Muscle Force-Length Relationship PDF

Muscle: Force-Length Relationship 1  Force-Length Relationship Muscles at very long and very short lengths can not produce high forces Maximal force produc on of a muscle depends on its length 2  Sliding Filament Theory Developed by Andrew F. Huxley and Hugh...

Muscle: Force-Length Relationship 1  Force-Length Relationship Muscles at very long and very short lengths can not produce high forces Maximal force produc on of a muscle depends on its length 2  Sliding Filament Theory Developed by Andrew F. Huxley and Hugh E. Huxley (Both from the UK, not related, working independently) Muscle shortening results from the relative movement of thick and thin filaments past each other MYOSIN link to ACTIN to form cross-bridge Cross-bridge activity is asynchronous 3  Sliding Filament Theory H. Huxley and Hanson, Nature, 1954 A.F. Huxley and Niedergerke, Nature, 1954 4  Force-length relationship Little force Observation: force is proportional to filament overlap Lots of force 5 A.F. Huxley and Niedergerke, Nature, 1954  Force-length relationship Gordon, Huxley and Julian (1966) 6  Force-length relationship Force-length (F-L) relationship: describes the relationship between maximal force in a muscle and its length Specifically, the effect of resting fiber length on muscular contraction 7  Active force production Involves production of force by cross-bridge cycling and use of ATP When a muscle uses ATP to enable cross-bridge cycling, the muscle is actively producing force. Note: we will talk about passive force generation in a later lecture 8  Active F-L Active force-length relationship is established for isometric contractions 9  Active F-L Relationship with 3 regions Ascending Limb (a-b-c) Force [%] Plateau Plateau (c-d) 100 Descending Limb (d-e) c d b What is the 75 Descending origin of this Limb relationship? 50 Ascending Limb 25 a e 0 10 sarcomere length [m] Nigg & Herzog (2007). Biomechanics of the Musculo-skeletal System  Active F-L Sarcomere has overlap Cross bridges attach More overlap –> more attachments 11  Active F-L Descending Limb: d-e Force [%] Plateau 100 c d b 75 Descending Limb 50 Ascending Limb 25 a e 0 12 sarcomere length [m] Nigg & Herzog (2007). Biomechanics of the Musculo-skeletal System  Active F-L e The sarcomere is completely stretched No contact between thick and thin filaments No cross bridges able to attach 13  Active F-L Descending limb: d-e Sarcomere has overlap Cross bridges attach More overlap  more attachments 14  Active F-L Plateau: c-d Force [%] Plateau 100 c d b 75 Descending Limb 50 Ascending Limb 25 a e 0 15 sarcomere length [m] Nigg & Herzog (2007). Biomechanics of the Musculo-skeletal System  Active F-L Plateau: c-d H zone – no cross bridges More overlap  no more attachments 16  Active F-L Ascending Limb: a-b-c Force [%] Plateau 100 c d b 75 Descending Limb 50 Ascending Limb 25 a e 0 17 sarcomere length [m] Nigg & Herzog (2007). Biomechanics of the Musculo-skeletal System  Active F-L Ascending Limb: a-b-c Thin filaments partially overlap Reduced number of cross bridges Compression of thick filament Complete overlap of thin filaments No cross bridges 18  Active F-L What are a, b, c, d, and e in terms of sarcomere length? Knowing that, in frogs: Length of the thick filament = 1.60 μm Length of the thin filament = 0.95 μm Width of the Z line = 0.10 μm Length of the H zone = 0.20 μm 19  Active F-L Descending Limb: d-e e = 0.05 + 0.95 + 1.6 + 0.95 + 0.05 = 3.6 μm d = 0.05 + 0.95 + 0.2 + 0.95 + 0.05 = 2.2 μm 20  Active F-L Plateau: c-d c = 0.05 + 0.95 + 0.95 + 0.05 = 2.0 μm 21  Active F-L Ascending Limb: a-b-c b = 0.05 + 1.6 + 0.05 = 1.7 μm 22  Active F-L Force [%] Plateau 100 c d b 75 Descending Limb 50 Ascending Limb 25 a e 0 1.27 1.70 2.00 2.20 3.60 sarcomere length [m] 23 Nigg & Herzog (2007). Biomechanics of the Musculo-skeletal System  Active F-L Thick filament length is well conserved among species, but length of thin filaments varies 24 Nigg & Herzog (2007). Biomechanics of the Musculo-skeletal System  Active F-L Shape of the F-L? Regions? Length of each region? 25  Active F-L 26 Nigg & Herzog (2007). Biomechanics of the Musculo-skeletal System  Active F-L 1.70 2.51 4.24 2.34 3.94 3.60 27 Nigg & Herzog (2007). Biomechanics of the Musculo-skeletal System  Active F-L Factors influencing active force in a muscle? Temporal summation Spatial summation Muscle cross-sectional area Muscle architecture Amount of overlap, number of attaches cross bridges 28  Active F-L Small vs large area Short vs long muscle Thin vs thick muscle 29  Muscle with different cross sectional areas Two muscles of the same length, but different cross sectional areas For same change in muscle length, the muscle with the larger cross sectional area, and therefore more fibers, can generate more force Muscle Force Muscle 1 Muscle 2 Large area Small area Muscle Length 30 Nigg & Herzog (2007). Biomechanics of the Musculo-skeletal System  Muscle with different lengths Two muscles of the same cross sectional area, but different lengths These muscles will differ in muscle length change while achieving the same force Muscle Force Long muscle Muscle 1 Muscle 2 Short muscle Muscle Length 31 Nigg & Herzog (2007). Biomechanics of the Musculo-skeletal System  Different lengths and different widths Muscle Force Short thick muscle Long thin muscle Muscle Length 32 Nigg & Herzog (2007). Biomechanics of the Musculo-skeletal System  Passive F-L Passive Force – Length Relationship Represents the force generated if a muscle is stretched to various lengths without stimulation, i.e., no cross bridges As the tissue is stretched, we have an increase in force until the elements are maximally stretched, producing Fmax Stretching after that point will result in the tissue yielding, and fibres breaking, until we have ultimate failure and get rupture of the tissue Kovanen et al., 1983 33 Passive F-L Is it elastic or viscoelastic?  Passive stretch and release test Hysteresis Loss of energy Modified from Taylor, Dalton, Seaber, & Garrett, 1990 35  Passive stress relaxation test Tissue held at constant length Force (or stress) decreases over time but only to a certain extent https://ouhsc.edu/bserdac/dthompso/web/namics/hyster.htm#refs 36  Passive creep test Tissue held at constant stress Tissue lengthens over me Eventually settles https://ouhsc.edu/bserdac/dthompso/web/namics/hyster.htm#refs 37  Structures responsible for passive force Connective tissue Fascia Endomysium Perimysium Intra-fiber structures Titin Desmin 38  Titin Elastic protein linking neighboring Z lines Prado et al., 2005 39  Titin Molecular spring of skeletal muscle The largest protein ever discovered Each molecule of titin extends from the Z line to the M line in the middle of A band Bears most of the passive force in muscle fibers 40  What happens if you remove titin? When titin is degraded there is little increase in tension when sarcomere is stretched Granzier et al., 2000 41  Desmin filaments Intermediate filaments Form longitudinal connections between the peripheries of successive Z lines Form a three-dimensional scaffold around the Z lines Connect the entire contractile apparatus to the sarcolemma and its proteins 42  Active plus passive F-L Force [%] 100 75 50 25 0 sarcomere length [m] Kovanen et al., 1983 Nigg & Herzog (2007). Biomechanics of the Musculo-skeletal System 43  Total F-L relationship Resting Length Total Tension \\ Tension Passive \ Active Tension Tension Length Adapted from Gotti et. al. (2020) 44  Force-length properties of whole muscle Kulig et al. 1984 45  Force-length properties of whole muscle TA SOL Maganaris 2001. 