Joint Replacements

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Joint Replacements

• Causes
• Trauma
• Osteoarthritis
• Reumatoid Arthritis
• Indication for Surgery
• Severe Pain
• Severe Deformation (knee in particular)
• Risks
• Infection,
• Mechanical Failure (loosening etc.)

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Joint Replacements

• The Joint Surface Problem (tribology)
• The lubrication problem
• Synovial fluid has to be the lubricant
• Artificial joint does not employ the same
  hydrodynamic mechanism
• How does a bearing work (hydrodynamics)
• The wear debris and their consequences
• The interface problem

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Hip Mechanics and Standing Posture
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Shock Absorption of the Joint

• Strictly essential in the lower limb joints, to
  protect the bone implant interface
• Cartilage Hydrodynamics in the Biological joint
• Metal-UHMWPE (plastic)

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Bone Morphology
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Hip Mechano-Morphology
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Bone Disease Osteoporosis

• Normal Bone

Osteoporosis
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Osteoporotic Femoral Head

• Normal Hip

Osteoporotic Hip
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Hip Fractures (From Howmedica)
Over 250,000 hip fractures occur in the United
States annually. 90 of these are in patients
over 50 years old. With the growing aging
population, the number of hip fractures is
expected to double in less than 50 years.
Types of hip fractures include femoral neck
fractures and fractures of the intertrochanteric
and subtrochanteric regions. Femoral neck and
intertrochanteric fractures occur with equal
frequency and account for over 90 of all hip
fractures. The remainder are subtrochanteric
fractures. Treatment options range from internal
fixation to total joint replacement.
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Severity Based on Fracture Site
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Subcapital v. Per-Trochanteric
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Gardens Classifications of Hip Fractures
Type I fractures have the best outcome. The bone
ends are impacted into one another, which
facilitates vascular re-growth.
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HIP FRACTURE SOLUTIONS
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OMEGA PLUS COMPRESSION FEMORAL SCREW SYSTEM
The Complete System for Faster, Easier Surgery.
The Omega Plus CHS System includes such features
as sideplates made of superstrong alloy material,
improved instrumentation, and the unique 98o
ergonomically designed Supracondylar Plate which
conforms to distal condyles with minimal
contouring. Omega Plus plates and lag screws are
available in sterile or non-sterile packaging for
customer preference and convenience.
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The Austin Moore Hip Implant
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Nailing the Head-Neck
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Hip Replacement
If there is damage to the acetabulum the patient
may require a Complete hip replacement.
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Hip Joint Prosthesis
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The Bone-Prosthesis Interface

• Long stem in hip and elbow prostheses
• Short stem in knee
• Method of fixation
• Acrylic bone cement
• Simple contact (contour congruency)
• Porous technology

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Composite Beam (two materials)

• For the beam to bend as one it should transmit
  shear
• If one material is much more rigid it bears most
  of the stress
• Preference in prosthetics is to have materials
  with rigidity similar to bone

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Criteria to be Observed

• Minimal bone removal
• Mechanical compatibility (adjustment of
  compliance, Youngs moduli etc.)
• Avoid stress concentration
• Avoid stress shielding
• Provide for easy extraction?? In case of revision
  surgery
• Anything else??

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Fracture Fixation Examples of Fractures

• Simple fracture
• Displaced fracture
• Comminuted fracture
• Long bone fracture
• Vertebral fracture
• Rib fracture
• Clavicular fracture

• Pelvic fracture
• Radial fracture
• Finger fracture

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Bone-Plate Fixation

• Dynamic loading required
• Double plating may produce stress shielding
• Care is needed with the periosteum
• In some cases, compression plate is preferred

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Bone Plates Cont.

