Orthotists must be able to perform accurate evaluations of a patient's joint range of motion and muscle volition to provide successful outcomes to patient management. Discussed are basic concepts related to the successful achievement of these evaluations. Because physical therapists perform these evaluations daily as an integral part of their therapy, references are made to their texts and methods.
As orthotists we are expected to evaluate a patient's range of motion (ROM) and muscle strength to develop recommendation for treatment. More and more we do this as part of a healthcare team consisting of physician, physical therapist and orthotist. The American Board for Certification in Orthotics & Prosthetics Inc. (ABC) Role Delineation Study has identified the need for orthotists to perform range-of-motion and muscle strength evaluations as part of their clinical assessment. The testing of these skills comprises a significant portion of the orthotic exam. That being said, we could benefit from a review of evaluation techniques.
Proper evaluation of joint ROM and muscle strength (volition) are essential to successful patient management. Success in these evaluations is based on use of accepted measuring methods. As orthotists we would benefit from observing our colleagues in physical therapy who have extensive training in these evaluations. They assess patient improvement based on increases in range of joint motion and muscle strength.
For joint motion, the accepted method is that of the American Academy of Orthopaedic Surgeons (AAOS) whose handbook Joint Motion - Method and Recording is excellent (1). AAOS's method is based on six basic principles:
Neutral Zero Method as described by Caves and Roberts in 1936 (2).
All motions of a joint are measured from defined zero starting point positions. The degrees of motion of a joint are added in the direction the joint moves from the zero starting position.
The extended "anatomical position" of an extremity is accepted as zero degrees rather than as 180 degrees.
Motions are described as active or passive.
Active motion is the patient's movement of the joint through a specified arc of motion.
Passive motion is the examiner's movement of the joint through a special fled arc of motion.
Both motions are compared to the accepted ROM for that joint, and any limitation in range due to muscle contracture; capsule restriction; or ligamentous. bony or spastic antagonist is noted.
A distinction is made between the terms extension and hyperextension. Extension is the natural motion opposite to flexion at the zero starting position. This is present in wrist and shoulder joints. If, however, the motion opposite to flexion at the zero starting position is an unnatural one, such as that of the elbows or knees, it is referred to as hyperextension.
Limitation of joint motion is described simply. An example of a limitation of joint motion is an elbow that can only be flexed from 30 degrees (above 0 deb./neutral) to 90 degrees (above 0 deb./neutral). Normal ROM is 0 degrees to 150 degrees.
The elbow flexes from 30 degrees to 90 degrees.
The elbow has a flexion deformity of 30 degrees with further flexion to 90 degrees.
Limitations of joint motion can be soft tissue or bony. In either case, these limitations must be noted so that during testing the patient or examiner does not try to move the joint past the limitation. Also, muscles are graded on the ability to move the joint through the entire ROM available, not the average range.
To obtain the most accurate ROM, two people should work together. One person should range the joint while the other places and reads the goniometer. A goniometer that is easy to read and holds its position while being read will increase accuracy.
Experience has shown the most accurate ROMs are obtained if the joints are ranged slowly and smoothly. Avoid grasping the extremities too tightly. Move elbow or knee joints into hyperextension slowly and with support.
As orthotists, we must appreciate the need to measure joint ROM in the functional positions for which we will be providing our orthoses.
In addition, problems can occur when we try to perform ROM and muscle testing on joints affected by multi-joint muscles. For example, the ankle and knee joints are crossed by the gastrocnemius. We must remove its affect on the ankle by flexing the knee when trying to range that joint, but we must include its affect on the ankle by extending the knee when we develop our orthotic management plan.
Many methods can be used to increase muscle strength. The two most accepted methods in physical therapy training programs are the Lovett Method and the Aids to Investigation of Peripheral Nerve Injuries (AIPNI) Method. An excellent text on this subject is Muscles Testing and Function by Kendell, Kendell and Wadsworth (3).
As orthotists we should focus on functional muscle groups when we perform our evaluations-i.e., hamstrings and quadriceps. We provide orthotic management, i.e., knee flexion and knee extension, because of the effects of these groups.
Patient Positioning is crucial to accurate muscle testing. Muscle testing considers the patient's ability to move the tested joint through its range of motion against gravity. For a patient who cannot do this, the joint is placed in a position where gravity does not affect muscle test. The intelligent handling of affected joints and muscles is more important than demanding the patient be tested in a gravity-free position.