46  Can the F-L length relationship change? Cyclists: relatively stronger at short RF Cyclists: negative force vs. length muscle lengths. slope Runners: relatively stronger at long RF Runners: positive force vs. length muscle lengths slope Herzog et al. 1991. MSSE. 23(11), 1289-1296 47 Joint Anatomy and Function KNES 363 November 19th, 2024  Overview Joints by structure Joints by movement/function Supporting components of joints Joint functional classifications Joint movements Planes of motion Degrees of freedom 2  Joints in Real Life Why do we care about joint movement? Mobility and functionality Injury prevention and rehabilitation Training and athletic advancement Joint health and aging Surgical intervention mapping Biomechanical and clinical research 3 Image Source: https://opentextbc.ca/biology/chapter/19-3-joints-and-skeletal-movement/  Definition Joint: a point where two or more bones meet, allowing for movement and support within the skeletal system Joint Classification 1. Structure Fibrous Cartilaginous Synovial 2. Function/Movement Synarthroses Amphiarthroses Diarthroses 4 Image Source: https://smart.servier.com/  Joints by Structure Fibrous Cartilaginous Synovial Joint Joint Joint 5  Fibrous Joint Definition: Bones connected by connective tissue Types & Examples: Sutures → Skull Ossify to synostosis (bony junction) No movement Syndesmoses → Radius+Ulna Connected by ligament/membrane More movement than suture Gomphoses → Tooth+Jaw Peg in socket, fibrous tissue No movement ROLE: stability, structural integrity of connected bones 6 Image Source: https://smart.servier.com/  Cartilaginous Joint Definition: bones connected by cartilage (hyaline or fibrocartilage) Types & Examples: Synchondroses → Sternocostal Joint Hyaline cartilage Immovable Symphyses → Intervertebral Discs Fibrocartilage Slightly moveable ROLE: allow limited movement Shock absorption, distributing loading 7 Image Source: https://smart.servier.com/  Synovial Joint Definition: Highly movable joints surrounded by a fluid-filled cavity Most common type of joint, allow for wide range of motion Types & Examples: Different types based on movement E.g. Hinge → Knee Ball-and-socket → Hip ROLE: allow limited movement Eccentric action of muscle across joints → shock absorption Distributing loading 8 Image Source: https://smart.servier.com/  Synovial Joint Synovial Fluid: Fluid (water, hyaluronic acid, lubricin) Produced by synovial membrane lining the joint capsule Function: Joint lubrication Reduces friction between articular cartilage surfaces Assists in shock absorption through eccentric action Dissipates force during loading Nutrient Supply and Waste Removal Synovial Fluid Supports cartilage health Articular Cartilage 9 Image Source: https://smart.servier.com/  Joint Functions/Movement Synarthroses Amphiarthroses Diarthroses (Immovable Joints) (Slightly Movable Joints) (Freely Movable Joints) Description: Permit little Description: Allow limited Description: Permit a wide to no movement. movement. range of motion; these are typically synovial joints. Examples: Skull sutures, Examples: Intervertebral gomphoses. discs, pubic symphysis. Examples: Shoulder, hip, knee, elbow. 10 Image Source: https://smart.servier.com/  Supporting Components of Joints Menisci Ligaments Bursae Tendons Labrum Articular 11 Cartilage Image Source: https://smart.servier.com/  Ligaments Purpose: Connect BONES to other BONES Stabilize joint by limiting certain movement Examples: Anterior Cruciate Ligament (ACL) Prevents excessive forward movement of the tibia 12 Image Source: https://smart.servier.com/  Menisci/Articular Discs Purpose: Pads of fibrocartilage that improve joint fit, enhance stability, and distribute load within the joint. Example: Meniscus of the knee joint 13 Image Source: https://smart.servier.com/  Articular Cartilage Purpose: Covers the ends of bones Lubricate surface to reduce friction and help dissipate force Example: Articular cartilage of the knee joint Proximal surface of the tibia Distal surface of the femur 14 Image Source: https://smart.servier.com/  Tendons Purpose: Connect MUSCLES to other BONES Stabilize joint by limiting certain movement Examples: Triceps tendon Stabilize the elbow 15 Image Source: https://smart.servier.com/  Bursae Purpose: Fluid-filled sacs located between bones, tendons, or muscles to reduce friction and cushion pressure points. Example: Subacromial bursa in the shoulder 16 Image Source: https://glenelgorthopaedics.com.au/shoulder/subacromial-bursitis/  Labrum Purpose: A ring of fibrocartilage that deepens the joint socket Enhances stability and increases the surface area for articulation Example: Acetabular labrum of the hip joint 17 Image Source: https://smart.servier.com/  Joint Functional Classifications Pivot Gliding Condyloid Ball and Saddle Socket Hinge 18 Image Source: https://opentextbc.ca/biology/chapter/19-3-joints-and-skeletal-movement/  Plane/Gliding Joint Purpose: Allow sliding movements Example: Intercarpal joints of the hand Intertarsal joints of the foot 19 Image Source: https://smart.servier.com/  Hinge Joint Purpose: Flexion/Extension in one plane Example: Knee Elbow 20 Image Source: https://smart.servier.com/  Ball and Socket Joint Purpose: Allow movement in all axes, including rotation Example: Hip Shoulder 21 Image Source: https://smart.servier.com/  Pivot Joint Purpose: Allow rotational movement around a single axis Examples: proximal radioulnar joint 22 Image Source: https://smart.servier.com/  Condyloid (Ellipsoidal) Joint Purpose: Enable movement in two planes (flexion/extension and abduction/adduction) Example: wrist joint 23 Image Source: https://smart.servier.com/  Saddle Joint Purpose: Allow greater range than condyloid joints Two concave surfaces fitting together Example: thumb's carpometacarpal joint 24 Image Source: https://smart.servier.com/  Joint Movements Flexion- Rotation Extension Inversion- Supination Eversion -Pronation Depression Adduction- -Elevation Abduction Protraction Circumduction -Retraction 25 Image Source: https://open.oregonstate.education/aandp/chapter/9-5-types-of-body-movements/  Flexion/Extension Flexion: Decreasing the angle between two body parts (bending) Extension: Increasing the angle between two body parts (straightening) Example: Flexion: Bending your elbow to bring your hand toward your shoulder Extension: Straightening your elbow to return the arm to the extended position 26 Image Source: https://open.oregonstate.education/aandp/chapter/9-5-types-of-body-movements/  Rotation Rotation: Movement around an axis, where one body part moves around a central point or axis Example: Neck rotation: Turning your head to the left or right (e.g., shaking your head "no") Shoulder rotation: Rotating the arm inward (internal rotation) or outward (external rotation) 27 Image Source: https://open.oregonstate.education/aandp/chapter/9-5-types-of-body-movements/  Inversion/Eversion Inversion: Turning the sole of the foot inward, so the bottom faces toward the midline Eversion: Turning the sole of the foot outward, away from the midline Example: Inversion: When you roll your ankle inward, the foot turns toward the midline of your body Eversion: When you roll your ankle outward, the sole faces away from the midline 28 Image Source: https://open.oregonstate.education/aandp/chapter/9-5-types-of-body-movements/  Supination/Pronation Supination: Rotating the forearm so the palm faces up or forward (anteriorly) Pronation: Rotating the forearm so the palm faces down or backward (posteriorly) Example: Supination: Turning your palm up to hold a bowl of soup Pronation: Turning your palm down as if you're pushing the ground away 29 Image Source: https://open.oregonstate.education/aandp/chapter/9-5-types-of-body-movements/  Adduction/Abduction Adduction: Moving a limb or body part toward the midline of the body Abduction: Moving a limb or body part away from the midline of the body Example: Abduction: Lifting your arm sideways away from the body (e.g., raising your arm for a lateral raise) Adduction: Bringing your arm back down towards the body (e.g., lowering the arm from the raised position) 30 Image Source: https://open.oregonstate.education/aandp/chapter/9-5-types-of-body-movements/  Depression/Elevation Depression: Moving a body part downward Elevation: Moving a body part upward Example: Elevation: Lifting your shoulders toward your ears (shrugging) Depression: Lowering your shoulders