CONSCIOUS AND UNCONSCIOUS KT-1000 MEASUREMENTS

Abstract

Introduction: The KT-1000 arthrometer is an instrument to measure anterior-posterior displacement of the tibia to evaluate the knee instability. Some reports indicated that the reliability of anterior laxity measurements obtained by using KT-1000 arthrometer were questionable. The lack of muscle relaxation is one of the greatest source of measurement error with the arthrometer. In a attempt to evaluate the effects of muscle relaxation on KT-1000 assessment, the laxity measurements of 22 patients (44 knees) in both conscious and unconscious states were obtained by using 15, 20, 30 pounds and manual maximum anterior displacement forces.
Patients and methods: Twelve of the patients had anterior cruciate ligament (ACL) deficiency on one knee, while the others had normal ACLs. All the conscious and unconscious KT-1000 measurements of 44 knees and, conscious and unconscious sideto- side differences of 22 patients were evaluated. T-test for paired samples was used in statistical assessment.
Results: The mean KT-1000 measurements of 44 knees during concious state at 15, 20, 30 pounds and manual maximum anterior displacement forces were 4.2, 6.0, 8.3 and 11.5 mm respectively. The same values for the same acting forces during uncuncious state were 4.8, 6.9, 9.3 and 13.1 mm. The side-to-side mean differences at 15, 20, 30 pounds and manual maximum anterior displacement forces for cuncious state were 1.5, 1.9, 2.5 and 4.8 mm respectively. The values for the same acting forces for uncuncious state were 1.5, 2.0, 3.4 and 6.2 mm. All the differences between the cuncious and uncuncious measurement were statistically significan (p=0.000). There were no difference between the cuncious and uncuncious side-to-side differences at 15 and 20 pounds (p>0.05), while the differences at 30 pounds and manual maximum were statistically significant (p=0.009, p=0.023 respectively).
Conclusion: The present study demonstrated that muscle relaxation effects the KT-1000 measurements.