Load-deformation Characteristics Of The Patella: Relationship To Intraosseous Pressure

Subchondral nociceptors may be stimulated by an increase in intraosseous pressure during elastic deformation. PURPOSE: To investigate application of pressure to the patella and invoked intraosseous pressure and deformation. METHODS: In a model of the knee extensor mechanism (Figure), applied pressure measured by a pressure film transducer (Tekscan 5076, South Boston, MA), was recorded with intraosseous pressure using a monitor (Stryker Orthopedics, Mahwah, NJ) placed in the lateral facet of human cadaver patellae. 8 patellae underwent 3 trials each. Linear regression was performed to establish the relationship between the applied traction load and the intraosseous pressure. Compressive pressure was applied to 2 patellae while crosshead displacement was recorded concurrently. (MTS Systems, Eden Prairie, MN).FigureRESULTS: The intraosseous pressure in the lateral compartment of the patella was directly related to patella-femoral pressure (R2 = 0.38, p < 0.001).TableCONCLUSION: Applied pressure to human patellae in a physiological range results in an increase in intraosseous pressure. Beyond approximately 1000 N this deformation ceases to be elastic.