Fracture Fixation Internal & External Fracture Types http://health.allrefer.com/health/bone-fracture-repair-fracture-types-1.html Influencing Healing Systemic Factors Age Hormones Functional activity Nerve function Nutrition Drugs (NSAID) http://www.orthoteers.co.uk/Nrujp~ij33lm/Orthbonefracheal.htm Local Factors Energy of trauma Degree of bone loss Vascular injury Infection Type of bone fractured Degree of immobilization Pathological condition Stages of Fracture Healing 1. Inflammation & Hematoma Osteoprogenitor cells, Fibroblasts 2. Callus Formation Periosteal and Endosteal Fibro-cartilage differentiation 3. Woven Bone Substitution of avascular and necrotic tissue Haversian remodeling 4. Remodeling Lamellar or trabecular bone Restoration of continuity and ossification Bone union **When compression is applied via implant, these stages are minimized** http://www.orthoteers.co.uk/Nrujp~ij33lm/Orthbonefracheal.htm http://www.ivis.org/special_books/ortho/chapter_03/03mast.asp?Type=IPRP&LA=1 Healing Complications Most often due to severe injury Energy dissipation to bone and soft tissue results in damage to blood supply Compartment syndrome Severe swelling resulting in decreased blood supply can cause the muscles around the fracture to die Bad osmotic pressure lets blood out instead of across damaged muscle Neurovascular injury As pressure remains high, blood cannot get to damaged muscle Arteries and nerves around the injury site are damaged Infection Imbalance of bacteria and body’s ability to cope with it when amount of necrotic tissue and contraction of bacteria are not being cleared (by surgeon or patient) http://www.hughston.com/hha/a.fracture.htm Healing Complications (Cont’d) Delayed union Nonunion Abnormal alignment Post-traumatic arthritis Failure to heal Malunion Extended healing time Fractures that extend into the joints can cause premature arthritis of a joint Growth abnormalities A fracture through an open physis, or growth plate, could result in premature partial or complete closure of the physis; Part or all of a bone will stop growing unnaturally early http://www.hughston.com/hha/a.fracture.htm Treatment When will a cast suffice? Fracture is stable Patient preference No complications (Ex.-infection, burn) When is fixation necessary? Fracture is unstable Quick Mobilization Occupation Athletes http://www.defence.gov.au/dpe/dhs/infocentre/publications/journals/NoIDs/ADFHealthApr01/adfhealthapr01_2_1_24-28.pdf Principles of fracture fixation Obtain and maintain alignment Reduction Transmission of compressive forces Minimum motion across fracture site Achieve stability Avoid tensile/ shear/torsion forces Across fracture site Prevent motion in most crucial plane Fixation: Internal vs. External Internal Plates, screws, etc. completely within the body Less expensive Types Comminuted – nail with interlocking screw Transverse or Oblique –plates or screws External Pins coming through skin interconnected by external frame Has complications http://www.defence.gov.au/dpe/dhs/infocentre/publications/journals/NoIDs/ADFHealthApr01/adfhealthapr01_2_1_24-28.pdf Internal Fixation http://www.nlm.nih.gov/medlineplus/ency/imagepages/18023.htm Internal Fixation Priciples Rigid, anatomic fixation Allows an early return to function Reserved for those cases that cannot be reduced and immobilized by external means Open reduction of a fracture Good blood supply to undisturbed tissues http://www.umm.edu/ency/article/002966.htm Physiological Response to IF Primary healing Minimal extramedullary callus Minimal intra-medullary callus Sub-periosteal Rapid Related to motion Crosses miniature gaps Depends on soft tissue viability Stress Concentrations Geometric discontinuities (hole, base of threaded screw, corner) Local disturbance in stress pattern High stresses at site of discontinuity Drilling a hole reduces the bone strength by 10 – 40 % Types of IF Devices Lag screws Kirschner wire Wire loop Tension band wiring Combination of wire loop and screw Combination of Kirschner and wire loop Plate Intramedullary rods and nails Interlocking screws Hemi-Arthroplasty In the hip, used for femoral neck fractures Avascular necrosis Fractures of the proximal humerus Early mobilization is facilitated http://www.orthogastonia.com/patient_ed/html_pages/hip/hip_hemiarthrooplasty.html Bilboquet Device