Functions Flashcards
Bone (6)
Supports load Protects organs Provide muscle attachments Store calcium Produce Cells Enable hearing
Osteoblasts (3)
Deposit calcium, phosphate and apatite to form bone matrix crystals.
Make collagen fibres and PG.
Can be turned into osteocytes.
Osteoclasts (2)
Secrete H+ to dissolve minerals in bone.
Secrete collagenase to clear protein.
Factors affecting bone mechanics (4)
Loading rate.
Orientation.
Creep.
Age.
Factors affecting trabecular bone adaptation (4)
Number.
Thickness.
Spacing.
Orientation.
Risk of osteoporosis (5)
Age. Genetic (partially). Low peak bone mass. Diet. Physical inactivity.
Treatments for osteoporosis (4)
Calcium supplements.
Bisphosphonates.
Oestrogen replacement therapy.
Exercise.
Internal treatment for fracture (4)
Screws.
Compression plate.
Wires.
Tension banding.
Complications in fracture (4)
Non-union.
Unequal limb length.
Compartment syndrome.
Infection.
Types of cartilage (3)
Hyaline / Articular - in joint surface, thought to be inert.
Elastic - in throat, lots of elastin.
Fibrocartilage - in intervertebral disc / meniscus, can replace articular cartilage in pathological situations
Contents of hyaline cartilage
Collage Type II.
Water.
Proteoglycans.
Aggrecans.
Roles of chondrocytes (4)
Synthesis, modification, assembly and organisation of PG’s.
Synthesis and secretion of collagen.
Degradation and turnover of the matrix.
Balancing anabolic and catabolic activities.
Function of cartilage (3)
Absorbs shock.
Spreads load.
Friction, lubrication and wear resistance.
Factors affecting cartilage mechanical properties (6)
Compression. Tension. Shear. Time-scale (viscoelastic). Permeability. Pressure.
Mechanical testing of cartilage (3)
Indentation.
Unconfined compression.
Confined compression.
Viscoelastic Constitutive Models (3)
Maxwell - spring and dashpot in series, good for relaxation bad for creep.
Kelvin-Voight Body - spring and dashpot in parallel, good for creep bad for relaxation.
Standard Linear Model - combination of above, good for creep and stress relaxation but can’t describe interstitial fluid.
Mechanobiology of cartilage (5)
- Physiochemical Effects.
- Cell deformation.
- Hydrostatic pressure.
- Fluid transport.
- Electrochemical transduction.
Issues with cartilage repair (2)
Low blood supply - no haemorrhage or inflammatory cells.
Lack of cells - limited synthesis of matrix for large damage.
Types of OA (2)
Primary - spontaneous and no known cause.
Secondary - post traumatic from joint injury / obesity / developmental factors.
Risk factors of OA (3)
Genetic - endochondral ossification genes.
Environmental - age/gender/obesity/high bone density.
Biomechanical - injury.
Treatment of OA (5)
Weight loss. Moderate exercise and stretching. Drugs (Analgesics and Non-steroid anti inflammatory) Nutritional supplements. Surgery.
Types of joint (9)
Fibrous - fibrous connective tissue.
Cartilaginous - bones connected by cartilage.
Synovial - Bones connected by fluid filled cavity.
Factors affecting stability of joint (3)
- Bones
- Ligaments
- Muscles
Function of synovial joint (3)
Secretes synovial fluid.
Packing changes shape while moving.
Maintain volume of synovial.
Types of synovial joint (6)
Pivot - C1&C2 vertebra. Hinge - elbow. Saddle - base of thumb. Ball & Socket - hip. Condyloid - proximal wrist. Plane - tarsal bones.
Lubricating components of the synovial joint (2).
Hyaluronic acid and lubricin.
Maintenance components of the synovial joint (2).
Proteinases and collagenases.
Function of fluid in the synovial joint (3)
Lubricate.
Absorb shock.
Supply nutrients and remove waste.
Factors of joint’s low friction surface (2).
- Adhesion of one surface to another.
2. Viscosity of sheared lubricant film between surface.
Lubrication methods (5).
Fluid-film lubrication - low load high velocity.
Mixed boundary lubrication - high load, slow velocity.
Boosted lubrication.
Adsorbed molecules.
Biphasic lubrication.
Requirements for successful implants (7)
Biocompatible. Load-bearing. Long-lasting. Reliable. Revisable. Restore pain function. Relieve pain.
Metals used for joint replacement (3)
Stainless steel.
Cobalt chrome alloys.
Titanium alloys.
