This document provides an overview of intramedullary nailing, including: - Evolution from 1st to 3rd generation nails with improved stability and anatomical fit - Classification by entry point and direction of insertion - Biomechanical principles of load transfer and stability depending on nail design, number/location of locking screws, and reaming - Applications for treating fractures of long bones and considerations for special circumstances

1. Dr.S.V.Hari krishnan
PGT , M.S .(Ortho)
INTRAMEDULLARY NAILING
BASIC CONCEPTS

2. Learning Objectives
 Introduction
 Evolution
 Classification
 Biomechanics
 Applications
 Special Circumstances
 Recent Advances

3. Introduction
 Fracture stabilized by one of two systems
 Compression
 Splinting
 Intramedullary fixation - internal splinting
 Splintage -micro motion between bone & implant
 Relative stability without interfragmentary compression.
 Entry point - distant from fracture site – hematoma retained.
 Closed reduction and fixation (biological)

4. Evolution
1st generation
 Splints(1˚)
 Rotational
stability
minimal
 Closed fit
 Longitudinal slot
along entire
length
 Eg –K nail , V nail
2nd generation
• Locking screw -
improved rotational
stability
• Non- slotted.
• Eg-russel taylor nail,
delta nail
3rd generation
• Fit anatomically as
much as possible
• Aid insertion and
stability
• Titanium alloy
• Eg-trigen nail, universal
femoral nail nails with
multiple curves
,multiple fixation
systems
• Tibial nail with
malleolar fixation

5. Classification
 Entry Portals :
 Centromedullary
 K nail
 Cephalomedullary
 Gamma nail
 Russell taylor nail
 PFN
 Condylocephalic nail
 Ender nail
Direction :
Antegrade
Retrograde

6. Centromedullary Nails
 First generation
 Contained within medullary canal
 Usually inserted from piriformis fossa
 Proximal locking bolts - transverse or
oblique in pertrochanter
 Requires LT be attached to proximal
fragment for adequate # stabilization

7. Cephalomedullary Nails
 second generation nails
 More efficient load transfer than SHS
 Shorter lever arm of IM device decreases
tensile strain on implant - low risk of implant
failure
 screws/blade inserted cephald into femoral
head and neck.
 Gamma nail
 Recon nail

8. C o n d y l o c e p h a l i c F i x a t i o n
 Elastic stable intramedullary nailing (ESIN) - primary definitive
paediatric fracture care .
 3 – point fixation or bundle nailing.
 Elastic and small - micro-motion for rapid fracture healing.
 Flexible -insertion through a cortical window.
 Examples :
 Lottes nails
 Rush pins
 Ender nails
 Morote nails
 Nancy nails
 Prevot nails
 Bundle nails

9. Opposite  Apex of curvature - at level of fracture
site.
 Nail diameter - 40% of narrowest
medullary canal diameter
 Entry point - opposite to one another
 Used without reaming.
 Commonest biomechanical error is lack of
internal support.

10.  Schneider nail [ solid, four fluted cross section
and self broaching ends.
 Harris condylocephalic nail [curved in two
planes, and designed for percutaneous,
retrograde fixation of extra capsular hip
fractures.
 Lottes tibial nail specially curved to fit tibia,
and has triflanged cross section.

11. Ender Nails
 Solid pins with oblique tip and an eye
in flange at or end
 Designed for percutaneous, closed
treatment of extra capsular hip
fractures

12. Rush Nails
 Intended for fractures of diaphyseal
or metaphyseal fractures of long bones
like femur, tibia, febula, humerus,
radius and ulna.
 Pointed tip facilitates easy insertion.
 Curve at top prevents rotation and
stabilizes fracture.

13. Bundle Pinning
 C- or S – shaped, act like spring.
 Principle introduced by hackethal.
 Many pins are inserted in to bone until
jammed within medullary cavity to provide
compression between nails and bone.
 Bending movements neutralized, but
telescoping and rotational torsion not
prevented

14. Applications
 Diaphyseal fractures of long bones
 High proximal and low distal fractures of
long bones
 Floating hip, floating knee, floating elbow.
 Aseptic and septic non-union
 Osteoporotic long bone fractures
 Pathological fractures
 Open fractures up to grade IIIA

15. Contraindications
 Narrow and anomalous medullary canal
 Open growth plates
 Prior malunion - prevents nail placement
 History of intramedullary infection
 Associated ipsilateral femoral neck or acetabular fracture (relative)

16. Mechanics (K Nail)
 Elastic deformation or “elastic
locking” of nail within medullary
canal
 Adequate friction of nail in both
fracture fragments
 To achieve elastic impingement-
 “V” profile or even better “clover-leaf”
design.

