Basic Principles and Techniques of Internal Fixation of Fractures

1. Basic Principles and Techniques of Internal Fixation of Fractures Michael Archdeacon, MD, MSE Original Author: Dan Horwitz, MD; March 2004 New Author: Michael Archdeacon, MD, MSE; Revised January 2006

2. Fracture Definitions • Union • Bone restored in terms of mechanical stability • Delayed Union • Fx not consolidated at 3 months, but appears to be moving in that direction • Non Union • No improvement clinically or radiographically over 3 month period • A fibrocartilaginous interface From: OTA Resident Course – Russel, T

3. High Energy vs Low Energy • “High Energy" • Energy imparted into the bone disrupts the soft tissue envelope as a very destructive process • “Low Energy“ • Less energy imparted into the fracture environment, thus a less destructive process “High Energy" “Low Energy"

4. Fracture Patterns • Fracture patterns occur based on mode of application, magnitude and rate of force applied to bone • Bending Load = transverse fx or wedge segment • 3-point Bend = Wedge fragment • 4-point Bend = Segmental fragment • Torsional Load = oblique or spiral fx • Shear Load = Axial impaction (Plateau, Pilon, ect)

5. Fracture Patterns • Understanding these patterns and the inherent stability or instability of each type is important in choosing the most appropriate method of fixation

6. Biology of Bone Healing THE SIMPLE VERSION... High Rate of Healing Relative Stability =20 Bone Healing Rigid Fixation =10 Bone Healing Fibrous Matrix > Cartilage > Calcified Cartilage > Woven Bone > Lamellar Bone Haversion Remodeling Spectrum of Healing

7. Biology of Bone Healing • Primary bone healing • Requires rigid internal fixation and intimate cortical contact • Cannot tolerate soft tissue interposition • Relies on Haversian remodeling with bridging of small gaps by osteocytes Figure from: OTA Resident Course - Russel

8. Biology of Bone Healing • Secondary Bone Healing = CALLUS • Divided into stages • Inflammatory Stage • Repair Stage • Soft Callus Stage • Hard Callus Stage • Remodeling Stage 3-24 mo Figures from: OTA Resident Course - Russel

9. Practically speaking... • Plates and screws = Rigid Fixation • IM Rods = Relative Stability • Small Wire / Tension Band = Relative Stability • Cast = Non-Rigid Fixation

10. Fixation Stability • Relative Stability • Absolute Stability • IM nailing • Ex fix • Bridge plating • Lag screw/ plate • Compression plate

11. Fixation Stability Ender’s Nails IM Nail Ex Fix Cast Bridge Plating Compression Plating/ Lags Unstable Stable Spectrum of Stability

12. Practically speaking…. • Most fixation probably involves components of both types of healing. Even in situations of excellent rigid internal fixation one often sees a small degree of callus formation...

13. Fixation Stability Reality Callus No callus Unstable Stable

14. Intrafragmentary Compression Lag Screw Intrafragmentary Compression & Plates Dynamic Compression Plating Plate Functions Neutralization Buttressing Bridging Tension Band Compression Intramedullary Nails Functions of Internal Fixation

15. Indications and Benefits of Internal Fixation • Displaced intraarticular fracture • Axial or angulatory instability which cannot be controlled by closed methods • Open fracture • Malreduction/interposed soft tissue • Multiple trauma • Early functional recovery MULTIPLE REASONS EXIST BEYOND THESE...

16. Screws • Cortical screws: • greater surface area of exposed thread for any given length • better hold in cortical bone • Cancellous screws: • core diameter is less • the threads are spaced farther apart • lag effect option with partially threaded screws • theoretically allows better • fixation in soft cancellous bone. Figure from: Rockwood and Green’s, 5th ed.

17. Lag Screw Fixation • Screw tensioned across fx = compression of fx • Terminal threads and smooth shank OR • Overdrill near cortex & engage only far cortex

18. Compression Lag Screws • Stability by compression between bony fragments • Step One: Pilot hole = thread diameter of screw & perpendicular to fx • Step Two: Guide sleeve in pilot hole & drill far cortex = to the core diameter of the screw 1 2 Figure from: Schatzker J, Tile M: The Rationale of Operative Fracture Care. Springer-Verlag, 1987.

