Surgical fracture treatment, fixation types. dr. Varga Attila

Transcription

1 Surgical fracture treatment, fixation types III. External Skeletal Fixation dr. Varga Attila

2 History of External Fixation Already used at the end of the 19th century Gained popularity during/after II WW Widespread use delayed (missing standards) Widely used at present (biological osteosynthesis)

3 Advantages Minimally invasive Robust mechanical environment Effective in infected areas as well Dynamization at a later stage of healing Highly customizable (PMMA/APEF)

4 Disadvantages Outside of weight bearing axis Pin tracts are infection risks Some systems are not flexible in use (K-E) Somewhat limited range of orthopedic situations Can injure patient/owner

5 Indications TIBIA RADIUS & ULNA HUMERUS & FEMUR (with restrictions) Shearing injury, Gunshot trauma Some mandibular fractures Very small patients Mature patients/ Immature patients (growth plate!!)

6 Tibia & Radius/Ulna ESF most applicable to shaft fractures highly comminuted diaphyseal fracures

7 Humerus & Femur Less appropriate than R & U Only unilateral frames Thick soft tissue coverage (pin tract infection) Bigger mobility of soft tissues (ex femoropatellar lig, quadriceps etc)

8 Shearing injuries ESF provides easy access to the wound thus facilitates daily management Rigid fixation a major advantage in the case of articular injuries

9 Shearing injuries

10 Shearing injuries

11 Shearing injuries

12 Shearing injuries

13 Gunshot trauma

14 Gunshot trauma

15 Gunshot trauma

16 Gunshot trauma

17 Mandibular fractures

18

19 Debridement

20 Fixateur externe

21 Very small & Immature patients Very small Minimally invasive Preserving soft tissue & blood supply Yorkshire radius, foot, carpus/tarsus tarsus,, MC/MT Immature MUST NOT bridge active growth plate Limb elongating operations

22 Bridging a joint Only mature animals!! When extra place is required to insert pins Temporary fixation!! Keep joint in functional angle!! Supporting a weak internal fixation

23 Limb correction osteotomy

24 Elements of an ESF system Fixation pins Fixation column (connecting column/rod rod)

25 The different systems K-E system Securos, Imex-SK Synthes-Aesculap PMMA/APEF Manuflex

26 Kirschner-Ehmer system Elements Disadvantages no potential for using smaller/larger larger pins difficulty to use positive profile pins frequent failure/loosening loosening of clamps overcomplex frames to protect weak frame components Straight connecting bar makes ideal pin placement difficult

27 Securos system/ / IMEX-SK system Elements Advantages to K-E system Better strength and versatility Positive profile pins

28 Securos system

29 IMEX-SK system

30 IMEX-SK system

31 Elements PMMA/APEF

32 PMMA/APEF Advantages ease of use no preop planning/preassembly preassembly minimal risk of pin/bar loosening or failure FREEDOM of placing pins pin location not subservient to connecting bar position Easily combined with other types

33 PMMA/APEF Disadvantages Single use Postop adjustment not easy Dynamising not easy K-E

34 Elements Manuflex

35 Classification of frames Unilateral (type I) type Ia type Ib type I tie-in in config (IM pin) Bilateral (type II) Multiplanar (type III) -ex.. a unilateral/type type Ia added to a bilateral Circular/Ilizarov Strength & stiffness: type type Ia < type Ib < type I tie- in < type II < type III)

36 Classification of frames Unilateral (type I) type Ia type Ib type I tie-in in config (IM pin)

37 Classification of frames Bilateral (type II) Multiplanar (type III) -ex.. a unilateral/type type Ia added to a bilateral Circular/Ilizarov

38 Pin Types Smooth pins (K-wire, Steinmann pins) Cheap but minimal resistance to pullout Inserted in an angle (70 degrees) Positive profile threaded pins More expensive Increased pin-bone interface ( pin-loosening loosening) No need for angulation Preserves core diameter Less prone to pin breakage

39 Pin Types Negative threaded pins Bigger pin-bone interface Prone to pin breakage (not recommended) Full pins Better strength & stability Harder to find safe soft tissue corridors Demands more careful alignment Half pins

40 Pin Insertion MOST IMPORTANT: correct limb alignment M-L alignment and torsion!!(valgus valgus/varus, abnormal stresses on adjacent joints) Some CRAN-CAUD CAUD malalignment can be tolerated (elbow/carpus,stifle/tarsustarsus can accomodate)

41 Pin Insertion Releasing soft tissues (prevent windup) Pre-drilling pin holes(decrease heat necrosis) Pins should be min 0,5-1 1 cm from joint surface and min 2 cm from fracture line (fissures!) Two cortices engaged Begin with prox/dist ones alignment

