Dr Pooja Joshi presented on motor control in ankle instability. The ankle is a stable hinge joint made unstable by injury or repeated trauma. Assessment of ankle instability includes history, physical exam testing ranges of motion and ligaments, and evaluating proprioception and neuromotor control. Treatment focuses on reducing pain and swelling followed by motor control training using techniques like motor imagery, mirror therapy, and bracing to prevent further injury and give closed loop feedback to the central nervous system.

1. Presenter: Dr Pooja Joshi
Moderator : Dr D.N.Bid
MOTOR CONTROL IN ANKLE
INSTABILITY

2. Functional Anatomy
 Ankle is a stable hinge joint
 Medial and lateral displacement is prevented by
the malleoli
 Ligament arrangement limits inversion and
eversion at the subtalar joint
 Square shape of talus adds to stability of the ankle
 Most stable during dorsiflexion, least stable in
plantar flexion

3.  Degrees of motion for the ankle range from 10
degrees of dorsiflexion to 50 degrees of plantar
flexion
 Normal gait requires 10 degrees of dorsiflexion
and 20 degrees of plantar flexion with the knee
fully extended
 Normal ankle function is dependent on action
of the talocrural joint and subtalar joint

4. Stability
1. static stability
2.dynamic stability

5.  1.static stability
 Mechanical static or passive stability of a joint may
be due to geometry of the articular restraints as well
as primary and secondary static restraints.
 The lateral ligaments provide static stabilization of
the AJC, along with the medial deltoid ligament,
distal anterior tibiofibular ligament, interosseous
membrane, and joint capsule.
 The unique AJC bony articulation of the tibia, fibula,
talus and calcaneus defines the articular restraints.
Passive structures such as ligaments and capsule
provided passive stiffness at the extremes of motion

6. 2.Dynamic ankle stability can be defined as the
ability of the ankle joint to maintain equilibrium
in response to an external perturbation.
 Maintaining ankle stability during gait and other
activities is necessary in order to prevent any
injuries.
 Dynamic ankle stability is influenced by passive
mechanisms such as ligamentous stiffness,
active mechanisms such as muscle stiffness, and
neuromotor mechanisms such as reflex and
voluntary control.

7. Instability
 Types :
 1.mechanical
 2.functional

8. 1.functional joint instability
 If a patient complains of instability, but has a
normal physical exam (no laxity) the instability
may be a result of the deficits in the sensorimotor
system (proprioception or neuromuscular control)
and has been diagnosed as functional ankle
instability.
2.mechanical joint instability
 excessive laxity and subjective instability of the
AJC suggest mechanical tissue damage (ligament
and/or capsule) that may be accompanied by
reduced sensorimotor control. These patients
have been diagnosed with mechanical ankle
instability.

9. Prevalence
 Prevalence of ankle instability is 35% in
normal population
 In sports population it is 50%
 80% of ankle instability because of ankle
sprain

10. causes
 Ankle sprain
 Repetitive trauma
 Change in muscle tone
 Sensory-motor disturbance

11.  Symptoms
 1.pain
 2.swelling
 3.repetitive injury
 4.balance problem
 5.feeling of giving away

12. Assessment
 History
 Past history
 Mechanism of injury
 Type of, quality of, duration of pain?
 disability
 Previous treatments

13. Examination
 Ankle joint complex range of motion (ROM) is
determined in each of the six degrees of freedom of
a joint.
 Excessive ROM or laxity may be inversion/eversion,
plantarflexion/dorsiflexion, and abduction adduction
rotations, or anterior/posterior, medial/lateral and
upward/downward translations.
 Ligament, capsule, muscle and tendon length will
affect the AJC ranges of motion.
 Many clinicians attempt to determine if the ROM
was normal or abnormal based on their “feel” and
clinical experience with comparisons to the other
side.

14.  Ankle Stability Tests
 Anterior drawer test
 Used to determine damage to anterior talofibular
ligament primarily and other lateral ligament
secondarily
 A positive test occurs when foot slides forward
and/or makes a clunking sound as it reaches the end
point
 Talar tilt test
 Performed to determine extent of inversion or
eversion injuries
 With foot at 90 degrees calcaneus is inverted and
excessive motion indicates injury to calcaneofibular
ligament and possibly the anterior and posterior
talofibular ligaments
 If the calcaneus is everted, the deltoid ligament is
tested

15. Anterior Drawer Test
Talar Tilt Test

16.  Kleiger’s test
 Used primarily to determine extent of damage to
the deltoid ligament and may be used to evaluate
distal ankle syndesmosis, anterior/posterior
tibiofibular ligaments and the interosseus
membrane
 With lower leg stabilized, foot is rotated laterally to
stress the deltoid
 Medial Subtalar Glide Test
 Performed to determine presence of excessive
medial translation of the calcaneus on the talus
 Talus is stabilized in subtalar neutral, while other
hand glides the calcaneus, medially
 A positive test presents with excessive movement,
indicating injury to the lateral ligaments

17. Kleiger’s Test
Medial Subtalar Glide Test

18. Stress Radiographs
Anterior drawer – Absolute Displacement:
10mm
Side to side: >3mm
Talar Tilt – Side to side: >10º

19.  Functional Tests
 While weight bearing the
following should be performed
 Walk on toes (plantar flexion)
 Walk on heels (dorsiflexion)
 Walk on lateral borders of feet
(inversion)
 Walk on medial borders of feet
(eversion)
 Passive, active and resistive
movements should be manually
applied to determine joint
integrity and muscle function
 If any of these are painful they
should be avoided

21. Motor control
 According to Brooks, a neurophysiologist,
“Motor control is the study of posture and
movements that are controlled by central
commands and spinal reflexes, and also to
the functions of mind and body that govern
posture and movement.”

