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Chapter: Stability and Motor Function in OT

Stability, Motor Behavior, ROM, and MMT – Study Notes

  • Definitions and scope

    • Body functions: the physiological functions of the musculoskeletal and movement-related systems. This chapter focuses on core musculoskeletal and movement-related body functions relevant to occupational therapy.
    • Joint mobility: the actual range of motion (ROM) available within a joint.
    • Joint stability: the maintenance of the structure/integrity of a joint.
    • Power: the strength or amount of force a muscle can produce.
    • Muscle tone: the degree of muscle tension; describes how flaccid/loose or how tight/taut a muscle is.
    • Muscle endurance: the sustainability of a muscle contraction over time.
    • Reflexes and primitive patterns (innate, automatic responses):
    • ATNR (asymmetric tonic neck reflex)
    • STNR (symmetrical tonic neck reflex)
    • Palmar grasp reflex
    • Moro reflex
    • Spinal Galant reflex
    • These reflexes are present from birth and typically integrate as motor development progresses.
    • Involuntary movement reactions (postural reactions): automatic adjustments that contribute to posture and balance; less conscious control.
    • Gait and mobility: walking patterns and the use of assistive devices (wheelchairs, crutches) in daily activities.

  • Performance skills (OT definition)

    • Observable, goal-directed actions that enable a client to perform occupations with quality.
    • Examples: standing up, walking to a water fountain, opening a door, bending to obtain a drink, etc.

  • Key components of motor behavior

    • Motor development: occurs over months/years/decades; reflexes integrate; progression from primitive patterns to mature movements (e.g., ATNR/STNR → rolling, crawling, standing, walking).
    • Motor learning: acquisition/modification of learned movement patterns over hours/days/weeks; builds upon existing patterns to participate in specific activities (e.g., learning to play a sport).
    • Motor control: the outcome of motor learning; the ability to perform purposeful movements reliably and with control to accomplish a task.
    • Relationship: development → learning → control; all contribute to functional movement across the lifespan.

  • Movement patterns and adaptive motor behavior

    • Motor skills: voluntary movements used to complete a task or achieve a goal; goal-directed and observable.
    • Movement characteristics (movement requires purpose; linked to function):
    • Movement is more than “movement”; it has a function and context.
    • Normal movement can vary; atypical/malformed movements may still be functional in context.
    • Categories of adaptive motor behavior:
    • Abnormal/atypical movement: inability to produce the movement strategy needed for a task (e.g., post-stroke arm paralysis).
    • Normal atypical: movement that is awkward/inefficient but feasible (e.g., tremor while reaching).
    • Normal typical: standard, expected movement pattern with no major issues.
    • Normal enhanced: high efficiency, adaptability, and consistent performance; e.g., expert athletes.
    • Posture and stability require coordinated changes in posture during transitions (static vs dynamic positions) to maintain balance and function.
    • Static vs dynamic postures examples:
    • Static sitting vs dynamic sitting
    • Static standing vs dynamic standing
    • Visual input and posture: the eyes contribute to posture and balance; visual focus can influence stability (e.g., closing eyes can destabilize a previously steady stance).

  • Posture, base of support, and center of gravity (CoG)

    • Center of gravity (CoG): the balance point of the body or a body segment; it is not fixed and shifts with position.
    • Line of gravity: the vertical line from the CoG to the earth.
    • Base of support (BoS): the area that contains the body’s contact with the supporting surface.
    • Stability requires maintaining the line of gravity within the BoS; proximal stability supports distal control.
    • Proximal stability precedes distal control in functional tasks.
    • Examples: hip surgery can shift CoG; poor posture can shift CoG forward, affecting balance and reach.

  • Principles of stability (six keys to influence stability and CoG)

    • Lower the center of gravity to increase stability.
    • Increase the base of support (BoS): wider stance (shoulder-width) increases resistance to tipping.
    • Keep the line of gravity inside the BoS to maintain balance.
    • Increase mass to resist tipping (note: not a practical manipulation for most clients, but conceptually relevant).
    • Increase friction between the object and surface to reduce slipping.
    • Focus attention on a stable visual target (focusing on a spot improves postural stability).
    • Visual input can dramatically alter postural control (demonstration with eyes open vs closed).
    • Practical takeaway: posture and balance are multimodal and rely on alignment, contact, and sensory input.

  • Posture control and anticipatory adjustments

    • Posture control: regulation of the body’s position in space for stability and orientation.
    • Anticipatory postural movements: pre-emptive adjustments in posture in response to anticipated tasks or environmental demands.
    • This framework helps explain how posture adapts to different tasks or surfaces.

