Knee functional recovery and limb-to-limb symmetry restoration after anterior cruciate ligament (ACL) rupture and ACL reconstruction

Snyder-Mackler, LynnLogerstedt, DavidAnterior cruciate ligament (ACL) rupture is a common sport injury of young athletes who participate in jumping, cutting, and pivoting activities. Although ACL reconstruction (ACLR) surgery has the goal of enabling athletes to return to preinjury activity levels, treatment results often fall short of this goal. The outcomes after ACLR are variable and less than optimal with low rate of return to preinjury activity level and high risk for second ACL injury. Factors related to the knee functional limitations, strength deficits, and limb-to-limb movement asymmetry may be associated with poor outcomes after ACLR. Additionally, the criteria that are used to determine a patient's readiness to return to the preinjury activity level are undefined which may also be associated with poor outcomes after ACLR. The clinical decision-making to clear patients' for safe and successful return to high physical activities should be based on a universal comprehensive set of objective criteria that ensure normal knee function and limb-to-limb symmetry. A battery of return to activity criteria (RTAC) that emphases normal knee function and limb-to-limb movement symmetry has been constituted to better ensure safe and successful return to preinjury activity level. Yet, only variables related to patients' demographics, concomitant injuries, and treatment measures have been used to predict return to preinjury activity levels after ACLR. However, the ability of RTAC variables that ensure normal knee function and limb movement symmetry to predict the return to participate in the same preinjury activity level after ACLR has not been investigated. In light of this background, the first aim of the present study was to compare functional knee performance-based and patient-reported measures of those who PASS and who FAIL on RTAC at 6 months (6-M) following ACLR with those at 12 months (12-M) and 24 months (24-M) following ACLR and to determine how performance-based and patient-reported measures change over time. Further to investigate whether RTAC variables at 6-M following ACLR predict return to the same preinjury activity level at 12 and 24 months following ACLR. The findings of this work revealed that patients who fail on RTAC 6-M after ACLR are more likely to demonstrate impaired knee function and limb-to-limb movement asymmetry at 12-M and 24-M after ACLR. Additionally, RTAC variables can predict the return to participate in the same preinjury activity level at 12-M and 24-M after ACLR. The combination of RTAC variables explain more than one-fourth to one-third of returning to participate in the same preinjury activity level 12-M and 24-M respectively after ACLR. For athletes choosing non-surgical management, the physical therapy recommendation is to administrate progressive strength training augmented with manual perturbation training. Manual perturbation training is a type of specialized neuromuscular training that includes purposeful manipulations of support surfaces by a therapist. While manual perturbation promotes dynamic knee stability, enhances dynamic knee function, mitigates abnormal movement pattern and normalizes the muscle co-contraction, perturbation training is not widely used as part of the ACL rehabilitation program in the United States. Further, the perturbation training requires extensive physical labor and one-on-one time from the treating therapist. The effect of administering perturbation training using mechanical device as part of the ACL rehabilitation program has not investigated. An automated "Reactive Agility System" device provides perturbation stimuli including multidirectional translations similar to those of manual perturbation training. Administrating the perturbation training using a mechanical device may facilitate the use of controlled and standardized training in a wide range of the rehabilitation clinics and allow administering controlled and standardized training. However, it is unknown whether administering perturbation training using mechanical device provides effects similar to manual perturbation training on knee mechanics, knee functional performance, and neuromuscular activation pattern in patients with ACL rupture. The second aim of this study was to measure whether the mechanical perturbation training provides an effect similar to that of manual perturbation training on gait mechanics, knee functional performance, muscle co-contraction, and neuromuscular activation pattern in athletes with an acute ACL rupture who are managed non-surgically. The findings of this work revealed that mechanical perturbation training provides effects similar to the manual perturbation training on knee kinematics and kinetics during walking and performance-based and patient-reported measures. Gait limb-to-limb asymmetries continue persist after the training regardless of the treatment group which may indicate that patients require participating in an extended rehabilitation program. Additionally, Perturbation training attempts to resolve the neuromuscular deficits and restore a balance in muscle activation and strength between knee flexors and extensors to enhance the dynamic stability of the knee joint. There are moderate to strong relationships between time duration of muscles' activities and the muscle co-contraction that may reflect neuromuscular adaptations to provide dynamic knee stability.University of Delaware, Department of Physical Therapy.Ph.D