how to read X ray of Total hip- total hip prosthesis - hip arthoplasty- THR Radio-logical Evaluation evaluation of THR follow up total hip - X ray of total hip - assessment of total hip

1. • Dr. Bahaa Ali Kornah
• Prof.. Of Orthopedic
• Al-Azhar University
• Cairo - Egypt

2. • Initial Evaluation Alignment and
Positioning
• Normal Findings at Follow up
• Cemented THA , Non Cemented THA
• Complications at Follow Up
• Loosening
• Particle Disease
• Polyethylene wear
• Infection
• Fractures
• Dislocation
• Component fracture
• Heterotopic Ossification

3. • Modern Total Hip Arthroplasty (THA) systems are
modular.
What do you
mean Modular !!
This means that the femoral
stem, head, acetabular shell
and liner are separate pieces.

4. • frontal view of the pelvis
• orthogonal views, either a “frog leg” or cross-table
lateral,
• For me “frog leg”

5. Alignment and Positioning
• Transicheal Line
–
• Horizontal center
of rotation
C -Lateral
acetabular
inclination
• Vertical center of
rotation
E -Leg length
F -Position of
femoral stem

6. A -Vertical
center of
rotation
B -Horizontal
center of
rotation
C -Lateral
acetabular
inclination
E -Leg length
F -Position of
femoral stem
Alignment and Positioning

7. The horizontal center of rotation is the
horizontal distance measured from the
center of the femoral head to a medial
landmark, such as the teardrop.

8. The vertical center of rotation is the vertical
distance from a line joining the centers of
the femoral heads (A) to the transischial
line (B)

9. initial postoperative films
• Alignment and Positioning
The horizontal
center of rotation.
The transischial line
= angle (Lateral
acetabular inclination

10. initial postoperative films
• Alignment and Positioning
The transischial line
1.measure the lateral inclination of the
acetabular cup (35-55?).
2.measure any leg length discrepancy.
Leg length discrepancy up to 1 cm is
well tolerated.
A high positionened cup is better tolerated
than a lateral positioned cup.
The horizontal center
of rotation. equal bilaterally
Excessive lateral positioning of the
acetabular component increases the risk
for dislocation and may cause limping.

11. acetabular abduction angle
= Lateral acetabular
inclination
The inclination of the
acetabular component (θ)
is the angle it makes with
the transischial line
(range: 35–55 degrees).

12. • The anteversion of the acetabular
cup >>>>5-25?.
Measment by =cross-table or true
lateral
• Measurement with CT is more
accurate, but you still have to
compensate for pelvic angulation.

13. the femoral stem
➢The preferred position
>>>>the stem centered in
the femoral canal.
➢Femoral head >>>>The
center of rotation at the
level of the tip of the
greater trochanter.
➢Varus position of the
femoral stem predisposes
to loosening and fracture.

14. Varus or valgus stem
femoral stem aligment
varus valgus

15. subsidence

16. conditions predispose to
dislocation:
1. - Increased lateral inclination of the acetabular
cup.
2. Decreased or increased anteversion of the cup.
3. Excessive lateral positioning of the acetabular
cup
4. Increased or decreased anteversion of the
femoral stem.

17. Normal Findings at Follow up
• Observe any lucencies at the bone-cement or
cement-prosthesis interface,
• 3-4mm layer of cement around the prosthesis.
• Abundant cement packing leads to loosening.

18. The
prosthesis,
periprosthetic
bone, and
juxta-articular
soft tissues
• fracture,
• periosteal reaction,
• stress shielding,
• calcar resorption,
• osteolysis,
• bony remodeling,
• metallic debris, and
• heterotopic ossification.

