Orthopedic Implants

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Schematic illustration of thevarious fixation
methods

• direct interference or (passive)
• noninterference fit
• (b) mechanical fixation using
• screws, bolts, nuts, wires, etc.
• (c) bone cement
• (d) porous ingrowth (biological) fixation
• (e) direct chemical bonding
• using adhesives or after coating
• with direct bonding material layer
• (f) bone cement with resorbable particles
• (g) porous ingrowth controlled by using
• electrical or electromagnetic stimulation

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Bone Cement

• Polymethylmethacrylate (PMMA) bone cement
• made from methylmethacrylate,
  polymethylmethacrylate, esters of methacrylic
  acid, or copolymers containing polymethylmethacryl
  ate and polystyrene
• Companies
• Johnson Johnson, Stryker, Zimmer,
• Smith Nephew, Exactech, Heraeus Holding, Biomet

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Examples of currently used surface coatings on
stems ofTHA to enhance both short- and long-term
fixation
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Approximate Average Concentrations (ng/ml or ppb)
of Metal in Human Body Fluids with and without
Total JointReplacements
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Bone Void Fillers

• A resorbable calcium salt bone void filler device
  is a resorbable implant intended to fill bony
  voids or gaps of the extremities (leg hand),
  spine, and pelvis that are caused by trauma or
  surgery
• Homework Find different types of bone fillers?

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Knee degrees of freedom

• Flexion 50
• IE Rotation 25
• AP Translation - 25 mm
• Axial load 4500 N

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Total Knee Replacement

• -Partial knee replacement
• (unicompartmental)
• Replacement of one or two parts of knee
• instead of total.
• Retain more of patient natural knee.
• Total knee replacement
• Resurfaces the bones (tibia and femur)
• with an implant made of metal and
• plastic parts.
• Medical-grade plastic spacer providing
• a smooth surface as cartilage

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The time of TKR

• Step I
• If patients answer yes to any of the questions,
  it may be time to speak with an
• orthopedic surgeon about knee replacement surgery
• 1. Does the knee hurt one or more days per
  week?___Yes___No
• 2. Does the pain interfere with sleep?
  ___Yes___No
• 3. Is it painful to walk more than a block?
  ___Yes ___No
• 4. Are pain medications no longer working?
  ___Yes___No
• 5. Is knee pain limiting participation in
  activities? ___Yes___No
• 6. Has inactivity from knee pain caused weight
  gain? ___Yes___No
• 7. Have you ever received hyaluronic acid
  injections? ___Yes___No
• 8. Would it be possible to limit activities for a
  few months to recover from surgery?
• ___Yes___No
• 9. Are you willing to commit to work hard during
  rehabilitation for a successful
• recovery? ___Yes___No

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Knee joints FDA Approved

• Knee joint femorotibial metallic constrained
  cemented prosthesis
• Knee joint femorotibial metal/composite
  non-constrained cemented prosthesis
• Knee joint femorotibial metal/polymer
  constrained cemented

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Examples of new THA and TKA oxidized zirconium
components currently gaining popularity because
of enhanced mechanical and biocompatibility
properties
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Spinal fixation device
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Ankle Joint Replacement
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Ankle Joint Replacement
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Some ankle prostheses
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FDA Approved

• Metal/composite cemented semi-constrained
• ankle prosthesis
• Metal/polymer cemented semi-constrained
• ankle prosthesis
• Non-constrained cemented ankle prosthesis
• Co-Cr alloy and UHMWPE or UHMWPE carbon fiber
• Companies Johnson Johnson, Stryker, Biomet,
• wright medical technology, Tornier

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Shoulder Joint Replacement
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Shoulder Joint Prosthesis
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Shoulder joints FDA Approved

• Shoulder joint metal/metal or metal/polymer
  constrained cemented prosthesis
• Shoulder joint metal/polymer semi-constrained
  cemented prosthesis
• Shoulder joint metal/polymer non-constrained
  cemented prosthesis
• Shoulder joint metal/polymer/metal
  nonconstrained or semi-constrained porous-coated
  uncemented
• Shoulder joint glenoid (hemi-shoulder) metallic
  cemented prosthesis
• Humeral Metal/Polymer Cemented Or Uncemented

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Elbow Joint Prosthesis
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Wrist Joint Prosthesis
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FDA Approved

• Wrist joint carpal lunate polymer prosthesis
• Wrist joint carpal scaphoid polymer prosthesis
• Wrist joint carpal trapezium polymer prosthesis
• Wrist joint polymer constrained prosthesis
• Proximal AScaphoid, BLunate,
• CTriquetral, DPisiform
• Distal ETrapezium, FTrapezoid,
• GCapitate, HHamate