19. COMPRESSION - LAG SCREWS • Step Three: Screw glides through the near cortex & only engages the far cortex • Step Four: When screw engages far cortex it compresses it against the near cortex Figure from: Schatzker J, Tile M: The Rationale of Operative Fracture Care. Springer-Verlag, 1987.

20. Functional Lag Screw - note the near cortex has been drilled to the outer diameter = compression Neutralization Screw - note the near cortex has not been drilled to the outer diameter = lack of compression & fx gap Compression - Lag Screws

21. Compression Lag Screws • Malposition can lead to a loss of reduction • Ideally lag screw should pass perpendicular to fx Figure from: OTA Resident Course - Olsen

22. Neutralization Plates • Protect intrafragmentary compression (lag screws) from large forces across fx’s

23. The Neutralization Plate • Lag screws provide compression & initial stability • Neutralization plate bridges the fracture & protects the screws from bending and torsional loads • “Protection Plate" Figure from: Schatzker J, Tile M: The Rationale of Operative Fracture Care. Springer-Verlag, 1987.

24. Buttress / Antiglide Plates • Resist shear forces or bending forces during axial loading of fx • Stabilize intra-articular fragments • Plate must be “contoured” to fit the bone • Screws placed to minimize movement of plate with tightening

25. Buttress Concepts • The bottom 3 cortical screws • provide the basis for the buttress • effect. • The top 3 screws are in effect • interfragmentary screws and the 2 • top screws are lag screws because • they are only partially threaded. • Underbending the plate can be • advantageous in that it can increase • the force with which the plate • pushes against the proximal fragment. • NOTE: screws are placed from distal to proximal maximizing the buttress action and aiding in reduction. Figure from: Schatzker J, Tile M: The Rationale of Operative Fracture Care. Springer-Verlag, 1987.

26. Antiglide Concepts • In this model the white plate is secured by three black • screws distal to the red fracture line. • The fracture is oriented such that displacement from • axial loading requires the proximal portion to move • to the left. • The plate acts as a buttress against the • proximal portion, prevents it from “sliding” • and in effect prevents displacement from • an axial load. • If this concept is applied to an intraarticular • fracture component it is usually referred to as a • buttress plate, and when applied to a diaphyseal • fracture it is usually referred to as an antiglide • plate.

27. Buttress and Antiglide Plates • The plates on the right are thin, pliable and often used as buttress plates in the distal radius • Those on the are left also fairly thin and are designed for subcutaneous antiglide applications in the distal tibia & fibula Figure from: Rockwood and Green’s, 5th ed.

28. Buttress Reconstruction Plates • Both small frag (3.5mm) and large frag (4.5mm) sizes • Often used to buttress acetabular wall fractures Figure from: Rockwood and Green’s, 5th ed.

29. Bridging Plates • “Bridge” comminution with proximal & distal fixation, but minimal fixation in zone of injury • Maintains length & axial alignment • Avoids soft tissue disrutpion @ fracture

30. Tension Band Plates • Plate counteracts natural bending moment seen w/ physiologic loading of bone • Applied to tension side to prevent “gapping” • Examples: Proximal Femur & Olecranon

31. JOINT SURFACE Tension band • Tension Band Theory • The concept here is that a “band” of fixation at a distance from the articular surface can provide reduction and compressive forces at the joint. • The fracture has bending forces applied by the musculature or load bearing and these forces have a component which is perpendicular to the joint/cortical surface.

32. JOINT SURFACE Tension band • Since the tension band prevents distraction at the cortex the force is converted to compression at the joint. • The tension band itself essentially functions like a door hinge, converting displacing forces into beneficial compressive forces at the joint.