http://www.maitrise-orthop.com/corpusmaitri/orthopaedic/100_bilboquet/bilboquet_us.shtml Problems in IF Infection Delayed union Non-union External Fixation http://www.nlm.nih.gov/medlineplus/ency/imagepages/18021.htm External Fixation Method of immobilizing fractures Employing percutaneous pins in bone attached to Rigid external metal Plastic frame For treatment of open and infected fractures Indications for EF Open grade III fractures Compound tibia fractures Generally from motorcycle injuries Gunshot wounds Major thermal injuries Open fractures associated with polytrauma Management of infected nonunions Forces in an External Fixator Compression Neutralization Distraction Angulation Rotation Translation or displacement Compression For transverse fractures Adds stability at nonunion site Neutralization For comminuted fracture Compression may lead to excessive shortening Used to maintain: Length Alignment Stability Distraction For distal metaphyseal or intra-articular injuries Same principle of traction Distraction of fragments Alignment of injury Angulation A – unacceptable alignment B – loosening clamps; loss of distr. and compr. force C – after frames completely loosened; angulation is corrected D - compression on distraction forces are reapplied Rotation Exert rotational force Along longitudinal axis Release of forces first Can be done with repositioning pins Most of present frames cannot apply rotational forces Translation or Displacement Volkov apparatus Double ring unit Moves one ring in parallel to other For translation Types of EF Devices Unilateral Bilateral Triangular Quadrilateral Semicircular & Circular ring Ilizarov http://www.ilizarov.org.uk/content.htm Unilateral EF Bilateral EF Triangular EF Quadrilateral EF Semicircular and Circular EF Advantages of EF Easy application Good stability Excellent pain relief Adjustable Alignment, Angulation, Rotation Access to open wounds Frequent dressing change Monitoring of damaged tissue Disadvantages of EF Application may cause soft tissue damage Lacks advantages of cyclic loadings as seen in casts Constrained in time Pins may drain Infection The End Granulation Tissue damage repair begins with growth of new capillaries Red dots are new clusters of capillaries Bleed easily Bright red tissue of a healing burn is granulation tissue http://medweb.bham.ac.uk/http/depts/path/Teaching/FOUNDAT/repair/grantiss.html Hematoma Blood collection localized to an organ or tissue Usually clotted Example: Contusions (bruises), black eye, blood collection beneath finger or toenail Almost always present with a fracture http://www.healthscout.com/ency/68/677/main.html Fibrocartilage Cartilage with a fibrous matrix and approaching fibrous connective tissue in structure Produced by fibroblasts Forms in areas where size of the fracture gap is 1mm or greater Subsequently replaced by bone Mechanical properties inferior to other types of cartilage Contains: Large amounts of collagen type I Reduced amounts of proteoglycans Collagen type II, found only in cartilage http://www.vetmed.ufl.edu/sacs/notes/Cross-Healing/page9.html http://wberesford.hsc.wvu.edu/histolch6.htm http://www.nuigalway.ie/anatomy/wilkins/practicals/bone/html/bone_1.html http://www.bm.technion.ac.il/courses/336529/web/Cartilage/major%20types.htm Inflammation & Hematoma http://www.ivis.org/special_books/ortho/chapter_03/03F2.jpg Inflammation & Hematoma Inflammation begins immediately after a fracture Initially consists of hematoma and fibrin clot Hemorrhage and cell death at location of fracture damage Fibroblasts, mesenchymal cells, osteoprogenitor cells appear next Formation of granulation tissue Ingrowth of vascular tissue Migration of mesenchymal cells http://www.aans.org/education/journal/neurosurgical/apr01/10-4-1.pdf Simon, SR. Orthopaedic Basic Science. Ohio: American Academy of Orthopaedic Surgeons; 1994. Inflammation & Hematoma (Cont’d) Primary nutrient and oxygen supply provided by exposed cancellous bone and muscle Use of anti-inflammatory or cytotoxic medication during first week may alter the inflammatory response and inhibit bone healing http://www.healthscout.com/ency/68/677/main.html Callus Formation http://www.ivis.org/special_books/ortho/chapter_03/03mast.asp?Type=IPRP&LA=1 Callus Formation Begins when pain and swelling subside Ends when bone fragments are immobilized by tissue Size inversely dependent on immobilization