Background
Methods
Implant-dependent classification of periprosthetic fractures of the distal femur
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Type I: Fracture is distant from the TKA (proximal of the femoral component) referring to Su type I
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Type II: Fracture starts at the level of the proximal border of TKA and extends proximally referring to Su type II
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Type III: All fracture parts are below the proximal prosthesis border referring to Su type III
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Type IV: Supracondylar fracture with prosthetic loosening referring to Lewis and Rorabeck type III
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Type A: bicondylar uncoupled endoprosthesis (surface replacement)
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Type B: Semi-constraint bicondylar sledges prosthesis (posterior stabilized)
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Type C: Constraint prosthesis with intramedullary anchoring
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Type D: Distal femur replacement
Classification-related therapeutic recommendations
I | II | III | IV | |
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A | Locking plate, retrograde nail, (antegrade nail) | Locking plate, retrograde nail, | Locking plate, revision arthroplasty (constraint endoprosthesis, eventually distal femoral replacement) | Revision arthroplasty (constraint endoprosthesis, eventually distal femoral replacement) |
B | Locking plate, antegrade nail | Locking plate, revision arthroplasty (distal femoral replacement, eventually constraint endoprosthesis) | revision arthroplasty (distal femoral replacement) | revision arthroplasty (distal femoral replacement) |
C | Locking plate (polyaxial, attachment plates), revision arthroplasty (distal femoral replacement) | Locking plate (polyaxial, attachment plates), revision arthroplasty (distal femoral replacement) | revision arthroplasty (distal femoral replacement) | revision arthroplasty (distal femoral replacement) |
D | Locking plate (polyaxial, attachment plates), revision arthroplasty (distal femoral replacement) | revision arthroplasty (distal femoral replacement), Locking plate (polyaxial, attachment plates), | revision arthroplasty (distal femoral replacement) | revision arthroplasty (distal femoral replacement) |
Results
interobserver reliability (Kappa) | Su et al. classification | Lewis & Rorabeck classification | new implant-associated classification |
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without exclusion (n = 55) | 0.388 (fair) | 0.309 (fair) | 0.743 (substantial) |
with exclusion (n = 41) | 0.633 (substantial) | 0.445 (moderate) | 0.696 (substantial) |