principles of internal fixation
- 1. PRINCIPLES OF INTERNAL FIXATION » DR MANU MATHEW » MODERATOR DR GAURAV SHARMA
- 2. • Historical Background • Preoperative Planning • Fracture Reduction • Techniques and Devices for Internal Fixation
- 3. Historical Background • First reports on modern techniques of internal fixation are only about 100 years old. • Elie and Albin Lambotte “osteosynthesis” of fractures with plates and screws, wire loops and external fixators
- 4. Robert Danis (1880 to 1962) introduced the term of “soudure autogéne
- 5. Maurice Müller was impressed by DANIS &founded the Arbeitsgemeinschaft für Osteosynthesefragen (AO)
- 6. Gerhard Küntscher (1900 to 1972) in Germany had developed the technique of IM nailing,
- 7. • GOAL OF OPERATIVE FRACTURE FIXATION • full restoration of function • faster return to his preinjury status • • minimizethe risk and incidence of complications. • Predictable alignment of fracture fragments
- 8. The purpose of implants to provide a temporary support to maintain alignment during the fracture healing to allow for a functional rehabilitation
- 9. Biology and Biomechanics on Fracture Healing fractured bone needs - a certain degree of immobilization -optimally preserved blood supply -biologic or hormonal stimuli in order to unite.
- 10. Soft Tissue Injury and Fracture Healing “every fracture is a soft tissue injury, where the bone happens to be broken,” The more extensive the zone of injury and the tissue destruction, the higher is the risk for a delay of the healing process or for other complications
- 11. mechanical stability, Absolute stability rigid fixation that does not allow any micro motion elastic fixation provided by internal or external splinting of the bone
- 12. High Rate of HealingHigh Rate of Healing Spectrum of Healing Absolute Stability = 10 Bone Healing Relative Stability = 20 Bone Healing Biology of Bone Healing THE SIMPLE VERSION... Fibrous Matrix > Cartilage > Calcified Cartilage > Woven Bone > Lamellar Bone Haversian Remodeling Minimal Callus Callus
- 13. Absolute (Rigid) – eg Lag screw/ plate – Compression plate Relative – (Flexible) – eg – IM nailing – - Bridge plating No callus Fixation Stability Callus Reality
- 14. Functions of Fixation • Interfragmentary Compression – Lag Screw • Plate Functions – Neutralization – Buttress – Bridge – Tension Band – Compression – Locking • Intramedullary Nails – Internal splint • Bridge plate fixation – Internal splint • External fixation – External splint • Cast – External splint *Not internal fixation
- 15. Indications for Internal Fixation • Displaced intra-articular fracture • Axial, angular, or rotational instability that cannot be controlled by closed methods • Open fracture • Polytrauma • Associated neurovascular injury
- 16. The components of a preoperative plan • Timing of surgery • Surgical approach • Reduction maneuvers • Fixation construct • Intraoperative imaging • Wound closure/coverage • Postoperative care • Rehabilitation
- 17. Prophylactic Antibiotics • In general a second generation cephalosporin with a broad spectrum is recommended, applied as single dose • 30 minutes before the start of surgery or for a period of a maximum • 24 to 48 hours postoperatively
- 18. Fracture Reduction • The goal of reduction is to restore the anatomical relationship
- 19. Direct Reduction • Direct reduction – fragments are manipulated directly by the application of different instruments or hands, via open exposure of the fracture •
- 20. joysticks
- 22. Reduction Forceps provide an excellent purchase on the fragments without stripping or squeezing the periosteum EG WEBERS FORCEPS
- 25. ADVANTAGES precise restoration of anatomy; DISADVANTAGES 1 more interference with bone and soft tissue biology. 2 higher risk of infection and 3 possibly a delay in bony union
- 26. Open Reduction • Open reduction implies that the fracture site is exposed, allowing to watch and inspect the adequacy of reduction with our eyes.