17.  Compressible in two directions
 Directions right angles to each
other
V Nail Clover Leaf Nail
 Compressible in only one
direction

18. Elastic Compressibility Of Clover – Leaf Nail

19. Solid Nail Elastic Nail
 Not occupy full width of
medullary canal
 Nail with elastic cross section
adjust to constrictions of
medullary canal.

20. Grosse – Kempf nail Russell – Taylor nail Brooker–Wills nail

21. Biomechanics of deforming forces

22. D
F = Force Bending moment = F x D
D
PlateIM Nail
Bending moment for plate
greater due to force being applied
over larger distance.
D = distance from force
to implant.

23. Comparision
• Nail cross section round
• Resisting loads equally in all
directions.
• Plate cross section
rectangular resisting greater
loads in one plane versus the
other

24. Cortical contact
 - compressive loads borne
by bony cortex
 - compressive loads
transferred to interlocking
screws (“four-point bending
of screws ”)
+
-

25. Ideal Intramedullary Nail
 Strong and stable - maintain alignment and position
 Prevent rotation - interlocking transfixing screws
 Promote union - contact-compression forces at fracture
surfaces
 Accessible for easy removal

26. Pre Requisites
 Adequate preoperative planning
 Patient tolerance to a major surgical procedure
 Availability of nails of suitable length and diameter
 Suitable instruments, trained assistants, and optimal hospital
conditions
 Closed nailing techniques - whenever possible

27. Pre Operative Planning
Biplaner Radiographic
Images
• Bone Morphology
• Canal Dimensions
• Fracture Personality
• Comminution
• Fracture Extensions
Length Of Nail
• Radiographs of contra lateral
femur (magnified)
• Traction radiographs
(comminuted #)
• Palpable greater trochanter to
lateral epicondyle.
• TMD (tibial tubercle–medial
malleolar distance) for tibial
nail
Diameter Of Nail
• Narrowest portion of
femoral canal at femoral
isthmus – lateral
radiograph
• 1.0 to 1.5 mm greater in
diameter than anticipated
nail diameter.

28. Nail Length
 Preoperative radiographs of fractured long bone
with proximal and distal joints
 AP radiograph of opposite normal limb at a tube
distance of 1meter
 Kuntscher measuring device :
 Ossimeter used to measure length and width
 Magnification is taken in to account

29. Biomechanics
 Stability determined by
 Nail design
 Number and orientation of locking screws
 Distance of locking screw from fracture site
 Reaming or non reaming
 Quality of bone
 IM nails assumed to bear most of load initially,gradually
transfer it to bone as fracture heals.

30. Nail Design
 Factors contributing to biomechanical profile :
 Material properties
 Cross-sectional shape
 Diameter
 Curves
 Length and working length
 Ends of nail

31. Nail design
 Material properties
 Titanium alloy and 316l
stainless steel.
 Modulus of elasticity
 Titanium alloy – same as
cortical bone
 SS – twice as cortical bone
 CROSS SECTIONAL
SHAPE
 Determines bending and
torsional strengths
 Polar moment of inertia
 Circular nail  diameter
 Square nail  edge length
 High in nails with sharp
corners or fluted edges

32. A-schneider
B-diamond
C-sampson fluted
D-kuntscher
E-rush
F-ender
G-mondy
H-halloran
i-huckstep
J-AO/ASIF
K-grosse –kempf
L-russell-taylor
J,k,l-now commonly used

33. Nail diameter
Nail diameter affects bending rigidity
 solid circular nail,
 Bending rigidity  third power of nail
diameter (D3)
 Torsional rigidity  fourth power of
diameter (D4)
 Large diameter with same cross-
section are both stiffer and stronger
than smaller ones.

