Orthopaedic Plates - types and applications

a brief introduction about orthopaedic plates, its uses and types

1. PLATE- TYPES AND APPLICATIONS Dr. Mohammed Roshen JR Academic Department Of Orthopaedics MODERATOR : Dr. Sudeep Kumar

2. History Plates for fixation of long bones were first recorded by HANSMANN (Heidelberg university, Germany, 1886)

3. Hansmann’s plate Bend at the end to protrude through skin Attached to bone by screw with long shanks that projected outside the soft tissues

4. Since 1958, AO has devised plates for long bone fractures starting with a round holed plate. In 1969, dynamic compression plate was developed In 1994,LCDCP was created In 2001, LCP was developed In 2011, LCP with combination holes came into use

5. Introduction Bone plates are like internal splints holding fracture ends of bones together Bone plate has two mechanical function Transmitting force from one end of bone to the other bypassing the fracture site Hold fracture ends together while maintaining proper alignment

6. FORM- to understand how changes in design of plates has evolved to meet the needs of the patient FUNCTION – to understand how we can use a plate in different ways to achieve different types of fixation

7. Orthopaedic Alloys

8. Stainless Steel Vs Titanium Titanium is stronger and lighter in weight compared to stainless steel. Titanium has a large resistance to repeated loads making it ideal for its application as an implant. Titanium has greater superior strength under repeated load stresses, making this metal capable of withstanding strain during internal fixation. With a lower modulus of elasticity compared to stainless steel , titanium is less rigid which limits the amount of stress on bone structures. Titanium is less prone generating an immune reaction based on the fact that this material is corrosion resistant compared to stainless steel implants.

9. Plate Form- Types DCP (Dynamic Compression Plate) LCDCP (Limited Contact Dynamic Compression Plate) LCP (Locking Compression Plate) RECONSTRUCTION PLATE 1/3 RD TUBULAR LISS (Less Invasive Stabilisation System)

10. DCP First introduced in 1969 by Danis Concept-compression plating New hole design- axial compression

11. 3.5mm for forearm, fibula, clavicle 4.5mm narrow – humerus 4.5mm broad - femur

12. PROBLEMS WITH DCP Unstable fixation leads to fatigue and failure Compromised blood supply due to intimate contact with underlying cortex Refractures after plate removal

13. the flat undersurface of the DCP interfered with the blood supply of the underlying cortex onto which it was compressed by the screws. The concept of the “footprint” of a plate emerged. The "footprint" is the area of the undersurface of the plate in contact with the underlying bony cortex.

14. LC-DCP Design change Plate footprint reduced Advantages Minimized kinking at screw holes, more contourable, reduced fatigue at holes Allows more inclination of screw in longitudinal plane and transverse plane

15. Tubular Plate 3.5mm – 1/3 rd tubular 4.5mm – semitubular Limited stability Collared hole

16. Used for Lateral malleoli Distal ulna

17. Reconstruction Plate Deep notches present between holes Accurate contouring in any plane Used for Pelvis Acetabulum Clavicle Distal humerus

18. LCP Latest evolution “INTERNAL FIXATOR” Extraperiosteal location of plate

19. COMBIHOLES Advantages of DCP principle and locking head principle Flexibility of choice Screw holes have been designed to accept either cortical or locking screw

20. TECHNIQUE Traditional plating techniques produced stability by: Compression the plate to the bone surface and Engaging both cortices, thereby producing a rectangular hoop with two bicortical screws .The locking screws, by achieving angular stability within the plate holes are able to produce a similar hoop with just two unicortical screws.

21. Why LCP ? 1 – Biomechanically stronger implant as stability not dependent on plate screw interface . In DCP , failure of one screw can jeopardize whole construct while all screws of LCP need to be failed in order for LCP to fail.    2 – Unicortical screws are equivalent In strength of construct to that of DCP bicortical screws.    3 – Construct not dependent on quality of host bone for purchase like in DCP.    4 – MIPO is possible .    5 – Bridge plating possible

22. INDICATIONS: Complete periarticular fractures Comminuted distal femur fracture Tibial plateau fracture Distal tibia fracture Periprosthetic fracture Pathological fracture Comminuted proximal humerus fracture Intra articular distal radius fracture

23. LISS Preshaped plates with self drilling self tapping screws with threaded heads. Through a small incision (using this jig ) plate is slid along the bone surface. position of plate and wire are checked radiologically before insertion of metaphyseal screw .

24. Plate Function - Types NEUTRALIZATION PLATE COMPRESSION PLATE BUTTRESS PLATE BRIDGE PLATE TENSION BAND

25. Neutralization Plate A neutralization plate acts as a “”bridge”. It transmits various forces from one end of the bone to the other, bypassing the area of the fracture. Its main function is to act as a mechanical link between the healthy segments of bone above and below the fracture.