  • Occupational therapy assessment and intervention (role of the OTA)

    • OTAs identify functional movement patterns during therapeutic interventions and grade activities accordingly.
    • Therapeutic interventions/activities: purposeful tasks used to assess or train movement (e.g., reacher use, shoe horn for dressing).
    • Monitoring during treatment: fatigue, resistance, pain, and progress to determine if the task is appropriate.
    • Initial and ongoing assessment by therapists: ROM and strength measurements define goals and indicate progress or need to adjust goals.
    • Common assessment measures during sessions:
    • Pain scales (e.g., “how much pain today?” on a 0–5 scale).
    • Sleep quality/impact on movement (questionnaires).
    • ROM (range of motion) measurements, such as wall slides for shoulder ROM.
    • Manual Muscle Testing (MMT) to assess strength progression.
    • Reassessment cadence: do ROM and strength testing regularly (often weekly for MMT) to guide progression or modification of therapy.
    • Movement strategies: observe if patients are compensating (e.g., using other joints or trunk movement) to complete a task versus truly recovering the targeted movement.
    • Neuromotor processes: sensation, perception, strength, and coordination influence movement; consider neuromuscular contributions when planning interventions.
    • Reference: Page 85, Box 44 (in the text) for body functions and performance skills and examples; ROM and major muscle testing are common sensing tools.
    • Case example: assess a patient with a shoulder restriction by noting ROM limits, pain, and how the patient completes the task (e.g., wall slides) to guide therapy progression.

  • Range of motion (ROM): definitions and measurement basics

    • ROM: the arc through which a joint moves.
    • Active Range of Motion (AROM): the joint is moved by the client alone.
    • Passive Range of Motion (PROM): the therapist moves the joint while the client remains relaxed.
    • Active Assist ROM: client moves the joint partially with assistance from therapist or device (e.g., cane, stick, pulley, wall slides).
    • How ROM is measured in practice:
    • Start in neutral/anatomical position.
    • Use a stable arm to align with the body and a moving arm along the moving segment.
    • For the shoulder flexion example: neutral is 0 degrees; measure to the end angle (e.g., 130^ ext{o}).
    • If baseline is not zero (e.g., post-surgery forward posture), establish a new starting point (e.g., 15^ ext{o}) and measure to the end point (e.g., 90^ ext{o}) to report a range like 15^ ext{o}
      ightarrow 90^ ext{o}.
    • Recording ROM: document the starting point and the end angle; sometimes negative values are used in small joints to denote hyperextension or deficits (e.g., a deficit of -15^ ext{o} from neutral).
    • End feel: subjective assessment of the joint end-feel at the end of ROM to guide safety and progression.
    • Soft end feel: muscles compressing or tissue give a little.
    • Firm end feel: ligaments/joint capsule stretch; resistance felt before full ROM.
    • Hard end feel: bone-on-bone contact; little or no give.
    • Abnormal end feel: atypical resistance or laxity indicating instability or pathology.
    • End feel and ROM are interrelated: the clinician must assess the quality of end feel to determine safe progression.
    • For small joints (e.g., fingers), negative values or abnormal end feels may be more common as ROM changes are recorded.
    • Practical lab notes: feel and distinguish soft vs firm vs hard end feel; abnormal end feel (laxity) suggests instability.

  • Techniques and concepts for ROM assessment

    • End feel assessment: palpate gently at the end range and determine resistance quality.
    • Infill sensation: soft vs firm end feel is about tissue compression/give; hard end feel is bony contact; abnormal end feel includes excessive laxity or rapid stopping.
    • In clinical practice, ROM tests are often performed with the patient in various positions (sitting, supine) depending on gravity effects and joint access.
    • The lab portion includes practice with neutral alignment, axis placement, and interpretation of end feel to decide if ROM should be advanced or guarded.
    • “Open chain” vs “closed chain”: open-chain (distal segment moves freely) vs closed-chain (distal segment fixed); some patients benefit from closed-chain positioning to enhance proprioceptive feedback and joint awareness during ROM testing.

