Six weeks after surgery, Mike had Bonnie at-tempt functional activities in therapy. He noted that she had fine motor problems due to muscle weak-ness and sensory loss to her thumb and index fin-ger. Work activities such as writing equations on a chalkboard were difficult for Bonnie. Problems using her hand stemmed largely from very limited finger range of motion. Thus, Mike developed and implemented a treatment plan that involved stretch-ing the involved tendons and surroundstretch-ing scar tis-sue that were limiting range of motion.
Mike also recommended using large diameter chalk or a chalk holder that would allow for firmer grasp. This allowed Bonnie to write on the chalk-board adequately. Eight weeks after her surgery, Mike measured Bonnie’s grip strength and lateral pinch strength using a dynamometer. Her grip strength was found to be 9 pounds per square inch (PSI) in her affected right hand and 46 PSI in her unaffected left hand. Her lateral pinch strength was 4 PSI on her right side and 15 PSI on her left side.
These measurements of her right hand were well below average for a woman her age and provided objective evidence that the strength in Bonnie’s right hand was significantly compromised. Thus, Mike’s next step was to give Bonnie activities to do
that strengthened her hand, focusing on her grip and her ability to pinch with her thumb and fore-finger. In addition to goals for increasing strength and range of motion, Mike and Bonnie also set goals to improve her chalkboard writing, computer use, and general fine motor performance.
At 14 weeks post-operation, Bonnie’s fingers had enough active range of motion to meet the goal that she and Mike had set. Active range of motion had improved in all of Bonnie’s digits.
After six months, Bonnie’s active range of motion was within normal limits in all of her right finger joints and her grip and pinch strengths were functional. Her grip strength on her right hand had improved to 40 PSI and her lateral pinch on her right side had improved to 10 PSI.
Bonnie was performing all work, activities of daily living, and instrumental activities of daily living without difficulty.
As this case illustrates, Mike employed both preventative and restorative intervention strate-gies. At first, because of the risk of damage fol-lowing surgery, the focus of therapy was preven-tative. Later, Mike addressed the range of motion and strength problems that were interfer-ing with Bonnie’s occupations. Because they were able to achieve restoration of most of her biomechanical capacities, compensatory strategies were not necessary.
Box 7.1 (continued)
Bonnie’s hand in a CPM machine.
Mike stretching Bonnie’s injured hand.
Table 7.1 Terms of the Model
Active range of motion Degree of self-initiated movement possible at a joint.
Biomechanical activity analysis Examination of the endurance, range of motion, and muscle strength needed for the completion of an activity.
Body mechanics Position and movements of the body during the performance of occupations.
Compensatory treatment Therapy involving adaptations to deal with existing limitations.
Elasticity The capability of tissue to stretch and to return to its original shape and size.
Endurance The ability to sustain effort over the time required to do a particular task.
Functional motion Movement required for daily occupations.
Joint range of motion The potential for motion at the joints.
Kinematics The study of how the body moves in terms of movement path, velocity, and acceleration.
Manual muscle testing Examination of an individual’s muscle strength by asking the client to produce movement against manual resistance.
Orthosis (pl, orthoses) Device used to correct joint misalignment or to substitute for lost function.
Passive range of motion Amount of movement at the joint when the joint is moved by means other than the individual.
Physical reconditioning The process of returning the body to a state of fitness.
Prosthesis (pl, prostheses) Device that replaces an amputated body part.
Strength The ability of muscles to produce tension to maintain pos-tural control and move body parts.
Tendon Connective tissue that connects a muscle to a bone.
Work hardening Program applying biomechanical principles by using simula-tions of the physical requirements of a work situation to recondition persons for work.
2004). Given the centrality of movement prob-lems in occupational therapy clients and the long history of this approach in occupational therapy
practice, there is no doubt that the model will con-tinue to be a vital part of occupational therapy sci-ence and practice.
