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Muscle Strength Testing. University of the Philippines Manila COLLEGE OF ALLIED MEDICAL PROFESSIONS PT 142 Assessment in Physical Therapy Mitch B. Encabo , MPA, PTRP Edited for instruction by: Aila Nica J. Bandong , PTRP. LEARNING OBJECTIVES .
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Muscle Strength Testing University of the Philippines Manila COLLEGE OF ALLIED MEDICAL PROFESSIONS PT 142 Assessment in Physical Therapy Mitch B. Encabo, MPA, PTRP Edited for instruction by: AilaNica J. Bandong, PTRP
LEARNING OBJECTIVES At the end of the session the students should be able to: • Define muscle strength and their functional implications • Discuss basic considerations in performing muscle strength testing • Differentiate methods of doing muscle strength testing • Discuss Daniels and Worthingham’s manual muscle testing • Discuss modified tests used in assessing muscle strength • Instrumental muscle strength testing • Functional muscle strength testing • Discuss probable conditions that require modifications of the standard technique
MUSCLE STRENGTH TESTING • Refers to the determination of the strength of a muscle or muscle group • Does not reflect muscle function • Test based on the • Effective performance of movement • Manual resistance • Gravity
MUSCLE STRENGTH TESTING Purpose • Diagnostic • Examine the improvement or deterioration of a patient’s status over time • Predictive or prognostic tool • Determine the extent of strength loss • Outcome measures in clinical research • Determine the need for compensatory measures or assistive devices • Helps in the formulation of the treatment plan • Evaluates the effectiveness of treatment
MUSCLE STRENGTH vs ENDURANCE Muscle Strength • Force production • Voluntary exertion in one maximal effect • Results in isotonic or isometric contractions • Gross indicator of functional ability Muscle Endurance • Repeated contractions • Maintenance of isometric contraction
MUSCLE WEAKNESS • Any reduction of the normal ability of the muscle to generate force • Causes: • Muscle strain • Pain, reflex inhibition • PNI, Nerve root lesion, UMNL • Tendon pathology, avulsion, rupture • Prolonged disuse/immobilization • Psychological overlay
Test Performance • Muscle origin, insertion and action • Function of participating muscles • Patterns of substitution • Ability to detect contractile activity • Ability to palpate muscle or tendon • Ability to detect atrophy • Recognize abnormal position or movement
Test Performance • Awareness of deviation from normal ROM , laxity or deformities • Identify muscles with the same innervation • Relationship of diagnosis to sequence and extent of test • Ability to modify test procedures as necessary • Effect of fatigue • Effect of sensory loss and movement
Evaluation of Muscle Strength • Detect substitution whenever weakness exist • Accurate grading of muscle strength
BASIC CONSIDERATIONS • Observation • Palpation • Positioning • Stabilization • Resistance • Validity and reliability
Observation and Palpation • Observe the size and contour of muscles • Palpate contractile tissues
Positioning • Patient comfort • Depends partly on the effect of gravity • Use position that offers the best fixation of the body as a whole • Use antigravity positions as applicable • Two jointed muscles
Stabilization • Proximal attachment of muscles • Used to isolate the desired action to a specific joint • Stabilize the part proximal to the part being tested • Stabilization of the proximal attachment of the muscle through: • Muscle tension • Gravitational pull • External pressure from manual stabilization
Resistance • Force that acts in opposition to a contracting muscle • Applied in the direction opposite the line of pull • Must never be sudden or jerky • Applied gradually, but not to slowly, to allow the patient to “get set and hold” • Applied uniformly • Long lever arm vs Short lever arm • Break test vs Active resistance test
Validity and Reliability • Inherent limitation • Types of muscle contractions • Rate of tension development • Affected by • Difference in testing methods • Magnitude of resistance • Force application, point of application, speed • Factors • Patient factors • Therapist factors • Environmental factors • Others
Validity and Reliability • Patient Factors • Age • Gender • Pain • Fatigue • Lower motor neuron disease • Spasticity • Therapist factors • Experience • Manner and content of instructions • Interaction • Environmental factors • Temperature • Distractions • Other factors • Muscle factors • Psychological factors • Methodological factors
METHODSOFMMT What is being tested? Resistance Type of Contraction Method of Grading
Daniels and Worthingham MMT • Criteria used in assigning a muscle grade • Factors considered include the following: • Subjective Factors • Examiner’s impression of the amount of resistance to give before the actual examination • Amount of resistance that the patient tolerates during the actual test Objective Factors • Ability of the patient to move the body part against gravity • Ability of the patient to complete full range of motion • Ability of the patient to hold the position once at the end of the range of motion Other Factors • Amount of manual resistance applied • Ability of the muscle to move the part through the full ROM • Effect of gravity • Evidence of contraction
Daniels and Worthingham MMT: GRADING • Normal ( N or 5 ) • Full range against maximum resistance and gravity • Good ( G or 4 ) • Full range against moderate resistance and gravity • “Gives” or “yields” at the end of the range given maximum resistance • Functional threshold for the lower extremity • Fair Plus ( F+ or 3 ) • Full range against mild resistance and gravity • “Gives” or “yields” to some extent at the end of its range given moderate or maximum resistance • For users of orthosis • Fair ( F or 3 ) • Full range against gravity • “Gives” at the end of the range against mild resistance • Functional threshold for the upper extremities
