for orthopaedic postgraduates.

1. A CASE REPORT
Basic principles of deformity
correction.
Dr kishore vemula
Junior resident
Department of orthopaedics
SVRRGGH, tirupathi

2. Brief history
• A 19 year male came to orthopaedic opd with
complaints of deformity of rt knee,limping
since 4 years.
• Past history:: he had operated for tumour
around knee along with bone grafting from his
father(iliac graft) 4years back.

3. pre op

5. Post op
4 months follow up

6. Present radiographs
varus at knee
Limb shortening

7. Assesment of deformity and planning

8. OT room and post op

9. 8 weeks follow up after osteotomy

10. • Planning for limb length correction later
………….

11. BASIC
PRINCIPLES
OF
DEFORMITY
CORRECTION

12. MECHANICAL AXIS
• Straight line connecting the
joint center points of the
proximal & distal joints.
• Its always a straight line
whether in frontal or sagittal
plane.

13. ANATOMICAL AXIS
• Is mid diaphyseal line.
• Anatomical axis line can be
straight (frontal) & curved
(sagittal).

14. JOINT CENTER POINT
HIP CENTER
MOSE CIRCLE …. MOST ACCURATE
Longitudinal diameter of head.
Goniometer .

16. JOINT ORIENTATION LINE
• Line representing the orientation of a joint in a
particular plane /projection.

17. ANKLE JOINT ORIENTATION
Frontal : along the flat
subchondral line of tibial plafond.
Sagittal : line from distal tip of
posterior lip to tip of anterior lip

18. KNEE JOINT LINES
• FRONTAL :
1. along the subchondral line of tibial
plateau
2. along the Line tangential to most
distal point on the femoral condyle
• SAGITTAL :
1.along flat subchondral line of
plateau.
2.Line connecting 2 points where the
condyles meet the metaphysis.

19. HIP JOINT LINE
• FRONTAL : from tip of greater trochanter to center
of femoral head.

20. JOINT ORIENTATION ANGLES
• Angle formed between joint line & axis.
• Each axis & joint line form 2 angles.

23. MALALIGNMENT
 Malalingment refers to the loss of collinearity of hip , knee & ankle.
• MAD arises from 4 anatomic sources :-
Femoral frontal plane deformity.
Tibial frontal plane deformity.
Knee joint laxity.
Femoral or tibial condylar deficiency.

24. Radiographs of the lower limbs:
• Long films (51 Inches)..
4-5degree magnification... (Or)
Two 17inches radiographs each,
Femur, tibia saperately with
involving corresponding joint
• Stand in attention posture
• 10 feet distance from source
• Source perpendicular to knee
• Both frontal, lateral views
• No pelvic tilt.. If needed correct
by block method

25. RADIOGRAPHS
• Patella must be forward
between the femoral
condyles irrespective of foot
position
• Square the pelvis if needed
• Stress views may needed in
ligamentous laxicity
• Wt bearing radiographs
needed to rule out cartilage
loss causing lax joint

26. Draw lines?????
• Use always pencil on radiograph,,,erase easily
with alcohol swab
• Draw joint lines
• Mark joint centres
• Then draw mechanical or anatomical axes
• Measure angles????
protractor > goniometer

27. MECHANICAL AXIS DEVIATION(MAD)
• malalignment is loss of collinearity of hip,
knee, ankle in a particular plane
• mad is a measure of malalignment
• MAT is malalignment test, for analysis of
malalignment

28. MAT (MALALIGNMENT TEST)
• STEP 0
• Draw mechanical
axis, mark center of
knee
• Measure MAD
(normal=1-15mm
medial to knee
center point)

29. STEP 1
• Measure m LDFA..
 Normal range is
85⁰-90⁰.

30. STEP 2
• Measure MPTA.
 Normal range is
85⁰-90⁰.

31. STEP 3
• Measure JLCA
normally joint lines
are parallel within
0-2 degrees.
angles greater then
3⁰ are considered
as a source of MAD

32. ADDENDUM 1
RULE OUT KNEE JOINT SUBLUXATION
• mark the mid point of femur, tibia joint lines
• the distance between them normally is 3mm
• > 3 mm indicates knee joint subluxation

33. ADDENDUM 2
RULE OUT CONDYLAR MALALIGNMENT
• the two halves of each joint lines are
continuous
• any step or angulation of joint lines indicates
condylar malalignment or deficiency

34. DEMERITS OF MAT
• Identifies only which joint surface/bone
contribute to deformity but not level of
deformity
• Cannot identify tibia / femur deformities
around ankle/ hip respectively
• Cannot identify any sagittal plane deformity.

35. MOT (MAL ORIENTATION TEST)
• Done To identify sagittal plane deformity
• MOT is necessary to know whether hip and
ankle are normally oriented to mechanical axis
• Malorientation of ankle near tibial plafond or
malorientation of hip at proximal femur
cannot cause MAD

36. • Deformity Assessed??? Yes
• Then Correction….
• How??
• Where??
• Reference Point???
• Which Plane???

