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Dr.S.V.Hari krishnan
PGT , M.S .(Ortho)
INTRAMEDULLARY NAILING
BASIC CONCEPTS
Learning Objectives
 Introduction
 Evolution
 Classification
 Biomechanics
 Applications
 Special Circumstances
 Re...
Introduction
 Fracture stabilized by one of two systems
 Compression
 Splinting
 Intramedullary fixation - internal sp...
Evolution
1st generation
 Splints(1˚)
 Rotational
stability
minimal
 Closed fit
 Longitudinal slot
along entire
length...
Classification
 Entry Portals :
 Centromedullary
 K nail
 Cephalomedullary
 Gamma nail
 Russell taylor nail
 PFN
 ...
Centromedullary Nails
 First generation
 Contained within medullary canal
 Usually inserted from piriformis fossa
 Pro...
Cephalomedullary Nails
 second generation nails
 More efficient load transfer than SHS
 Shorter lever arm of IM device ...
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
paediatr...
Opposite  Apex of curvature - at level of fracture
site.
 Nail diameter - 40% of narrowest
medullary canal diameter
 En...
 Schneider nail [ solid, four fluted cross section
and self broaching ends.
 Harris condylocephalic nail [curved in two
...
Ender Nails
 Solid pins with oblique tip and an eye
in flange at or end
 Designed for percutaneous, closed
treatment of ...
Rush Nails
 Intended for fractures of diaphyseal
or metaphyseal fractures of long bones
like femur, tibia, febula, humeru...
Bundle Pinning
 C- or S – shaped, act like spring.
 Principle introduced by hackethal.
 Many pins are inserted in to bo...
Applications
 Diaphyseal fractures of long bones
 High proximal and low distal fractures of
long bones
 Floating hip, f...
Contraindications
 Narrow and anomalous medullary canal
 Open growth plates
 Prior malunion - prevents nail placement
...
Mechanics (K Nail)
 Elastic deformation or “elastic
locking” of nail within medullary
canal
 Adequate friction of nail i...
 Compressible in two directions
 Directions right angles to each
other
V Nail Clover Leaf Nail
 Compressible in only on...
Elastic Compressibility Of Clover – Leaf Nail
Solid Nail Elastic Nail
 Not occupy full width of
medullary canal
 Nail with elastic cross section
adjust to constrictio...
Grosse – Kempf nail Russell – Taylor nail Brooker–Wills nail
Biomechanics of deforming forces
D
F = Force Bending moment = F x D
D
PlateIM Nail
Bending moment for plate
greater due to force being applied
over larger ...
Comparision
• Nail cross section round
• Resisting loads equally in all
directions.
• Plate cross section
rectangular resi...
Cortical contact
 - compressive loads borne
by bony cortex
 - compressive loads
transferred to interlocking
screws (“fou...
Ideal Intramedullary Nail
 Strong and stable - maintain alignment and position
 Prevent rotation - interlocking transfix...
Pre Requisites
 Adequate preoperative planning
 Patient tolerance to a major surgical procedure
 Availability of nails ...
Pre Operative Planning
Biplaner Radiographic
Images
• Bone Morphology
• Canal Dimensions
• Fracture Personality
• Comminut...
Nail Length
 Preoperative radiographs of fractured long bone
with proximal and distal joints
 AP radiograph of opposite ...
Biomechanics
 Stability determined by
 Nail design
 Number and orientation of locking screws
 Distance of locking scre...
Nail Design
 Factors contributing to biomechanical profile :
 Material properties
 Cross-sectional shape
 Diameter
 C...
Nail design
 Material properties
 Titanium alloy and 316l
stainless steel.
 Modulus of elasticity
 Titanium alloy – sa...
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
...
Nail diameter
Nail diameter affects bending rigidity
 solid circular nail,
 Bending rigidity  third power of nail
diame...
Nail curves
 Long bones have curved medullary cavities
 Nails contoured to accommodate curves of bone
 Straight, curved...
Nail curves
 Angle of herzog :
 11o bend in AP direction at junction of upper
1/3rd and lower 2/3rd of tibia nail
 Mism...
Hoop stress
 Circumferential expansion stress
during nail insertion
 Larger hoop stress can split bone
 Hoop stress red...
Posterior - loss of
proximal fixation
Ideal - posterior portion
of piriformis fossa
Anterior - generates
huge forces, can ...
Nail length
A-Total nail length - Anatomical length
B-working length - length between proximal and
distal point of firm fi...
Nail length
 Shorter working length stronger fixation
 Transverse fracture has a shorter working length than
comminuted ...
Extreme ends
 K-nail
 Slot/eye in ends for extraction
 One end tapered to facilitate insertion .
 Holes for interlocki...
Interlocking of nail
 Recommended for most cases of IM nailing.
 Principle :
 Resistance to axial and torsional forces ...
Interlocking screw
 Location of distal locking screws affects
biomechanics of fracture
 Distal locking screws
 Closer t...
Poller /blocking screws
 Corrects mal-alignment.
 Centers IM nail.
 Planned and inserted before
IM nail insertion.
 Sa...
Static locking
 Screws placed proximal and distal to fracture site
 Restrict translation and rotation at fracture site.
...
Dynamic locking
 Screws inserted only at one end (short fragment)
 Unlocked end stabilized by snug fit inside medullary ...
Dynamisation
 “Weaken stability”
 Never done in progressive normal healing
 Indications
 Established nonnunion
 Pseud...
Dynamisation
 Primary Dynamisation
 Dynamic locking of axially and rotationally stable
fractures at time of initial frac...
Reamed Versus Unreamed
 Endosteal thermo-necrosis & endosteal cortical blood supply disruption
 Minimized by using sharp...
Reamed Versus Unreamed
 Reamed nail :
 High chance of embolization of bone marrow fat to lungs but this phenomenon is li...
Open intramedullary nailing
Primary indication :
 Failure to do closed nailing
 Nonunions
 Fractures requiring intramed...
 Advantages :
 Less expensive equipment required than for closed nailing.
 No special fracture table / preliminary trac...
DISADVANTAGES :
Skin scars
Fracture hematoma evacuated.
 Bone shavings created by reaming medullary canal often are los...
Nailing in open fractures
 If initial debridement adequate and timely , definitive stabilization with
reamed intramedulla...
Nailing in open fractures
 Fractures with delay in initial debridement of more than
8 hours - staged nailing.
 Acceptabl...
Aseptic non unions
 Without bone defects - primary im nailing or exchange
nailing if well aligned
 With bone defects - i...
Exchange nailing
 Biological effects :
 Reaming of medullary canal – promotes union
 Mechanical effects :
 Larger-diam...
Septic non union
 Main aim - eradicating infection
 Osseous stability important in management of infected nonunion
 Sta...
Antibiotic impregnated cement nail
Nailing in damage control orthopaedics (DCO)/early total care (ETC)
 In polytrauma , early femoral stabilization decrease...
Nailing in damage control orthopaedics (DCO)/early total care (ETC)
 50% (↓) in mortality patients who underwent femoral ...
Removal
 Timing controversial
 Indications :
 Patient request(after union)
 Pain, swelling secondary to backing out of...
Failure
 When fracture healing is delayed or nonunion occurs.
 IM nails usually fail in predictable patterns.
 Unlocked...
Recent advances
 Biodegradable polymers
 Nickel-titanium shape-modifiable alloys
 can improve stability as they change ...
Conclusion
 Implant of choice in diaphyseal fractures
 Multiple factors determine final construct stiffness,
should be u...
Bibliography
 Campbell operative orthopaedics 12th edition
 Rockwood and green – fractures in adults 8th edition
 Eleme...
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Inra medullary nailing - basic concepts

