Ea. Friis et al., EFFECT OF BONE BLOCK REMOVAL AND PATELLAR PROSTHESIS ON STRESSES IN THE HUMAN PATELLA, American journal of sports medicine, 22(5), 1994, pp. 696-701
Thermoelastic stress analysis was used to examine stresses on the ante
rior surface of patellae after patellar bone block excision for autoge
nous graft anterior cruciate ligament reconstruction. Complications of
anterior cruciate ligament injury often lead to degenerative changes
in the knee that can require total knee joint replacement. It was hypo
thesized that stresses in a bone block-compromised patella may be incr
eased even further by insertion of a patellar prosthesis. All patellae
were first tested intact and then were retested after a sequence of s
urgical modifications including patellar prosthesis implantation, tape
red bone block excision, square bone block excision, and both shapes o
f excised bone blocks with a patellar prosthesis in place. Stresses in
patellae with bone blocks excised were significantly greater than str
esses in intact patellae. The anterior surface stress pattern in the l
oaded patella was significantly altered by excision of a bone block. T
here were no significant differences between maximum stress in patella
e with tapered and square bone blocks excised. A finite element analys
is showed that excision of a larger trapezoid-shaped bone block greatl
y increased maximum stress levels. Insertion of a patellar prosthesis
did not significantly alter stress patterns or maximum stress levels i
n the patella.