Types of joint replacement failure (6)
Wear. Fracture from repeated load. Stress shielding. Failed bonding. Dislocation. Infection.
Advantages of cemented joint replacement (3)
Suitable for osteoporotic patients.
Antibiotics can be added to cement.
Drys quickly.
Disadvantages of cemented joint replacement (2)
Breakdown leads to loosening.
Debris can cause inflammation and enter bloodstream.
Advantages of uncemented joint replacements (2).
No breakdown of cement.
Potentially better long term bond.
Disadvantages of uncemented joint replacements (2)
Needs good quality bone.
Extended recovery of the bone.
Factors affecting performance of joint replacement - Implant (3)
Design details.
Production technology.
Surgical guidelines.
Factors affecting performance of joint replacement - Surgeon (5)
Point at which they operate. Which joint they pick. Pre-planning that occurs. Reeming procedure. Experience in doing surgery.
Factors affecting performance of joint replacement - Patient (5)
Weight and dimensions. Age. Activity level. Musculoskeletal condition. Health condition.
Types of UHMWPE wear (3)
Adhesive
Abrasive
Fatigue
Testing methods of joint replacements (3)
Experimental - cadaveric specimens.
Computer models.
Animal models
Issues with anatomical approach (2)
Complex geometry is tricky to manufacture.
Difficult surgery.
Congruent surface
+ low contact stress so low wear
- high constraint force because restricted movement
Non-congruent surface
+ free movement so less constraint force
- high contact stress so high wear
Contact stress results in…
bone resorption
Constraint force results in…
loosening
Issues with mobile-bearings (2)
More likely to dislocate.
Don’t last as long.
Types of shoulder arthroplasty (4)
Total joint - metal ball and socket.
Hemiarthroplasty - use normal socket.
Resurfacing arthroplasty.
Reverse total arthroplasty.
Types of elbow arthroplasty (3)
Linked.
Unlinked.
Linkable - revision surgery can link or unlink.
Where is the meniscus found? (4)
Temporomandibular joint.
Sternoclavicular joint.
Acromioclavicular joint.
Knee Tibiofemoral joint.
Meniscus tear types (8)
Partial/Complete. Longitudinal. Flap - can't be sutured. Degenerative. Radial - can't be sutured. Horizontal. Bucket Handle Tear. Pedunculated Tag.
Zones of the meniscus (2)
Red zone - periphery of the meniscus.
White zone - nourishment comes from synovial fluid.
Meniscal Replacement (4)
Allograft transplantation.
Artificial.
Collagen Meniscal Implant.
Polycarbonate-Urethane Elastomer.
Role of menisci (5)
Protect cartilage and subchondral bone from excessive loading. Increase the stability of the joint. Joint lubrication. Nutrition from articular cartilage. Assist with prioception.
Causes of menisci tears (4)
Younger patients of a flexed loaded knee.
Squatting.
Associated with an injury.
Degenerative process in older patients.
Symptoms of menisci tears (6)
Pain. Swelling. Clicking. Catching. Giving-way. Locking.
Sections of the spinal column (5)
Cervical C1-C7 - supports head. Thoracic T11-T12 - midback/dorsal region. Lumbar L1-L5 - the lower back. Sacrum - Base of spine. Coccyx - a few small bones.
Parts of the intervertebral disc
Nucleus Pulposus - gelatinous inner region.
Annulus Fibrous - firm and banded outer region.
Cartilage Endplates - between vertebral body and disc.
Forces acting on the spine (5)
Bodyweight. Tension of spinal ligament. Tension in the surrounding muscle. Intra-abdominal pressure. External loads.
COM is ______ to the spinal column when standing
Anterior
Affect of disc degeneration on macroscopic behaviour (3).
Pressure and flexibility affected.
Shear modulus increases 8X with degeneration.
Annulus fibrosis undergoes an increase in compressive and shear moduli.
The hierarchical structure of tendons and ligaments.
Fibrils - Fibres - Subfasicles - Fasciles - Tendon/Ligament
Regions in ligament stress strain curve (3)
Toe Region.
Linear Region.
Yield.
Challenges of mechanical testing ligaments (2)
Short segments.
Slippage.
Cross-sectional measurement techniques for tendons (2)
Contact - callipers, moulding methods.
Non-contact - laser micrometre.
Factors affecting the biomechanics of ligaments (6)
Components. Orientation. Location. Hydration. Temperature. Strain rate.
Effects of ageing on tendons (4)
Stiffness and elastic modulus increase.
No and quality of cross-links increase.
Collagen fibril diameter increase.
