Jp. Furia et al., ISOMETRY MEASUREMENTS IN THE KNEE WITH THE ANTERIOR CRUCIATE LIGAMENTINTACT, SECTIONED, AND RECONSTRUCTED, American journal of sports medicine, 25(3), 1997, pp. 346-352
When assessing isometry during anterior cruciate ligament surgery, it
is assumed that points determined to be isometric remain so after reco
nstruction. We sought to evaluate if isometric measurements vary with
the status of the anterior cruciate ligament. A computerized electroni
c isometer was used to measure the magnitude and pattern of change in
separation distance between a constant point in the tibial insertion o
f the anterior cruciate ligament and five positions within the femoral
insertion with the anterior cruciate ligament intact, sectioned, and
reconstructed. For the center position, the magnitude and pattern of t
he change in separation distance was physiologically isometric in all
conditions (maximal length change, 3.0 mm). For the posterior position
, the isometry pattern remained physiologic in each condition, and the
magnitude of the separation distance was nearly isometric in all cond
itions (maximal length change, 3.7 mm). The superior and inferior posi
tions had similar isometric measurements in the intact and sectioned c
onditions but significantly different measurements after anterior cruc
iate ligament reconstruction. Intraoperative assessment of isometry at
positions in the center or posterior portion of the anterior cruciate
ligament's femoral insertion provides useful information that is not
altered by reconstruction. For superior and inferior positions, howeve
r, points found to be isometric in the anterior cruciate ligament-defi
cient knee did not remain isometric after reconstruction.