Focus
Musculoskeletal capacities that underlie functional motion in everyday occupational performance
How the body is designed and used to accom-plish motion for occupational performance
Applied to persons who experience limita-tions in moving freely, with adequate strength, and/or in a sustained fashion
Theory
Kinetic and kinematic principles concerning nature of movement and forces acting on the human body as it moves
Anatomy of musculoskeletal system
Physiology of bone, connective tissue, and muscle and cardiopulmonary function
Capacity for functional motion is based on:
•Potential for motion at the joints (joint range of motion)
•Muscle strength (ability of muscles to pro-duce tension to maintain postural control and move body parts)
•Endurance (ability to sustain effort [i.e., intensity or rate] over time required to do a particular task)
Joint range of motion depends on structure and function of joint and integrity of surrounding tissue, muscle, and skin
Muscles cross one or more joints and exert force to control or produce movements allowed by the structure of the joints
Performance depends on simultaneous action of muscles across many joints producing stability and movement required for a task
The ability to sustain muscle activity (i.e., endurance) is a function of muscle physiology in relationship to work being done and supply of oxygen and energy mate-rials from cardiopulmonary system
Movements produced during occupational performance are as much a function of dynamic circumstances of performance as
they are of structure of the musculoskeletal system
Capacity for movement (i.e., strength, range of motion, and endurance) affects and is affected by occupational performance Problems and Challenges
Problems exist when a restriction of joint motion, strength, and/or endurance interferes with everyday occupations
Joint range of motion may be limited by joint damage, edema, pain, skin tightness, muscle spasticity (excess muscle tone producing tightness), or muscle and tendon shortening (due to immobilization)
Muscle weakness can occur as a result of:
•Disuse
•Disease affecting muscle physiology (e.g., muscular dystrophy)
•Diseases and trauma of lower motor neu-rons (e.g., polio), spinal cord, or peripheral nerves, which can result in de-innervation of muscles
Endurance can be reduced by:
•Extended confinement or limitation of activity
•Pathology of cardiovascular or respiratory systems
•Muscular diseases
It is common for sensory loss and loss of motion to co-occur because tactile sensations or touch are often affected by the same dis-eases or traumas that affect muscles
Pain can be chronically or periodically pres-ent in association with disease or trauma that affects the musculoskeletal system
Biomechanical Intervention
Interventions focus on intersection of motion and occupational performance and can be divided into three approaches:
•Prevention of contracture and maintenance of existing capacity for motion
•Restoration by improving diminished capacity for motion
S U M M A R Y : T H E B I O M E C H A N I C A L M O D E L
•Compensation for limited motion (some-times referred to as a rehabilitation approach)
Intervention aims to minimize any gap between existing capacity for movement and functional requirements of ordinary occupa-tional tasks
Practice Resources
Range of motion is usually measured with a goniometer calibrated to degrees of move-ment about an axis
Strength is normally tested by manual mus-cle testing in which the therapist (alone or using some instrument) tests the ability of a person to produce resistance and/or move-ment under standardized circumstances
Endurance is usually measured by determin-ing duration or number of repetitions before fatigue occurs
Methods of intervention address not only targeted limitations of motion, strength, and endurance, but also their underlying causes because the latter may determine the most appropriate intervention
Strength is developed by increasing stress on a muscle through:
•Amount of resistance offered to the movement
•Duration of resistance required
•Rate (speed of movement) of an exercise session
•Frequency of sessions
Occupations
•Provide natural and motivating circum-stances for maintaining musculoskeletal functioning
•Employ attention, thereby encouraging greater effort, diminishing fatigue, and diverting attention from pain or fear of movement
•Provide conditioning that more nearly replicates normal demands for movement in everyday life
Attention to functional purpose of a task is important because purpose does appear to exert an organizing influence on movement
Activity may be modified to:
•Reduce or alter task demands and prevent musculoskeletal problems
•Match permanently reduced musculoskeletal capacity
•Intensify task demands that will increase musculoskeletal capacity
Ways to modify an activity include:
•Positioning the task
•Adding weights or other devices that provide assistance or resistance to move-ments performed in the activity
•Modifying tools to reduce or increase demands
•Changing materials or size of objects used
•Changing method(s) of accomplishing task
When using adapted activities it is important that the client be involved in occupational performance that does have some meaning and relevance
When persons do not have biomechanical capacity to perform daily living, leisure, and work tasks in ordinary ways, special equip-ment and modified procedures can compen-sate (i.e., close the gap between a person’s capacities and task demands)
Prescription, design, fabrication, checkout, and training in use of orthoses may be employed to support, immobilize, or position a joint to prevent/correct contractures and/or enhance function
Current approaches (such as work harden-ing) emphasize strengthening by having the client perform tasks required by that person’s occupation
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