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Inra medullary nailing - basic concepts

  1. 1. Dr.S.V.Hari krishnan PGT , M.S .(Ortho) INTRAMEDULLARY NAILING BASIC CONCEPTS
  2. 2. Learning Objectives  Introduction  Evolution  Classification  Biomechanics  Applications  Special Circumstances  Recent Advances
  3. 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. 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. 5. Classification  Entry Portals :  Centromedullary  K nail  Cephalomedullary  Gamma nail  Russell taylor nail  PFN  Condylocephalic nail  Ender nail Direction : Antegrade Retrograde
  6. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 17.  Compressible in two directions  Directions right angles to each other V Nail Clover Leaf Nail  Compressible in only one direction
  18. 18. Elastic Compressibility Of Clover – Leaf Nail
  19. 19. Solid Nail Elastic Nail  Not occupy full width of medullary canal  Nail with elastic cross section adjust to constrictions of medullary canal.
  20. 20. Grosse – Kempf nail Russell – Taylor nail Brooker–Wills nail
  21. 21. Biomechanics of deforming forces
  22. 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. 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. 24. Cortical contact  - compressive loads borne by bony cortex  - compressive loads transferred to interlocking screws (“four-point bending of screws ”) + -
  25. 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. 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. 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. 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. 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. 30. Nail Design  Factors contributing to biomechanical profile :  Material properties  Cross-sectional shape  Diameter  Curves  Length and working length  Ends of nail
  31. 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. 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. 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. 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. 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. 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. 37. Posterior - loss of proximal fixation Ideal - posterior portion of piriformis fossa Anterior - generates huge forces, can lead to bursting of proximal
  38. 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. 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. 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. 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. 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. 43. Poller /blocking screws  Corrects mal-alignment.  Centers IM nail.  Planned and inserted before IM nail insertion.  Saggital or coronal plane.
  44. 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. 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. 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. 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. 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. 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. 50. Open intramedullary nailing Primary indication :  Failure to do closed nailing  Nonunions  Fractures requiring intramedullary fixation in existing internal fixation device.
  51. 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. 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. 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. 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. 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. 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. 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. 58. Antibiotic impregnated cement nail
  59. 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. 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. 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. 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. 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. 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. 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

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