back down after a shrug 31  Protraction/Retraction Protraction: Moving a body part forward in a horizontal plane (e.g., moving the scapula away from the spine) Retraction: Moving a body part backward in a horizontal plane (e.g., moving the scapula toward the spine) Example: Protraction: Pushing your jaw forward Retraction: Pulling your jaw backward to neutral 32 Image Source: https://open.oregonstate.education/aandp/chapter/9-5-types-of-body-movements/  Circumduction Circumduction: A circular movement in which the distal end of a limb moves in a circle, while the proximal end stays relatively stable. This is a combination of flexion, extension, abduction, and adduction Example: Shoulder Circumduction: Moving the arm in a circular motion, such as during a windmill exercise or when reaching overhead in a circular motion Hip Circumduction: Moving the leg in a circular motion at the hip joint 33 Image Source: https://open.oregonstate.education/aandp/chapter/9-5-types-of-body-movements/  Planes of Motion Z 1. Sagittal Plane: left and right halves Movement in Y-Z plane Rotation about frontal axis (X-axis) E.g., Flexion and extension X Y 2. Frontal (Coronal) Plane: front and back Movement in the X-Z plane Rotation about sagittal axis (Y-axis) E.g., Abduction and adduction 3. Transverse (Horizontal) Plane: Divides the body into upper and lower portions. Movement in the X-Y plane Rotation about transverse axis (Z-axis) E.g., Rotation 34 https://www.physio-pedia.com/Cardinal_Planes_and_Axes_of_Movement  Degrees of Freedom Degrees of freedom (DOF) in biomechanics refer to the number of independent ways in which a joint or body segment can move in space. The maximum DOF in any joint or system is 6 DOF, which includes: 1. 3 Rotational Movements around the three perpendicular axes (x, y, and z): 1. Flexion/Extension (rotation around the x-axis) Z 2. Abduction/Adduction (rotation around the y-axis) 3. Internal/External Rotation (rotation around the z-axis) 2. 3 Translational Movements along these same axes: 1. Medial/Lateral Translation (movement along the x-axis) X Y 2. Anterior/Posterior Translation (movement along the y-axis) 3. Superior/Inferior Translation (movement along the z-axis) 35  Degrees of Freedom Constraints Constraint: limits or restricts movement at a joint or within a system Example 1: Example 2: Hinge Joint in 3D Space: 1 DOF Ball Joint in 3D Space: 3 DOF Translate: Translate: XY plane X XY plane X YZ plane X YZ plane X ZX plane X ZX plane X Rotate about: Rotate about: X-axis X X-axis ✓ Y-axis X Y-axis ✓ Z-axis ✓ Z-axis ✓ Image Source: 36 LEFT: https://sequencewiz.org/2016/11/10/knee-joint/ RIGHT: https://opentextbc.ca/biology/chapter/19-3-joints-and-skeletal-movement/  Degrees of Freedom Applications 1. Common Joint Movements Elbow: 1 DOF (flexion and extension) ideal for tasks requiring straightforward movements provides stability Shoulder: 3 DOF (flexion/extension, abduction/adduction, rotation) complex actions like reaching overhead, throwing, or lifting provides mobility 37  Degrees of Freedom Applications 2. DOF Affects Stability/Mobility Trade-Offs Lower Limb: Hip + Knee: Hip = 3 DOF (ball-and-socket) → mobility for actions like walking, sitting, and bending. Knee = 1 DOF (hinge) → adds stability for supporting body weight during standing or squatting. This balance between the hip's mobility and the knee's stability allows for efficient walking and weight-bearing tasks. 38  Degrees of Freedom Applications 3. Sports and Physical Performance Running and Jumping: Ankle: 2 DOF (dorsiflexion/plantarflexion, inversion/eversion) Fine adjustments → balance/propulsion during activities like running and jumping. DOF directly impacts agility and balance, allowing for swift adjustments on uneven terrain. Throwing and Swinging: Sports that involve throwing (e.g., baseball) or swinging (e.g., tennis) rely on the shoulder's 3 DOF to generate complex, high- speed movements. A high DOF in the shoulder → rotation and power while maintaining a full range of motion 39  Degrees of Freedom Applications 4. Limitations and Injury Prevention Lifting Mechanics: Maintain safe postures and avoid excessive rotation or bending → might strain or injure the back Movement efficiency Preventing Overuse: Joints with more DOF → injuries often due to higher mobility Joints with fewer DOF → injuries often due to higher restriction Recognizing this risk allows for better injury prevention practices, like strengthening surrounding muscles to stabilize and support these joints during repetitive tasks. 40  Measuring Motion Marker-Based Motion Capture (MoCap) Recording movement using camera system and markers to represent anatomical positions Use in biomechanics: Joint movements Gait analysis Posture Motion Capture Methods: Optical: cameras and reflective markers Mechanical: sensors attached to body Electromagnetic: measures positions of sensors using electromagnetic fields 41 Image Source: https://engcourses-uofa.ca/books/ortho/gait-analysis/  MoCap Technology and Equipment Cameras: Optical Cameras: Track the position of reflective markers from multiple angles. Infrared Cameras: Detect markers coated with retro-reflective material, which bounce infrared light back to the cameras. Common Types of Sensors: Markers: Small spheres placed on key anatomical landmarks, detected by multiple cameras. Inertial Measurement Units (IMU): Use accelerometers, gyroscopes, and magnetometers to capture motion. Image Source: 42 Top: http://bestperformancegroup.com/?page_id=31 Bottom: https://www.qualisys.com/accessories/markers/  Using Data from MoCap 1. 2. 1. Place markers on anatomical/bony landmarks 2. Motion is performed → cameras collect marker position 3. MoCap system converts markers in space to relevant positions 4. 3. 4. Post processing A. Identify individual markers B. Identify markers in relation to each other to create segments C. Identify segments in relation to each other to identify angles Image Source: 43 1. Scherpereel et al 2023; Scientific Data. 10. 10.1038/s41597-023-02840-6. 2. https://navigator.innovation.ca/en/facility/northern-alberta-institute-technology- nait/motion-capture-studio. 3. Zhou et al., 2018; App. Sci. 8(9):1554. 4. Berkelman et al., 2007; DOI: 10.1109/ICORR.2007.4428460  Using Data from MoCap 1. 2. 1. Place markers on anatomical/bony landmarks 2. Motion is performed → cameras collect marker position 3. MoCap system converts markers in space to relevant positions 4. 3. 4. Post processing A. Identify individual markers B. Identify markers in relation to each other to create segments C. Identify segments in relation to each other to identify angles Image Source: 44 1. Scherpereel et al 2023; Scientific Data. 10. 10.1038/s41597-023-02840-6. 2. https://navigator.innovation.ca/en/facility/northern-alberta-institute-technology- nait/motion-capture-studio. 3. Zhou et al., 2018; App. Sci. 8(9):1554. 4. Berkelman et al., 2007; DOI: 10.1109/ICORR.2007.4428460  Joint Angles Joint angles measure the relative angular position between two adjacent body segments connected by a joint (e.g., thigh and shank for the knee). These angles represent the flexion, extension, rotation, or other movements occurring within the joint. 45 Image Source: https://csb-scb.com/  CSB Gait Standards Canadian Society of Biomechanics hip Anatomical position is trunk zero degrees. thigh knee RIGHT sagittal leg view foot ankle segment angles joint angles 46 Image Source: https://csb-scb.com/  Gait Analysis Using Motion-Capture 47  Joint Angles Example: Compare healthy controls to clinical populations 48 Image source: https://www.mdpi.com/2076-3417/14/21/9646  Joint Angles and Segment Angles A. Segment Angles (Absolute Angles): angles formed A. between adjacent body segments. trunk Angle between segment and axis Typically used to describe the orientation or alignment of body thigh parts in space relative to each other. Can be used to find the positions of segments leg B. Joint Angles (Relative Angles): angles formed at the B. foot joints themselves, typically defined as the relative angle hip between two bones that form the joint. Angle between longitudinal axes of two adjacent segments knee Joint angles help quantify the motion occurring within a joint during movement. ankle Joint angles are calculated using segment angles. 