- 27. Indications for open reduction 1 Displaced articular # with impaction of the joint surface 2 #which require exact axial alignment (e.g., forearm #, simple metaphyseal #) 3 failed closed reduction due to soft tissue interposition 4 Delayed surgery where granulation tissue or early callus has to be removed 5 high risk for neurovascular structures 6 no or limited access to perioperative imaging to check reduction
- 28. Indirect reduction • Indirect reduction means that the reduction and alignment of the # by applying reduction forces indirectly • via the soft tissue envelope—to the main fragments by manual Or skeletal traction, a distractor, or some other means.
- 29. • classical example of indirect reduction is the “closed” insertion • of an intramedullary nail on a fracture table
- 30. The distractor
- 31. Indirect reduction ADVANTAGES virtually NO exposure of the fracture site ; LESS damage to the vascularity of the tissue DISADVANAGES 1demanding technique and that 2the correct overall alignment of the fracture is more difficult to assess, especially in rotation
- 32. Closed Reduction • Closed reduction relies entirely on indirect fragment alignment by ligamentotaxis or the pull of the soft tissue envelope
- 33. • Traction is the most common means to reduce a fracture – D/A applied across a joint and that there are limited possibilities to move the limb. Eg The fracture table
- 34. The distractor offers many possibilities and more freedom of movement •D/Aquite demanding to manipulate and requires considerable practice
- 35. advantages of closed reduction • minimal damage to soft tissues • safer • more rapid fracture repair • lesser infection.
- 36. Indications for closed reduction • Most diaphyseal fractures • • Minimally displaced articular fractures. • Geriatric femoral neck fractures, trochanteric fractures, subcapital humerus fractures, and certain distal radius fractures
- 37. Techniques and Instruments for Fracture Reduction
- 38. Screws • The two basic principles of a conventional screw are • to compress a fracture plane (lag screw) and • to fix a plate to the bone (plate screw)
- 39. • Cortical screws: –Greater number of threads –smaller pitch –Outer thread diameter to core diameter ratio is less –Better hold in cortical bone –Usually fully threaded –Size1-4.5mm diameter –Self tapping ,cannulated etc Figure from: Rockwood and Green’s, 5th ed.
- 40. •Cancellous screws: – Larger thread to core diameter ratio –pitch is greater -Lag effect with partially-threaded screws - – Theoretically allows better fixation in cancellous bone - indicated for meta-epiphyseal , cancellous bone Tapping is recommend
- 41. LHS •The LHS have a head with a thread •that engages with the reciprocal thread of the plate hole. •a screw-plate device with angular stability variable angular stability, which allows angulating locking screws within the plate hole to address specific fracture configurations
- 42. LAG SCREW
- 43. Positioning Screw a fully threaded screw that joins two anatomical parts at a defined distance without compression. The thread is therefore tapped in both cortices. example is a screw placed between fibula and tibia in a malleolar fracture
- 46. Plates • Conventional non locked screws used to fix a plate to the bone plate is pressed against the bone which produces preload and friction between the two surfaces. • #forearm bones , • simple metaphyseal fractures of long bones, malunion and nonunions, D/A local cortical necrosis
- 47. HISTORY OF PLATES • Early modern plates - round holes the conical--firm fit the dynamic compression • plate (DCP) by Perren . spherical screw head and an inclined oval screw hole
- 48. •Angle blade plates tubular plates, •reconstruction plates, the sliding hip screw and dynamic condylar •LC-DCP (limited contact- •DCP)
- 49. THE FIVE FUNCTIONS OF PLATING • Neutralization or protection • Compression • Buttressing • Tension band function • Bridging
- 50. Neutralization Plates • Neutralizes/protects lag screws from shear, bending, and torsional forces across fx • “Protection Plate"
- 51. Buttress / Antiglide Plates • “Hold” the bone up • Resist shear forces during axial loading – Used in metaphyseal areas to support intra-articular fragments • Plate must match contour of bone to truly provide buttress effect • Buttress Plate – When applied to an intra- articular fractures • Antiglide Plate – When applied to diaphyseal fractures
- 52. • Order of fixation: • Articular surface compressed with bone forceps and provisionally fixed with k-wires 1. Bottom 3 cortical screws placed • Provide buttress effect 2. Top 2 partially-threaded cancellous screws placed • Lag articular surface together 3. Third screw placed either in lag or normal fashion since articular surface already compressed Buttress Concepts Figure from: Schatzker J, Tile M: The Rationale of Operative Fracture Care. Springer-Verlag, 1987.
