Intraoperative pivot-shift accelerometry combined with anesthesia improves the measure of rotatory knee instability in anterior cruciate ligament injury

Gastón Caracciolo,Héctor Zamorano,Rony Silvestre,Lars Strömbäck,Alejandra Ossio,Carlos De La Fuente,Sebastian Abusleme,Felipe P Carpes,Roberto Yáñez

doi:10.1186/s40634-021-00396-1

Abstract

PurposeThe knee stiffness acquired following an Anterior Cruciate Ligament (ACL) injury might affect clinical knee tests, i.e., the pivot-shift maneuver. In contrast, the motor effects of spinal anesthesia could favor the identification of rotatory knee deficiencies prior to ACL reconstruction. Hence, we hypothesized that the intra-operative pivot-shift maneuver under spinal anesthesia generates more acceleration in the lateral tibial plateau of patients with an injured ACL than without.MethodsSeventy patients with unilateral and acute ACL rupture (62 men and 8 women, IKDC of 55.1 ± 13.8 pts) were assessed using the pivot-shift maneuver before and after receiving spinal anesthesia. A triaxial accelerometer was attached to the skin between Gerdys’ tubercle and the anterior tuberosity to measure the subluxation and reduction phases. Mixed ANOVA and multiple comparisons were performed considering the anesthesia and leg as factors (alpha = 5%).ResultsWe found a higher acceleration in the injured leg measured under anesthesia compared to without anesthesia (5.12 ± 1.56 m.s− 2 vs. 2.73 ± 1.19 m.s− 2, p < 0.001), and compared to the non-injured leg (5.12 ± 1.56 m.s− 2 vs. 3.45 ± 1.35 m.s− 2, p < 0.001). There was a presence of significant interaction between leg and anesthesia conditions (p < 0.001).ConclusionsThe pivot-shift maneuver performed under anesthesia identifies better rotatory instability than without anesthesia because testing the pivot-shift without anesthesia underestimates the rotatory subluxation of the knee by an increased knee stiffness. Thus, testing under anesthesia provides a unique opportunity to determine the rotational instability prior to ACL reconstruction.

Highlights

The anterior cruciate ligament (ACL) rupture has an incidence of 68.6 per 100,000 people-years [31], and most cases (~ 80%) involve rotatory instability [3, 25]
Acceleration was higher when the pivot-shift maneuver was performed under anesthesia compared to Discussion In this study, we demonstrated that the pivot-shift maneuver conducted without spinal anesthesia generates lower acceleration of the lateral tibial plateau during the reduction phase than under anesthesia in ACL injury
This suggests that false-negative outcomes may be induced during the pivot-shift maneuver for ACL injury conducted without anesthesia

Summary

Introduction

The anterior cruciate ligament (ACL) rupture has an incidence of 68.6 per 100,000 people-years [31], and most cases (~ 80%) involve rotatory instability [3, 25]. The rotatory instability is tested through the pivotshift maneuver [30], and it has high specificity for ACL insufficiency [12] and correlates well with self-reports of knee function [20]. The altered activity of Caracciolo et al J EXP ORTOP (2021) 8:80 gamma motor neurons may increase knee stiffness after an ACL rupture [17, 25]. A sudden higher posterior and lateral shift of the lateral tibial plateau (reduction) is caused [11, 16]. This joint movement relates to residual knee instability, mainly triggered during cutting, twisting, or pivoting motions [34]. The scintigraphy activity in the subchondral bone and the risk of early knee osteoarthrosis increase [34]

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