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Patellar component failure in cementless total knee arthroplasty
A G Rosenberg1, T P Andriacchi, R Barden
1Rush Medical College, Chicago, Illinois.
Clinical Orthopaedics and Related Research
|November 1, 1988
Summary
Patellar component fatigue fractures in total knee arthroplasty occurred due to shear forces at the peg-plate junction, particularly in younger, heavier males. This highlights the need for caution with peg fixation systems lacking plate ingrowth.
Area of Science:
- Orthopedic Surgery
- Biomedical Engineering
- Materials Science
Background:
- Total knee arthroplasty (TKA) commonly uses patellar components with porous ingrowth fixation.
- Early TKA designs utilized peg fixation for patellar components.
Purpose of the Study:
- To investigate the incidence and causes of fatigue fracture in porous ingrowth patellar components.
- To analyze biomechanical factors contributing to patellar component failure.
Main Methods:
- Retrospective review of 122 TKAs with porous ingrowth patellar components.
- Examination of fractured components for ingrowth and fixation.
- Biomechanical analysis of patellofemoral joint forces.
Main Results:
- Twelve patellar components (9.8%) fractured at the peg-plate junction.
- Fractured components showed excellent peg ingrowth but no plate ingrowth.
- Males, younger patients, and those with higher BMI and greater range of motion were more prone to fracture.
- Average time to fracture was 24 months.
Conclusions:
- Eccentric loading on the patellar dome generates high shear forces at the peg-plate junction.
- Peg fixation without concurrent plate ingrowth can lead to fatigue failure.
- Caution is advised for peg-plate systems with incomplete plate fixation.