Internal Fixation Devices

1. Screws
   1. Cannulated screw = hollow shaft screw inserted over guide pin (K-wire = Kirschner wire)
      Use: fracture of femoral neck
   2. Cortical screw = shallow finely threaded over entire length, blunt tip
      Use: fixation of plates anchored in bone cortex
   3. Cancellous screw = wide thread diameter with varying length of smooth shank between head + threads
      Use: compression across fracture site anchored in soft medullary bone
   4. Malleolar screw = partially threaded
   5. Herbert screw = cannulated screw threaded on both ends with wider pitch of proximal portion causing fragment compression, no screw head
      Use: scaphoid + other carpal bone fractures
   6. Interference screw = short, fully threaded, cancellous thread pattern, self-tapping tip, recessed head
      Use: within tunnel holding bone graft of ACL and PCL reconstruction
   7. Acutrak screw = cannulated screw fully threaded with variable thread pitch causing fragment compression, submerged without screw head
      Use: scaphoid fracture
   8. Dynamic hip screw = lag screw telescopes (= free to slide) within hollow metal barrel of angular side plate allowing impaction of fracture without perforation of subarticular cortex
      Use: intertrochanteric, subtrochanteric, subcapital fracture
   9. Knowles pin
      Use: proximal femoral neck fracture with tenuous blood supply
   10. Radiolucent absorbable polycarbonate screw = “stealth hardware”
2. Washer
   1. Flat washer = increase surface area over which force is distributed
   2. Serrated washer = spiked edges used for affixing avulsed ligaments / small avulsion fractures
3. Plates
   • compression plate
     Use: compression of tension side of stable fractures
   • neutralization plate = protects fracture from bending, rotation + axial-loading forces
   • buttress plate = support of unstable fractures in compression / axial loading
     1. Straight plate
        1. straight plate with round holes
        2. dynamic compression plate (DCP) = oval holes
        3. tubular plate = thin pliable plate with concave inner surface
        4. reconstruction plate = thin pliable / malleable plate to allow bending, twisting, contouring
     2. Special plates
        T-shaped, L-shaped, Y-shaped, cloverleaf, spoon, cobra, condylar blade plate, dynamic compression screw system
   
   
   
   
   
   
   
4. Staples
   Fixation = bone = epiphyseal = fracture staples with smooth / barbed surface
   • Coventry = stepped osteotomy staple
   • stone = table staple
5. Wires
   1. K wire (= Kirschner wire) = unthreaded segments of extruded wire of variable thickness
      Use: temporary fixation
   2. Cerclage wiring = wire placed around bone
      Use: fixation of comminuted patellar fracture, holding bone grafts in position
   3. Tension band wiring = figure-of-eight wire placed on tension side of bone
      Use: olecranon / patellar fractures