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Finger joint prostheses
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Finger joint prostheses
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FDA Approved

• Phalangeal (hemi- toe) prosthesis
• Made of silicone elastomer
• Replace the base of the phalanx of the toe
• Companies Wright medical technology, Arthrex,
  Ascension
• orthopedics, Dow Corning
• Polymer constrained toe prosthesis
• Made of silicon or polyester reinforced silicon
• To replace the first metatarsophalangeal (big
  toe) joint
• Companies Biomet, Smith Nephew, Zimmer
  holdings, Dow corning
• Semi-Constrained Metal/Polymer Joint Toe
  (Metatarsophalangeal) Prosthesis
• Companies Ascension Orthopedics, Biomet, Acumed

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Laminoplasty

• A surgical procedure for treating
• spinal stenosis by relieving pressure
• on the spinal cord
• The MOUNTAINEER Laminoplasty
• System is a complete set of implants
• and instruments designed to allow for
• a systematic approach to laminoplasty
• procedures in the cervical spine.
• Stenosis abnormal narrowing of a bodily canal
  or passageway

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Cartilage injuries

• Disease, accidents and age
• Limited repair capability avascular
• Differences in the types of cartilage lesions
• No absolutely approved and perfect method
• Tissue engineering as a new
• treatment method based on
• cells, scaffolds and growth factors

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Methods for Articular Cartilage Repair
orRegeneration
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Limitations

• Needs two surgeries
• Ages 15 to 45
• Defect size (6mm7mm)
• BMI lt 30
• Not used in the presence of
• osteoarthritis, inflammatory
• disease, rheumatoid arthritis
• Not used for patients whose
• knee meniscus has been
• surgically removed

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Application of natural biomaterials
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Commonly Used Scaffolds in Autologous
ChondrocyteImplantation (even distribution and
settlement of cells in the defect)
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Injections for Knee Pains

• Corticosteroid injections for osteoarthritis as
  an antiinflammatory
• treatment
• Hyaluronic acid injections as
  viscosupplementation
• Exercise and simple pain medications no longer
  effectively manage
• knee pain caused by oseoarthritis
• Injections reintroduce healthy joint fluid
• Injections restores cushioning and lubricating
  properties to the knee
• joint
• Orthovisc (high molecular weight hyaluronan)
• FDA approved non-drug therapy
• Made from ultra-pure natural hyaluronan, a
  naturally occuring lubricant
• found in healthy knee joints
• Provide up to six months of pain relief

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Meniscectomy

• Remove the damaged portion of the meniscus
• Starts by making several small incisions in the
  knee, and insertion a
• very small video camera called an arthroscope
• The surgeon watches on a video screen while
  probing the meniscus
• Surgical instruments are used to remove the
  torn portion of meniscus
• A small motorized cutter is used to trim and
  shape the cut edge of the
• meniscus
• The joint is flushed with sterile saline to
  wash away debris from the
• injury or from the surgery
• The entrances are closed with sutures
• Tip
• Special fasteners, called suture anchors, are
  sometimes used to anchor
• the torn edges of the meniscus together for
  younger patients

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PTFE Ligament Prosthesis
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Ligament Repair

• A graft taken either from the individual with
  the injury or a donor
• Small incisions for insertion an arthroscope to
  determine the extent of the injury the
  appropriate surgical procedure
• The torn pieces of the ligament are removed
• The pathway for the new ligament is prepared
• A guide wire is drilled in the thighbone
  (femur)
• A drill is placed over the guide wire and a
  hole equal to the graft size is drilled through
  the bone
• A stitch is connected from the femur to a guide
  wire and this is pulled through predrilled holes
  in the thighbone and shinbone
• Fixation of the surgeons choice is then placed
  in the thighbone
• The new ligament graft is then tensioned and a
  second method of fixation is placed in the
  shinbone to secure the new ligament to the
  surrounding bone
• After reconstructing the ligament, the portals
  are closed with stitches or surgical tape

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Fibrin sealants

• Production of a fibrin clot as an adhesive and
  wound-covering agent
• In synthetic process the fibrinogen is at a
  much higher
• concentration (70 mg/ml) than that in human
  plasma
• After mixing fibrinogen polymerized to fibrin
  monomers and A white fibrin clot is initiated
  under the action of thrombin And CaCl2
• Aprotinin, an inhibitor of fibrinolysis, may
  also be Included in solution A

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Advantages of Fibrin

• It is hemostatic
• It adheres to connective tissue
• It promotes wound healing
• It is biodegradable with excellent tissue
  tolerance

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