2015 ISAKOS Biennial Congress ePoster #1306

Comparative Evaluation of the Pivot-Shift Test Measured in a Gyroscope Between Anterior Cruciate Ligament Deficient Knees and Contralateral Intact Knees

Atsunori Murase, MD, PhD, Kasugai, Aichi JAPAN
Masahiro Nozaki, MD, PhD, Nagoya, Aichi JAPAN
Masaaki Kobayashi, MD, PhD, Nagoya, Aichi JAPAN
Hideyuki Goto, MD, PhD, Obu, Aichi JAPAN
Tetsuya Takenaga, MD, PhD, Nagoya, Aichi JAPAN
Yuko Nagaya, MD, PhD, Nagoya, Aichi JAPAN
Hiroto Mitsui, MD, PhD, Nagoya, Aichi JAPAN
Hideki Okamoto, MD, PhD, Nagoya City JAPAN
Hirotaka Iguchi, Prof., Nagoya, Aichi JAPAN
Takanobu Otsuka, MD, PhD, Prof., Nagoya, Aichi JAPAN

Department of Orthopaedic Surgery, Nagoya City University, Nagoya, Please Select, JAPAN

FDA Status Not Applicable

Summary: Our study compared the acceleration and the rotational angular velocity measured in a gyroscope between anterior cruciate ligament deficient knees and contralateral intact knees during a pivot-shift test under anesthesia, the acceleration and the rotational angular velocity in anterior cruciate ligament deficient knees were significantly higher than in contralateral intact knees.

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Abstract:

Introduction

The pivot-shift test is commonly used for patients with suspected anterior cruciate ligament (ACL) deficit to evaluate knee stability. However, this test is evaluated by surgeons subjectively, therefore several authors reported the importance of quantitative evaluation of the pivot-shift test recently. A gyroscope can detect acceleration in three-dimensional directions and rotational angular velocity in three-dimensional directions.
The purpose of this study was to compare the acceleration and the rotational angular velocity measured in a gyroscope between anterior cruciate ligament deficient knees and contralateral knees under anesthesia.
ACL deficient knees increase rotational knee instability, therefore we hypothesized that ACL deficient knees might significantly increase both peak acceleration and maximum rotational angular velocity in comparison with ACL intact contralateral knees.

Methods

20 consecutive patients with isolated anterior cruciate ligament (ACL) unilateral deficiency were involved in this study between 2013 and 2014. The gyroscope was fixed on the tibial tuberosity with exclusive strap and a single examiner performed the pivot-shift test on bilateral knees under general anesthesia before ACL reconstruction. For the gyroscope, we defined the medio-lateral axis of the tibial axis as the x-direction, the supero-inferior axis as the y-direction, and the antero-posterior axis as the z-direction, respectively. The acceleration in x-direction and z-direction, and the rotational angular velocity in the y-direction were repeatedly measured with a gyroscope during the pivot-shift test. Statistical analysis for differences between the two groups were performed using the Wilcoxon T test. Statistical significance was defined as p < 0.05.

Results

With regard to acceleration, there was a high spike wave during a pivot-shift for the ACL deficient knee, however no high spike was present for the contralateral knees. The difference between positive and negative peak values of acceleration in ACL deficient knees was significantly higher than in contralateral intact knees.
The difference values in x-direction were 12.2 ± 5.0 m/s2 in ACL deficient knees and 4.8 ± 1.9 m/s2 in contralateral knees.(P=0.007)
The difference value in z-direction were 15.6 ± 6.6 m/s2 in ACL deficient knees and 1.6 ± 2.3 m/s2 in contralateral knees. (P=0.003)
The maximum tibial external angular velocity in the y-direction on average was 149.1 ±81.2 deg/s in ACL deficient knees and 58.2 ± 51.0 deg/s in contralateral knees respectively. (p = 0.03).

Discussion And Conclusion

Recently several studies have reported on quantitative assessment of dynamic rotational knee instability using such means as electromagnetic devices, navigation and triaxial accelerometry. Our study evaluated rotational knee instability by acceleration and angular velocity using a gyroscope. We hypothesized that the gyroscope could identify rotational knee instability of ACL deficient knees. The results of this study support our initial hypothesis. Regarding clinical relevance, these findings may help to improve preoperative or postoperative quantitative measurement in ACL deficient patients. In conclusion, the acceleration and the rotational angular velocity in anterior cruciate ligament deficient knees were significantly higher than in contralateral intact knees during the pivot-shift test.
There are some limitations in this study: The gyroscope was skin-fixed, therefore soft tissue artifacts may have influenced the result. Our study did not evaluate the quantity of power gained against knees by the examiner during the pivot-shift test.