34. Nail curves
 Long bones have curved medullary cavities
 Nails contoured to accommodate curves of bone
 Straight, curved or helical
 Average radius of curvature of femur - 120(±36) cm.
 Complete congruency minimizes normal forces and
hence little frictional component to nail’s fixation.
 Femoral nail designs have considerably less curve,
with radius ranging from 150 to 300 cm
 Im nails - straighter (larger radius) than femoral canal

35. Nail curves
 Angle of herzog :
 11o bend in AP direction at junction of upper
1/3rd and lower 2/3rd of tibia nail
 Mismatch in radius of curvature –
 Distal anterior cortical perforation
 more reaming required during insertion

36. Hoop stress
 Circumferential expansion stress
during nail insertion
 Larger hoop stress can split bone
 Hoop stress reduction :
 Use flexible nails
 Over-ream entry hole by 0.5 to 1 cm
 Selection of ideal entry point

37. Posterior - loss of
proximal fixation
Ideal - posterior portion
of piriformis fossa
Anterior - generates
huge forces, can lead to
bursting of proximal

38. Nail length
A-Total nail length - Anatomical length
B-working length - length between proximal and
distal point of firm fixation to
bone
Working length
Affected by various factors
Type of force (Bending ,Torsion )
Type of fracture
Interlocking and dynamization
Reaming
Weight bearing

39. Nail length
 Shorter working length stronger fixation
 Transverse fracture has a shorter working length than
comminuted fracture
 Torsional stiffness 1/ to l
 Bending stiffness 1/ to l2
 Surgeon’s techniques to modify “ l ”
 Medullary reaming
 Interlocking

40. Extreme ends
 K-nail
 Slot/eye in ends for extraction
 One end tapered to facilitate insertion .
 Holes for interlocking screws
 Some nails have slots near distal end
for placement of anti rotation screw
 Anterior slot-
Improved flexibility
 Posterior slot -
Increased bending
strength
 Non-slotted -
Increased torsional
stiffness and strength
in smaller sizes

41. Interlocking of nail
 Recommended for most cases of IM nailing.
 Principle :
 Resistance to axial and torsional forces depends on
screw – bone interface
 Length of bone maintained even in bone defect.
 Number of interlocks :
 Fracture location
 Amount of fracture comminution
 Fit of nail within canal.
 Placing screws in multiple planes - reduction of minor movement

42. Interlocking screw
 Location of distal locking screws affects
biomechanics of fracture
 Distal locking screws
 Closer to fracture site - less cortical contact -
increased stress on locking screws
 Distal from fracture site - fracture becomes
more rotationally stable
 Interlocking screws positioned at least 2 cm
from fracture provides sufficient stability

43. Poller /blocking screws
 Corrects mal-alignment.
 Centers IM nail.
 Planned and inserted before
IM nail insertion.
 Saggital or coronal plane.

44. Static locking
 Screws placed proximal and distal to fracture site
 Restrict translation and rotation at fracture site.
 Acts as a “bridging fixation”
 Indications :
 Communited
 Spiral
 Pathological fractures
 Fractures with bone loss
 Atropic non union

45. Dynamic locking
 Screws inserted only at one end (short fragment)
 Unlocked end stabilized by snug fit inside medullary cavity
(long fragment)
 Prerequisite: at least 50% cortical circumferential contact
 Indications
 Fractures with good bone contact
 Non unions
 With axial loading , working length in bending and torsion is
reduced - improving nail-bone contact

46. Dynamisation
 “Weaken stability”
 Never done in progressive normal healing
 Indications
 Established nonnunion
 Pseudoarthrosis
 Caution: premature dynamisation adds to
shortening, instability and non-union.

47. Dynamisation
 Primary Dynamisation
 Dynamic locking of axially and rotationally stable
fractures at time of initial fracture fixation
 Secondary Dynamisation
 Removing interlocking screw from longer fragment
/ moving proximal interlocking screw from static to
dynamic slot in nail
 Done in long bone delayed union and nonunion

48. Reamed Versus Unreamed
 Endosteal thermo-necrosis & endosteal cortical blood supply disruption
 Minimized by using sharp reamers with deep cutting flutes.
 Reaming - slow and smooth.
 Endosteal blood supply regenerates rapidly - high healing rates in reamed
nails.
 No difference in infection rates
 No overall difference in time to union

49. Reamed Versus Unreamed
 Reamed nail :
 High chance of embolization of bone marrow fat to lungs but this phenomenon is limited &
transient
 Fat extravasation greatest during insertion of nail in medullary cavity
 Not dependent upon increased intra medullary pressure
 Reamed nailing generally report no statistical difference in pulmonary complications
as compared to unreamed nailing

50. Open intramedullary nailing
Primary indication :
 Failure to do closed nailing
 Nonunions
 Fractures requiring intramedullary fixation in existing
internal fixation device.

