10 - Biomaterials and Implants

Question 1

Biomaterials

Answer 1

Biomaterials are those products that are brought into contact with body tissues 
o	Compatible
o	Facilitate Surgery
o	Minimize Complications
o	Improve Results

Question 2

Injectable silicone

Answer 2

• Soft tissue replacement
• Uses: Heloma, tyloma, neurotrophic ulcers
• Disadvantages: Migration

Question 3

Injectable collagen

Answer 3

• Matrix for fibroblasts and vascular ingrowth
• Uses: Diabetic foot ulcers
• Disadvantages: Expensive, short acting

Question 4

Silastic sheeting

Answer 4

• Prevents scarring and adhesions
• Uses: Tendon Repair
• Example: posterior tibial tendon has a tendon sheath and if there is a rupture of the tendon that you need to repair, there is a possibility that scar tissue would attach the tendon to the tendon sheath, so you wrap the repaired tendon in this sheeting

Question 5

Bovine collagen bioprosthesis

Answer 5

• Tendon graft procedures can utilize a silicone “Hunter Tendon Graft” (xenograft)
• Uses: Stabilization procedures and tendon repairs
• Example: patient with peroneus longus rupture in the middle of the osseous tunnel in the arch of foot over to base of 1st metatarsal, use it to keep osseous tunnel open during tendon repair

Question 6

Polyolefin

Answer 6

• Polyethylene and Polypropylene
• UHMWPE
• STA-Peg/STJ Arthroereisis
• Disadvantages: Creeping and Damage

Question 7

Hydroxylapatite

Answer 7

• Coral (from the ocean) used for bone grafts
• Acts as a trellis for osseous ingrowth, but it takes a very long time for the body to “resorb” the coral and make it part of itself

Question 8

Dacron and gortex mesh grafts

Answer 8

• Synthetic fiber used to prevent adhesions, surgical repair of ruptured tendons and ligaments, entubulation and vascular grafts (not used that much in podiatry)
• Gortex mesh is used more for abdominal/vascular surgeries for abdominal wall or gortex vessels

Question 9

Acrylic polymers

Answer 9

• Polymethylmethacrylate(PMMA) – used a lot in dental procedures (“bone cement”)
• Undergoes an exothermic reaction (gets warm)
• Uses = bone cement implants (orthopedics), PMMA antibiotic beads (wound packing-podiatry)

Question 10

Silastic gel sheeting

Answer 10

Reduces or softens hypertrophic scars, place directly on the scar
o Gel sheet (Neosporin) can be placed over scar to reduce scarring (actually works, OTC)

MOA is unknown

Not to be used on open wounds

Question 11

Hemostatic agents = KNOW FOR EXAM

Answer 11

Definition = things that we can use to decrease bleeding during surgery
o If patient is bleeding so much that you can’t see what you’re doing, it is a problem

Types
o Topical Thrombin (“Thrombostat”), Absorbable Gelatin Sponge, Microfibrillar Collagen, Oxygen-regenerated Cellulose, Bone Wax, Drains

Question 12

Topical thrombin

Answer 12

• “Thrombostat”
• Bovine protein which clots the fibrinogen of blood
• Applied, not injected
• Some concerns for patient sensitivity to product

Question 13

Absorbable gelatin sponge

Answer 13

• “Gelfoam” –> looks like the green blocks for fake flowers
• Purified animal protein
• Liquefies in 2-5 days, Absorbed in 4-6 weeks
• Used for the treatment of ulcers (if you’re debriding and get a lot of bleeding, you can pack it)

Question 14

Microfibrillar collagen

Answer 14

• “Avitene”
• Adheres to blood soaked surfaces and attracts platelets
• Does not interfere with bone healing, but causes an inflammatory response
• Autologous Platelet Gel
  o Within patient, randomized, single-blind controlled trial
  o No change in recovery time or pain

Question 15

Oxygen-regenerated cellulose

Answer 15

• “Surgicel” – regenerated cellulose, can be used if patient did not want any animal products
• Absorbable fabric
• Provides hemostasis through absorption
• May inhibit bone healing

Question 16

Bone wax

Answer 16

• Provides hemostasis through tamponade (“seals over” bone)

- Inhibits bone healing – that’s a good thing if you just removed a bone spur

Question 17

No drain, no brain

Answer 17

Advantages: evacuate fluid, prevent hematoma, reduce pain, increase healing, help prevent infection
o Tube goes into surgical site in order to evacuate blood from the wound
o Blood buildup provides the perfect environment for bacterial growth

Disadvantages: possible infection, maintenance
o Double-edged sword – tube and open wound in skin increases risk of infection as well

Question 18

Drains

Answer 18

Gravity drain
o Penrose Drain - Uses a piece of gauze in the incision, gravity drains it

Closed Suction drain
o TLS (small tube), Hemovac (large tube), Jackson-Pratt (large tube)
o TLS = “tiny little sucker” – little tube that has a vacuum in it, used for small surgical sites

Closed Suction Irrigation
o Ingress-Egres (it is inside the skin – a drain that can be seen on x-ray)