19. Comparison
radiographs
• implant migration,
• subsidence, and
• aseptic loosening.
• Infection,
• particle disease,
• reaction to metal,
• mechanical
impingement

20. terms
• Radiolucency: refers to the relative permeability of a material
to x-rays
• Sclerotic reaction
• Spot welds are areas of endosteal sclerosis that arise as a
direct result of pressure from the distal implant on the femur.
• Stress shielding =Calcar resorption
• Remodelling and osseointegration
• The cement mantle =cement around the prosthesis
• Subsidence: The femoral stem sink either within the femoral
shaft along with the cement mantle or within the cement
itself
• Osteolysis :bone resorption

21. three DeLee and
Charnley zones of the
acetabular component
(I–III)
It is quite common to
see a radio lucent line in
zone I, but you shouldn't
see it in zone II and III.
Cemented THA

22. the 14 Gruen zones of the
femoral component
(1–7 on the frontal view and
8–14 on the lateral view).
It is very common to see
radiolucency in zone 1,
occasionally in zone 7, but it
should not occur in the
subtrochanteric region zones
2-6.
Cemented THA

23. Non Cemented THA
• Stress shielding = bone resorption
• bone ingrowth prosthesis results in altered
stress distribution to the native bone.
• In full coated stem >>Stress loading distally
may result in cortical thickening and
bridging sclerosis at the tip of the
prosthesis ( called pedestal).
• Proximal coated >>not find proximal stress
shielding.

24. ❖ Stress shielding or bone
resorption is seen in areas that
are relatively unstressed.
The forces are transmitted
through the relative stiff femoral
stem and is seen as
osteoporosis in the proximal
femur with thinning of the
cortex and bone resorption of
the femoral neck.
This is seen medially as calcar
resorption, as the calcar has lost
it's function
It is also called calcar round off.

25. • In stable non-cemented hip
arthroplasties lucent zones at
the metal-bone interface do
occur, as it usually is a
combination of bone ingrowth
and fibrous tissue ingrowth,
that provides the fixation in
most cases.
This fibrous tissue presents as
a lucent zone at the interface .
it should be stable and well
within a range of 1 -2 mm.

26. Thin lucent
zones
They should be less
than 2mm and
accompanied by a
sclerotic line parallel
to it.
If they stay stable for
2 years than fixation
by a strong fibrous
tissue has taken
place.

27. 1. most important
complications are
*Mechanical loosening,
**Particle disease and
***Infection.

28. 1. *Mechanical loosening
presents as
diffuse
lucency.,

29. 1.
Particle disease
OSTEOLYSIS
presents as focal
lucency.
Evidence of
polyethylene wear,
which appears as
asymmetric positioning
of the femoral head
within the acetabular
cup, often coexists with
particle disease. .

30. Infection presents as irregular
lucency with periosteal
reaction,
Infection is often low grade
and is difficult to detect with
any imaging method.
In more aggressive cases there
will be
**irregular osteolysis,
**no sclerotic border,
**cortical bone resorption
**a periosteal reaction.

31. Loosening
• Aseptic – mechanical
- Improper techniques.
- Improper implants.
• Septic (Infections)

32. • Loosening (CUP)
• Mechanical loosening
• - Lucent zone > 2 mm at
interface (indicative)
- Component migration
(diagnostic).
• A lucent zone of more than 2
mm at the bone-prosthesis
interface or at the bone-cement
interface is very indicative of
loosening. Plus more than zone

33. • Component migration =
loosening.
CUP>>
tilting or cranial migration
• Stem>>
subsidence (>10mm) and
varus tilting

34. • Particle Disease
• called cement disease or aggressive
granulomatosus.
• reaction to small polyethylene wear
particles
• Radiographically =
• **focal radiolucencies around the
prosthesis.
** associated with smooth
endosteal scalloping.
** With no secondary bone
response.( infection)
** eccentric position of the femoral
head within the cup, look for focal
lucencies.