49  Calculating Segment Angles II I NOTE: Calculate proximal segment minus distal segment to get correct sign III IV Proximal = closest to centre of body E.g. 𝜃thigh = 𝜃hip – 𝜃knee 𝑦 𝜃 = 𝑄 + arctan Hint! 𝑥 Arctangent is the inverse function of tangent Quadrant Reference Angle On a calculator is (tan-1) I 𝜃𝑅𝐸𝐹 = 𝜃1 II 𝜃𝑅𝐸𝐹 = 180° + 𝜃2 “Q” → Quadrant Adjustment III 𝜃𝑅𝐸𝐹 = 180° + 𝜃3 Arctan does not account for quadrant angle so this must be considered manually IV 𝜃𝑅𝐸𝐹 = 360° + 𝜃4 50  Joint Angle Plots Flexed position → values and slope = positive Extended position → values and slope = negative Flexed position Position curve Extended position 51 Image Source: https://mikereinold.com/ankle-mobility-exercises-to-improve-dorsiflexion/  Joint Angles Ankle Angle: hip Foot Segment Shank Segment ankle = foot - shank - 90o Knee Angle: Shank Segment knee = thigh - shank Thigh Segment knee Hip Angle: Thigh Segment Trunk Segment hip = thigh - trunk ankle 52  Practice Question: Segment and Joint Angle Given the following 2D motion capture position data, calculate… A) the segment angle of the shank (4,10) B) the segment angle of the thigh C) the joint angle of the knee thigh (6,4) Hip = (Hx, Hy) = (4,10) knee Knee = (Kx, Ky) = (6,4) Ankle = (Ax, Ay) = (5,0) (5,0) shank 53  Practice Question: Segment and Joint Angle Given the following 2D motion capture position data, calculate… A) the segment angle of the shank: (4,10) 𝑦 𝜃𝑠ℎ𝑎𝑛𝑘 = 𝑄 + arctan thigh 𝑥 (6,4) (4 − 0) 𝜃𝑠ℎ𝑎𝑛𝑘 = arctan (6 − 5) Shank = Quadrant 1 knee Q= 0 (5,0) shank (4 − 0) 𝜃𝑠ℎ𝑎𝑛𝑘 = arctan = 76.0° (6 − 5) 54  Practice Question: Segment and Joint Angle Given the following 2D motion capture position data, calculate… thigh B) the segment angle of the thigh: (4,10) 𝑦 𝜃𝑡ℎ𝑖𝑔ℎ = 𝑄 + arctan thigh 𝑥 (6,4) (10 − 4) 𝜃𝑡ℎ𝑖𝑔ℎ = 180° + arctan (4 − 6) Thigh = Quadrant 2 knee Q = 180° 𝜃𝑡ℎ𝑖𝑔ℎ = 180° + (-71.6°) = 108.4° (5,0) shank 55  Practice Question: Segment and Joint Angle Given the following 2D motion capture position data, calculate… C) the joint angle of the knee: (4,10) knee = thigh - shank thigh 𝜃𝑠ℎ𝑎𝑛𝑘 = 76.0° (6,4) knee = 𝟑𝟐. 𝟒° 𝜃𝑡ℎ𝑖𝑔ℎ = 108.4° (5,0) shank 𝜃𝑘𝑛𝑒𝑒 = 108.4° − 76.0° = 𝟑𝟐. 𝟒° 56  Alternative Method for Joint Angle (4,10) a 2 2 a = 2 + 6 = 6.32  (6,4) 2 2 c b = 1 + 4 = 4.12 knee 2 2 (5,0) b c = 1 + 10 = 10.05 c2 = a2 + b2 - 2ab(cos) 10.052 = 6.322 + 4.122 - 2(6.32)(4.12)(cos) knee= 180o -  = 180o - 147.8o = 32.4o 57  Alternative Method for Joint Angle Ax = 6-4 = 2 (4,10) a Ay = 10-4 = 6 2 2 a = 2 + 6 = 6.32  (6,4) 2 2 c b = 1 + 4 = 4.12 knee 2 2 (5,0) b c = 1 + 10 = 10.05 c2 = a2 + b2 - 2ab(cos) 10.052 = 6.322 + 4.122 - 2(6.32)(4.12)(cos) knee= 180o -  = 180o - 147.8o = 32.4o 58  Alternative Method for Joint Angle Ax = 6-4 = 2 (4,10) a Ay = 10-4 = 6 2 2 a = 2 + 6 = 6.32  (6,4) 2 2 c b = 1 + 4 = 4.12 knee 2 2 (5,0) b c = 1 + 10 = 10.05 c2 = a2 + b2 - 2ab(cos) 10.052 = 6.322 + 4.122 - 2(6.32)(4.12)(cos) knee= 180o -  = 180o - 147.8o = 32.4o 59  Next Class! A) More on Assessing Movement In-vivo Revisit Motion Capture and Joint Angle Calculations Fluoroscopy In-vitro Cadaveric B) Joint Injury and disease E.g. Sprains, ligament tears, dislocations, arthritis, etc. 60 Joint Motion Assessment, Injury and Disease KNES 363 November 21st, 2024  Overview Joint Angle Calculations Revist Different Types of Motion Analysis Quantifying Joint Loads Joint Health Problems and Pathologies Injury, Disease, Degeneration Gait Alterations Assessment of symptoms and diagnosis 2  Last Class Fibrous Joint Cartilaginous Synovial Joint Joint Synarthroses Amphiarthroses Diarthroses 3 Image Source: https://smart.servier.com/  Last Class Joint Movements Supporting Components Functional Classifications 4 Image Source: https://smart.servier.com/  Joint Angles and Segment Angles A. Segment Angles (Absolute Angles): A. Angle between segment and axis trunk Orientation or alignment of body parts in space relative Can be used to find the positions of segments thigh B. Joint Angles (Relative Angles): B. leg Angle between longitudinal axes of two adjacent segments foot Joint angles help quantify the motion occurring within a joint during movement. Joint angles are calculated using segment angles. 5 Image Source: https://csb-scb.com/  Calculating Segment Angles: Method 1 II I Segment Angles: 𝑦 𝜃 = 𝑄 + arctan 𝑥 III IV Joint Angles: Ankle Angle: Foot Segment 𝜃ankle = 𝜃foot - 𝜃shank - 90o Shank Segment Quadrant Reference Angle Knee Angle: Shank Segment 𝜃knee = 𝜃thigh - 𝜃shank I 𝜃𝑅𝐸𝐹 = 𝜃1 Thigh Segment II 𝜃𝑅𝐸𝐹 = 180° + 𝜃2 Hip Angle: III 𝜃𝑅𝐸𝐹 = 180° + 𝜃3 Thigh Segment 𝜃hip = 𝜃thigh - 𝜃trunk Trunk Segment IV 𝜃𝑅𝐸𝐹 = 360° + 𝜃4 6  Calculating Segment/Joint Angles: Method 2 Vector Magnitude: 𝐴 = 𝑥2 + 𝑦2 Dot Product: 𝐴 ∙ 𝐵 = 𝐴 𝐵 cos 𝜃 𝐴 ∙ 𝐵 = 𝐴𝑥𝐵𝑥 + 𝐴𝑦𝐵𝑦 Cross Product: 𝐴 × 𝐵 = 𝐴 𝐵 sin 𝜃 𝐴 × 𝐵 = 𝐴𝑥𝐵𝑦 − 𝐴𝑦𝐵𝑥 7 Image Source: https://csb-scb.com/  Practice Question 1: Segment and Joint Angle Given the following 2D motion capture position data, calculate… A) the segment angle of the shank (6,16) B) the segment angle of the thigh C) the joint angle of the knee thigh (9,11) Hip = (Hx, Hy) = (6,16) knee Knee = (Kx, Ky) = (9,11) Ankle = (Ax, Ay) = (3,0) (3,0) shank 8  Try it out! To be solved in class 9  Extra Practice Question 2: Segment and Joint Angle Given the following 2D motion capture position data, calculate… A) the segment angle of the foot B) the segment angle of the shank C) the joint angle of the ankle (6,4) Knee = (Kx, Ky) = (6,4) Ankle = (Ax, Ay) = (5,2) (4,2) Toe = (Tx, Ty) = (5,0) ankle (5,0) 10  Marker-Based Motion Marker-Based Motion Capture (MoCap) Recording movement using camera system and markers to represent anatomical positions Requires: Camera system Markers Processing software 11 Image Source: https://engcourses-uofa.ca/books/ortho/gait-analysis/  Marker-Based Motion Capture Pros Cons High-accuracy in movement tracking Expensive system Precise joint angles and kinematics Skin motion artifact Reliable and established technology Limited to laboratory set up Robust and controlled collection environment Limited in anatomical positioning/interpretation 12  Marker-Based Motion Capture Pros Cons High-accuracy in movement tracking Expensive system Precise joint angles and kinematics Skin motion artifact Reliable and established technology Limited to laboratory set up Robust and controlled collection environment Limited in anatomical positioning/interpretation What if we want to track motion in “real life”? 13  Marker-Based Motion Capture Pros Cons High-accuracy in movement tracking Expensive system Precise joint angles and kinematics Skin motion artifact Reliable and established technology Limited to laboratory set up Robust and controlled collection environment Limited in anatomical positioning/interpretation What if we want to track motion in “real life”? What if we want to track motion of small joints? 