51.  Advantages :
 Less expensive equipment required than for closed nailing.
 No special fracture table / preliminary traction
 Absolute anatomical reduction
 Direct observation of bone - undisplaced / undetected comminution
 Improved rotational alignment and stability.
 Prevents torquing and twisting in segmental fractures
 In nonunions, opening of medullary canals of sclerotic bone is easier.

52. DISADVANTAGES :
Skin scars
Fracture hematoma evacuated.
 Bone shavings created by reaming medullary canal often are lost.
Infection rate increased.
 Rate of union decreased.
 If a locking nail is used, locking is difficult without image intensification

53. Nailing in open fractures
 If initial debridement adequate and timely , definitive stabilization with
reamed intramedullary nailing
 with severe soft tissue injuries that require a second debridement,
temporary external fixation reasonable
 increased risk of infection after use of external fixation pins longer than 2
weeks followed by reamed intramedullary nailing.
 Rapid initial management approach allows delayed conversion to a
medullary implant at 5 to 10 days.

54. Nailing in open fractures
 Fractures with delay in initial debridement of more than
8 hours - staged nailing.
 Acceptable complication rate (11 % infection rate in type
iii open fractures)
 No relationship between infection rate, non union with
timing of nailing or associated soft tissue injury

55. Aseptic non unions
 Without bone defects - primary im nailing or exchange
nailing if well aligned
 With bone defects - im nailing with bone grafting
 corticocancellous graft material - harvested with
ria(little donor morbidity)

56. Exchange nailing
 Biological effects :
 Reaming of medullary canal – promotes union
 Mechanical effects :
 Larger-diameter intramedullary nail – improved
stability
 Exchage nail – atleast 1mm larger than
previous nail
 Canal reaming until osseous tissue observed
in reaming flutes
Removal of current
intramedullary nail
Reaming of medullary
canal
Placement of an larger
intramedullary nail

57. Septic non union
 Main aim - eradicating infection
 Osseous stability important in management of infected nonunion
 Stabilization with antibiotic impregnated cement coated nail after serial
debridement.
 Cement nail elute high concentration of antibiotic in local sites for up to 36 weeks.

58. Antibiotic impregnated cement nail

59. Nailing in damage control orthopaedics (DCO)/early total care (ETC)
 In polytrauma , early femoral stabilization decreases incidence of
severe fat embolism and pulmonary complications (ARDS).
 Nailing with reaming will not increase pulmonary complications
 Early intramedullary nailing may be deleterious and is associated with
elevation of certain proinflammatory markers - (il)-6.
 Early external fixation of long bone fractures followed by delayed
intramedullary nailing – high risk patients.

60. Nailing in damage control orthopaedics (DCO)/early total care (ETC)
 50% (↓) in mortality patients who underwent femoral shaft
fracture stabilization beyond 12 hours
 This timing was hypothesized to allow for adequate
resuscitation
 Exact and optimal timing of femoral shaft fracture nailing
remains unclear in polytrauma(esp. Chest injuries)

61. Removal
 Timing controversial
 Indications :
 Patient request(after union)
 Pain, swelling secondary to backing out of implant.
 Infected nailing
 Full weight bearing immediately after removal
 Femoral nail removed after 24-36 months , tibial nail 18-24 months

62. Failure
 When fracture healing is delayed or nonunion occurs.
 IM nails usually fail in predictable patterns.
 Unlocked nails
 fail at fracture site or through a screw hole or slot.
 Locked nails
 screw breakage or fracturing of nail at locking hole sites(proximal
hole of distal interlocks )

63. Recent advances
 Biodegradable polymers
 Nickel-titanium shape-modifiable alloys
 can improve stability as they change shape after
insertion and recover curvature as they warm.
 IM nails coated with bmp

64. Conclusion
 Implant of choice in diaphyseal fractures
 Multiple factors determine final construct stiffness,
should be understood and considered when
choosing IM nail
 Ideal intramedullary nail is yet to be invented

65. Bibliography
 Campbell operative orthopaedics 12th edition
 Rockwood and green – fractures in adults 8th edition
 Elements of fracture fracture fixation – anand J.Thakur(3rd edition)
 History of intramedullary nailing ,matw R. Bong, M.D., Kenneth J.
Koval,m.D., And kenneth A. Egol, M.D., Bulletin of NYU hospital for
joint diseases • volume 64, numbers 3 & 4, 2006