Daniels and Worthingham MMT: GRADING • Poor ( P or 2 ) • Full range, gravity eliminated • Poor Minus ( P- OR 2 - ) • Partial range gravity eliminated • Trace ( T or 1 ) • Visible or palpable contraction • No movement of the body part • Zero (0) • No visible or palpable contraction
How to Document??? All muscles of the trunk and extremities are grossly graded 5/5 EXCEPT: ® Shoulder abductors – 3/5 ® Knee flexors – 3/5 Significance: Muscle weakness 2 to deconditioning
How to Document??? • BREAK TEST All the muscles of the wrist and hand are grossly graded 5/5 EXCEPT: ® wrist flexors – 4/5 ® radial deviators – 4/5 ( 10 deg ) Significance: Muscle weakness 2 to pain brought about by reflex inhibition
How to Document??? • RANGE TEST All of the muscles of the lower limb are grossly graded as 5/5 EXCEPT for ® hip extensors = 4/5 (0-90 degrees) ® hip adductors = 4/5 (0-20 degrees) Significance: Muscle weakness due to prolonged immobilization, range test was used 2 to contractures of the hip flexors and adductors
Daniels and WorthinghamMMT:LIMITATIONS • Presence of UMNL/ Spasticity • Presence of joint instability due to chronic flaccidity • Presence of severe contractures
Daniels and Worthingham MMT:AREAS/CONDITIONS THAT REQUIRE MODIFICATIONS • Hands and toes • Face • Neck • Weight bearing muscles • Children
Hands and Toes • Weight is minimal so effect of gravity is unimportant and need not be considered • Tested in either gravity eliminated or gravity-assisted position • Grading: • 5 Full range with max resistance • 4 Full range with mod resistance • 3 Full ROM (whether gravity eliminated or assisted) • 2 Partial ROM (whether gravity eliminated or assisted) • 1 Palpable or observable flicker of muscle contraction
Face • Not always practical or possible to palpate muscle, apply resistance, or position the patient • Grading: • N/F (N)or light impairment Completes test movement with ease and control • WF Moderate impairment that affects the degree of active motion Performs test with difficulty • NF Severe impairment Minimal muscle contraction • 0 Absent
Neck • Using gravity eliminated position when testing for neck flexion and extension is impractical • A muscle grade of 2 is assigned when the patient can complete partial ROM while in a gravity resisted position Weight Bearing Muscles • To be resisted maximally, some muscles require the assistance of body weight • For gastrocnemius and soleus only
Children • May not cooperate with standard MMT procedures • 2-5 y/o can initiate test position, but they cannot sustain it because they don’t understand the concept of exerting counterforce vs examiners resistance • Needs to be modified for 4-6 y/o
Daniels and Worthingham:MODIFIED TESTS • Combined tests for the extremities • Quickie tests • Squatting • Walking on heels and toes • Break test • Movement cannot be totally prevented but can be minimized by telling the patient “don’t let me move you” • Evaluation of functional activities • Donning and doffing • Gripping the examiners hand
Daniels and Worthingham:CONSIDERATIONS • Always start the test at grade 3 • In case a movement needs to be tested in the non-standard position , indicate the position used • When in doubt about the grade assigned to a muscle group place a (?) beside the grade • Note special cases ( MMT of fingers or toes, UMNL ) • Freedom from discomfort or pain • Quiet non-distracting well ventilated environment • Adequately firm and wide plinth with adjustable height • Minimal position changes • Presence of all materials needed for the test
Instrumented Muscle Testing • Advantage: increases the level of accuracy and reliability of strength testing • Instruments/ devices • Cable tensiometer • Strain gauge • Hand-held dynamometer • Modified sphygmomanometer • Grip strength dynamometer • Pinch meter
Instrumented Muscle Testing: LIMITATIONS • Measures isometric strength only • Not useful for testing trunk strength Instrumented Muscle Testing: CONSIDERATIONS • Reliability is reasonable • Important to standardize strength • Instruments are not interchangeable
Dynamic Muscle Testing • Makes more sense since muscles function dynamically • Machine use: Isokinetic machines
Isokinetic Testing Machine: LIMITATIONS • Validity has not yet been established • Movement occurring at constant speed is artificial • Positions and movement constraints are not realistic
Functional Muscle Testing • Utilized in cases when muscle strength cannot be tested by MMT: • Presence of spasticity and flaccidity • Patients with poor comprehension • Patients who are unable to follow instructions • Observations and description of certain movements or activities of the patient
REFERENCES Clarkson & Gilewich(1989), Musculoskeletal Assessment. Joint Range of Motion and Manual Muscle Strength: Williams & Wilkins. Erickson and McPhee(1993) Clinical Evaluation. In Delisa: Rehabilitation Principles and Practice (2nd ed). Philadelphia: JB Lippincott Company. Harms - Ringdahl(1993)International Perspectives in Physical Therapy.Muscle Strength. New York: Churchill Livingstone. Hislop and Montgomery(2002): Daniels and Worthingham’s Muscle Testing: Techniques of Manual Examination(7th ed) Philadelphia:WB Saunders Company. Kendall,McCreary, Provance: Muscle Testing and Function (4th ed)Baltimore: Williams and Wilkins, 1993. Magee(1997) Orthopedic Physical Assessment(3rd ed) Philadelphia: WB Saunders Company. Tobis and Hong (1990) Muscle Testing in Kottke and Lehmann: Krusen’s Handbook of Physical Medicine and Rehabilitation (4th Ed) Philadelphia:WB Saunders Company