Principle of internal and external fixation slideshare

Principle of internal and external fixation: Plates, screws, intramedullary nail, types of external fixation

1. Principle of Internal & External Fixation Presenter: Dr. Kisan Nepali

2. Historical Background Term Osteosynthesis : Albin Lambotte , Belgian surgeon Father of modern internal and external fixation. Devised external fixator and numerous different plates and screws. ( Arbeitsgemeinschaft Fur Osteosynthesefragen )- set their goal to improve the outcome of injured patient.

3. Fracture fixation Principle: Identification / recognition of fracture Fracture reduction to restore anatomic relationship. Fracture fixation providing absolute or relative stability Preservation of blood supply to soft tissues and bone. 4. Early and safe mobilization of the injured part and the patient as a whole.

4. Goal of fracture fixation Full restoration of function of the injured limb. Implants - Provide a temporary support. - To maintain alignment during the fracture healing, and - To allow for a functional rehabilitation.

5. Fracture Reduction Restoring anatomical relationships Realignment of a displaced fracture Reduction Method Metaphyseal and diaphyseal fractures usually need functional reduction. 2. Joint fracture need anatomical reduction.

6. Reduction of Meta and Diaphyseal fracture The functional anatomy is restored (length, alignment and rotational axis). The load bearing axis of the extremity is restored (especially important in the lower limb).

7. The joint surface is restored anatomically. Gaps and steps in the articular surface must be avoided. Gaps: means that there is some space between two adjacent main articular fragments. Steps: means that there is difference between the levels of two main articular fragments. The axial alignment is restored. Reduction of articular fracture

8. Stability Relative stability Movement at fracture site. No interfragmentary compression at fracture site. It is achieved by splinting or bridging, eg . elastic nails. Callus formation. Indirect bone healing is achieved

9. Absolute stability No movement at the fracture site. Achieved by interfragmentary compression, eg . Lag screws, compression plate, Tension band. No callus formation. Direct bone healing is achieved Cutting cone mechanism. Lag screw Compression screw Tension Band

10. Preservation of blood supply –soft tissue Only devitalized and dead tissue removed. Preserve good soft tissue envelope around bone Minimal and gentle soft tissue handling Keep exposed tissues moist MIPO technique

11. Preserving blood supply -bone Reducing Periosteal stripping Indirect reduction Using implant saving blood supply (LC DCP, locking plates, ring fixators) Implant : leave least footprints

12. Early and safe mobilization Immediately after surgery Elevation of limb positioned above the level of the heart to minimize swelling. Early joint motion: Use of CPM machine

13. Early and safe mobilization Partial weight bearing Adequate pain control Thrombosis prophylaxis Early recognition of complications

14. External fixation A device placed outside the skin that stabilizes bone fragments with pins or wires connected to bars.

15. Indication of External Fixation Fractures with soft tissue damage Polytrauma – damage control surgery Skeletal infection Corrective surgery

16. External fixators implants: Schanz screws Steinmann pins Clamps Rods

17. 1. Schanz screws • Different lengths • Different diameters • Self-tapping • Self-drilling Tip —drill hole Thread —engages in far cortex of bone. Shaft —engages in near cortex of bone. Top —quadrangular top firmly holded by T-handle.

18. Drilling Tapping Drilling refers to creating a smooth hole in a material with a drill and motor. Tapping is the action that creates a thread into the side of the hole. Drilling Tapping combination

19. 2. Steinmann Pins Unthreaded and threaded With a sharp tip Through body of bone, e.g. calcaneus, tibial head, etc Use: Skeletal traction

20. Combining pin-to-rod Closed Open Combining rod-to-rod Only rod-to-rod Rod-to-pin which can be combined with pin fixation Clamps

21. 4. Rods to link pins with clamps Rods come in steel, or carbon fiber, in different lengths and diameters, to stabilize the frame by linking pins, via clamps.

22. External Fixator constructs Uni -plane Bi-plane Multi-plane Ring

23. Uniplanar Fixators Uniplanar fixator single Bar Uniplanar fixator Z frame Uniplanar fixator Double stacked

24. Types of external fixators 1.Modular system can be applied anywhere individual bone fracture or joint bridging fractures. optimal for temporary use. It is rapidly applied without need for intraoperative x-rays and can be adjusted later.

25. 2.Ring fixator To achieve complex corrections in several planes, or just fracture stabilization. Corrective procedures: Lengthening of shortened limbs. Correction of (rotational) deformities. Segemental bone transport.

26. Distraction Osteogenesis Inherent capacity of bone tissue to regenerate and remodel according to the mechanical and tension forces to which it is gradually submitted . Uses: limb length discrepancies, bone deformities secondary to trauma, infections or malformations, as a compensation after surgical excision of bone tumors

27. 3. Hybrid system combination of two types of fixator, such as a half-ring fixator plus unilateral external fixator system. Uses: fix periarticular fractures.

