Is triaxial accelerometer reliable in the evaluation and grading of knee pivot-shift phenomenon?

Dynamic laxity is clinically demonstrated with the pivot-shift (PS) test. Recently, a new system that measures the acceleration of the tibia during the PS test was validated. The goal of the present study was to use the accelerometer "KiRA" to evaluate the efficacy of measuring PS. Between 2010 and 2011, a total of 100 patients with anterior cruciate ligament (ACL) lesions were enrolled. They underwent surgical reconstruction of the ACL. Among them, 30 patients were re-evaluated at least 6 months after surgery. Each patient underwent a clinical examination (Lachman test, anterior drawer test, and PS test) and then was subjected to an instrumental examination: KT1000 evaluation to quantify the Lachman test and KiRA to quantify the PS test. The accelerometer found a positive acceleration difference in favour of the pathologic knee. In the 100 patients evaluated preoperatively, the analysed acceleration parameters on the pathologic knee were found to be significantly different with respect to the contralateral joint. Correlating the clinical subjective data with numerical data, we identified mean reference values for every grade of the PS test (negative, glide, and clunk). Our experience showed us that the use of KiRA accelerometer for quantitative measurement of the PS is both promising and reliable. The efficacy of this instrument is strictly related to an inevitable learning curve and to proper execution of the test. It has the value of being easy to set up and easy to use in both the clinic and the operating room.