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Purpose: To assess measurement equivalence, inter- and intra-rater reliability, standard error of measurements (SEM) and false positive measurements (FPM) of four different knee arthrometers (KLT,Karl Storz; KiRA, I + ; KT-1000 MEDmetric Corp; Rolimeter, Aircast) in healthy patients., Methods: Four different investigators (two advanced (AR) and two beginners (BR)) examined 12 participants with healthy knees at two time points with regards to anterior tibial translation (ATT) and side-to-side difference (SSD). Test equivalence was assessed using the TOST (two-one-sided t test) procedure with ± 1 mm equivalence boundaries. Intraclass correlation coefficients (ICCs) were calculated using two-way mixed effects models. Furthermore, false positive-(SSD > 3 mm) and SEMs were assessed., Results: A total of 2304 Lachman Tests were performed. Between-rater SSDs were equivalent between AR and BR raters for the Rolimeter only. Inter-rater ICC values (SSD, ATT) were graded as "poor" to "moderate" for all devices. Equivalent test-retest results were observed for all raters using the Rolimeter, KLT and KT-1000, whereas measurement consistency with KiRA was given in the advanced examiners group only. Intra-rater ICC values (Range: SSD, ATT) were graded as "poor" to "moderate" for SSD values and "moderate" to "good" for ATT. SEMs were lowest for the Rolimeter and highest for KiRA. FPM were never obtained with the Rolimeter (0%), twice (2.1%) with the KT-1000, three times (3.1%) with the KLT and 33 times (34.4%) using KiRA., Conclusion: There is acceptable intra-rater but poor inter-rater reliability with all tested arthrometers. Measures of knee laxity are comparable between Rolimeter, KLT and KT-1000 but higher for KiRA. Clinically, the present study shows that repeated arthrometry measurements should always be performed by the same investigators., (© 2021. The Author(s).)

The anterolateral ligament (ALL) has been suggested as an important secondary knee restrain on the dynamic laxity in anterior cruciate ligament- (ACL-) deficient knees. Nevertheless, its kinematical contribution to the pivot-shift (PS) phenomenon has not been clearly and objectively defined, and noninvasive sensor technology could give a crucial contribution in this direction. The aim of the present study was to quantify in vitro the PS phenomenon in order to investigate the differences between an ACL-deficient knee and an ACL+ALL-deficient knee. Ten fresh-frozen paired human cadaveric knees ( n = 20) were included in this controlled laboratory study. Intact, ACL-deficient, and ACL+ALL-deficient knees were subjected to a manual PS test quantified by a noninvasive triaxial accelerometer (KiRA, OrthoKey). Kinematic data (i.e., posterior acceleration of the tibial lateral compartment) were recorded and compared among the three statuses. Pairwise Student's t -test was used to compare the single groups ( p < 0.05). Intact knees, ACL-deficient knees, and ACL+ALL-deficient knees showed an acceleration of 5.3 ± 2.1 m/s 2 , 6.3 ± 2.3 m/s 2 , and 7.8 ± 2.1 m/s 2 , respectively. Combined sectioning of ACL and ALL resulted in a statistically significant acceleration increase compared to both the intact state ( p < 0.01) and the ACL-deficient state ( p < 0.01). The acceleration increase determined by isolated ACL resection compared to the intact state was not statistically significant ( p > 0.05). The ALL sectioning increased the rotatory laxity during the PS after ACL sectioning as measured through a user-friendly, noninvasive triaxial accelerometer., Competing Interests: The authors declare that there is no conflict of interest regarding the publication of this paper., (Copyright © 2021 Alberto Grassi et al.)

Purpose: To assess the relationship between the KiRA triaxial accelerometer and the KT-1000 measurements in the intact, anterior cruciate ligament (ACL) deficient, and ACL reconstructed knee joint for the quantification of the Lachman test. Moreover, the intra- and inter-examiner repeatability of the KiRA device will be determined. It was hypothesized that the side-to-side difference of the anterior tibial translation as measured by the KiRA device would be equivalent to the one measured by the KT-1000 during the Lachman test., Methods: Sixty patients were divided into three groups and have been prospectively included in the present study. Group&#95;A composed of 20 patients with a diagnosis of an isolated ACL tear. Group&#95;B composed of 20 patients who underwent ACL reconstruction with a Single-Bundle Lateral Plasty (SBLP) technique with at least 20 years of follow-up. Group&#95;C was the control group and included 20 patients with no history of ACL lesion. Lachman test has been performed at manual-maximum load on both sides, the involved and the contralateral and analyzed with the two different devices., Results: The KiRA device in terms of side-to-side difference resulted not statistically different from the measurement of the KT-1000 arthrometer for the three study groups (n.s): Group&#95;A: (4 ± 2 mm KiRA, 4 ± 2 mm KT1000), Group&#95;B: (4 ± 2 mm KiRA, 4 ± 2 mm KT-1000), Group&#95;C: (4 ± 2 mm KiRA, 4 ± 2 mm KT-1000), an excellent intra- (ICC = 0.88-0.89) and inter-examiner (ICC = 0.79) agreement was found for KiRA measurements., Conclusion: The KiRA (I+, Italy) device offers a valid method to quantify the Lacham test., Level of Evidence: II.

