Can rotatory knee laxity be predicted in isolated anterior cruciate ligament surgery?

Anatomic Anterior Cruciate Ligament Reconstruction Using Hamstring Tendons Restores Quantitative Pivot Shift

Background:

It is still uncertain how surgical reconstruction of the anterior cruciate ligament (ACL) is able to restore rotatory laxity of the involved joint. The desired amount of restraint applied by the ACL graft, as compared with the healthy knee, has not been fully clarified.

Purpose:

To quantify the ability of single-bundle anatomic ACL reconstruction using hamstring tendons in reducing the pivot-shift phenomenon immediately after surgery under anesthesia.

Study Design:

Case series; Level of evidence, 4.

Methods:

An inertial sensor and image analysis were used at 4 international centers to measure tibial acceleration and lateral compartment translation of the knee, respectively. The standardized pivot-shift test was quantified in terms of the side-to-side difference in laxity both preoperatively and postoperatively with the patient under anesthesia. The reduction in both tibial acceleration and lateral compartment translation after surgery and the side-to-side difference were evaluated using the Wilcoxon signed-rank test. Alpha was set at P < .05.

Results:

A total of 107 patients were recruited for the study, and data were available for 89 patients. There was a statistically significant reduction in quantitative rotatory knee laxity between preoperatively (inertial sensor, 2.55 ± 4.00 m/s²; image analysis, 2.04 ± 2.02 mm) and postoperatively (inertial sensor, –0.54 ± 1.25 m/s²; image analysis, –0.10 ± 1.04 mm) between the involved and healthy joints, as measured by the 2 devices (P < .001 for both). Postoperatively, both devices detected a lower rotatory laxity value in the involved joint compared with the healthy joint (inertial sensor, 2.45 ± 0.89 vs 2.99 ± 1.10 m/s², respectively [P < .001]; image analysis, 0.99 ± 0.83 vs 1.09 ± 0.92 mm, respectively [P = .38]).

Conclusion:

The data from this study indicated a significant reduction in the pivot shift when compared side to side. Both the inertial sensor and image analysis used for the quantitative assessment of the pivot-shift test could successfully detect restoration of the pivot shift after anatomic single-bundle ACL reconstruction. Future research will examine how pivot-shift control is maintained over time and correlation of the pivot shift with return to full activity in patients with an ACL injury.

Validity of rotational laxity coupled with anterior translation of the knee: A cadaveric study comparing radiostereometry and the Rotab®

BACKGROUND

In current practice, anterior cruciate ligament (ACL) tears can be diagnosed using several devices to measure anterior tibial translation and rotational knee laxity, but these measures are never collected together. The Rotab®, which yields simultaneous measurements of anterior tibial translation and passive lower limb rotation under stress, would therefore be advantageous in current practice, but its reliability has never been tested.

AIM OF STUDY

To evaluate the accuracy and reliability of the Rotab® compared to the reference system, radiostereometric analysis (RSA).

METHODS

This anatomical study was conducted on 14 lower limbs collected from fresh cadavers. Simultaneous measurements of anterior tibial translation and rotation were obtained with both systems, with antero-posterior (AP) forces of 134N and 250N using the Rotab®. Measurements were made on intact ACL and then repeated after ACL section. Variables were analyzed in univariate analysis by ANOVA, and the intraclass correlation coefficient (ICC) between the systems was determined by the Bland and Altman method.

RESULTS

The difference between the two methods for evaluating anterior tibial translation was 0.05±0.98mm at 134N and 0.29±1.04mm at 250N. The correlation between the tests was high (r₁₃₄=r₂₅₀=0.97, p=0.8). The difference between the two methods for rotational laxity was 0.69±2.7° at 134N and 0.5±0.6° at 250N. The Rotab® showed a significant difference only at 250N for rotational laxity after the ACL tear.

CONCLUSION

The Rotab® is a reliable device to measure rotational laxity coupled with anterior translation of the knee.

Current use of navigation system in ACL surgery: a historical review

PURPOSE

The present review aims to analyse the available literature regarding the use of navigation systems in ACL reconstructive surgery underling the evolution during the years.

METHODS

A research of indexed scientific papers was performed on PubMed and Cochrane Library database. The research was performed in December 2015 with no publication year restriction. Only English-written papers and related to the terms ACL, NAVIGATION, CAOS and CAS were considered. Two reviewers independently selected only those manuscripts that presented at least the application of navigation system for ACL reconstructive surgery.

RESULTS

One hundred and forty-six of 394 articles were finally selected. In this analysis, it was possible to review the main uses of navigation system in ACL surgery including tunnel positioning for primary and revision surgery and kinematic assessment of knee laxity before and after different surgical procedures. In the early years, until 2006, navigation system was mainly used to improve tunnel positioning, but since the last decade, this tool has been principally used for kinematics evaluation. Increased accuracy of tunnel placement was observed using navigation surgery, especially, regarding femoral, 42 of 146 articles used navigation to guide tunnel positioning. During the following years, 82 of 146 articles have used navigation system to evaluate intraoperative knee kinematic. In particular, the importance of controlling rotatory laxity to achieve better surgical outcomes has been underlined.

CONLUSIONS

Several applications have been described and despite the contribution of navigation systems, its potential uses and theoretical advantages, there are still controversies about its clinical benefit. The present papers summarize the most relevant studies that have used navigation system in ACL reconstruction. In particular, the analysis identified four main applications of the navigation systems during ACL reconstructive surgery have been identified: (1) technical assistance for tunnel placement; (2) improvement in knowledge of the kinematic behaviour of ACL and other structures; (3) comparison of effectiveness of different surgical techniques in controlling laxities; (4) navigation system performance to improve the outcomes of ACL reconstruction and cost-effectiveness.

LEVEL OF EVIDENCE

IV.

Objective measures on knee instability: dynamic tests: a review of devices for assessment of dynamic knee laxity through utilization of the pivot shift test

Current reconstructive methods used after anterior cruciate ligament (ACL) injury do not entirely restore native knee kinematics. Evaluation of dynamic knee laxity is important to accurately diagnose ACL deficiency, to evaluate reconstructive techniques, and to construct treatment algorithms for patients with ACL injury. The purpose of this study is to present recent progress in evaluation of dynamic knee laxity through utilization of the pivot shift test. A thorough electronic search was performed and relevant studies were assessed. Certain dynamic knee laxity measurement methods have been present for over 10 years (Navigation system, Electromagnetic sensor system) while other methods (Inertial sensor, Image analysis system) have been introduced recently. Methods to evaluate dynamic knee laxity through the pivot shift test are already potent. However, further refinement is warranted. In addition, to correctly quantify the pivot shift test, the involved forces need to be controlled through either standardization or mechanization of the pivot shift test.

Anterolateral rotatory instability of the knee

Recent publications have generated renewed interest in the anatomy of the anterolateral capsule. Knowledge of the biomechanical function of the anterolateral components is lacking. Further research is required to evaluate the influence of the anterolateral capsule on rotatory laxity of the knee. The role of surgical procedures, such as an extra-articular tenodesis or lateral plasty, has to be defined based on quantification of the injury. This article seeks to summarize the current literature and discusses the role of the anterolateral capsule and reconstructive techniques in combined ligamentous knee trauma. Level of evidence V.