Biodegradable implants are made of materials like polyglycolic acid and polylactic acid that degrade over time and are absorbed by the body, eliminating the need for removal surgery. Such implants have been used since the 1960s and are increasingly used in orthopedic procedures of the knee, shoulder, spine, foot and ankle to fix fractures and injuries. While they avoid long-term complications of metallic implants, biodegradable implants may cause delayed inflammatory reactions and currently do not provide as rigid of a fixation as metals. Researchers continue working to develop biodegradable implants that degrade at optimized timeframes and can be used for a wider range of fractures and procedures.

1. BIODEGRA
DABLE
IMPLANTS

2.  The implants which undergo gradual
degradation by biological process and
absorbed and excreted by the body are called
Biodegradable Implants.

3. Why biodegradable implants?
 There will be need for a second operation for
removal of metallic implants,with considerable
additional inconvenience,expense and at some
risk of operative complication.
 This led to the development of so called
biodegradable/bioabsorbable/biologically inert
implants which undergo gradual degradation after
their purpose is being served.

4. HISTORY
 The history of absorbable implants in the
repair of bone tissue began in late 1960’s.
 The first studies were performed in the field
of maxillofacial and mandibular surgery.
 Implants of more complex design,such as
screws and small plates became possible in
late 1970’s and early 1980’s.

5. Types of materials
 Polyglycolic acid
 Polylactic acid
 Polyparadiaxonone
Chemically these compounds
are Alpha polyesters.

6. Structure, strength and
properties
 Polyglycolic acid (PGA) is a hard, tough, crystalline polymer
with an average molecular weight of 20,000 to 145,000 and a
melting point of 224-230°C.
 Polylactic acid (PLA)is a polymer with initial molecular
weights of 180,000 to 530,000 and a melting point of about
174°C.
 In orthopaedic implants Poly-L-lactic acid (PLLA) has been
used more extensively because it retains its initial strength
longer than Poly-D-lactic acid (PDLA).
 PGA belongs to the category of fast degrading polymers, and
intraosseously implanted PGA screws have been shown to
completely disappear within 6 months. PLLA on the other
hand has a very long degradation time and has been shown
to persist in tissues for as long as 5 years post implantation.

7.  Polyglycolic acid and polylactic acid
copolymers in a ratio of 90:10 and
polydiaxonose are used as absorbable
sutures world wide.

8.  The most important characteristic which
determines the behaviour of these polymers is
the glass transition temperature at which the
polymer becomes rigid and brittle.
 This ranges from 58 degree celsius for
polylactic acid and 16 degree celsius for
polypara diaxonone.

9.  The commercially available resorbable
polymers include pure polyglycolic (PGA) acid
in the form of PINS and SCREWS. Pure poly-
l-lactic acid (PLLA) and a co-polymer of PLLA
and PGA.
 They maintain most of their strength for 8
weeks and will completely resorb in the body
in 12–15 months.

12. BIODEGRADABLE
CERAMICS(CALCIUM
PHOSPHATE)
 Uses :
• Repair material for bone damaged with
trauma or disease.
• Void filling after resection of bone
tumours
• Repair and fusion of vertebrae
• Repair of herniated discs
• Repair of maxillofacial and dental
defects
• Drug-delivery

13. KNEE
 It is used extensively for ACL reconstruction in the form of
interference screws and transfixation screws.
 Osteochondral fractures can be well fixed by using
arthroscopic techniques and biodegradable pins.
 Meniscal tacks and biodegradable suture anchors have
opened new avenues for soft tissue reconstruction in
complex knee injuries.
 At 5 years, this bioaborbable interference screw
appeared clinically safe and MRI showedcomplete
absorption and replacement with new bone.

15. Shoulder
 Biodegradable implants provide viable options
for the repair and reconstruction of rotator cuff
tears, shoulder instability, and biceps lesions
that require labrum repair or biceps tendon
tenodesis.
 In a study of arthroscopic Bankart
reconstruction using either PGA polymer or
PLA polymer implants the overall clinical
results.

16. Spine
 Coe and Vaccaro published the first clinical series
using bioresorbable implants as interbody spacers in
lumbar interbody fusion. The clinical and radiographic
results allowed them to recommend the use of
bioresorbable devices in structural interbody support in
the TLIF procedure.
 Bioabsorbable polymer-calcium phosphate composite
cages were implanted in cervical spines; the latter
showed significantly better distractive properties, a
significantly higher biomechanical stiffness, and an
advanced interbody fusion.
.

17. FOOT and ankle
 Self reinforced absorbable implants
in medial malleolar fractures.
 Brunetti et al used bioresorbale
implants in the fixation of
osteotomies for hallux valgus.
 Bioabsorbable implants offer specific
advantages in the foot where
removal of the hardware is
mandatory in some fixations like
syndesmotic disruptions and
Lisfranc’s dislocations.
.