- 53. Bridge Plates • “Bridge”/bypass comminution • Proximal & distal fixation • Goal: – Maintain length, rotation, & axial alignment • Avoids soft tissue disruption at # = maintain # blood supply
- 54. Tension Band Plates • Plate counteracts natural bending moment seen wih physiologic loading of bone – Applied to tension side to prevent “gapping” – Plate converts bending force to compression – Examples: Proximal Femur & Olecranon
- 55. Plate Pre-Bending Compression • Prebent plate – A small angle is bent into the plate centered at the # – The plate is applied – As the prebent plate compresses to the bone, the plate wants to straighten and forces opposite cortex into compression – Near cortex is compressed via standard methods • External devices as shown • Plate hole design
- 56. Screw Driven Compression Device • Requires a separate drill/screw hole beyond the plate • Currently, more commonly used with indirect fracture reduction techniques
- 58. Dynamic Compression Plating • Compression applied via oval holes and eccentric drilling – Plate forces bone to move as screw tightened = compression
- 59. Lag screw placement through the plate • Compression + rigidity obtained a with one construct • Compression plate first • Then lag screw placed through plate Figure from: Rockwood and Green’s, 5th ed.
- 60. Locking Plates • Screw head has threads that lock into threaded hole in the plate • Creates a “fixed angle” at each hole • Theoretically eliminates individual screw failure • Plate-bone contact not critical Courtesy AO Archives
- 61. Locking Plates • Increased axial stability • It is much less likely that an individual screw will fail • But, plates can still breakIndications: – Osteopenic bone – Metaphyseal fractures with short articular block – Bridge plating
- 62. Intramedullary Nails • Relative stability • Intramedullary splint • Less likely to break with repetitive loading than plate • More likely to be load sharing . • Secondary bone healing • Diaphyseal and some metaphyseal fractures
- 63. Intramedullary Fixation • Generally utilizes closed/indirect or minimally open reduction techniques • Greater preservation of soft tissues as compared to ORIF • IM reaming has been shown to stimulate fracture healing • Expanded indications i.e. Reamed IM nail is acceptable in many open fractures
- 64. Intramedullary Fixation • Rotational and axial stability provided by interlocking bolts • Reduction can be technically difficult in segmental and comminuted fractures • Difficult to Maintain reduction of fractures in close proximity to metaphyseal flare
- 65. • Open segmental tibia fracture treated with a reamed, locked IM Nail. • Note the use of multiple proximal interlocks where angular control is more difficult to maintain due to the metaphyseal flare.
- 66. • Intertrochanteric/ Subtrochanteric fracture treated with closed IM Nail • The goal: • Restore length, alignment, and rotation • NOT anatomic reduction • Without extensive exposure this fracture formed abundant callus by 6 weeks Valgus is restored...
- 67. Percutaneous Plating • Plating through modified incisions – Indirect reduction techniques – Limited incision for: • Passing and positioning the plate • Individual screw placement – Soft tissue “friendly”
- 68. •Classic example of inadequate fixation & stability •Narrow, weak plate that is too short •Insufficient cortices engaged with screws through plate •Gaps left at the fx site Unavoidable result = Nonunion Failure to Apply Concepts
- 69. Summary • Respect soft tissues • Choose appropriate fixation method • Achieve length, alignment, and rotational control to permit motion as soon as possible • Understand the requirements and limitations of each method of internal fixation
- 70. Thankyou