22.  among motor control theorists. Bernstein is
most well-known for his “degrees of
freedom” problem: How does the brain
control so many different joints and muscles
of the body?
 The statement of the degrees of freedom
problem brought renewed focus on the
physical aspects of the body, particularly the
musculoskeletal system and its role in motor
control.

23.  Motor control problems may include deficits in
initiation of movement, termination of movement,
and speed and direction control.
 These difficulties often are associated with
abnormal movement patterns. Many factors may
contribute to a patient exhibiting an abnormal
movement pattern.
 These contributing factors may originate centrally,
peripherally, or both.
 Central factors may include damage to the neural
circuitry that generates the movement pattern,
aberrant input (inhibition or facilitation) to the
circuitry, or abnormal motor neuron recruitment.
 Peripheral factors may include muscle fiber atrophy,
changes in muscle stiffness, and muscle shortening

24. Types of concepts
 1.open loop control
 2.closed loop control
 3.voluntary control

25. Open-loop control
 The open system model is characterized by a
single transfer of information without feedback
loops
 This model is used in the traditional reflexive
hierarchical theory of motor control
 before stimulus onset muscle activation to
prepare oneself for the stimulus .
 In the ankle, this consists of activating the
musculature surrounding the joint before
stimulus onset (landing) to control dynamic
stability.

26. Closed-loop control
 the closed system model has multiple feedback
loops and supports the concept of distributed
control
 In the closed model, the nervous system is viewed as
an active agent with structures that enable the
initiation and generation of movement
 They proposed that damage to the proprioceptive
ligamentous structures. after LAS created a void in
the proprioceptive feedback to the central nervous
system and predisposed those individuals to
episodes of the ankle “giving way”

27. Arthrogenic muscular
inhibition
 It has been postulated that altered neuromuscular
control patterns may be due to residual arthrogenic
muscle inhibition
 which is described as a continuing inhibition of the
musculature surrounding a joint after swelling or
damage to the structures of that joint
 Swearingen and Dehne , who found the decreased stress
tolerance of an injured joint triggers a reflexive inhibition
which affects muscles that are capable of increasing
tensile stress on the damaged ligaments.
 It follows that the ankle invertors would be inhibited
after lateral ankle joint injury because they can initiate
movement in the same direction as the initial injury.

28. ANKLE JOINT MECHANORECEPTORS
Type I: slow adapting, low threshold Convey
postural sense
Type II: rapid adapting, low threshold Convey
sense at beginning of joint movement
Type III: slow adapting, high threshold
Convey sense at extreme end ROM

29. JOINT MECHANORECEPTORS
• influence gamma motor neuron output:
 determine length of muscle spindle fibers
• Influence discharge of spindle afferents and
input on alpha motor neurons adjust
muscle length or tension to protect joint
from injury

31.  Role of Proprioception in Sensorimotor Control of
Functional Joint Stability
 Motor control for even simple tasks is a plastic
process that undergoes constant review and
modification based upon the integration and
analysis of sensory input, efferent motor
commands, and resultant movements.
 Proprioceptive information stemming from joint
and muscle receptors, as previously demonstrated,
plays an integral role in this process.
 Underlying the execution of all motor tasks are
particular events, often very subtle, that are aimed
at preparing, maintaining, and restoring stability of
both the entire body (postural stability) and the
segments (joint stability).

32. neuroplastisity
 CNS is massively adaptable. If we can drive
both spontaneous and purposeful changes in
structure and function with attended,
repetitive, rewarded behaviors, then we
should be able to reverse negative
musculoskeletal and neurological behaviors
through focused, selective, goal-directed
repetitive behaviors

34.  Use of external ankle
support to provide
sensory motor input
during exercise

35. 1

44. Motor imagery and mirror
therapy

45. Types of imagery
1. Affirmation imagery
2. Healing imagery
3. Treatment imagery
4. Performance imagery

49. Tapping and bracing
 Taping the AJC prior to
participation in highrisk sports such as
football, basketball,
soccer, and volleyball
has been successful in
preventing ankle
injuries

51. summary
 After reducing pain and swelling motor control
training is necessary to give to prevent further
injury
Concepts
 Open loop control
 Closed loop control
 Muscular inhibition
Recent techniques
 Motor imagery
 Mirror therapy
 Tapping

52. References
.

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