this presentation is for educational purpose ONLY presentation.It is about manufacturing,classification and results of uncemented femoral stems

1. UNCEMENTED
FEMORAL
COMPONENTS
Dr Sameer Ashar (M.S.)
Assistant professor,
Orthopaedics,
M.p.shah medical
college,
Jamnagar. 1

2. disclosure
• This presentation is for educational purpose only
• All the copy rights are owned by original authors
2

3. MATERIAL
COBALT CHROMIUM
• ADVANTAGE
• Stronger than titanium
• DISADVANTAGES
• More bone resorption proximally
• Toxic to the body
TITANIUM
ADVANTAGES
• Elastic modulus near to bone
• Better bone growth
• Better tolerated at cellular level
DISADVANTAGES
• Notch sensitive
• Increased risk of fracture
3

4. • For uncemented stem stable fixation is achieve at the time of
implantation depends on
• MACROLOCK- related to implant shape
• MICROLOCK- surface finish
• However ,long term fixation depends on osteointegration
• INGROWTH
• ONGROWTH
4

5. BONE INGROWTH
• Three dimensional structure where bone grows INTO the structure
• Pore size -50-400 microns
• Porosity – 30% to 40 % to maintain mechanical shear strength
5

6. BONE INGROWTH
SINTERED BEADS
• Beads of either Co-Cr or Ti fused to stem with high temperature
• Finite element study has shown that
sintering process reduces the fatigue
strength of stem
• Typical coating thickness is- 1.5mm
6

7. BONE INGROWTH
• Fiber mesh
• The diffusion bonding process -- CPTi wire is cut into predetermined
lengths, compacted, and diffusion bonded to a Ti alloy implant
substrate. overall porosity in the range of 50% can be achieved.
7

8. BONE INGROWTH
• POROUS METALS
• Porous metals have a uniform three
dimensional network, with high
porosity (75% to 85%)
• production - chemical vapor deposition/ infiltration of
tantalum onto a vitreous carbon core that was formed from the
pyrolysis of a thermosetting polymer foam precursor. The
material can be made into a bulk implant of specified size and shape
or it can be used as a surface coating on a solid substrate
8

9. BONE ONGROWTH
• PLASMA SPRAY
• Powder particles of metal are melt at
high temperature and in the presence
of inert gas like Argon(Ag) sprayed
over stem
• Typical thickness is of 0.1 – 0.3 inch
• Processing parameters such as
powder feedstock, gun pressure,
amperage, and voltage can be altered
to modify the physical and mechanical
properties of the coating.
9

10. BONE ONGROWTH
• GRIT BLASTED
• Blasting involves the use
of a pressurized spray of
aluminum oxide particles
to produce an irregular
surface ranging from 3 to
8 μm in depth
• BOMBARDING TO
PRODUCE SURFACE
ROUGHNESS
10

11. HYDROXYAPPETITE
• Applied to implants by plasma spray ,
thickness of the coating is typically 50 to 155
μm.
• Rapid osteointegration
• At 12 weeks bone ingrowth is virtually
identical between two surfaces
• HA coating appears to decrease migration of
components
• The literature reports mixed results with
regard to whether hydroxyapatite coating
improves outcomes, there is no evidence
that it is deleterious.
11

12. CLASSIFICATION
• Harpal S. Khanuja, Jeffrey J. Vakil, Maria S. Goddard, and Michael A.
Mont
• Classified based on geometry, it excludes short uncemented stems
• Future stems may not fit into this classification but this classification
incorporates majority of available uncemented stems with long follow
ups !
12

13. 13

14. TYPE -1
• Single wedge stem
• Engage in metaphysis M-L
• Three point fixation
• Usually fixed with broach
only without distal reaming
• In Dorr type A femur If fits
distally leading to rotational
instability
• e.g..-taper lock, accolade,
14

15. TYPE - 2
• Double wedge
• Proximal cortical contact
in two planes AP and ML
• Involves broaching and
reaming
• Safely used in Type A canal
• E.g..-synergy, summit
15