14  Markerless Motion Capture – Camera System Camera Setup: Multiple cameras are positioned around the subject to capture 2D or 3D video data from different angles Image Processing: Software analyzes the images to detect and track key points on the human body (e.g., joints or body parts) by recognizing shapes, contours, and movement patterns Application: Sports/Performance during dynamic movement Real time coaching/feedback Rehabilitation Assessment of movement during daily movement Clinical inferences/treatment plan 15 Image source: https://freedspace.com.au/tracklab/products/brands/theia3d/  Markerless Motion Capture – Camera System Pros Cons Flexibility of environment Lower accuracy in movement tracking Ease and lower cost of system Computationally demanding Great for gross motor analysis and general Limited precision feedback No physical markers → less movement Limited clinical application restriction 16  Markerless Motion Capture Fluoroscopy Fluoroscopy is an imaging technique that uses X-rays to obtain real-time moving images of the internal structures of the body Process: X-ray Source: A continuous X-ray beam is directed at the body from one side. Image Detection: On the opposite side of the body, a detector captures the X-rays that pass through the body. Utility: Imaging/interaction of small joints E.g. intervertebral, foot/ankle, etc. 17 Image Source: https://www.twomeyconsulting.com/learn/fluoroscopy; https://www.osmosis.org/learn/Joints_of_the_ankle_and_foot  Markerless Motion Capture Fluoroscopy Pros Cons Assessment of small joints/interactions Radiation exposure Joint kinematics in-vivo Expensive set up and limited availability Minimally invasive Limited field of view Guidance for complex procedures Limited soft tissue interaction/detail 18  Fluoroscopy 19 Image Source: Unpublished data from Clinical Movement Assessment Lab; Work by Ben Lutzko 2024  Fluoroscopy 20 Image Source: Unpublished data from Clinical Movement Assessment Lab; Work by Ben Lutzko 2024  Assessing Movement - Quantifying Joint Loads In-vivo Inverse dynamics Force Transducer/Strain Gauge Finite Element Analysis In-vitro Donor/Cadaveric 21 Image Source: Dijkstra et al., 2015; J. Biomech. 48(14) 3776-3781; : Zhang, et al., 2016. Sci Rep 6, 35493; Unpublished data from the Bone Imaging Laboratory 2024  Inverse Dynamics Inverse dynamics is a computational technique used in biomechanics to calculate the forces and moments acting on a system based on observed motion or force plate data. Calculates the internal forces and torques required to produce a given motion Allows for estimate of the internal forces (e.g., joint forces) and moments within a body segment 22 Image Source: Dijkstra et al., 2015; J. Biomech. 48(14) 3776-3781  In-vivo: Force Transducer A force transducer is a device used to measure the force applied to an object and convert it into an electrical signal that can be quantified. A strain gauge is a key component used in many force transducers. It is a sensor that measures the strain (deformation) of an object when a force is applied. Used to measure forces in-vivo Highly invasive Image Source: https://www.researchgate.net/figure/Intraoperative-experimental-setup-A-Achilles-Tendon-is-exposed-under- 23 general_fig1_369030369  In-vivo: Force Transducer Applications Bone and Joint Force Measurement: Force transducers can be implanted or attached to bones or joints to measure forces during movement Providing insight into joint health, alignment, and potential for injury Muscle Force Measurement: Force transducers can measure the forces generated by muscles during contraction. This can help evaluate muscle performance, fatigue, and recovery in response to therapy Implant Monitoring: Force transducers can be embedded in prosthetic devices or joint implants (e.g., artificial hips or knees) to monitor the mechanical stresses they experience during use, helping to detect abnormal wear or failure Image Source: https://www.researchgate.net/figure/Intraoperative-experimental-setup-A-Achilles-Tendon-is-exposed-under- 24 general_fig1_369030369  In-vivo: FEA Finite Element Analysis (FEA) is a computational technique used to simulate and analyze the mechanical behavior of structures and systems by breaking them down into small elements Used to simulate/estimate the mechanical behavior of bones and joints under various loading conditions (e.g., walking, running, or lifting) Useful in understanding… stress distributions bone remodeling joint degeneration bone strength and failure load 25 Image Source: Unpublished data from the Bone Imaging Laboratory 2024  In-vitro Cadaveric/Donor specimens provide invaluable insight into the structure, function, and mechanical behavior of biological tissues, joints, and systems in ways that cannot be replicated using in-vivo models or simulations alone. Benefit: Allow for direct study/testing Can test to failure Inform in-vivo models with “ground truth” 26 Image source: Zhang, et al., 2016. Sci Rep 6, 35493; https://smart.servier.com/  Joint Health Issues Injury Disease Degradation 27 Image Source: https://smart.servier.com/  Categories of Joint Health Joint Injury: Damage or trauma to the joint E.g., sprains Not often seen in isolation Joint Degradation: Large overlap and intersection Progressive breakdown/wear of the tissue Injury/disease→ degradation/disease E.g. osteoarthritis ACL tear → post traumatic osteoarthritis Joint Disease: Conditions that affect the health of the joint E.g., Marfan syndrome 28  Ligament Injury - Sprain Grade 1 A sprain is a stretch or tear in a ligament classified based on severity of damage: Grade 1 (Mild): A slight stretch or minor tear in mild pain and swelling no joint instability. Grade 2 Grade 2 (Moderate): A partial tear Moderate pain, swelling, bruising Some joint instability. Grade 3 (Severe): A complete tear or rupture Substantial pain, swelling, bruising, and Grade 3 difficulty moving the joint Significant joint instability 29 Image Source: https://smart.servier.com/  Ligament Injury - Tear Ligament tears can either be partial (some of the ligament fibers are torn) or complete (ligament is fully ruptured) A complete tear often requires surgical repair, especially if it results in joint instability. Common: ACL → cutting/pivoting MCL → twisting/lateral impact Ankle/Wrist Shoulder 30 Image Source: https://steveshivelydo.com/services/acl-tears/  Dislocation A dislocation occurs when the bones in a joint are forced out of their normal position, causing a loss of contact between the bone surfaces that make up the joint. Results in joint instability and damage to the surrounding tissues including ligaments, tendons, and muscles Treatment: Repositioning Immobilization Rehabilitation Surgical Intervention 31 Image Source: https://fuchsmd.com/posts/shoulder/3-types-of-shoulder-dislocation-and-how-they-are-treated/  Dislocation - Hypermobility Ehlers-Danlos Syndrome (EDS) is a group of connective tissue disorders that affect the production and processing of collagen, a protein essential for the strength and elasticity of tissues like skin, joints, and blood vessels. Hypermobility Ehlers-Danlos Syndrome (hEDS): Joints can move beyond their normal range of motion Connective tissues (including ligaments and tendons) are more elastic and less stable than in individuals without the condition This laxity in the connective tissues can lead to increase risk and frequency of dislocations/subluxations 32 Image source: https://healthwatch-centralbedfordshire.org.uk/hypermobile-ehlers-danlos-syndrome  Marfan Syndrome Marfan Syndrome is a genetic disorder that affects the connective tissue in the body, leading to a range of symptoms, including issues with the bones, and joints. Mutations in FBN1 gene Encodes fibrillin-1 which is a protein crucial for the strength and elasticity of connective tissues Additional MSK health risks: Tall stature, long limbs, and long, thin fingers (arachnodactyly), curved spine (scoliosis) or a chest deformity (pectus excavatum or pectus carinatum) Flat feet and joint pain due to the overstretched connective tissue 33 Image Source: https://www.mayoclinic.org/diseases-conditions/marfan-syndrome/symptoms-causes/syc-20350782  Fracture at a Joint Joint fractures refer to breaks or cracks in the bones that make up a joint Typically involves the articular surface Can affect any joint in the body, though fractures in the elbow, wrist, ankle, shoulder, and knee are most common Often categorized by their severity, location, and how they impact the surrounding structures Lasting fracture implications: Post-traumatic Osteo Arthritis (PTOA): Joint fractures, especially those involving the articular surface, can lead to early-onset osteoarthritis due to damage to the cartilage or joint surface 34 Image Source: https://orthoinfo.aaos.org/en/diseases--conditions/ankle-fractures-broken-ankle/  Bursitis Bursitis is the inflammation of a bursa, which is a small, fluid-filled sac Bursae reduce friction and cushion contact