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1. K NAIL- HISTORY, DESIGN AND
BASIC
PRINCIPLES
DEEPAK CHAUHAN
(J.R.orthopaedics)
MODERATOR-Prof.VIJAY G.GONI

2. History of Intramedullary
nailing
 The beginnings -16th century
In Mexico aztec physicians have
Placed wooden sticks in to the
medullary canal of patients with
long bone non-unions.
 Mid 1800s
Ivory pegs were inserted in to
the medullary canal.
 In 1917s-hoglund of the united states
reported use of autogenous bone as
intramedullary implant

4. Evolution of KÜNTSCHER
NAILING
 Gerhard Küntscher was born in1900 in Germany.
 Development occurred
during World War-2(1939-42)
while Germany was at war,
Küntscher was deployed as
Chief medical officer in german army.
The german military had the upper hand in
treating soldiers with the IM nail and having
return to fighting status in few weeks.
Worldwide knowledge was not established
Until prisoners of war returned to their home
Countries carrying Kuntscher legacy in form of
Of Steel nail in their legs.

5.  The technique of femoral neck nailing
described by smith –peterson has been
expanded by Küntscher for the nailing of long
shaft bones.
 His original intramedullary nail was a V-
shaped stainless steel that was inserted
antegrade.
 Küntscher first reported use of V-shaped nail
in 1940.
 Early in the development of his
technique,he recommended inserting the
nail through a portal remote from fracture
site-differs from all operative fracture
methods used in the past.
 By late 1940- küntscher abandon use of the
V-shaped nail design in favour of another
design-the cloverleaf nail.

6.  Küntscher first nail in a human was inserted
in 1939 & reported at university of Keil
medical society on dec 1939.
 His method was essentially unknown in
U.S. during war and was first Described in
US march,1945,Time magazine
article,entitled“Amazing Thighbone”.
 Küntscher published his his first book in
1945 on intramedullary nailing.

7. Principle of KÜNTSCHER nailing
(GERHARD B. G. KÜNTSCHER J Bone Joint Surg Am. 1958;40:17-26.)
 The basic principle -stable osteosynthesis
through - flexible impingement of nail in the
bone
- adequate friction of the nail in both fracture
fragments .
 The device firmly impinged in the bone by elastic
forces in such a way that a carpenter’s nail
becomes impinged in wood.
 However the analogy does not follow in every
detail.
 As in cross section a carpenter’s nail is almost
rigid,when driven in to wood,it pushes wood
aside.by contrast medullary cavity is quite rigid;
therefore to achieve elastic impingement,the
cross section of nail must be design to have
elasticity with a V profile or even better clover-

8. Drawings showing cross sections of two types
of intramedullary nails.the V nail is
compressible in only one direction,whereas the
clover-leaf nail is compressible in two
directions,these directions being right angles
V - nail Cloverleaf nail

9. A SIMPLE EXPERIMENT DEMONSTRATES THE
ELASTIC COMPRESSIBILITY OF THE CLOVER –LEAF
NAIL.
If a clover –leaf nail 12mm in width is mounted in to a
vise,it can be compressed about 3 mm but will
immediately recover its original shape,when released from
the vise.

10.  Use of this principle of elasticity will
achieve the idea of complete and
permanent immobilization of the
fragments and offers an absolute
guarantee of bone union.There are two
reasons for this:
1.Lateral movement can be eliminated
only if the nail occupies the entire width
of canal througout its length.this can’t be
accomplished with a solid rod which can
not be compressed for varying canal
width.

