instruments for assessing joint motion are generally of two types: (1) devices with universal application (e.g., full-circle or half-circle universal goniometer), which remain the most versatile and popular ( Fig. 5-1 ), and (2) goniometers designed to measure a single range of motion for a specific joint ( Fig. 5-2 ). Although not as common as universal goniometers, gravity-dependent goniometers or inclinometers use the effect of gravity on pointers or fluid levels to measure joint position and motion and can either be mechanical or electronic. Mechanical inclinometers are either (1) pendulum goniometers that consist of a 360° protractor with a weighted pointer hanging from the center of the protractor ( Fig. 5-3 , A ) or (2) fluid goniometers that have a fluid-filled circular chamber containing an air bubble, similar to a carpenter’s level ( Fig. 5-3 , B ). Electrogoniometers, which convert angular motion of the joint into an electric signal, can also be used. They are generally used for research purposes because of their expense and the time needed to calibrate and attach to a patient.
As goniometry evolved, efforts were focused on standardizing methods of measurement, including developing common nomenclature and definitions of terms, clearly defining movements to be measured, and establishing normal ranges of motion. In 1965, the American Academy of Orthopaedic Surgeons published a manual of standardized methods of measuring and recording joint motion; since then, the manual has been reprinted numerous times. Norkin and White and Reese and Bandy have also provided thorough descriptions of goniometry.
Anatomic Zero Position
The anatomic zero position is the starting 0° orientation for most measurements. The exceptions are shoulder rotation, hip rotation, and forearm pronation-supination, for which the starting position is between the two extremes of motion. If the individual to be measured cannot assume the starting position, the position of improvisation should be noted when joint motion is recorded. Normal range of motion varies among individuals and is influenced by factors such as age, gender, and whether the motion is performed actively or passively.
Three methods of recording range of motion are accepted: the 0°–180° system, which is the most common system used; the 180°–0° system; and the 360° system ( Box 5-3 ). In the 0°–180° system the neutral starting position is noted as 0°, and the degrees of joint motion are added in the direction of joint movement. When a range of motion is documented, both the beginning (where the motion starts) and ending (where the motion ends) readings are reported. Motion that is beyond the anatomic zero position can be denoted with a plus (+) sign (hypermobility), and when motion is unable to reach the zero position, a minus (−) sign is used (hypomobility). Average ranges of motion for the upper and lower extremities are presented in Table 5-1 .
Determines the anatomic 0° starting point for all joints except the forearm, which is fully supinated. Extension of a joint is recorded as 0°, and as the joint flexes, motion progresses toward 180°. It is the most common system used.
Neutral extension at each joint is recorded as 180°; movement toward flexion approaches 0°, and movement toward extension past neutral also approaches 0°.
Full 360° Circle
The 0° position of each joint is full flexion, neutral extension is recorded as 180°, and motions toward extension past neutral approach 360°.
|Joint||Motion||Range of Motion (°)|
|American Academy of Orthopaedic Surgeons||Kendall and McCreary|
|Digits 2 to 5|
Validity and Reliability of Goniometric Measurement
The purpose of goniometry is to measure the joint angle or range of motion. It is assumed that the angle created by aligning the arms of a universal goniometer with bony landmarks truly represents the angle created by the proximal and distal bones composing the joint. One infers that changes in goniometer alignment reflect changes in joint angle and represent a range of joint motion. Additionally, goniometer measurements are generally compared with radiographs, which represent the “gold standard” for measurements. Several studies have indicated a degree of relationship between measurements obtained with radiography and goniometry.
The reliability of goniometric joint motion measurements has been studied both within and between instruments/techniques, as well as clinicians. Several reports have noted that joint range of motion can be measured with good to excellent reliability. Intratester reliability appears to be higher than intertester reliability regardless of the device used. Additionally, it appears that upper extremity joint measurements are more reliable than those of the lower extremity joints, and reliability can be less for different joints. This may be due to the complexity of the joint or the difficulty in palpating anatomic landmarks. Because reliability is different for each joint, the standard error of measurement can also differ for each joint. Norkin and White and Reese and Bandy documented the standard deviation and standard error of measurement for each joint in their books on goniometry. Boone et al indicated that the same individual should perform the goniometric measurements when the effects of treatment are evaluated. Visual estimation is used by some clinicians to assess joint positions. Investigations assessing the accuracy and reliability of visual estimation versus goniometer measurements report the latter to be more accurate and reliable.
Synthesis of investigations evaluating the interchangeability of different types of goniometers shows that this is not an acceptable clinical practice. Furthermore, the results of research assessing the interreliability and intrareliability and validity of inclinometers and electrogoniometers vary depending on the technique used and the joint measured.
The positioning of the patient should be consistent. The prone or supine position provides greater stabilization through the patient’s body weight. Measurements should be acquired with the use of passive range of motion when possible, and the body part should be uncovered for better accuracy. The goniometer is placed next to or on top of the joint whenever possible, and three landmarks are used for alignment. The goniometer arms are placed along the longitudinal axis of the bones of the joint after the motion has occurred. The fulcrum of the goniometer is placed over a point that is near the joint’s axis of rotation. Because this axis of rotation is not stationary during motion, this is the least important of the three landmarks, and emphasis is placed on proper alignment of the goniometer arms.
In evaluating the joint and assessing range of motion, the clinician should view the affected joint from above and below to determine whether any additional limitations are present in the involved extremity. The opposite extremity must also be assessed to determine normal motion for that patient. Box 5-4 suggests guidelines to improve the reliability of goniometry. Box 5-5 describes the principles for measuring range of motion for joints.
Use consistent, well-defined testing positions and anatomic landmarks to align the arms of the goniometer.
Do not interchange different types of goniometers for repeated measures from day to day on the same patient.
The same clinician should measure the patient from day to day if possible.
Use a standardized protocol for measuring joint motion.
Take repeated measurements on a subject with the same type of measurement device.
Use large universal goniometers when measuring joints with large body segments.
Inexperienced examiners should take several measurements and record the average of those measurements to improve reliability, but one measurement is usually sufficient for more experienced examiners using good technique.
Note: Successive measurements are more reliable if they are taken by the same clinician rather than by different clinicians.
The clinician places the patient in a posture that is closely related to an anatomic position.
It may be necessary to explain and demonstrate the procedure to the patient before the activity.
The clinician should make a visual estimate of the approximate range of motion that the joint will allow during active movement.
The clinician stabilizes the proximal segment of the joint to prevent error.
The landmarks are located and marked with a pen to ensure proper placement and alignment.
The axis of the joint is observed and the fulcrum of the goniometer is placed at this juncture. The goniometer is held 1 to 2 inches from the patient’s body.
The stationary arm is aligned parallel to the longitudinal axis of the proximal limb segment and the appropriate anatomic landmarks.
After the goniometer is aligned properly, the patient is instructed to move the distal segment as far as it can go.
The movable arm is aligned parallel to the longitudinal axis of the distal limb segment and the appropriate anatomic landmarks.
The clinician reads the goniometer.
It is not necessary to move the stationary arm when the measurements are repeated.
The clinician records and reports the data.