points between the bones and tendons or muscles around the joints Causes: Repetitive Movement/Overuse Trauma/Injury Infection Health Conditions Age 35 Image source: https://www.thefeetpeople.com.au/symptoms-we-treat/bursitis/  Impingement Joint impingement refers to a condition in which the structures within a joint, such as bones, tendons, or cartilage, become compressed or pinched during movement. Compression can lead to pain, inflammation, and restricted range of motion Typically occurs in ball-and-socket joints like the shoulder or hip “Impingement syndrome" is often used to describe this phenomenon, particularly when it involves chronic irritation of joint tissues 36 Image source: https://orthoinfo.aaos.org/en/diseases--conditions/femoroacetabular-impingement/  Degradation - Arthritis Arthritis is a broad term that refers to inflammation of the joints, leading to pain, stiffness, swelling, and limited range of motion. Examples: Osteoarthritis (OA) Metabolic Post-traumatic Age-related Rheumatoid Arthritis (RA) Ankylosing Spondylitis (AS) Normal joint Osteoarthritis Rheumatoid arthritis 37 Image Source: https://smart.servier.com/  Osteoarthritis Osteoarthritis (OA) is a degenerative joint disease characterized by the breakdown of articular cartilage, changes in the underlying bone, and inflammation of the surrounding tissues. It is the most common form of arthritis and a leading cause of joint pain and disability, especially in older adults. 38 Image Source: https://smart.servier.com/  Osteoarthritis Pathophysiology: Cartilage Degeneration: Cartilage becomes damaged and breaks down over time, leading to loss of joint cushioning. Bone Changes: Subchondral bone (beneath cartilage) becomes more sclerotic, leading to the formation of bone spurs (osteophytes) and changes in joint structure. Synovial Inflammation: Mild inflammation in the synovial membrane can contribute to joint stiffness and pain. Joint Space Narrowing: The space between bones decreases as cartilage wears away. 39 Image Source: https://smart.servier.com/  Post-Traumatic Osteoarthritis Post-Traumatic Osteoarthritis (PTOA) is a form of osteoarthritis that develops after a joint injury. Secondary form of OA that results from damage to the joint structures, such as cartilage, ligaments, and bone, which can lead to abnormal joint mechanics, inflammation, and ultimately degeneration of the joint over time. PTOA comes years following: Fractures Dislocations Ligament injuries (e.g., ACL tears) OA in general is primarily associated with aging and wear-and-tear → PTOA is directly linked to mechanical injury or trauma to the joint disrupts normal joint function and accelerates the degenerative process. 40 Image source: Early, et al. 2021; Front. Immunol, 12. 10.3389/fimmu.2021.695257.  Post-Traumatic Osteoarthritis Methods of Degeneration Cartilage Degeneration Matrix Degradation Chondrocytes are activated in response to injury but may produce enzymes that degrade the extracellular matrix of the cartilage → leads to thinning and loss of function Chondrocyte Death: Prolonged inflammation and mechanical stress can cause chondrocyte apoptosis, further weakening the cartilage Altered Biomechanics Abnormal Joint Load Distribution: Joint injury often alters the normal load-bearing function of the joint. → accelerates cartilage breakdown and promotes the development of PTOA. Subchondral Bone Changes: The abnormal forces on the joint lead to changes in the subchondral bone Becomes sclerotic or develop osteophytes (bone spurs) 41 Image source: Early, et al. 2021; Front. Immunol, 12. 10.3389/fimmu.2021.695257.  Metabolic Osteoarthritis Metabolic Osteoarthritis refers to a type of osteoarthritis that is influenced or exacerbated by metabolic factors, such as obesity, diabetes, and other systemic metabolic disorders. Metabolic OA may result from biochemical changes in the body that impact joint health, particularly cartilage. Contribute to the breakdown of cartilage, synovial inflammation, and other joint changes, even in the absence of significant mechanical trauma 42 Image Source: Sun, et al. (2016); Cur. Rheumatol. Rep. 18. 10.1007/s11926-016-0605-9.  Age-related Osteoarthritis Age-related osteoarthritis is a degenerative joint disease that primarily affects articular cartilage. Most common form of OA and is primarily associated with aging The joints experience wear-and-tear, and the cartilage gradually deteriorates, leading to pain, stiffness, and decreased joint function 43 Image Source: https://smart.servier.com/  Rheumatoid Arthritis Rheumatoid Arthritis (RA) is a chronic, autoimmune disorder that primarily affects the synovial joints, leading to inflammation, pain, and ultimately, joint damage. Unlike OA, RA is caused by the immune system mistakenly attacking the body's own tissues, specifically the synovium Autoimmune reaction → Inflammatory cascade → Synovial proliferation → Bone erosion and joint damage Genetic and environmental risk factors 44 Image Source: https://smart.servier.com/  Ankylosing Spondylitis Ankylosing spondylitis (AS) is a chronic inflammatory arthritis that primarily affects the spine and sacroiliac joints but it can also impact other joints and organs. Systemic inflammatory disease that involves the entheses Sites where tendons and ligaments attach to bone Inflammation in these areas can lead to the formation of new bone → causes the fusion of affected joints, particularly in the spine Genetic and environmental risk factors 45 Image Source: https://my.clevelandclinic.org/health/diseases/ankylosing-spondylitis  Gait Alterations Gait: Pattern of walking or moving on foot Series of coordinated, cyclic movements of the lower limbs, pelvis, and trunk to achieve forward progression Proper gait is essential for joint health Ensures balanced load distribution across joints Abnormal gait patterns can lead to joint pain degeneration altered biomechanics increases risk of long-term musculoskeletal issues 46  Gait Disorders and Abnormalities - Causes Some underlying health conditions that can cause gait abnormalities include: Parkinson’s disease Multiple sclerosis Stroke Arthritis Cerebral palsy Hemiplegia Others 47 Image Source: https://www.footbionics.com/For+Patients/gait_cycle.html  Types of Gait Abnormalities A. Antalgic gait: A limping pattern where the stance phase is shortened to avoid pain E.g., due to hip arthritis A. B. Steppage gait (neuropathic): High stepping to clear the foot E.g., foot drop due to peripheral neuropathy B. C. C. Lurching/Waddle gait: Swaying side-to-side motion, weak hip abductors E.g., muscular dystrophy 48 Image Source: Jun et al 2020; IEEE Access, 8, 139881-139891  Types of Gait Abnormalities D. Stiff-legged and spastic gait (hemiplegic): Stiff leg with circumduction and foot dragging E.g., stroke E. Trendelenburg gait Unilateral weak hip abductors, sideways lean E.g., muscular dystrophy Other Examples: Propulsive gait: A forward-leaning, shuffling gait E.g., Parkinson's disease Scissor gait: D. E. Knees and thighs cross in a scissoring motion E.g., Cerebral palsy 49 Image Source: Jun et al 2020; IEEE Access, 8, 139881-139891  Assessment of Symptoms Using Medical Imaging to Assess Joint Problems Medical imaging plays a crucial role in diagnosing, monitoring, and managing joint problems by providing detailed views of bones, soft tissues, and joint structures. Helps identify the cause of joint pain, detect injuries, and evaluate the severity of degenerative or inflammatory conditions. Provides insight to joint state that cannot be assessed without looking at internal structures and interactions within the joint. Image Source: https://smart.servier.com/; https://www.siemens-healthineers.com/en- ca/computed-tomography; Stern, et al., 2021. Eur Radiol 31, 6793–6801; 50 https://www.medserena.co.uk/mri-scans/limbs-and-joints/knee-mri-scan; : https://www.mskultrasoundinjections.co.uk/post/what-is-a-knee-ultrasound-scan;  Traditional X-Ray Uses ionizing radiation to create images of the inside of the body Tissue attenuation: