Biomechanics and Orthopedic Biomechanics

Biomechanics

• Biomechanics is the study of motion and its causes in living tissues (human and animal)
• It provides conceptual and mathematical tools for understanding animal and human movement
• It helps professionals improve movement and make it safer
• It provides key information on the most effective and safest movement patterns, equipment, and exercises
• Physical educators, coaches, and athletic trainers use biomechanics to improve movement techniques
• Physical therapists use biomechanics to analyze movement in injured patients qualitatively

Orthopedic Biomechanics

• Orthopedic biomechanics is a branch of biomechanics focused on the human musculoskeletal system motions and forces.
• Ortho is a medical specialty focusing on correcting and preventing skeletal deformities.
• Orthopedic treats musculoskeletal disorders and bone-related issues.

Areas of Study, Research, and Practice

• Biomechanics is applicable in sport, exercise science, coaching, equipment design (ergonomics), gait and locomotion, rehabilitation (physical and occupational therapy), prosthetics and orthotics, motor control, computer simulation, and video games (e.g., FIFA).

Different Sub-Fields of Biomechanics

• Exercise and sport biomechanics aims to improve athletic performance and reduce injury through aspects such as landing strategies for injury prevention
• Orthopedic biomechanics involves the study of artificial limbs, biological tissues, and ergonomic considerations for occupational tasks
• Biomechanics of other biological systems looks at subjects like animal locomotion in creatures such as fish, apes, and the performance of horses and dogs.

Biomechanical Applications

• Engineers and occupational therapists use biomechanics to design work tasks and assistive equipment to prevent overuse injuries
• It is used in designing prosthetics and artificial limbs
• Biomechanics is used in prescribing rehabilitative exercises, assistive devices, and orthotics to correct deformities and improve patient function

Biomechanical Testing, Evaluation, and Factors affecting Movement

• Biomechanical testing is used for identifying aberrant movement patterns and altered neuromuscular strategies due to musculoskeletal and neurological injuries, where standard clinical evaluation may not capture them. It aids in patient risk prediction for injuries.
• It examines the complexities of human musculoskeletal function by analyzing segments' role, connective tissues, muscles, and external influences on these structures.
• Human motion is fundamentally complex, involving multiple body segments and forces acting simultaneously.

Types of Human Movement

• Translational/Linear Movement: Movement along a straight or curved line
• Angular/Rotational Movement: Rotation around an axis; it is often combined with linear movement.
• General Motion is a combination of both angular and linear motions.

Human Movement Mechanics, Internal and External

• Internal mechanics: The mechanical factors originating from inside the body (e.g., muscle contraction, ligaments and tendons) are considered for producing and controlling movement.
• External mechanics: The mechanical factors acting on the body from outside (e.g., gravity, collision forces).

Mechanics of Motion: Statics and Dynamics

• Statics: The study of bodies in equilibrium where all forces acting on the object are balanced (ΣF=0)
• Dynamics: The study of bodies that are accelerating due to unbalanced forces (ΣF≠0)

Kinematics and Kinetics

• Kinematics describes movement without considering the forces causing that motion.
• Kinetics describes and studies the forces that produce or change motion (e.g., force, mass, inertia, torque)

Kinematics: Temporal and Spatial Characteristics

• Temporal characteristics examines details like time spent during a movement, speed changes (accelerations and decelerations), and rate of motion.
• Spatial characteristics describes the movement path, its direction, magnitude and location of motion
• Kinematics variables are used to evaluate movement quality and efficiency.

Kinematic Variables: Displacement, Velocity, and Acceleration

• Displacement is the change in position independent of the path taken
• Velocity is the rate of change in displacement with respect to time
• Acceleration describes the rate of change in velocity over time.

Vectors and Scalars

• Vectors have both magnitude and direction, such as force and velocity.
• Scalars have only magnitude, such as distance and speed.

Kinematic Measurements

• Temporal aspects like the time in the air during a jump or exercise.
• Spatial aspects like the direction and location.
• Measuring magnitude and speed like velocity or acceleration in a movement.

Goniometry and Motion Analysis Lab

• Goniometry is used to measure the magnitude of joint motion.
• Motion analysis labs, and tools like video recording, help measure kinematic variables like displacement, velocity, and acceleration during human movement.

ROM (Range of Motion), Measurement Tools

• Various tools – such as goniometers and motion-capture systems are used by therapists to measure ROM

Videotaping and Motion Analysis Lab

• Video recording is used alongside motion analysis equipment for measuring movement details

Kinematic variables (Angular)

• Angular position (θ) describes the orientation of a segment
• Angular velocity (ω) is the rate of change in angular position over time.
• Angular acceleration (α) is the rate of change of angular velocity over time

Statistical Analysis, Diagrams and Reports

• Data from various analyses (motion capture, video recording or other methods) allows for detailed descriptions of movement.
• Free body diagrams show forces acting on a body
• Kinematic analysis enables understanding of motion and forces impacting human bodies.

Center of Mass (COM)

• COM is a representation of the body or body segment to reduce the mass distribution to a single point or a location on the object. It is an important factor for posture analysis and balance.
• A reference for measuring the position of objects, and for calculations, or for theoretical analyses

Segmental Centers of Mass and Gravitational Forces

• Two or more segments of a body can be analysed as a whole to simplify force applications regarding posture, or movement.
• COM of the composed body changes if the segments change their arrangements.
• Gravity's application is affected by segment arrangement and the joint or rotational centre..

Posture Analysis

• Analyzing posture helps prevent injuries and ensure good long-term health by identifying appropriate positions, especially in posture evaluations
• The ideal posture involves balancing the body weight in a way that the plumb line of the body passes through several key points, ensuring stability and avoiding disproportionate weight bearing.
• Posture analysis can measure shoulder, hip, knee, and ankle symmetry, which are important for assessing a person’s health and preventing injuries.

Isokinetic

• Isokinetic exercises involve a constant/same speed (velocity).
• Dynamometers are used for applying and measuring during these exercises.

Injury-Causing Situations

• Several factors contribute to injury, including force magnitude, location, duration of application, frequency, variability, and rate of force application
• Assessing these factors helps in understanding injury risk factors and designing appropriate prevention strategies

Different Types of Forces

• Internal forces originate from within the body, such as muscle contractions or ligament pulls
• External forces come from sources outside the body, such as gravity, wind, or contact with other objects

Force Characteristics

• Force: A push or pull that changes a body’s state of rest or motion
• Vectors: Force is a vector quantity including magnitude, direction, and point of application.
• Gravity: The Earth's attraction acting at the center of mass of an object (CoM or center of gravity).
• Internal Forces such as those from muscle contraction, ligaments, bones and blood flow/fluid.
• External Forces, such as gravity, wind, and other objects impacting the body. This includes force during collisions (e.g., in sports).