33. Classic Tension Band of the Olecranon • 2 K-wires up the ulnar shaft maintain initial reduction and anchor for the tension wire • Tension wire brought through a drill hole in the ulna. • Both sides of the tension wire tightened to ensure even compression • Bend down and impact wires Figure from: Rockwood and Green’s, 4th ed.

34. Compression Plating • Reduce & Compress transverse or oblique fx’s • Exert compression across fracture • Pre-bending • External compression devices (tensioner) • Dynamic compression w/ oval holes & eccentric screw placement in plate

35. Examples- 3.5 mm Plates • LC-Dynamic Compression Plate: • stronger • more difficult to contour. • usually used in the treatment radius and ulna fractures • Semitubular plates: • very pliable • limited strength • most often used in the treatment of fibula fractures Figure from: Rockwood and Green’s, 5th ed. Figure from: Rockwood and Green’s, 5th ed.

36. Compression • Fundamental concept critical for primary bone healing • Compressing bone fragments decreases the gap the bone must bridge creating stability by preventing fracture components from moving in relation to each other. • Achieved through lag screw or plating techniques.

37. Plate Pre-Bending Compression • Prebent plate • As plate is compressed, prebend forces opposite cortex into compression • Near cortex is compressed via standard methods

38. Plate Pre-Bending Compression

39. Screw Driven Compression Device • Requires a separate drill/screw hole beyond the plate • Replaced by the use of DCP plates. • Concept of anatomic reduction with added to stability by compression to promote primary bone healing has not changed • Currently used with indirect fracture reduction techniques Figure from: Schatzker J, Tile M: The Rationale of Operative Fracture Care. Springer-Verlag, 1987.

40. Dynamic Compression Plates • Note the screw holes in the • plate have a slope built into • one side. • The drill hole can be purposely placed eccentrically so that when the head of the screw engages the plate the screw and the bone beneath are driven or compressed towards the fracture site one millimeter. This maneuver can be performed twice before compression is maximized. Figure from: Schatzker J, Tile M: The Rationale of Operative Fracture Care. Springer-Verlag, 1987.

41. Dynamic Compression Plating • Compression applied via oval holes and eccentric drilling • Plate forces bone to move as screw tightened = compression • DCP is a misnomer = static compression is applied once the screw is tightened

42. Combined Plating and Lag Screw • Compression can be achieved and rigidity obtained all with one construct. Figure from: Rockwood and Green’s, 5th ed.

43. Intramedullary Nails • Relative stability achieved via intramedullary splint • Allows axial loading of fracture • Healing primarily by secondary bone healing

44. Intramedullary Fixation • Generally utilizes closed 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

45. Intramedullary Fixation • Rotational and axial stability provided by interlocking screws • Reduction can be technically difficult in segmental, comminuted fractures • Fractures in close proximity to metaphyseal flare may be difficult to control

46. Open segmental tibia fracture treated with a reamed, locked IM Nail. • Note the use of multiple proximal interlocks where angulatory control is more difficult to maintain due to the metaphyseal • flare.

47. Subtroch fracture treated with closed IM Nail. • The goal here is to restore alignment and rotation, not to achieve anatomic reduction. • Without extensive • exposure this fracture formed abundant callous • by 6 weeks. Valgus is restored...

48. Reduction Techniques…some of the options • Traction • Direct external force i.e. push on it • Percutaneous clamps - INDIRECT METHOD • Percutaneous K wires - INDIRECT METHOD • Minimal incision, debridement of hematoma • Incision and direct fracture exposure and reduction- DIRECT METHOD

49. Reduction Techniques • Over the last 25 years the biggest change regarding ORIF of fractures has probably been the increased respect for soft tissues. • Whatever reduction or fixation technique is chosen, the surgeon should attempt to minimize periosteal stripping and soft tissue damage. • EXAMPLE: supraperiosteal plating techniques

50. Reduction Technique • The use of a pointed reduction clamps to reduce a complex • distal femur fracture pattern. • Excellent access to the fracture to place lag screws with the clamp in place • Can be done open or percutaneously, as long as the • neurovascular structures are respected.