• In the epiphyseal region more screw support is
  needed
• Nail-Plate combination

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Intramedullary Nailing

• Femoral nail vs. plating

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Intramedullary Nailing
http//www.smithnephew.com/orthopaedics/products.
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The Knee Goes BadRadical Solution Tibio-Femoral
Fusion
Knee Arthrodesis
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Total Knee Arthroplasty
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Bone Preparation for Total Knee Arthroplasty
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Procedure of Total Knee Arthroplasty
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Cemented versus Cementless Total Knee Arthroplasty
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Radiographic Imaging of Total Knee Arthroplasty
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Prosthetic Knee
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Hinge Knee Joint
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Artificial Knee
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Knee
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Hoffman External Fixator
Based on the long-standing tradition of the
original Hoffmann Fixator, the new Hoffmann II
design provides today's surgeon with advanced
technology and ease of application. The new
spring loaded snap fit mechanism allows the easy
connection of 8mm connecting rods or pins
providing versatile intraoperative frame
management and excellent stability. The system
allows independent pin placement of 4 or 5mm Apex
Pins and is ideally suited for proximally or
distally located fractures. The system is
designed with versatile and simple instruments
with a single wrench that fits all screws. A
multi pin clamp is designed to accept the same
pin placement as the original Hoffmann with
single or bi-lateral torx connections allowing 12
angular positions for a compact frame design.
http//www.howmedica.com/
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External Fixator
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Monotube External Fixator
http//www.howmedica.com/
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Fracture Fixation
http//www.howmedica.com/
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Bone Lengthening
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Arm Fractures Fixation
Bridging
Radial Fracture
http//www.howmedica.com/
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Pelvic Fracture
External Fixation
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Ligament Rupture
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Bioresorbable Materials
Stimulan, medical grade calcium sulfate
dihydrate and stearic acid, is an osteoconductive
material used to fill bone voids in non weight
bearing applications that resorbs and is replaced
with bone during the healing process. Stimulan is
indicated for uses in cases where there is a bony
defect or void in the boneTraumaSpinal fusions
Revision SurgeryInfected JointsCore
DecompressionsOsteoporosis
Advantages of Stimulan Predictable, consistent
resorption ratesEliminates need for second
surgical site and added pain for patient that
occurs with traditional autograft techniqueCost
and time savings per procedure over
autograftOsteoconductive material that acts as
scaffolding for new bone to formEliminates risk
of disease transmission and availability of
quality bone present with traditional allograft
techniqueProven dissolution rates
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Bioabsorbable ACL Cross Pin
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Bioabsorbable Screws
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Femoral Neck Fracture FixationProximal Femur
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The Shoulder Bones
Coracoid Process
Clavical
Acromion
Humerus
Scapula
Glenoid Cavity
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Ligaments of the Shoulder
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Muscles (Posterior Anterior)
Supraspinatus
Supraspinatus
Infraspinatus
Subclavius
Subscapularis
Teres Minor
Lattisimus Dorsi
Teres Major
Teres Major
Deltoid
Deltoid
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Noel PinsInter Trochanteric Nail
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Supracondilar Plate
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Proximal Tibia
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Carpal and Finger Plates
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The Spinal Segment
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Harrington Rod
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Spine Posterior
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Spinal Implants

• Isobar TTL Posterior Spinal System
• System allows the use of either "U" Screws or
  Hemispherical Screws with Offset Clamps Unique
  Claw Hooks provide firm and secure fixation The
  Monobloc Clamps allow the screws to be positioned
  according to the anatomy Screws are available in
  multiple sizes to accommodate all patient anatomy
  Rigid and Semi-Rigid Rod options are available to
  cover a wide variety of surgical indications A
  unique instrument prevents cross threading of the
  Blocker Nut when applied on the "U" Screws or Hook

http//www.encoreortho.com/products.html
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Spinal Implants
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Intervertebral Cage

• CC Lumbar Intervertebral Cage System
• The material, PEEK, has a modulus of elasticity
  close to that of bone, improving the
  biomechanical interface The radiolucent design
  allows direct visualization of the
  osteogenesisThe superior and inferior surfaces of
  the device are notched to achieve stabilization
  of the implants within the vertebral endplatesThe
  cages are available in straight and lordotic
  designs in order to replicate the normal anatomic
  lordosis of the lumbar spineCages are available
  in five thicknesses to accommodate a wide range
  of anatomy
• This product is not yet approved to sell in the
  United States.

http//www.encoreortho.com/products.html
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Spinal Interbody Fusion
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Zigomatic Fracture Fixation
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Distal Tibia
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Proximal Radius-Ulna Fracture Plates
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Distal Radius and Distal Ulna
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Distal Humerus
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See you next time