28. Method of Increasing Stability Pins Large Diameter More pins Closure to fracture site Bars Closer to limb More bars Rings Smaller is stiffer Use smallest diameter ring possible but allow for swelling More rings = more stable

29. External fixation advantages Minimal damage to blood supply Minimal damage to soft tissues Fixation is away from site of injury Good option when significant infection risk.

30. Complication Neurovascular injury Pin loosening Pin tract infection Joint stiffness Malaligment Malunion Nonunion.

31. Internal Fixation Stabilizes fracture ends of bone by implantation of various appliances: wires, pins, rods, nails, plates or screw. Principle To promote early active pain free movement and full weight bearing of affected limb. Prevent fracture disease (Muscle atropy , Joint stiffness, Tissue adhesions, Osteoporosis)

32. Indications of internal fixation Displaced intra-articular fractures Axial, angular or rotational instability that cannot be controlled by closed methods. Open fracture Polytrauma . Associated neurovascular injury.

33. Internal fixators Pins & Wire Fixation Screw fixation Plates and screw fixation Intramedullary nail

34. Pin and Wire Fxation K-Wire and Steinmann Pin Resistance to bending load is poor So supplemented by bracing/casting Inserted percutaneously or with limited open reduction. Use: Provisional Fracture fixation Definitive Fracture fixation: Hand, forearm, foot.

35. Screw Fixation Screw is a device that convert rotational force into linear motion. A screw has a core about which is wrapped a spiral surface. 4 parts: Head Shaft Thread Tip Lead = Pitch * No. of start Purchase

36. Screw Head: attachment for screwdriver through recesses Arrest forward motion If head is threaded:- screw locks in plate– provide angular stability. There is also a countersink for buttress which prevent sinking of head into bone. Recess types: A. Single slot head B. Cruciate Head C. Philips Head D. Recessed Hexagonal head E. New socket and driver tip (Star Drive)

37. Types of screws Machine Screws Threaded whole length Self tapping Cross section : V Use: Fasten Hip compression screw device to SOF. 2. ASIF screw Designed for osteosynthesis Thread fully/partially. Cross section: Buttress. Self tapping, non tapping. 3. Malleolar screw Cortical screw, Partially threaded, trocar tip

38. Cortical Screw Cancellous screw Modification of Machine screw Wood screw Core diameter More Less Thread depth Lesser More Pitch Lesser More Tip Simple Cork screw Cutting flutes Absent Present Solid or cannulated Mainly solid Both

39. Lag screw Compression between two bone fragments Achieves by providing purchase on the distal fragment while being able to turn freely in the proximal. Use : simple spiral and oblique fracture.

40. If the screw purchases in both cortices, it cannot produce interfragmentary compression. Perpendicular screw placement

41. Herbert screw In small bones, such as the scaphoid, self compressing, double pitch screws can be used. These are usually cannulated. As the fine pitch of the thread on the head engages the bone, it travels less far on turning than the coarse-pitched tip and so compression is applied across the fracture plane. used in scaphoid, capitellum , radial head and in osteochondral fractures.

42. Poller screws a/k/a blocking screw Effectively serving as a surrogate cortex in areas with insufficient nail- cortex contact Stability against translation and angulation

43. Dynamic Hip Screw Principle: Sequential collapse at the fracture site when joint is loaded. Uses: Intertrochanteric fracture Basal neck fracture

44. Tension Band principle In eccentrically loaded bone, Tensile force --- converted to compressive force on convex side—accompanied by placing a tension band (wire, bone plate) across the fracture line of convex side of the bone. Use: Olecranon, patellar fracture

45. Plates Like internal splints. Two mechanical function It transmits force from one end of a bone to the other, bypassing thus protecting the area of fracture. Holds the fracture together while maintaining the proper alignment of the fragements throughout the healing process.

46. Classification: Function Neutralization Compression Buttress Bridge Bridge Plate Compression plate

47. Neutralization Plate A protection plate neutralizes bending and rotational forces to protect a lag screw fixation Reduce the fracture and fix the fracture with one or more lag screws. The appropriately contoured plate is applied to the bone and screws inserted in a neutral mode.

48. Compression plate It negate torsional, bending and shearing forces and create compression across the fracture site either through external tension device or through specially designed self compression holes in the dynamic compression plate design. These holes exerts compression through translation of plate as the screw engage. USE: Type A shaft #, Transverse short oblique #

49. Dynamic Compression plate Principle: self compression plate due to the special geometry of screw hole which allow the axial compression.

50. LC DCP Further development of DCP The evenly distributed undercuts reduces the contact area between bone and plate to minimum. This significantly reduces impairment of the blood supply of the underlying cortical bone. Undercuts also allows for the formation of a small callus bridge.