Background: Return to sport after revision ACL reconstruction is a controversial topic, several studies reported the results of different techniques and graft in sportsman, presenting an incredibly wide range of return to the same pre-injury activity level, from 0% to 100%. The purpose of this study was to evaluate the clinical outcomes and return to sport rate in young athletes after non anatomic double-bundle revision ACL reconstruction with Achilles allograft., Hypothesis: The present revision technique was effective in terms of stability, return to sport and functional outcomes., Material and Methods: All the athletes undergone Revision ACL reconstruction with non-irradiated Achilles tendon allograft with a non-anatomical double-bundle technique were included in the study. A split Achilles tendon allograft was used to reproduce the anteromedial (AM) bundle using the over-the-top position, while the posterolateral (PL) bundle was reconstructed through a femoral tunnel located in the anatomical PL footprint. Sport activity, knee function with Lysholm score, knee laxity and re-injury or re-operations were evaluated., Results: Twenty-six athletes (23 males, three females) with a mean age of 23.4±3.6 years were evaluated at a mean follow-up of 6.0±1.6 years. Overall 69% of patients returned to sport both at elite (44%) or county level (56%) after a mean 6.7±1.5 (3-9 range) months. The mean Lysholm score showed a significant improvement from 64.4±8.1 at pre-operative status to 83.8±11.3 at final follow-up (P<.0001). Seven patients (30%) were rated as excellent, nine (39%) as good, five (22%) as fair and 2 (9%) as poor. Three patients (12%) experienced a further graft rupture after a mean 2.6 years, (3.5 months-48 months range) and two had >5mm side-to-side difference at KT-1000. Therefore, the overall survival rate at mean six years follow-up was 81%., Conclusion: The ACL revision with a double-bundle technique using Achilles tendon allograft was successful in 81% of athletes at six years mean follow-up., Type of Study and Level of Evidence: Retrospective case series, level IV., (Copyright © 2017 Elsevier Masson SAS. All rights reserved.)

Purpose: The hypothesis was that an alteration of different surgical variables of ACL reconstruction would produce significant changes in post-operative static laxity of knee joint., Methods: Joint laxity was acquired by a surgical navigation system for 17 patients just after graft fixation during single-bundle reconstruction with extra-articular lateral tenodesis. The analysed laxity parameters were: internal/external rotation at 30° (IE30) and 90° (IE90) of flexion, varus/valgus rotation at 0° (VV0) and 30° (VV30) of flexion and anterior/posterior displacement at 30° (AP30) and 90° (AP90) of flexion. As surgical variables, the angles between the tibial tunnel and the three planes were defined as well as the lengths of the tunnel and the relationship between native footprints and tunnels. The same analysis was performed for the femoral side. All surgical variables were combined in a multivariate analysis to assess for predictive factors between them and post-operative laxities values. To quantify the performance of each multivariate model, the correlation ratio (η 2 ) and the corresponding P value (*P < 0.050) have been evaluated., Results: Multivariate analysis underlined statistically significant models for the estimation of: AP30 (η 2  = 0.987; P = 0.014), IE30 (η 2  = 0.995; P = 0.005), IE90 (η 2  = 0.568; P = 0.010), VV0 (η 2  = 0.932; P = 0.003). The parameters that greatly affected the identified models were the orientation of the tibial tunnel with respect to the three anatomical planes. The estimation of AP30, IE30 and IE90 got lower value as the orientation of the tibial tunnel with respect to transverse plane decreases. Considering the orientation to sagittal ([Formula: see text]) and coronal ([Formula: see text]) plane, we found that their reduction provoked a decrease in the estimation of AP30, IE30 and IE90 (except [Formula: see text] that did not appear in the estimation of AP30). The estimation of VV0 got an increase of [Formula: see text], and [Formula: see text] which led to a laxity reduction., Conclusion: The main finding of the present in vivo study was the possibility to determine significant effects on post-operative static laxity level of different surgical variables of ACL reconstruction. In particular, the present study defined the conditions that minimize the different aspects of post-operative laxity at time-zero after surgery.

Purpose: To quantitatively describe the kinematic behaviour of the hip joint with particular interest in the contribution of the periarticular soft tissues to the stability. To quantitatively assess the sealing function of the acetabular labrum of an intact labrum, the effect of a labral-chondral separation and different surgical approaches. The biomechanics of the joint during specific clinical examinations was also assessed., Methods: All the kinematics tests, manually performed, have been acquired using a navigation systems. For the first part of the study, 4 hemi-corpse specimens were evaluated with the hip in 36 different positions with all the soft tissues intact, after removal of skin and muscles and after partial capsulectomy. During the second and the third part of the analysis 8 fresh frozen hips were analysed. They were tested during 3 different positions used for femeroacetabular impingement (FAI) diagnosis, during pivoting motion and distraction test. Contact area between acetabulum and femoral head, range of movement (RoM) and hip joint centre (HJC) displacement were evaluated., Results: Femoral head displacement occured in all 3 directions and increased as more tissue was removed. Considering both pivoting motion and distraction test there was an increase of the HJC displacement after labral tear. Analogously, the tested surgical approaches showed different results compared to intact condition. Our analysis confirmed that the hip position with Hyperextension-External Rotation is specific for the analysis of the posteriorsuperior region of the acetabulum., Conclusions: The study showed that hip joint does not act as a true ball-and-socket joint and the femoral head anatomical displacement is strongly affected by the removal of periarticular soft tissues, labral repair as well as labrectomy.