Rotational laxity greater in patients with contralateral anterior cruciate ligament injury than healthy volunteers

Abstract

Rotational stability of the knee has been traditionally difficult to quantify, limiting the ability of the orthopedic community to determine the potential role of rotational laxity in the etiology of anterior cruciate ligament (ACL) injuries. The purposes of this multicenter cohort study were to evaluate the reliability of a robotic axial rotation measurement system, determine whether the uninjured knees of patients that had previous contralateral ACL reconstruction demonstrated different rotational biomechanical characteristics than a group of healthy volunteers, and determine whether knee rotational biomechanical characteristics differ between male and female non-injured limbs in groups of both healthy volunteers and patients with a previous contralateral ACL injury. Fourteen healthy volunteers and 79 patients with previous unilateral ACL injury participated in this study. Patients were tested using a computerized tibial axial rotation system. Only the normal (non-operated) knee data were used for analysis. In order to assess the reliability of the robotic measurement system, 10 healthy volunteers were tested daily over four consecutive days by four different examiners. Rotational laxity and compliance measures demonstrated excellent reliability (ICC = 0.97). Patients with a contralateral ACL injury demonstrated significantly increased tibial internal rotation (20.6° vs. 11.4°, P < 0.001) and reduced external rotation (16.7° vs. 26.6°, P < 0.001) compared to healthy volunteers. Females demonstrated significantly increased internal and external rotation, as well as significantly increased rotational compliance compared with males (P < 0.05). Computer-assisted measurement techniques may offer clinicians an accurate, reliable, non-invasive method to select the most appropriate preventative or surgical interventions for patients with increased knee rotational laxity.

Objective measurements of static anterior and rotational knee laxity

“…As for rotational knee laxity, it has been shown that women have up to 40 % higher knee rotation compared to men [32]. This difference has been confirmed by several investigations [18,32,36,55]. It may represent one of the factors explaining the higher risk for ACL injuries in females.…”

“…Electromagnetic sensors placed on the proximal tibia showed that tibial rotation represented in average 48.7 % of the total rotation measured at the foot [36]. Inter-rater ICC for total range of rotation reached 0.97 at a torque of 5.65 Nm [36]. The average expected difference between two measurements as measured with the repeatability coefficient reached 6.9°for internal rotation and 3.5°for external rotation [37].…”

“…Individualized normative references have been established taking into account gender and body mass [18,35]. -Robotic Knee Testing system [36]: The patient lies supine with knees flexed at 25°. Electromagnetic sensors placed on the proximal tibia showed that tibial rotation represented in average 48.7 % of the total rotation measured at the foot [36].…”

“…-Robotic Knee Testing system [36]: The patient lies supine with knees flexed at 25°. Electromagnetic sensors placed on the proximal tibia showed that tibial rotation represented in average 48.7 % of the total rotation measured at the foot [36]. Inter-rater ICC for total range of rotation reached 0.97 at a torque of 5.65 Nm [36].…”

Clinical and Instrumented Measurements of Hip Laxity and Their Associations With Knee Laxity and General Joint Laxity

“…35 Despite these associations, it is not yet clear whether the assessment of hip laxity would further discriminate injury potential beyond the laxity variables previously examined. To date, associations between joint laxity and ACL injury risk are largely based on sagittal-plane joint laxity (GJL, anterior knee laxity, genu recurvatum), 1-3,37-41 with 1 study accounting for transverse-plane knee laxity 42 and none accounting for rotational hip laxity. Given the growing interest in the role of hip mobility and stability as a potential ACL injury risk factor 12,16,19,20 and the associations we observed in this study, further research is warranted to determine if the assessment of hip-joint laxity would (1) increase the sensitivity of GJL in predicting injury risk potential, (2) be a stronger discriminator of injury risk potential (either alone or in combination with discrete kneelaxity measures), or (3) simply provide information redundant to that already provided by GJL and other laxity variables.…”