Background: The role of the peripatellar retinaculum as a frontal
plane stabilizer of the patellofemoral joint has been well established.
However, as a result of its unique orientation, the retinaculum also may
influence the distribution of forces within the extensor mechanism. The
objective of this study was to determine the extent to which the peripatellar
retinaculum affects the magnitude of forces experienced by the patellar
Methods: Ten cadaver knees were used in this investigation. Each was
mounted on a custom test apparatus that was fixed to an Instron frame. The
extensor mechanism was loaded by applying forces through the individual heads
of the quadriceps femoris. Patellar tendon tension was measured at 0°,
20°, 40°, and 60° of knee flexion with use of a buckle transducer
under two conditions: (1) with the peripatellar retinaculum intact, and (2)
with the peripatellar retinaculum removed. Patellar tendon tension was
compared between the two conditions across the knee flexion angles.
Results: At each knee flexion angle, the patellar tendon tension was
greater with the retinaculum removed than it was with the retinaculum intact.
However, the difference was significant only at 0° and 60°, at which
positions the force transmitted to the patellar tendon was increased by 16.6%
and 9.6%, respectively.
Conclusions: The observed increases in patellar tendon
tension after removal of the peripatellar retinaculum is an indication of the
load-sharing function of that structure as a part of the extensor
Clinical Relevance: Our results suggest that compromise of the
peripatellar retinaculum may alter patellar tendon and/or patellofemoral joint