51. Locking Compression Plate A fixed angle construct where screw head is locked with plate Principle: Internal external fixator: Do not require friction between plate and bone for stabilitiy unlike DCP. Stability occur at screw plate interface : Increase pull-out strength of screw. No contact between plate and bone : do not hamper periosteal vascularity. Healing by secondary intention, callus formation

52. DCP LC-DCP Under cuts Absent Present Hole distance Even Uneven Bending force distribution Even uneven Cross section and stiffness Minimum at plate hole Uniform Blood supply More affected Minimally affected Magnitude of compression Less More Bone ingrowth at fracture site Less More Stress riser More Less Stess shielding More less Lag screw placement freedom 25 ° longitudinal and 7 ° sideway 40 ° longitudinal and 7 ° sideway

53. Conventional vs locking head screws They provide more stability in osteoporotic bone by reducing the risk of screw pullout and over tightening of the screws. Well reduced fractures stay reduced Unicortical screws may be used The plate does not need to be perfectly contoured to the bone As the plate is not pressed against the bone, the periosteum is not compromised Compression at fracture site is not produced.

54. Buttress Plate Negate compression and shear force that occur at metaphyseal-epiphyseal # Used in conjunction with interfragmentary screw fixation. Feature: Plate is anchored to main stable fragement Correct contouring is mandatory. Screw should be inserted so that they adhere to the shoulder of the screw hole closest to the fracture line to prevent axial deformation with loading.

55. Anti-Gliding plate Types of buttress plate 1/3 rd tubular plate used Applied in lower 1/3 rd Fibula fracture Prevents displacement of tip of fibula

56. Bridge Plate Bridge plating techniques are used for multifragmentary long bone fractures where intramedullary nailing or conventional plate fixation is not suitable. The plate provides relative stability by fixation of the two main fragments, achieving correct length, alignment, and rotation. The fracture site is left undisturbed and fracture healing by callus formation is promoted.

57. Working Length the length between the 2 screws closest to the fracture on each end of the fracture.   decreasing the working distance increases the stiffness of the fixation construct

58. MIPO The traditional ORIF results in extensive soft tissue dissection and periosteal injury and are associated with hight rates of infection, delayed union, and non-union. Because of these drawbacks, research and development to the invention of new plates called “BIOLOGICAL PLATE” and new surgical procedure, one of which is “MINIMALLY INVASIVE PLATE OSTEOSYNTHESIS”

59. In this technique, only the normal bone cortexes, both proximal and distal to the fracture site, are exposed for positioning the plate and inserting the screws, while the fracture site is not explored so that osteogenic tissues surrounding the fracture are well protected and their blood supply is also preserved. Relative stability

60. Intramedullary nail Nail is an internal splint that allows axial forces to be transmitted from on end of bone to other. This is a load sharing implant.

61. Classification: Centromedullary nail: For example, k-nail, V-nail Cephalomedullary nail: For example, proximal femoral nail Condylocephalic nail: For example, Ender’s nail Interlocking nail.

62. Cross section of nail: Cloverleaf- K-nail V-shaped- V-nail Square shaped - Talwalkar square nail

63. Generation of nail: 1st generation nail: Only internal splintage but no rotational stability, e.g. K-nail, V-nail. 2nd generation nail: Rotational stability with, entry from piriformis fossa, e.g. interlocking nail 3rd generation nail: Trochanteric entry, e.g. PFN, recon nail.

64. Working length of nail: Distance between two points on either side of fracture where metal firmly grips the bone. Working length determines: Bending stiffness: It is inversely proportional to square of working length. Torsional stiffness: It is inversely proportional to working length.

65. Hoop stress: When a nail is inserted into medullary canal, a circumferential expanding force generated on cortex of bone is called hoop stress. This may lead to fracture of bone. To reduce hoop stress: Over-reaming of canal U se undersize nail f lexible nail Proper entry point.

66. Anteroposterior (a) and lateral (b) radiographs of nonunion of a right femur fracture before dynamization. Both figures show measurements of callus diameter and diaphysis diameter that are used to determine the callus-to-diaphysis ratio Dynamization of nail: The production of micromovement at fracture site without any deformation when limb is loaded is called dynamization. Done at 6–10 weeks after fracture fixation. Prerequisite: Minimal callus around fracture site. Done by removal of static bolt from longer fragment (for minimal instability).

67. Interlocking nail These are cylindrical nails of various bends and angulations with proximal and distal holes for bolts. Principle: 3-point contact. • Mode of use: If only dynamic bolts are applied; it act as load sharing implant, e.g. useful in transverse or short oblique fractures. If only static bolts are applied; it act as load bearing implant, e.g. useful in comminuted fractures.

68. Reamed nailing Unreamed nailing Nail diameter Larger diameter Lesser diameter Working Length (WL) Increased working length No change in working length Stability More Lesser Endosteal or medullary blood supply Hamepered Intact Healing of fracture Periosteal callus Both periosteal and endosteal callus Thermal necrosis Present Absent Bone graft fracture site Present No Risk of fat embolism Present No Chance of infection More chances No Use in compound fracture No Yes

69. Summary Following principle of Fracture fixation is important: To ensure fracture heals well and properly To ensure patient returns to normal function as quickly as possible To reduce early and late complication of fracture

70. References AO principle of fracture fixation Rockwoods and Green Fracture in Adults, 8 th Edition Campbell’s operative orthopedics , 12 th edition The Elements of Fracture Fixation, 2 nd Edition Bedside clinics in orthopedics Internet & Related articles