11. A solid nail (left) will not occupy the full width of the
medullary canal in most places since its diameter must
be selected to fit the narrowest portion of the canal.
A nail with an elastic cross section (right ) will adjust to
the constrictions of the medullary canal.
Solid nail Elastic nail

12. 2.The second reason also of
great importance.
.Bone resorption will
soon loosen a solid
rod(left),even though at first
this rod accurately fit inside
canal.
. However nail with a
compressible cross section
(right)will expand during
bone resorption
. This nail is designed to
render the mechanical
effects of bone resorption
ineffective.
Solid nail elastic
nail

13. DESIGN-femoral ‘K’ nail (THE TECHNIQUE OF
INTRAMEDULLARY NAILING GERHARD KÜNTSCHER, MD and RICHARD MAATZ, MD Professor
ReaderSurgeons, Department of Surgery, Kiel University Hospital
 Cross section-roughly V or cloverleaf
shaped
 Sheet metal thickness reduced on back-
provides compressibility
 Hollow core-admits guide wire
 Slot-anterolaterally tension side
 Eye- at both ends
 Common sizes-lengths-
30,34,36,38,40,42cm diameter-8,9 and
10 mm
 Protude at least 3cm from trochanter
 Standard femur K nail-

14. Special designs
 Tapered end- subtrochanteric fracture
 Y nail- peritrochanteric fracture
 Some cases Saw teeth at its tip- for
bone containing central callus.eg-
refracture,delayed union

15. TIBIAL NAILS
 Double nails
 Curved in shape
 Cross section-U shaped
 Lengths-24-39 cm,at 1.5 cm
increments
largest diameter-8 and 9 mm
 Two designs of spreading nail-
Deflect to spread nail
Rotate to spread nail

16. Deflect to spread nail
 Two nails spreads distally by means of an
inclined plane on outer nail
 The inclined plane on outer nail & rear wall of
bone tube provides deflecting surfaces -
make inner nail veer in posterior direction
 Outer nail should be inserted first.
 Resistant to bending
 Used in fractures distal to isthmus-long
oblique fractures or segmental bone
loss(anterior edge).

17. Rotate to spread nail
 Also consists two nails
 Outer nail-standard pattern
 Inner nail-circular cross section and a
lazy S shape
 Inner nail should be inserted first
 Only for transverse or short oblique
fractures,bone loss(posterior cortex)
A=outer nail
B=inner nail

18. Instruments
 Nail guide-solid,circular cross section
Length-64 cm,diameter-3mm
 Awl- with an offset four sided tip
 Impactor-facilitates insertion of
nail,allows hammer blows directed
along main axis of middle portion of
nail.
nail guide
Awl
Tibial nail impactor

19.  Slotted hammer-most suitable
instrument for extraction even very
firm seated nail
 Kuntscher extractor-threaded rod
& Spring system combines traction and
hammer blows. pretension needs to
reset with every blow
Slotted hammer with extraction
hook
c b
a
a=threaded rod with fitting for hammer
b=spacer=prevent bone damage at
instrument placement site
C=extension

20.  Reamers-
 Nail bender- allows nail
contouring(other than femoral nails)

21.  Stepped scale- for radiographic
determination of medullary cavity
diameter
 Reduction apparatus-

22. Positioning

23. Küntscher policies:
 1.if a fracture is “nailable” it should be
nailed.
 2.nailing will be done in patients that are
at particular risk if kept at bed rest in cast
or on traction.
 3.nailing will be performed to manage
fractures that are notoriously
difficult,such as smooth transverse
fracture.
 4.one particular indication in
spontaneous fracture of metastatic

24. Uses
 Fractures- femur
,tibia,humerus,forearm,clavicle.
Compound fractures,gun-shot
fractures.
 For non union,delay union.
 Correction of malunion.
 Congenital or aquired deformities
 arthrodesis

25. Criteria of nailing- fractures?
Criteria of nailing will depend on
 shape of the bone
 Site of the fracture
 Pattern of fracture
 There are no definite cut –offs between
suitability grades- this is why fractures are
best classified as “very suitable”-
absolute indications
“suitable”
“borderline” extended indications
“unsuitable”

26. Intramedullary nailing is ruled out in all
intra-articular fractures :
 nail may force fragments apart
that are still in reasonable contact.
 the device will not be able to
obtain an adequate purchase.
 the joint may be at risk from nail
intrusion.