  • Manual Muscle Testing (MMT): overview and process

    • Purpose: assess muscle strength and grade strength from 0 to 5.
    • Steps of MMT (as taught in class):
    • Position the client appropriately for testing the targeted muscle group.
    • Stabilize the joint to isolate the muscle being tested.
    • Palpate the muscle to feel for contraction.
    • Observe the muscle contraction and movement.
    • Apply resistance to evaluate the muscle’s ability to resist and hold.
    • Grade the strength from 0 to 5.
    • Typical scoring scale (as described in lecture):
    • 0: no joint movement and no palpable muscle contraction.
    • 1: trace contraction with no visible movement (palpable contraction only).
    • 2: movement possible with gravity eliminated; less than half of full ROM in the tested plane.
    • 3: movement possible against gravity through full ROM.
    • 4: movement against gravity with moderate resistance.
    • 5: movement against gravity with full resistance (normal strength).
    • Recording example: for elbow flexion, a student demonstrated grading 5/5 when the client could resist the clinician’s maximal manual resistance.
    • Practical notes:
    • Most clinics perform MMT with the client seated or lying, depending on gravity involvement and joint access.
    • If the patient cannot move against gravity, begin testing in a gravity-eliminated position (supine or seated with the limb supported).
    • Re-assess strength regularly (often weekly) to track progress and adjust therapy goals.
    • Documentation and decision-making:
    • Note ROM limitations, muscle strength, pain response during testing, and any compensatory movements.
    • If strength appears to be progressing, gradually increase resistance or advance to more challenging positions.

  • Putting it together: assessment, planning, and lab work

    • The therapist uses ROM and MMT as foundational tools to establish baseline function, identify impairments, and set rehabilitation goals.
    • The OTA’s role includes ongoing assessment of movement patterns during treatment, making real-time adjustments to activities to optimize progress and minimize fatigue or pain.
    • Example workflow: initial ROM/strength baseline → select therapeutic activities (reacher/shoe horn) → monitor pain, endurance, and task performance → adjust ROM/strength goals → re-measure ROM/MMT to track progress.
    • Remember to consider neuromotor processes and coordination when interpreting test results (e.g., slow, uncontrolled movements may indicate perceptual or motor planning issues that require different interventions).

  • Quick cross-references and reminders

    • Box 44, page 85 (in the text) contains a consolidated view of body functions and performance skills and related assessment tools used in practice.
    • Core neuromotor considerations include sensation, perception, strength, and coordination as contributors to movement quality and safety.
    • Always assess both the movement itself and the strategy used (compensation vs. true recovery) to guide therapy planning.

  • Summary takeaways

    • Movement is not just movement; it has purpose and function, and stability is a prerequisite for functional distal actions.
    • Motor behavior unfolds across development, learning, and control, with motor learning able to occur more rapidly than motor development.
    • Postural control relies on a combination of biomechanical alignment, sensory input (vision), and neuromuscular coordination; perturbations to any component can alter stability.
    • ROM and MMT are foundational assessment tools that guide intervention planning, progression, and goals; end feel and gravity considerations are essential for safe testing.

  • Notes on terminology and ongoing study

    • Be comfortable distinguishing active, passive, and active-assisted ROM, and understanding when to test in gravity-eliminated vs. gravity-resisted positions.
    • Practice identifying end feel types and recognizing when an end feel indicates potential pathology or instability.
    • Use the standard MMT grading as a framework but be mindful that some clinical contexts may adapt grading scales or terminology.

  • Practical exam focus prompts

    • Define ROM, AR0M, PROM, and active-assisted ROM with examples.
    • List the six principles of stability and explain how to apply them in a lifting task.
    • Describe the differences among abnormal atypical, normal atypical, normal typical, and normal enhanced movement.
    • Explain how to perform the elbow flexion MMT and interpret a score of 5/5.
    • Outline the steps of manual muscle testing and explain why stabilization and palpation are important.

  • Formulas and numerical references (LaTeX syntax)

    • End-range angles and ROM examples can be written as ext{ROM} = heta{ ext{end}} - heta{ ext{start}} with specific values such as heta{ ext{start}} = 0^ ext{o} and heta{ ext{end}} = 130^ ext{o} for shoulder flexion.
    • Degrees are represented with the degree symbol, e.g., 130^ ext{o}.
    • MMT scale values can be denoted as 0, 1, 2, 3, 4, 5 or as 0/5, 1/5, \,\dots, 5/5 depending on the clinic's format.
    • Hyperextension noted as a positive extension value, e.g., a recorded value of +15^ ext{o} when hyperextension beyond neutral is present.

  • Reminder for lab/in-class practice

    • Practice ROM measurements with neutral starting positions, axis alignment, and awareness of gravity effects.
    • Practice distinguishing end-feel types by palpation and joint awareness.
    • Practice MMT with proper positioning, stabilization, palpation, observation, resistance application, and grading.
    • Use real-world tasks (reacher, shoe horn) to connect movement assessment to functional outcomes.