42 Pin Insertion -controlling heat- Adverse reactions: local thermal bone injury+excessive local stress Pin-bone interface affected necrosis necrosis fibrous connective tissue micromovement of pin bone resorption pin pin-loosening Trocar points of pins dont facilitate egress of bone shards impaction impaction HEAT >50rpm thermal necrosis minimized

43 Pin Insertion Larger pins greater pin-bone interface (don t exceed 30%) More pins increase strength (max 3-44 per segment) Stiffer pins more even load sharing Softer pins exerts more stress on near cortex stress resorption

44 Pin Insertion Summary At least 3 pins per fragment Near/far from fracture site Largest possible pins (dont exceed 30%) Stiff pins Positive profile threaded pins If using smooth pins 70 degrees!

45 Bone healing Factors affecting bone healing Age & general health Location & type of fracture Surrounding soft tissue damage Obtained degree of fragment apposition Mechanical environment provided by ESF Primary bony union Rigid internal fixation + close contact of fragments

46 Bone healing Secondary bone healing Fracture gaps + some interfragmentary motion ESF is good example as interfragmentay compr. usually is not applied (ESF preserves blood supply, important for 2ndary union)

47 Primary and secondary bony union

48 Bone healing TRAUMA Soft tissue and bone damage HEMATOME

49 Bone healing FIBRIN STABILIZATION HEMATOME CYTOKINES MESENCHYMAL CELL PROLIFERATION VASCULARISATION

50 Differentiation of mesenchymal cells Small amount of interfragmentary strain Osteoblasts And high O 2 environment More strain And lower O 2 environment Chondroblasts Large amount of strain And low O 2 environment Fibroblasts

51 Callus Formation Outside of callus has best mechanical & biological environment most resistant to bending forces (less strain) periosteal blood supply maintains high O2 environment Fracture ends under high strain + low O2 tension (more chondro/fibroblasts fibroblasts) Outer edge of callus gives most info on secondary callus formation!

52 Callus Formation Limited amount of strain helps bony union (max 2% of fracture area) Excess strain leads to chondro/fibroblast formation + low O2 env NONUNION! Axial forces promote bending bending/twisting forces hinder bony union

53 Postop Xray AAAA=alignment alignment, apposition, apparatus, activity Are there adequate number of pins/segments segments? Pin size correct? Are pins properly centered, safe distance away from skin/fracture lines? Does frame config match fracture type/patient patient size?

54 Postop Xray Amount of external callus is inversely proportional to the rigidity of the frame Osteomyelitis: rough/irregular callus margins Pin-loosening loosening: 1mm radiolucent area around pin

55 Postop Xray Resorption/lack of bridging callus indicates delayed/non non-union reexploration bone grafting new new fixation Generalized loss of bone density indicates stress protection staged dynamization

56 Postop Xray Ideally fractures fill up with bone density material after 6-8 weeks Rechecks at 7-10 days,, 6-86 weeks then every 3-4 weeks 7-10 days recheck Partially weight bearing Some edema Mild pain on pin site

57 Postop Xray 6-8 weeks recheck Usually healed by this time Weight bearing Pain free pin sites (otherwise loosening) Xrays (evaluate AAAAs) decision more time, removal, intervention or dynamization

58 ESF can be removed Animal is weight bearing Sufficient bony callus bridging the fracture gap (density adjacent bone) If severe lameness but good callus find reason (often loose pin!)

59 More time needed Weight bearing but callus not completely bridged Bridging callus of insufficient radiodensity (too stiff frame?)

60 Complications Soft tissue impalement: muscles, nerves (can be severe, wind-up ) tendons, vessels ESF faliure: frame faliure,, pin breakage, pin loosening Infection: osteomyelitis, sequestration, major/minor pin tract infections

61 Pin breakage and loosening Pin breakage: negative threaded pin?, reassess frame strength/rigidity rigidity Pin pullout: smooth pins inserted parallel Pramature pin loosening: very common complication, often poor placement! If good bone union process remove loose pin(s) = dynamization If frame is not stabile anymore review ESF

62 Pin loosening Pin tract drainage Instability Infection

63 Osteomyelitis and sequestrum ESF is a very effective method to manage ongoing osteomyelitis coming from other type of fixation method (internal!) Sequestrum result of thermal necrosis (poor technique, calcaneus!) Remove pin and drill out tract, drain freely

64 Major pin tract infection Common compl. causes premature pin loosening Bacterial colonization of pin-skin interface Pain Purulent discharge Pin loosening

65 Minor pin tract infection To some degree its normal (where thick soft tissue) Bacterial contamination of the pin-skin surface Limited granulation tissue formation Light serous discharge Lack of pain No pin loosening

66 Thank You!

67 Practical training