INSTRUMENTED ARTHROMETRY FOR DIAGNOSING PARTIAL VERSUS COMPLETE ANTERIOR CRUCIATE LIGAMENT TEARS

Nineteen patients with the clinical diagnosis of anterior cruciate lig ament injury were examined by KT-1000 arthrometry before arthroscopy i n an effort to differentiate partial from complete tears. To this end, the KT-1000 arthrometer was equipped with a strain gauge and processo r that permitted the required force to increase the anterior displacem ent by 1-mm increments, to be read on a light-emitting diode. The meas ured force has been plotted against anterior displacement expressed in nonlinear increments along the x-axis to allow for the viscoelastic n ature of the ligament. The results show that stress-strain diagrams of partially torn and completely torn ligaments are similar to those obt ained by graded stress radiography. Using arthroscopy as the standard of measurement, partial tears can be differentiated from complete tear s with a sensitivity of 80% and a specificity of 100%. The figures for complete tears versus partial tears are 100% and 80%, respectively. G raded arthrometry with x-y recording of the force-displacement relatio nship that allows for the viscoelastic qualities of ligament further e xtends the capabilities of instrumented arthrometry.