This document discusses the history and evolution of total hip arthroplasty (THA) and hip replacement component designs. It outlines key developments from the late 19th century experiments with ivory and tissue replacements, to modern THA pioneered by Professor Charnley in the 1960s using bone cement and low friction materials. Current designs aim to restore normal hip biomechanics and include cemented or cementless femoral and acetabular components with various fixation methods and bearing surfaces to reduce wear. Future advances focus on minimally invasive techniques, computer navigation, and developing more durable and compliant bearing materials to improve implant longevity.

1. Evolution of
Total Hip
Arthroplasty, and its
design.
Moderator: Dr (Prof) Anil Juyal
Presenter: Dr Tejasvi Agarwal

2.  The Original Intent of Arthroplasty
was to restore motion to an
ankylosed joint.
 Now this concept has been
expanded to include the retoration
as far as possible, of the integrity
and functional power of the
disease joint.

3. Goal of THR
Biomechanically
sound, stable hip joint
by restoration of
normal center of
rotation of femoral
head

4. HISTORY OF HIP
REPLACEMENT SURGERY
 Total hip arthroplasty (THA) has
completely revolutionized the nature
in which the arthritic hip is treated,
and is considered to be one of the
most successful orthopaedic
interventions of its generation.
 In 1891, Professor Themistocles
Glück presented the use of ivory to
replace femoral heads of patients
whose hip joints had been destroyed
by tuberculosis.

5.  Later, in 1917 William
Baer experimented with
interpositional
arthroplasty, which
involved placing various
tissues (fascia lata, skin,
pig bladders
submucosa) between
articulating hip surfaces
of the arthritic hip

6. In 1925, the American surgeon
Marius Smith-Petersen created the
first mold arthroplasty out of glass.
Later- Backelite and Celluloid
derivatives
1937- Vitallium implants
Vitallium was the first non-reactive
metal alloy to be used in orthopedic
surgery.

7. Professor John Charnley
(1911-1982)
A British Orthopedician, Pioneer of
modern hip replacement
Arthroplasty.
Developed the techniques of THR in
1960s.
It consisted of three parts;
a metal femoral stem, a polyethylene
acetabular component and acrylic
bone cement - which was borrowed
from dentists.
It was called the low friction
arthroplasty as Charnley advocated
the use of a small femoral head
which reduces wear due to its smaller
surface area.

8. TOTAL HIP
COMPONENTS AND
DESIGNS

9.  The Primary design goal of restoration of
the geometry and bearing quality of the
hip joint leads to recognition that all THR
devices involves 2 primary components.
 Femoral and Acetabular.
 Each components has 3 elements.

11. Fixation System Design:
 Press Fitting: Direct hard tissue apposition.
Goal is to achieve and maintain local tissue stresses
within a range that causes neither atrophy or
necrosis.
 Cement: PMMA and its variant is used.
 Ingrowth
 Adhesion

13. Total Hip
Components
1.Femoral
Components
(Head+ Neck+
Stem)
2.Acetabular
Components

14. The location of
center of rotation of
femoral head is
determined by
 1. Vertical offset
 2. Horizontal(medial)
offset
 3. Anterior offset
(Anteversion)

15.  MEDIAL RESTORATION
IS SIMPLY CORRECTED
BY MAKING NECK
ADJUSTMENT BUT……
LIMB LENGTH INCREASES

16. VERSION
 NORMAL FEMUR IS
10 TO 15 DEGREE
ANTEVERTED.
 USUALLY
ACCOMPLISHED BY
ROTATING THE
COMPONENT IN
FEMORAL CANAL.
 IF PRESS FIT
FIXATION IS USED –
MODULAR
FEMORAL
COMPONENT IS
USED.

17. HEAD NECK RATIO
 AFFECTS ROM ,IMPINGEMENT,STABILITY OF ARTICULATION.

18. Large Head size
 Increased ROM
 Decreased
Impingement
 Less chances of
Dislocation
 Less wear
 More stability
Small Head size
 Decreased ROM
 Impingement is more
 More chances of
dislocation
 More wear
 Less stability

19. TYPES OF FEMORAL COMPONENTS
The Femoral Component Replaces the natural femoral head portion or all of the femoral neck and bony elements in the proximal femur between Greater and lesser trochanters.
Cemented stems Cementless stems
porous surface
nonporous surface Specialized custom-made

20. CEMENTED STEMS
 Most designers favour- cobalt chrome alloy
PMMA cement is the standard for
femoral component fixation
Disadvantages- Debonding,
Mechanical loosening, Extensive bone loss with
fragmented cement
 Earlier the original Charnley’s component was
about 13 cm long. But current stem design ranges
from 120-150mm.

21. CPT stem:
Collarless, Polished
and tapered.
This design allows
control subsidence
and maintain
compressive stresses.

22. Summit
Stem
Integral Proximal
PMMA Spacer
and additional
centralizer
facilitate proper
stem postioning.

23. Omnifit EON
stem:
Normalized
proximal texturing
converts shear
forces into
compressive
forces.

24. Spectron EF
stem:
Rounded
Recatangular
shape and
longitudinal
groove improves
rotaional stability.

25. 2. Cementless stems with porous surface
 Fixation is more biological.
 Material- titanium alloy/ Cobalt-Chromium alloy
 Bone ingrowth into porous metal surface
 Requires: a)immediate mechanical stability at
the time of surgery
b) intimate contact between porous
surface and viable host bone
 So, surgical technique and instrumentation
need to be more precise than cemented
counterpart

26.  There are 6 types of Cementless
femoral components.
 Type I – Type V are straight stems
and fixation area increases with
type.
 Type VI is anatomical

27. Type 1:
 Single Wedge stem
 Flat in AP plane and
tapered in Medio-
lateral Plane.
 Fixation is by cortical
Engangement in
Medio-lateral plane
and 3 bony point
fixation.