18. Cipro-screw
World’s first antibiotic releasing bioabsorbable fixation device

19. FEATURES OF IMPLANTS
 Tensile and flex strength
are comparable to titanium
plating system ,Plates are
easy to adapt with aid of
heat pack;
 A wide selection of implant
sizes an shapes are
available
 A convenient hex-drive
breakaway delivery system
simplifies screw placement;

20.  Eliminates growth restriction and implant
migration for paediatric craniofacial
reconstruction;
 Resorbs completely and may eliminate the
need for second operation;
 Does not induce late stage inflammatory
Mreaction.

21.  The headed bioabsorbable tissue anchor has
a large thread surface per turn of thread.
 As the anchor is turned into bone for
engaging cancellous bone, the disk-shaped
head engages and anchors the tissue to the
bone.

22. DEGRADATION AND
ELIMINATION
 The implants of polyglycolic acid,polylactic acid or
polydiaxonone are completely absorbable within
the bone tissue and the new bone is deposited on
or within the implant as the degradation proceeds.
 The degradation of these polymers occurs
1.Mainly by hydrolysis
2.And to lesser extent through non specific
enzymatic action.

24.  Factors which influence the degradation process
1.molecular weight
2.crystallinity
3.Thermal history
4.Geometry
Poly-lactic acid copolymers have the slowest rate
of degradation(half-life 6months)
 The co-polymers of polyglycolyic acid and poly
paradiaxonone are much more rapid.
 The principal route of elimination is respirationand to
lesser exent in urine and faeces.

25. DO U KNOW?
 The fact that the interfragmentary
compression cannot be achieved with
polyester pins or rods should be recognized
when the indications for the use of these
implants are being considered.
 Polyester screws do provide compression of
the fracture but are more difficult to insert than
the comparable metallic screws.

26.  Only fractures affecting the cancellous bone can be
managed effectively with the array of implants currently
available.
 At the moment the INDICATIONS for the
biodegradable implants are
1.Radial head Fracture
2.Wedge fractures of the patella
3.Fractures of the proximal and distal ends
of the metatarsals and metacarpals
4.osteochondrosis Dessicans or Osteochondral
fractures of the femur condyle.

27. 5.Ankle Fracture
6.Adult capitellum Fracture
7.Displaced elbow fractures in children
8.Distal radius fracture
9.Pediatric fracture
10.Small fractures or osteotomies.

28.  Bioabsorbable meshes are available for
acetabular reconstructions.
 Bioabsorbable implants are also variously
used in cranio maxillo facial surgery and
dental surgery.

29. ADVANTAGES
1.No irritation of soft tissue
2.No Osteopenia
3.No need of secondary operation to remove
the implants.
4.Useful in pediatric fracture fixation.
5.No interference with the callus formation
and fracture healing.
6.Anti-biotic releasing Bioabsorbable screws
to reduce implant related infecion.

30. COMPLICATIONS
 The unique complication of these implants is
the delayed inflammatory reaction or sterile
inflammatory foreign body reaction.
 The other complications include
1.Failure of fixation
2.Postoperative wound infection

31. CLINICAL PRESENTATION
 The clinical presentation of the delayed sterile
inflammatory reaction is……
 The patient has no local or systemic signs of the
problems with the wound in the immediate post-op
period.,then a painfulerythematous,fluctuant
swelling suddenly develops about the healed
wound.
 The mean interval between the fixation of fracture
and clinical manifesation of reaction is twelve
weeks.

32.  A sinus draining the liquid remnants of the
implant material often form.
 Bacterial cultures of the drainage from the
sinuses are negative.

33. DRAWBACKS
 1.Fixation achieved with these type of implants is
often neither rigid not stable enough to hold the
fracture with motion or weight bearing force before
union.
 2.Cast support and use of cruchtes for lower
extremity fractures has been recommended,which
limits their further use.
 3.Bioabsorbable Implants have excessively low
moduli resulting in backing out of screws
 4.Poor handling characteristics when compared to
metals.

34.  5.The price of 45/50 mm fibre reinforced rod is
approximately 15 times that of a metallic
cancellous screw.
 6.The treatment of diaphyseal fractures of long
bones however would necessitate a larger device
such as a long plate and intramedullary nail,that
has a slow rate of degradation.
 Nevertheless the unsolved problem of
irritation of soft tissue and of osteopenia
beneath metallic plates will continue to
simulate research on absorbable implants.

35. FUTURE
 Resorbable plates can be covalently linked with
compounds such as HRP, IL-2, and BMP-2 and
represents a novel protein delivery technique. BMP-2
covalently linked to resorbable plates has been used to
facilitate bone healing.
 Covalent linking of compounds to plates represents a
noveL method for delivering concentrated levels of growth
factors to a specific site and potentially extending their
half-life.
 An area for future development would have to focus
developing implants that degrade at the “medium term”.
Since the screw that persists in its track for 5 years or
more does not offer the advantage of bioresorbability.

36. THANK
YOU