37. CORA(CENTER OF ROTATION OF
ANGULATION)
•The intersection of the proximal axis
and distal axis of a deformed bone is
called the CORA
•It is the point about which a
deformity
may be rotated to achieve correction.
•The angle formed by the two axes at
the CORA is a measure of angular
deformity in that plane.

38. IMPORTANCE OF CORA
• . It indicates where an axis of rotation,
named angulation correction axis or ACA
(Paley, 2002), should be placed about
which two intersecting axes of the
CORA can be brought in line and hence
deformity corrected
• This axis of rotation, which enables
appropriate realignment of intersecting
axes, should be positioned on either side
of CORA but along a line termed ‘the
bisector’.
• Bisector :- line that bisects angle
described by deformity .

39. RULES OF OSTEOTOMY
(CORA METHOD)
• STEP 0 :- DO MAT
Draw mechanical axis of both lower limb.
Calculate MAD.
If one side is considered as normal then its angle
can be used as template for deformed side.
If the other side also has deformity then the
normal angles are considered.

40. CORA METHOD
• STEP 1 :-
Draw proximal mechanical axis line.
• STEP 2 :-
Draw distal mechanical axis and perform MOT

41. CORA METHOD
• STEP 3 : Decide whether its uniapical or
multiapical angulation
Mark CORA
Measure the magnitude.
Intersection point of PMA& DMA is CORA.

42. STEP 3 CORA METHOD
• CORA lies at point of obvious deformity, with in
bone , joint orientations normal
UNIAPICAL
• CORA lies with in bone not at apex of defomity/
second cora/if joint orientations are abormal
MULTIAPICAL/TRANSLATIONAL DEFORMITY
• CORA lies outside of bone with joint orientations
normal
MULTIAPICAL DEFORMITY

43. 1.CORA AT APEX …UNIAPICAL
• Rotation axis to correct deformity can be sited
on bisector and osteotomy performed at same
level – this is equivalent to classic correction
through opening or closing wedge methods
• The type of wedge osteotomy is determined
by the location of the osteotomy relative to
the locations of the CORA and the correction
axis

44. Opening wedge osteotomy
• The CORA and correction axis
lie on the cortex on the convex
side of the deformity.
• The cortex on the concave side
of the deformity is distracted to
restore alignment, opening an
empty wedge that traverses the
diameter of the bone.
• Opening wedge osteotomy
increases final bone length.

45. Neutral wedge osteotomy
• The CORA and correction axis
lie in the middle of the bone.
• The concave side cortex is
distracted and the convex side
cortex is compressed.
• A bone wedge is removed from
the convex side.
• Neutral wedge osteotomy has
no effect on final bone length.

46. Closing wedge osteotomy
• The CORA and correction axis lie
on the concave cortex of the
deformity.
• The cortex on the convex side of
the deformity is compressed to
restore alignment, requiring
removal of a bone wedge across
the entire bone diameter.
• A closing wedge osteotomy
decreases final bone length.

47. 2.CORA OUT OF APEX
(ANGULATION + TRANSLATION)
• Rotation axis to enable correction should be
maintained on bisector of CORA but
osteotomy can be sited at either of two levels
(coincident with apex of deformity or at
CORA):

48. • b(1) when positioned on APEX, correction of both translation and
angulation is simultaneously accomplished at site of original
deformity.
• b(2) when sited on CORA, a new deformity is created which
correctly ‘balances’ the malalignment produced from original site

49. 3. CORA OUSIDE OF BONE
• When the CORA lies outside boundaries of
involved bone, a multi-apical deformity is
likely to be present (and the deformity more
akin to a curve). deformity would need to be
resolved through multiple osteotomies

50. Results when using osteotomy
A. The CORA, the correction axis, and the
osteotomy all lie at the same location; the bone
realigns through angulation alone, without
translation.
B. The CORA and the correction axis lie in the
same location but the osteotomy is proximal or
distal to that location; the bone realigns
through both angulation and translation.
C. The CORA lies at one location and the
correction axis and the osteotomy lie in a
different location; correction of angulation
results in an iatrogenic translational deformity.

51. Treatment By Deformity type : Length
• Acute distraction or compression
methods obtain immediate correction
of limb length by acute lengthening
with bone grafting or acute
shortening, respectively
• Gradual correction techniques for
length deformities typically use
Ilizarov external fixation/ LRS

52. Treatment By Deformity type :
Angulation
• Correction of angulation deformities
involves making an osteotomy,
obtaining realignment of the bone
segments, and securing fixation
during healing.
• Alternatively, the correction may be
made gradually using external fixation
to both restore alignment and
provide stabilization during healing

53. Treatment By Deformity type :
Rotation
• Correction of a rotational deformity
requires an osteotomy and rotational
realignment followed by stabilization.

54. Treatment By Deformity type :
Translation
• Translational
deformities may be
corrected in one of
three ways.

55. • These features of the CORA are, in essence, the rules
of osteotomy as described by Paley (2002).
• “It explains why it is permissible to perform
osteotomies away from apex of the deformity as long
as correction is achieved through a rotation axis
placed on CORA or on its bisector.”

56. • THANK you all ………..