Decrease in ultimate load.
Challenges to repair ligaments (4)
Difficult to restore normal function.
Relatively avascular.
Healed tissue needs to be able to glide for active motion - scar tissue leads to adherence.
Other pathology decreases repair ability.
Structure of muscles
Hierarchical. Sarcomere - Myofibril - Fibres - Fascicles - Muscles.
Regular structure to provide consistent force.
Factors affecting force production (3)
Amount of stimulation.
Length of muscle.
The velocity of muscle shortening.
What impacts the greatest force of a muscle contraction (4)
Contraction time
Cross-bridging
Tension in elastic components
Elastic energy stored in actin-myosin cross-bridges
Factors affecting muscle excursion (2)
Length of fibres composing the muscles - fibres shorten around 30% of its length.
Muscles moment arm - smaller moment arm, great excursion.
Muscle fibre types (3)
Type I - slow oxidative. Slow contraction, difficult to fatigue.
Type IIA - fast oxidative. Moderately fast contraction, long-term anaerobic.
Type IIB - glycolytic. Fast contraction, rapidly fatigued.
What affects strength (6)
Stretch of muscle. Contraction velocity. Level of fibre recruitment. Muscle size - PCSA. Fibre type. Muscle moment arm.
Effects of disuse on muscles (4)
Decrease in PCSA.
Muscle shortening (fewer sarcomeres in series)
Changes ratio of Type I and Type II.
Dependent on muscle.
Making a in-silco muscle model determinant (4)
Reduce muscles considered.
Only consider agonist muscle
No co-contraction.
Add equations.
Pitfalls of muscle models (5)
Muscle moment arms change over a range of motion.
Muscle force depends on length and velocity.
Pathological motions may not be optimised.
Datasets vary person-person.
Models are done for convenience.
Factors affecting EMG signal (4)
Cross-talk between muscles.
Changes in geometry between muscles and electrodes.
The impedance of the tissue.
External noise.
Types of ossification (2)
Intramembrane ossification
Endochondral ossification
Functional requirements of the foot and ankle
MUST: Transfer load from lower extremity Withstand high loads Be durable Provide traction for movement IDEALLY Adjust to various terrain Performs at a range of speeds Contributes to propulsion Augments awareness of body and joint position
Risk factors of hallux valgus (8)
Genetics. Age. Sex. Ligament laxity. Congenital abnormalities. Neuromuscular disorders. Excessive loading. Footwear.
Treatment of hallux valgus (5)
Shoe modification. Physiotherapy. Padding / splinters / toe spacers. Insoles. Painkillers.
Surgical treatment of hallux valgus (5)
Exostectomy McBride soft tissue Osteomy Arthrodesis Resection Arthroplasty.
Symptoms of gout (4)
Sudden and severe joint pain.
Joint swelling.
Joint stiffness.
Mild fever.
Risk factors of gout (7)
Age. Sex. Genetics. Meat / Seafood / Alcohol. Drugs Obesity and diabetes. Chronic kidney disease.
Joint fusion treats… (4)
Pain.
Disability.
Decrease function & range of motion.
Instability.
Joint fusion is a result of… (5)
Fractures. Osteoarthritis. Rhuematoid arthiritis Joint Instability Infection
Biomechanical effects of joint fusion in hand (4)
Change in carpal position.
Reduced wrist motion.
Altered force transmission.
Reduced grip strength.
Types of spinal fusion (2)
Posterolateral - Bone graft placed between transverse processes.
Interbody - intervertebral disc removed.
Biomechanical impacts of fusing the spine (2)
Alters load transmission.
Adjacent segment compensate for decreased range of motion.
Categories of disc replacement (8)
Composite. Mechanical. Elastic. Nucleus. Constrained. Semi-Constrained. Unonstrained. Deformable.
Complications of disc replacement (6)
Heterotopic ossification. Migration, loosening and subsidence. Implant of vetebral body fractures. Wear. Adjacent segment degeneration. Osteolysis.
What can cause high strain on Anteromedial Bundle? (4)
Anterior shear forces on proximal tibia.
Knee valgus moments.
Reduced flexion angle.
Strong quads.
Surgical repairs for ACL and a + & - (3)
Allograft: \+ No donor site - High cost, longer incorporation time, properties reduced by sterilisation Autograft: \+ native complex - donor site instability Synthetic Grafts: \+ can control material properties, High UTS, no associated donor site. - difficult to mimick properties.
Locations for ACL autograph (3)
Quadriceps tendon
Patella tendon
Hamstring tendon