28. Type 2:
 Dual Wedge stem
 Engages in AP
and Medio-lateral
Planes.

29. Type 3:
 Implant
tapered in 2
planes but
fixation is
achieved more
at the meta-
physial
diaphysial
junction than
proximally.

30. Type 4:
 Extensively Coated
Implant with Fixation
along The entire
length of the stem.

31. Type 5:
 Modular Stem,
Separate Meta-Physial
sleeve and diaphysial
segment that are
independentaly sized
and instrumented.

32. Type 6:
 Anatomical Femoral
Component incorporate
posterior bow in
metaphysial portion and
anterior bow in diaphysial
portion corresponding to
the geometry of femoral
canal.

33. Specialized custom-
made
Specialized femoral
components for replacement
of variable length of proximal
femur. Stem can be
combined with TKR to replace
entire femur

34. ACETABULAR
COMPONENTS
Cemented
Cementless
Constrained type
Specialized custom made

35. Cemented acetabular
component
 PMMA spacers (3
mm) are incorporated
into polymerizing
cement, yeilding
uninterrupted
cement mantle
 Satisfactory in elderly,
low demand patient,
Tumour
reconstruction, and in
revision arthroplasty.

36. Cementless acetabular
components
1. Porous coated
for bone-
ingrowth
2. Fixation with
trans acetabular
screw

37. Constrained acetabular components
 Mechanism to lock the
prosthetic femoral head into the
polythene liner
 Indications-
-Insufficient soft tissue,
-Deficient hip abductors,
-Neuromuscular disease,
-Hip with recurrent
dislocation despite well-
positioned implants.

38. Alternative bearings(evolution)
Ivory Femoral Head
Baer’s Membrane
Mould Arthroplasty- Glass, Bakelite,
vitallium.
Metal on metal bearings
Highly cross linked polyethylene
Ceramic on ceramic bearings

39. Ideal bearing surface
1. Low coefficient of friction
2. Small volume of wear particle generation
3. Low tissue reaction to wear particles
4. High resistance to third body wear
5. Enough deformation of articular surfaces
to permit adequate fluid film lubrication
during the stance phase without
increasing wear

40. Metal on metal bearings
 Low wear rate
 High carbon cobalt chromium
alloy
 Diametral clearance-gap between
the two implants at the equator of
articulation.
 Smaller clearance produce films
for lubrication and reduced wear.
 Elevated metal ions in blood that
excreted through urine.

41.  So contraindicated in impending renal failure.
 Placental transfer occur of these metal ions.
 Delayed type hypersensitivity (aseptic
lymphocytic vasculitis associated lesions)
 Pseudotumour
 Recommendation for symptomatic patients is
measurement of blood cobalt and chromium ion
level and/MRI or USG.

42. CERAMIC ON CERAMIC
BEARINGS
 ALUMINA CERAMIC IS USED.
 HIGH DENSITY, HYDROPHILLIC,
SMOOTHER THAN METAL.
 CERAMIC IS HARDER THAN
METAL AND MORE RESISTANT TO
SCRATCHING.
 LINEAR WEAR RATE IS 4000 TIME
LESS THAN COBALT CHROME
ALLOY ON POLYETHYLENE.

43. DISADVANTAGE
 CHIPPING/COMPLETE
FRACTURES
 IMPLANT
MALPOSITION
 STRIPE WEAR
 SQUEAKING
 OSTEOLYSIS

44. Comparison of Materials used in
Total Hip Arthroplasty

45. OXIDIZED ZIRCONIUM
 CERAMIC METAL ALLOY.
 NOT SUSCEPTIBLE TO
CHIPPING,FLAKING,OR FRACTURES.

46. Compliant bearings
 Cartilage is an example of a compliant bearing
that has a low modulus but is capable of large
deformation without failure.
 Polyurethanes are synthetic polymers having
properties comparable to those of articular
cartilage.
 Extensive laboratory and mechanical studies have
been underway over the last decade to
determine suitability of polyurethanes as a bearing
surface aimed at obtaining a bearing surface
couple in which the surfaces are separated by
pressure developed in joint fluid as well as by
deformation of articular surfaces.

47. Future Advances in THR
 Minimally invasive surgery :
Gaining popularity in
recent years, minimally
invasive techniques are
currently being developed.
The use of a single-incision,
less than 10 cm in length
using conventional surgical
approaches, provides soft-
tissue sparing and bone
conservation options.

48.  Computer-assisted surgery :
Computer-assisted total hip
replacement utilizes digital image
systems to map the position of
surgical instruments in relation to
anatomical landmarks, helping to
obtain reproducible and accurate
placement of implants. Computer
navigation may improve the
accuracy of prosthesis positioning
but, despite its obvious advantage
with respects to reducing
asymmetric wear, this has not yet
been shown to have a clinical
benefit.

49.  Since the first total hip arthroplasty in 1891,
research has developed from perfecting
surgical technique to advances in technology
(with respects to both prosthesis design and
materials) in order to provide a reproducible
technique that provides a good range of
motion, stability and most importantly
adequate life span.
 As the average age of those receiving hip
Arthroplasty decreases, such considerations will
continue to be of great value to increase
implant longevity in highly active patients.

50. Thank You