X-rays pass through the body and are absorbed by different tissues at varying rates Provides contrast between structures of interest Dense tissues (bones) → absorb more X-rays and appear light/white Less dense tissues (muscles and organs) → absorb less X-rays appear darker Good for: bones, generally structure Not good for: soft tissue, nerve damage, joint details cartilage → limited ability 51 Image Source: https://smart.servier.com/ and https://www.shutterstock.com/search/xray-broken-arm  Traditional X-Ray - Assessment Joint Space Narrowing: Reduced space between bones in a joint can indicate cartilage loss (OA) Bone Spurs (Osteophytes): Extra bone growths that form around a joint due to degeneration or injury Fractures or Dislocations: Identifies bone fractures/misalignments in joints that may cause pain Bone Deformities: Abnormal bone shapes or alignment Signs of Inflammation or Infection: Although soft tissues cannot be visualized directly, changes in bone structure or the presence of fluid buildup can suggest conditions like 52 arthritis or infection. Image Source: https://smart.servier.com/ and https://www.shutterstock.com/search/xray-broken-arm  Computed Tomography (CT) CT scans use X-rays and computer processing to create detailed cross-sectional images (slices) of the body. Processed to create detailed images of bones, soft tissues, and blood vessels Compared to traditional X-ray: Higher resolution → more detail Can be compiled into 3D images. Good for: bones, complex fractures, bone abnormalities, surgical assessment, joint alignment Not good for: soft tissue cartilage → limited ability 53 Image Source: TOP: https://www.siemens-healthineers.com/en-ca/computed-tomography; BOTTOM: Stern, et al., 2021. Eur Radiol 31, 6793–6801.  CT - Assessment Bone Fractures and Trauma: Complex Fractures Spinal Fractures Joint Fractures and Dislocations Bone and Joint Conditions: Osteoarthritis Visualize degenerative bone changes like joint space narrowing, bone spurs (osteophytes), and subchondral bone sclerosis Osteoporosis Bone Tumors and Cysts Bone Infections (Osteomyelitis) 54 Image Source: TOP: https://www.siemens-healthineers.com/en-ca/computed-tomography; BOTTOM: Stern, et al., 2021. Eur Radiol 31, 6793–6801.  CT Application: Bone-to-Bone Proximity Analysis Bone-to-bone proximity refers to the distance or spatial relationship between two bones within a joint. Crucial in understanding joint mechanics and the development of conditions like OA, spinal disk degeneration, and other joint pathologies Contact Area Analysis: When bones in a joint are too close together → abnormal pressure points → cartilage degradation/joint stress. Excessive spacing could indicate instability → leading to dysfunction Cartilage Wear: Bone-to-bone proximity can reveal early signs of cartilage thinning or breakdown, as the bones may start to come into contact more frequently due to loss of cushioning 55 Image Source: Marsh et al 2014; Orthop. J. Sports Med. DOI: 10.1177/2325967114541220.  C4-C5 Disc Degeneration Proximity Mapping Left Right [mm] 56 Image Source: Emily Bangsboll 2024 (Unpublished Thesis Data).  Ultrasound A.K.A Sonography Uses high-frequency sound waves to create real-time images of structures inside the body Sound waves are emitted by a probe, which bounces off tissues and returns to the probe Reflected waves are converted into images by a computer Good for: Joint components (tendons, ligaments, bursae) Soft tissue conditions Inflammation, tears, injuries Not good for: Bone imaging Cartilage imaging 57 Image Source: TOP: https://www.mskultrasoundinjections.co.uk/post/what-is-a-knee-ultrasound-scan; BOTTOM: https://theultrasoundsite.co.uk/ultrasound-education/region-specific-ultrasound/knee/  Ultrasound - Assessment Soft Tissue Injuries: Tendon and Ligament Tears Detects partial and full tears in tendons and ligaments, especially usefuly in the shoulder, knee, and elbow Bursitis Tendonopathies and Tendonitis: Assesses the thickness and texture of tendons Joint Effusions: Fluid Accumulation: Detecting and quantifying joint effusions (fluid buildup) Can indicate conditions like arthritis or infection. Guided Aspiration: It is commonly used to guide needle placement for joint aspiration, enabling the safe removal of fluid from a joint. 58 Image Source: TOP: https://www.mskultrasoundinjections.co.uk/post/what-is-a-knee-ultrasound-scan; BOTTOM: https://theultrasoundsite.co.uk/ultrasound-education/region-specific-ultrasound/knee/  Ultrasound - Assessment Inflammatory Conditions: Rheumatoid Arthritis Gout Monitoring Disease Progression: Chronic Conditions OA, RA, etc. Post-Surgical/Post-Injury Monitoring Dynamic Imaging: Movement Assessment: Ultrasound allows for the evaluation of joint movement and real-time imaging of structures as they move Useful in assessing joint instability or abnormal motion (e.g., patellar tracking issues) 59 Image Source: TOP: https://www.mskultrasoundinjections.co.uk/post/what-is-a-knee-ultrasound-scan; BOTTOM: https://theultrasoundsite.co.uk/ultrasound-education/region-specific-ultrasound/knee/  Magnetic Resonance Imaging (MRI) Uses strong magnetic fields and radio waves to create detailed images of the inside of the body, particularly soft tissues The scanner generates a magnetic field that aligns hydrogen atoms in the body, and then radiofrequency pulses are used to disrupt this alignment Atoms align and signal can be measured Good for: Soft Tissue (cartilage, ligament, tendon, etc) Not good for: Bone fracture assessment Bone-only conditions 60 Image source: https://www.medserena.co.uk/mri-scans/limbs-and-joints/knee-mri-scan  Magnetic Resonance Imaging (MRI) Soft Tissue Imaging: Cartilage Damage Ligament and Tendon Injuries Meniscal Tears Joint Degeneration and Arthritis: Osteoarthritis Rheumatoid Arthritis Degenerative Disc Disease Soft Tissue Inflammation and Infection: Bursitis and Tendonitis Infections: particularly when an infection has spread to bone (osteomyelitis) 61 Image source: https://www.medserena.co.uk/mri-scans/limbs-and-joints/knee-mri-scan  Magnetic Resonance Imaging (MRI) Joint Alignment and Instability: Dislocations and Subluxation Post-Surgical Evaluation Bone Marrow Assessment: Bone Marrow Edema Can detect bone marrow edema (swelling), which is an early sign of inflammation or injury is useful in diagnosing conditions like stress fractures, osteoarthritis, or bone infections 62 Image source: https://www.medserena.co.uk/mri-scans/limbs-and-joints/knee-mri-scan  Next Class! Now that we know what a joint is, how joints get injuries and how we assess joint injury, we will learn about joint replacement, surgical interventions and rehabilitation! 63 Surgical Interventions in Joint Injury KNES 363 November 26th, 2024  Overview Joint injuries that require surgery Joint replacements Surgical interventions Rehabilitation Case Studies and applications 2  Surgery Overview 3  Goal of Surgery Restoration of Function: The primary goal is to restore normal or near-normal joint function, allowing patients to perform daily activities with ease. Pain Reduction: Alleviating chronic pain caused by arthritis, injury, or degeneration is a central objective. Improved Quality of Life: Surgery aims to enhance overall quality of life, enabling participation in activities that were previously limited by joint issues. Structural Integrity: Rebuilding or replacing damaged components to restore joint stability and alignment. 4 Image Source: biorender.com  Restoring Range of Motion Pre-Surgery Limitations: Injuries or degenerative conditions can severely restrict motion due to pain, swelling, or mechanical blockages. Post-Surgery Improvements: Surgical interventions, such as arthroplasty, aim to maximize range of motion by removing impediments (e.g., osteophytes) and optimizing joint mechanics. Factors Affecting Outcomes: Rehabilitation Implant design Pre-existing tissue 5 Image Source: biorender.com  Pain Reduction Pre-Surgery Pain Sources: Chronic pain stems from joint inflammation, cartilage loss and bone-on-bone contact, or impingement. Mechanisms of Relief: Surgery eliminates or minimizes these pain sources through: Resurfacing damaged cartilage (e.g., arthroplasty). Replacing bone surfaces with smooth prosthetic materials. Fusing joints to prevent painful motion (as in spinal fusion). Post-Surgical Outcomes: Most patients report significant pain reduction, although some experience residual discomfort or complications. 