THR periprosthetic fractures

Question 1

Describe the epidemiology of THR periprosthetic fx?

Answer 1

• Classification
  
  • intraoperative fx - 3.5% uncemented cf** 0.4% **cemented primary THR
  • postoperative fx- 1% most common at tip
• incidence increasing as result of more arthroplasty proceedures and high demand elderly pts

Question 2

How are periprosthetic fx prevented?

Answer 2

• Preoperative templating reduces risk of intraop fx
• adequate surgical exposure
• special care when using cementless prosthesis in poor bone ( RA/Osteoporosis)

Question 3

What is the mechanism and risk factors for acetabular intraopertive periprosthetic fx?

Answer 3

• Typically occurs during acetbular component impaction
• risk factors
  
  • underreaming >2mm
  • epliptical modular cups
  • osteoporosis
  • cementless acetabular components
  • dysplasia
  • radiation
• Must determine stablity of implant

Question 4

What is the tx for acetabular intraopertive periprosthetic fx?

Answer 4

• Observation alone
  
  • if evaluated intraop and found to be stable
  • consider protected WB for 8-12 wks
• Acetabular revision w screws vs orif
  
  • if evaluated intra op and found to be unstable
  • addition of acetabular screw
  • may upgrade to jumbo cup
  • orif of acetabular fx with revision acetabular component
  • may add reamings if pt has poor bone stock
  • consider protected wb for 8-12 wks

Question 5

When does intra op femoral fx occur?

Answer 5

• Proximal
  
  • with bone preparation - ie aggressive rasping and prosthetic insertion
  • may occur during implant insertion from dimension mismatch
• Middle
  
  • usually occur when excessive force is used during surgical exposure of bone preparation
• ​Distal** **
  
  • ​usually occurs when tip of a straight- stem prosthesis impacting on femoral bow

Question 6

What is the tx of intraop periprosthetic femoral fx?

Answer 6

• Stem removal , cabling and reinsertion
  
  • intra op longitudinal calcar split
• Trochanteric fixation with wires, cables or claw-plate
  
  • intra op proximal femoral fx
• Removal of implant, insertion of longer stem prosthesis
  
  • complete 2 part fx of middle region
  • distal tip must bypass distal extent by 2 cortical diameters
  • may use cortical allograft struts for added stability
• Removal of implant, internal fixation with plate and reinsertion of prosthesis
  
  • distal fx that cannot be bypassed with a long stemmed prosthesis

Question 7

Describe the aetiolgy of postop femoral fx?

Answer 7

• early post op fx
  
  • cementless prosthesis tend to fx in the forst 6 months
  • likely caused by stress risers during reaming and broaching
  • wedge fit tapered designs cause prox fx
  • cyclindrical fully porous coated stems tend to cause a distal split in the femoral shaft
• Late post op fx
  
  • cemented prosthesis tend to fx later ( 5 yrs out)
  • Tend to fx around the tip of the prosthesis or distal to it

Question 8

What is the classification system for periprosthetic femoral fx?

Answer 8

• Vancover
  
  • simple and validated
  • often difficult to differentiate between B1 and B2 fx based on radiographs alone
• Type A
  
  • fx in trochanteric region - Lesser or greater
• Type B1
  
  • fx around stem or just below it with a well fixed stem
• ​Type B2
  
  • Fx around stem or just below it, loose stem, but good proximal bone stock
• ​Type B3
  
  • ​Fx around stem or just below with proximal bone that is poor quality or severly comminuted
• ​Type C
  
  • ​Fx occurs well below prosthesis

Question 9

What is the tx for

Answer 9

• Type A
  
  • orif of GT with wires or cables or claw plate
  • if osteolysis present use cancellous allograft to fill defect

Question 10

What is the tx for?

Answer 10

• Type B1
• orif using cerclage cables and locking plate

Question 11

What is the tx for ?

Answer 11

• type B2
• stem is loose so
• revision of femoral component to a long porous-coated cementless stem and fixation of fx fragment. revise acetabulum if indicated

Question 12

What is the tx for?

Answer 12

• B3
• fx around stem or just below with loose stem and poor proximal bone stock/ comminuted
• Femoral component revision with proximal femoral allograft ( young pt) or proximal femoral replacement ( elderly pt)

Question 13

What is the tx of?

Answer 13

• Type C
• Orif with plate
• leaves the hip and acetabular prosthesis alone