35. Eccentric position
of femoral head
within acetabular
cup as a result of
polyethylene
wear.

36. Creep is normal
remoulding and is
superomedial. thinning in
the area of the weight
bearing as the plastic
moulds itself.
Polyethylene wear
Wear is superolateral
and pathologic

37. Loosening of THA components
• Cemented THAs, the acetabulum is the
first component to fail from loosening
• Cementless THAs, the femoral
component loosens more often as a
result of osteolysis
• Can be septic or aseptic

38. Cemented Femoral loosening;
Radiographic features
• Definite loosening
• Stem failure – fracture/deformation
• Cement mantle fracture esp zone 4
• Radiolucency >1mm
• Changes in stem position- usually varus position
• Pistoning effect
• Probable loosening
• Continous radioluscent line at bone-cement interface
• Endosteal cavitation-linear and focal osteolysis
• Possible loosening
• Radioluscent lines at bone-cement interface 50-100%

39. 22
Cement Fracture
Debonding: implant-
cement interface is
disrupted
Subsidence: implant
slides into medullary
canal
Courtesy of Ferris Hall, MDCourtesy of Ferris Hall, MD
Cortical Reaction

41. FEMORAL LOOSENING

42. •Are all radioluscent line due to
loosening?

43. FEATURES AND CAUSES OF
INNOCENT RADIOLUCENT LINES
• Thin
• less than 2 millimeters thick
• Do not change on serial radiographs
• Can be due to cancellous bone that was not
completely removed at surgery.
• Normal age related expansion of femoral canal and
thinning of the femoral cortex.(0.33 mm/yr and
0.14 mm/yr)

44. INNOCENT vs OMINOUS
RADIOLUCENT LINES

45. Cemented Acetabular loosening;
radiographic features
• Bone-cement lucency >2mm
and/or progressive
• Medial migration and protrusion
of cement and cup
• Change in inclination of cup >50
• Eccentric PE wear of the cup
• Fracture of cup and/or
cement(rare)

47. MECHANISM

48. CEMENTLESS FEMORAL
COMPONENTS
• Engh and Bobyn proposed a simple classification
system for implant fixation.
• Classified as
1) Bone ingrowth
2) Stable fibrous fixation
3) unstable

49. BONE INGROWTH
• Defined as an implant
with no subsidence
and minimal or no
radiopaque line
formation around the
stem.
• Appears stable
• Cortical hypertrophy
• Stress shielding

50. STABLE FIBROUS FIXATION
• No progressive
migration occurs but
an extensive
radiopaque line forms
around the stem.
• Lines are parallel and
space of upto 1 mm.
• No local hypertrophy.

51. UNSTABLE
• Progressive subsidence or
migration within the canal
and is at least partially
surrounded by divergent
radiopaque lines that are
more widely separated
from the stem at its
extremities.
• Inc cortical density and
thickenning.

52. noncemented acetabular
component
• A well fixed may demonstrate close apposition to
the bone without any lucency around the
component, medial stress shielding,
• superolateral buttressing
• inferomedial buttressing, and a radial trabecular
pattern in the periacetabular bone
• If three or more of these findings are present, the
positive osseous integration

53. superolateral buttressing

54. radial trabeculae (horizontal
arrows) and inferomedial
buttressing (vertical arrows).

55. infection
•**irregular osteolysis,
**no sclerotic border,
**cortical bone resorption
**a periosteal reaction.

56. irregular
bone
destruction
and
periosteal
reaction.

57. Fractures
prosthesisbone

58. Fractures
• Operative
• post-operative:

59. Fractures
compouned fr.

60. Heterotopic Ossification
• Grade I = islands of bone
within soft tissues.
• Grade II = bone spurs
leaving > 1 cm between
opposing bone surfaces.
• Grade III = bone spurs
leaving < 1 cm between
opposing bone surfaces.
• Grade IV = radiographic
ankylosis of the hip.

61. 27
Courtesy of Ferris Hall, MD
Heterotopic ossification:
This patient had a h/o spondylitis
but any joint procedure has a small
chance of this complication

62. Take home massage
• Plain X is a good modality
• Initial film and follow up
• comparison with previous films
• There is different in cemented and cement less film
• Assess component stability.

63. Thank you for
your attention
‫د‬/‫قرنة‬ ‫بهاء‬
Bahaa Kornah , Cairo- Egypt