26. plate does not produce any compression at the fracture site it is crucial to use a plate that is long enough so that at least three bicortical screw can be inserted in to each main fragment.

27. The most common clinical application of the neutralization plate is to protect the screw fixation of a short oblique fracture, a butterfly fragment or a mildly comminuted fracture of a long bone, or for the fixation of a segmental bone defect in combination with bone grafting

28. Compression Plate A compression plate produces a locking force across a fracture site to which it is applied. The effect occurs according to Newton's Third Law (action and reaction are equal opposite). The plate is attached to a bone fragment. It is then pulled across the fracture site by a device, producing tension in the plate. As a reaction to this tension, compression is produced at the fracture site across which the plate is fixed with the screws.

29. ROLE OF COMPRESSION Reduction of the space between the bone fragments to decrease the gap to be bridged by the new bone Compaction of the fracture to force together the interdigitating spicules of bone and increase the Protection of blood supply through enhanced fracture stability. Static compression between two fragments maintained over several weak and does not enhance bone resorption and necrosis. Interfragmentary compression leads to absolute stability but has no direct influence on bone biology or fracture healing

30. INDICATIONS OF COMPRESSION PLATING: Simple transverse oblique fractures of the diaphysis or metaphysis Intra articular fractures Delayed union or non union Closed wedge osteotomy

31. METHODS OF ACHIEVING COMPRESSION With tension device Overbending DCP/ LCDCP principle Contouring the plate Additional lag screw through plate

32. Compression With An External Device it is recommended for fractures of the femur or humeral shaft, when the gap to be closed exceeds 1–2 mm, as well as for the compression of osteotomies and nonunions . After fixation of the plate to one main fragment, the fracture is reduced and held in position with a reduction forceps. The tension device is now connected to the plate and fixed to the bone by a short cortex screw.and then after comression another fragment is fixed to plate

33. In oblique fractures the tension device must be applied in such a way that the loose fragment locks in the axilla if compression is produced.

34. Compression With Overbending If a straight plate is tensioned on a straight bone, a transverse fracture gap will open up due to the eccentric forces acting on the opposite side.

35. If the plate is slightly prebent prior to the application (a), the gap in the opposite cortex will disappear as compression is built up (b), so that finally the whole fracture is firmly closed and compressed (c).

36. Compression Through Plate

37. Dynamic compression principle : a The holes of the plate are shaped like an inclined and transverse cylinder. b–c Like a ball, the screw head slides down the inclined cylinder. d–e Due to the shape of the plate hole, the plate is being moved horizontally when the screw is driven home. f The horizontal movement of the head, as it impacts against the angled side of the hole, results in movement of the plate and the fracture fragment already attached to the plate by the first screw This leads to compression of the fracture.

38. Buttress Plate A buttress is a construction that resists axial load by applying force at 90° to the axis of potential deformity Used in metaphyseal/epiphyseal shear or split fractures For application of a buttress plate, the first screw must be eccentric to prevent sliding of the plate

39. Antiglide Concepts 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.

40. Bridge Plate Transmits forces from one end of the bone to other bypassing the fracture site Mechanical link between the healthy segments of bone above and below the fracture Plate doesn’t produce compression at the fracture site

41. Tension Band If a body with a fracture is loaded at each end, over a bending point (fulcrum), tension (distraction) forces are generated, maximal on the side opposite the fulcrum, and angulation occurs.

42. However, if an inelastic band, such as a plate, is anchored to the tension side of the body, the same load will generate compression across the fracture interface. • This is known as the tension band principle

43. PREREQUISITES OF TENSION BAND FIXATION Bone which is eccentrically loaded and able to withstand compression An intact buttress of the opposite cortex A strong plate to withstand the tensile forces Plate placement on the tension side of bone A bone plate will act as a tension band only if it is applied to the tension side of the bone

44. Factors The success of bone-plate fixation depends on Plate thickness, dimension, geometry, material used Screw design, material, number and hold in bone Bone- mechanical properties and health Construct- placement of plate and direction of load Compression between the fragments

45. Prebending Of Plates When a straight plate is applied to a straight bone surface under static compression, the near cortex is brought under compression but the far cortex opens up Micromovements with subsequent bone resorption and loss of fixation

46. Prebent plate results in more uniform compressive contact across the fracture site without gaping than is achievable with a straight plate

47. PREBENDING PLATES Contour to fit the bone surface snugly Make a sharp bend opposite the fracture site, midsection is elevated Fix to bone, starting from either side of fracture and then moving outwards Plate then compresses the far cortex also Apply this technique only to two fragments fractures

48. Working Length The distance between the two screws closest to the fracture on either side of the fracture determines the elasticity of the fracture fixation and distribution of induced deformation caused by external load

49. RATIOS

50. Disadvantages Greater blood loss Decreased vascularization beneath the plate Exposure of fracture site Larger operative soft tissue trauma Cosmetic Risk of screws pulling out in osteoporotic bone Risk of implant failure