of fracture Mesenchymal cells form cells which become cartilage, bone, or fibrous tissue Increase in vascularity Stable enough to prevent deformity Callus does not appear on x-ray images http://www.orthoteers.co.uk/Nrujp~ij33lm/Orthbonefracheal.htm Simon, SR. Orthopaedic Basic Science. Ohio: American Academy of Orthopaedic Surgeons; 1994. Mechanical Role Enlarge diameter at fracture site Reduces mobility Reduces resulting strain Granulation Replaces Hematoma Granulation differentiates into Connective tissue Random orientation of collagen fibrils Their direction reflects the direction of tensile forces Fibrocartilage Deformation of Callus Strength of initial reparative tissue is low If forces surpass the strength of callus Unstable fracture Functional load deforms fracture Fracture fixation is recommended Woven Bone Woven Bone Callus changes from cartilaginous tissue to woven bone Callus mineralized but internal architecture is not fully matured/arranged Connective tissues and fibrocartilage thickens Osteon organization is not complete Fracture becomes increasingly stable Mineralization is sensitive to strain Mechanically stable scaffold Increased strength and stiffness with increase of new bone joining fragments Simon, SR. Orthopaedic Basic Science. Ohio: American Academy of Orthopaedic Surgeons; 1994. Bone Remodeling Woven bone becomes lamellar bone Bone union occurs at fracture gap Callus gradually reabsorbed by osteoclasts Replaced by bone Medullary canal reconstitutes Begins within 12 weeks after injury May last several years http://www.glaciermedicaled.com/bone/bonesc3p2.html Simon, SR. Orthopaedic Basic Science. Ohio: American Academy of Orthopaedic Surgeons; 1994. Mesenchymal Cells Source of cells for new bone production Derived from bone marrow cells Intramembranous bone formation Formation of bone directly from mesenchymal cells Cells become osteoprogenitor cells then osteoblasts. Development of Cartilage model Mesenchymal cells form a cartilage model of the bone during development http://www.grossmont.edu/shina.alagia/lectures/144/Bone%20physiology.ppt http://www.ecmjournal.org/journal/supplements/vol005supp02/pdf/vol005supp02a07.pdf Fracture Stability Direction of fracture & material (type of bone) define stability Stable Definition of direction of force important Fissure (Hairline) – not complete break, minimal trauma Greenstick – crack on outside of “bend” Unstable Comminuted – many bone fragments Oblique – break at an angle Spiral – corkscrew-like crack pattern http://pain.health-info.org/Pain%20Pages/fractures.htm Lag Screw Lag Screw Stability Exerts inter-fragmentary compression Static compression Distal head must be engaged Screw Holding Force Increase in area of bone within screw threads Decrease in pilot hole size Increase in length of engaged threaded portion Area available to resist shear Kirschner Wire Kirschner Wire (Cont’d) Rotational stability May be a problem Anchorage to tension band Twisting of wires on both sides Almost equally distributed compression Tension Band Tension Band (Cont’d) Dynamic compression When tension applied Compressive forces are at the fracture site Used Substitutes torn ligaments & tendons Allows injured ligaments to heal When fragments too small to be screwed http://www.wheelessonline.com/o2/1536.htm Tension band & Screw Tension Band & Screw Plating of Vertebral Column Vertebral Column Intramedullary Pin Types Open Closed 3-point fixation End fixed in epiphyses Intramedullary Pin (Cont’d) Stability is dependant on Friction / pressure between Deformable nail (elastic recoil) Endosteal surface of medullary canal Fracture “personality” Intramedullary Pin (Cont’d) Blood supply is from the medullary canal Compromised More by intramedullary fixation care has to be taken Open Fracture Bone ends have penetrated through and outside skin Important features Polytrauma victims Varying soft tissue damage Contaminated wound Requires emergency treatment Types of Open Fracture Type I – Low Energy Type II Puncture wound (1 cm dia. or lesser) Not much soft tissue contusion Usually simple transverse, short oblique fracture No crushing component Laceration (more than 1 cm long ) Not extensive soft tissue damage Not severe crushing component Type III – High Energy Extensive damage to soft tissue High velocity injury or severe crushing component Type I Type II Type III