27. Femur fractures-nailing
criteria
 Very suitable-transverse fractures and
oblique fractures with a short-fragment
medullary cavity providing at least 8 cm
of “nail-suitable” medullary cavity.
 Secure against angulation,lateral
displacement and shortening.
 Risk of rotation-little in oblique
fracture,more with transverse
fracture
 Immediate weight bearing allowed

28. “Suitable” fractures- spiral fractures
 well secure against angulation
and lateral displacement.
 Shortening will occur with
rotational malalignment-as
smooth fragments will slip
past each other when loaded.
 No weight-bearing before
the end of 3rd week.

29. Unsuitable fractures-
 supracondylar fracture with
separation of condyles(Y or T
fracture)-
 Peritrochanteric fractures-head end of
standard nail would not obtain
sufficient purchase in trochanter..but
they are very suitable with Y nail.

30. Butterfly and segmental fractures
 very suitable-large fragments with a
bone defect on one side OR non-
communited third fragment in
segmental fracture.
.Lateral dispalcement
ruled out
.secured against
angulation.
.shortening is not
possible-one side
continuous cortex.
.immediate weight bearing

31. Communited fractures- “suitable”
 secure against displacement and
angulation.
 Great risk of shortening and
malrotation.
 Supplementary support –skeletal
traction may require
 Weight bearing once sufficient
callus formed.

32. Tibia fractures
 Compared to femur –conditions are
more adverse.
 Nail has to be curved-since introduced
from lateral entry point.
 Very frequently producing
displacement of fracture in to
recurvation.
 Unlike femur,most of the thing
depends on shape of medullary
cavity..

33. Nailing criteria :tibia fractures
criteria of nailing in tibia dependson
 diameter of the nail (n)
 diameter of medullary cavity
at fracture site (m)
 thickness of cortex (k)
 If m-n<_k the fracture is
“suitable”(depending on fracture
pattern).
 If m-n>k the fracture is“unsuitable”

34. Proximal -third transverse
fractures-
 The difference
between medullary
cavity diameter and
the nail diameter is
equal to or greater
than thickness of
the cortex.In all
these cases all
fracture patterns
are “unsuitable”
with the standard
nail.
Fragments are secured
against rotational
only,but may displace in
all other directions

35. . m-n<k (borderline)
. lateral dislacement
. protected against
all other
displacements by
great friction b/w
bone & nail at x.
.No supplementary
support require.
.moblization at end
of 3 week
Proximal third oblique
fractures (border line)

36. .conditions are
same like oblique
fractures but
there is strong
torque forces
which can not be
neutralize by nail.
.Supplementary
long leg cast
requiredProximal third (spiral
fractures)-”borderline”

37. “Unsuitable”(m-
n>k)
since the nail can
not prevent
major anguation
Proximal third Butterfly and
Communited fractures

38. Middle -third tibia fractures
 Here the diameter of the medullary
cavity will be the same as that of nail-
all fractures in this part suitable for
nailing.
 Nail will fit snugly & provide adequate
friction
 Transverse fracture & oblique
fracture- “very suitable” .
 Spiral fractures- “suitable”as
risk of rotation

39. Middle third butterfly fractures-
“Borderline”-for standard nail
Very suitable- for spreading nail
. An anterior
butterfly fragment
should be
managed with
deflect to spread
nail.
.A posterior
fragment –
managed with
rotate to spread
nail.

40. Distal third tibia fractures
 Spreading nail are useful-splayed
pattern at distal end of this double nail
provide greater overall diameter.
 Oblique or transverse fractures:
m-n<k “unsuitable for standard double
nail
very suitable -spreading nail.

41. Nail removal
.
 Earlier removal may be indicated in
following:
1.displaced fragments and nail is
making impossible to obtain reduction.
2.migrating nail-threatening joints or
soft tissue at its end
3.bent or broken nail
4.in children after achieving sound
union.

43. THANK YOU