6 Image Source: biorender.com  Surgical Techniques Traditional Techniques: Large incisions and open access to the joint. High visibility for precise placement but longer recovery. Minimally Invasive Surgery: Smaller incisions and less tissue disruption. Benefits: Faster recovery, reduced pain, smaller scars. Robotics in Surgery: Robotic arms assist in precise bone cutting and implant placement. Examples: Mako for knees and hips. Mako Robotic-Arm Assisted Surgery System 7 Image Source: biorender.com  Surgical Intervention Methods for Joint Health 8  Arthroscopy Definition: Minimally invasive surgical technique using an arthroscope (camera) and small instruments. Examples: Knee: Meniscal repair, ligament debridement. Shoulder: Labral repair for instability or rotator cuff tears. Hip: Femoroplasty for impingement. Benefits: Faster recovery, reduced postoperative pain, minimal scarring. 9 Image Source: https://www.healthdirect.gov.au/arthroscopy  Reconstruction/Grafts Definition: Replacement of a completely torn ligament with graft tissue to restore stability and function. Indications: Severe ligament damage, such as ACL tears or chronic instability. Graft Types: Autografts: Patient’s own tissue (e.g., patellar tendon, hamstring). Allografts: Donor tissue, often used in revision surgeries. Procedure: Graft is fixed to bone at the ligament attachment points using screws or sutures. Biomechanical Goals: Restore joint kinematics and resist shear forces during movement. Rehabilitation: Focus on protecting the graft while rebuilding strength and range of motion (6–12 months). 10 Image Source: https://i0.wp.com/www.tristate-ortho.com/wp-content/uploads/2023/12/graft-options- e1703088026813.webp?ssl=1  Emerging Techniques Robotic-assisted surgery: Improved precision and outcomes. 3D printing: Customized implants for unique anatomies. Tissue engineering: Biomechanically similar cartilage replacements. 11 Image Source: https://www.yourpelvicfloor.org/conditions/robotic-assisted-laparoscopy/; https://www.wevolver.com/article/custom-3d-printed-medical-devices-trends-and-opportunities  Joint Health Surgeries 12  Ligament Repair Definition: Surgical or nonsurgical treatment to restore the structure and function of a damaged ligament. Indications: Partial ligament tears, instability, or acute injuries. Techniques: Primary Repair: Suturing the torn ligament directly Augmentation: Reinforcing with sutures or additional material. Examples: Ulnar collateral ligament (UCL) repair in the elbow. Lateral ankle ligament repair for chronic instability. Recovery Considerations: Immobilization followed by gradual return to activity. 13 Image Source: Sun et al. 2020; J. Ortho. Surg. 12(2)  Ligament Reconstruction Common Procedures: ACL reconstruction in athletes. Ulnar collateral ligament (UCL) reconstruction in baseball pitchers. Graft Choices: Autografts: Patient’s own tissue (patellar tendon or hamstrings). Allografts: Donor tissue, often used in revision surgeries. Biomechanical Challenges: Re-establishing normal kinematics and preventing graft failure. 14 Image Source: https://vishalpai.com.au/acl-surgery  Cartilage Repair Techniques: Microfracture: Drilling into subchondral bone to stimulate cartilage growth. Autologous Chondrocyte Implantation (ACI): Harvesting, culturing, and reimplanting patient’s cartilage cells. Osteochondral Autografts/Allografts: Transplanting cartilage with underlying bone. Challenges: Poor integration with surrounding tissue. Limited durability of repaired cartilage under high stress 15 Image Source: https://www.rjah.nhs.uk/our-services/cartilage-cell-transplantation/  Tendon Repair Definition: Surgical repair of torn tendons to restore continuity and function. Indications: Complete tendon ruptures (e.g., Achilles, rotator cuff). Techniques: Open Surgery: Traditional method with direct visualization. Minimally Invasive: Arthroscopic or percutaneous techniques for less scarring and faster recovery. Procedure: Torn tendon ends are sutured together or reattached to the bone. Biomechanical Challenges: Maintaining strength while minimizing tension to allow proper healing. Rehabilitation: Progression through immobilization, passive motion, and gradual strengthening over several months. 16 Image Source: https://www.footdoctorpodiatristnyc.com/procedures/achilles-tendon-surgery/  Joint Dislocation Repair Definition: Realignment of a displaced joint to restore normal anatomy and function. Indications: Acute dislocations, recurrent instability, or associated fractures. Techniques: Closed Reduction: Manual manipulation to realign the joint without surgery. Open Reduction: Surgical intervention for complex or irreducible dislocations. Common Sites: Shoulder, hip, knee, and fingers. Rehabilitation: Preventing stiffness through early motion exercises while protecting the joint with braces or slings. 17 Image Source: http://thelondonshoulderpartnership.co.uk/shoulder/shoulder-surgery/acromioclavicular-joint-stabilisation-delayed-chronic/  Joint Replacements 18  Joint Replacements Definition: Surgical procedure to replace a damaged joint with a prosthetic implant to restore mobility and relieve pain. Commonly replaced joints: Hip: Total hip replacement for conditions like osteoarthritis or femoral neck fractures. Knee: Total or partial knee replacement for osteoarthritis or rheumatoid arthritis. Shoulder: Total shoulder arthroplasty for degenerative joint disease or trauma. Indications: Severe pain unresponsive to conservative treatments. Joint deformity or functional limitations. Traumatic injuries leading to joint damage. 19 Image Source: biorender.com  Joint Replacement Materials and Design Materials Used: Metals: Titanium and cobalt-chromium alloys for durability and strength. Polymers: Polyethylene for smooth articulation and wear resistance. Ceramics: Alumina or zirconia for low wear rates and biocompatibility. Design Features: Anatomically shaped components for natural movement. Cemented vs. cementless fixation options (bone ingrowth vs. adhesive bonding). Modular designs to allow custom fit for individual anatomy. Biomechanical Properties: Must mimic natural joint motion while withstanding forces like compression, tension, and shear. 20 Image Source: https://www.franklinorthopedics.com/about/education.stryker_brochures.english.total_hip.5.php  Stress Shielding When an implant reduces the amount of stress on a bone, causing bone density to decrease In healthy bone stress is transmitted through the trabecular then down through the cortical bone (top left) If modulus of implant material is too high, the implant will bear most of the stress (bottom left) The reduction in bone stress/strain results in bone resorption and implant loosening (bottom right) 21 Image Source: Muhamad et al., (2022) Journal of Materials Research Technology, doi:10.1016/j.jmrt.2022.01.050.  Types of Replacement Partial Joint Replacement: Replaces only one side of the joint. Example: Unicondylar knee replacement. Total Joint Replacement: Replaces all articulating surfaces. Example: Total knee arthroplasty (TKA) with femoral, tibial, and patellar components. Examples by Joint: Hip: Total hip arthroplasty (THA) vs. hemiarthroplasty. Shoulder: Anatomic vs. reverse shoulder replacement. 22 Image Source: https://orthoinfo.aaos.org/en/treatment/total-joint-replacement/  Longevity Success Rates: Generally high patient satisfaction, particularly for pain relief. Lifespan of Implants: Typical lifespan: 15–20 years. Wear rates influenced by activity level, implant material, and surgical technique. Complications: Implant loosening, infection, wear