A telemetric tibial tray includes a lower plate that defines a plurality
of cylindrical transducer cavities having circular load diaphragms. An
upper plate is attached to the lower plate through support posts
projecting from the load diaphragms. The support posts have a circular
cross-section and a diameter of about 5.0 mm. The lower plate further
defines wiring channels communicating between the transducer cavities and
a central cavity housing the circuit board for the telemetric tray. The
wiring channels are arranged at a 45 degree angle relative to the
sagittal plane of the knee joint in order to reduce the effects of the
wiring channel intersection on the strain sensitivity of the tray. Each
transducer cavity includes a radial strain gage array with four pairs of
radially aligned strain gages, each pair aligned at a 45 degree angle
relative to the sagittal plane of the knee joint. Each pair of strain
gages includes an inner gage positioned at the point of maximum positive
micro-strain across the diaphragm when loaded, and an outer gage
positioned at the point of maximum negative micro-strain, to thereby
increase the differential strain measured by the gages and increase the
strain sensitivity of the tibial tray.