Test Position, Test Movement. Test position is the position in which the part (and joint) is placed by the examiner. The patient is asked to hold that position, if possible. By placing the patient's joint in the test position, the examiner is better able to detect any substitution for weak muscles because of a shift in the position of either the proximal and/or distal part. Test movement is a movement of the joint through a specified arc of motion. This movement is called active range of motion. Barring limitations in range, failure to complete a full ROM can be interpreted as muscle weakness.
Contracture, Shortness. A contracture causes an almost complete loss of ROM of a joint. Shortness is the partial loss of ROM.
Joint Instability can have a marked affect on muscle testing. A patient can have a full contraction of a functional muscle group at the hip, but due to a dislocated hip, little or no movement is achieved. Orthotically, we must protect the hip and manage it as if the muscle group were as weak as demonstrated.
Pressure is the force applied by the examiner's hand to determine the strength of the muscle holding the joint in the test position. This force is directly opposite the line of pull of the muscle or tendon. In general, this pressure is applied near the distal end of the lever in which the muscle is inserted.
For patients who demonstrate muscle strength above grade 3 (fair), the amount of pressure applied is the determining factor. At this grade the patient moves the part against gravity into the test position. Consideration must be made for the size of the patient and the cross-sectional area of the functional muscle group tested. The pressure exerted against a child whose wrist extensors are tested will be much less than that against an adult whose knee extensors are tested. However, both could be graded 5 (normal).
Pressure must be applied gradually in testing patients whose degree of strength is above grade 3 (fair). The patient must be able to "hold-on" against the examiner's gradually applied pressure. Even slight pressure applied suddenly can break the pull of a muscle with strength ranging from grade 3+ (fair+) to 5 (normal).
Substitution is when a muscle or muscle group attempts to compensate for a weak or paralyzed muscle. These substitutions appear similar to normal movements. The examiner must learn to identify these substitutions by placing the part in the test position and by using proper patient positioning as much as possible. The former action allows even inexperienced examiners to detect the sudden shift of the body part, which accompanies the substitution for muscle weakness. Placing the patient in the proper position tends to block known substitution patterns by resisting body shifting and turning the body part to use gravity.
Anti-Gravity, Gravity-Lessened. Gravity is a form of resistance affecting the testing of trunk, neck and extremity muscles. Anti-gravity movements are movements upward in the vertical plane, while gravity-assisted movements are horizontal movements downward in the vertical plane. Movements in the horizontal plane are gravity-lessened. All of grades 0 (zero) through 2+ (poor +) and part of grade 3- (fair-) are performed in gravity-lessened positions. To reduce fatiguing the patient, it is acceptable to perform an assistive movement in the anti-gravity position, when applicable, for grades 2 (poor) and 2+ (poor+).
Testing Children. A child's muscle strength can be tested up to grade (fair) without much difficulty. In higher grades, success depends on the child's cooperation and understanding Young children seldom cooperate in strong test movements.
We must perform our evaluations with consideration of the orthotic management we intend to provide. For example, if we are to provide HKAFOs for a child with Myelodysplasia, we must simultaneously evaluate the child's hips for internal rotation, extension, adduction and range. Evaluating these characteristics individually might cause us to miss an abduction contracture of one of the hip joints. This mistake could unwittingly lead to a created "pelvic obliquity" if the hips were equally abducted as is usual with HKAFOs. The side of the pelvis with the adducted hip would have to rise into an oblique position to allow the thigh to be placed into the thigh cuff. Not only would a pelvic obliquity be created, but also an apparent limb-length inequality. Additionally, a scoliosis might be created or an existing one increased.
Plan Test Format: Standing, Sitting, Supine, Prone and Side-laying. Use or develop an evaluation form that matches the flow of your testing. It should guide the examiner through the planned examination and should be clear enough to point out missing data.
Orthotic Prescription Development. Plan fatigue into the orthotic recommendation. An increasing number of patients with post-polio syndrome can no longer function without orthoses and require increased orthotic management. This population is quite prone to fatigue. When evaluating patients for orthoses, consider their pre-evaluation level of fatigue as well as their test-fatigue. Consider the strength of patients' upper extremities with respect to donning/doffing and choice of closures for orthoses and/or shoes where appropriate.
Although it is acceptable for a physical therapist to define a patient's ROM as "within normal limits," it does little for orthotists to use this terminology. We are concerned with the actual ranges of motion of a joint and whether we are to lock, limit, resist or assist at that joint. Therefore, we need to cite degrees for our evaluations.
Edward L. Barber, CO, is facility manager at Atlanta Orthotics Inc. in Atlanta, GA