16. TYPE -3 TAPERED STEM
TYPE – 3A TYPE – 3CTYPE – 3B
16

17. TYPE 4 – extensively coated
• Defined as one with porous coating on more than 80% of its surface
area.
• Solution (AML ,DEPUY ) is most studied implant in this category
• Surface is a powder-made CoCr beaded surface applied through a modified loose
sintering process .
• Beads Size - ranges from 187 to 250 μm.
• Average pore size 250 μm, with a range of 50 to 400 .
• The porosity distribution ranges around 87%.
• The average porosity is 40%.
17

18. • AML is straight, cylindrical, non tapered distal stem geometry.
• Does not depend on
wedge fixation but
fixed with “ scratch fit”
• Canal preparation is
important
• Difficult for type C canal
18

19. TYPE 5-MODULAR
• Have separate diaphyseal and metaphyseal components
• Very useful in altered rotational
malalignment, femoral osteotomy
and dysplasia
19

20. TYPE 6- ANATOMICAL
• Type-6 prostheses are curved, anatomic
stems that match the proximal femoral
endosteal geometry.
• They are wider proximally, both laterally and
posteriorly. In the lateral plane,
they bow posteriorly in the metaphysis and
anteriorly in the diaphysis.
• These stems have anteversion of the neck
and are produced for right or left femora.
Distally, they are either
tapered or cylindrical. Stability is achieved
through metaphyseal fill and the distal curve.
20

21. RESULTS
• TYPE 1 AND TYPE 2
• This stem has been the subject of more published reports than
any other design.it can be safely used in type c canal.
• McLaughlin JR, Lee KR. Total hip arthroplasty with an uncemented tapered femoral component. J Bone Joint Surg
Am. 2008;90:1290- 99% SURVIVAL AT THE END OF 20 YEARS
• Most common compliations –thigh pain ,loosening
21

22. RESULTS TYPE 3
Selected ref. comment
TYPE 3-A
. Lombardi AV Jr, Berend KR,
Mallory TH, Skeels MD, Adams JB.
Survivorship of 2000 tapered
titanium porous plasma-sprayed
femoral components. Clin Orthop
Relat Res. 2009;467:146-54
Kaplan-Meier cumulative survival
with aseptic revision for failure of
ingrowth as the endpoint was
99.4% at 5 years, 99.3% at 10, 15
and 20 years
TYPE 3-B
Wagner H, Wagner M. Cone
prosthesis for the hip joint. Arch
Orthop
Trauma Surg. 2000;120(1-
2):88–95.
• Altered femoral morphology
• idealy good contact between
the bone cortex and the middle
third of the prosthetic stem
TYPE 3-C
Grubl A et al.hip arthroplasty with
a tapered rectangular titanium
stem and a threaded cup:
a minimum ten-year follow-up. J
Bone Joint Surg Am.
2002;84A(3):425–431.
• 202 THA
• 10 years-99 % survival with no
femoral osteolysis
• 15 year-98 % survival with 18 %
varying dgree of osteolysis
22

23. RESULTS TYPE 4
• Belmont PJ Jr, Powers CC, Beykirch SE, Hopper RH Jr, Engh CA Jr, Engh CA.Results
of the anatomic medullary locking total hip arthroplasty at a minimum of
twenty years. A concise follow-up of previous reports. J Bone Joint Surg
Am.2008;90:1524-30.
23

24. RESULTS TYPE 5
24

25. RESULTS TYPE 6
• The first generation of these components performed poorly
• In a recent study of a titanium anatomic stem in 471 patients (601 hips) who had
a mean age of fifty-three years (range, twenty to sixty-two years) and were
followed for a mean of 8.8 years (range, five to twelve years), no components
required revision. There was no thigh pain or radiographic loosening
25

26. TAKE HOME MESSAGE
• Cement less femoral fixation is generally associated with excellent long-
term results.
• Understand the principles, use the most suitable design for a given case.
• No type is completely free of thigh pain or stress-shielding
• Cement less femoral fixation is durable in young patients and has promising
results in MOST OF THE older patients
26

27. THANK YOU
27