Forward lunge before and after anterior cruciate ligament reconstruction: Faster movement but unchanged knee joint biomechanics

Abstract

The forward lunge (FL) may be a promising movement to assess functional outcome after ACL reconstruction. Thus, we aimed to investigate the FL movement pattern before and after ACL reconstruction with a comparison to healthy controls to determine if differences were present. Twenty-eight ACL injured participants and 28 matched healthy controls were included. They performed FL movements while sagittal plane biomechanics of the knee and electromyography (EMG) of nine leg muscles was assessed. The ACL injured group was tested before and 10 months after surgery. The perceived knee function and activity level was assessed by questionnaires. The ACL injured group performed the FL significantly slower than the controls before surgery (mean difference: 0.41 s [95%CI: 0.04-0.79 s; p<0.05]) while they performed the FL as fast as the controls after surgery (~28% movement time reduction post-surgery). Perceived knee function and activity level improved significantly post-surgery. The knee joint flexion angle, extensor moment, power, angular velocity in the ACL injured group did not differ from pre to post-surgery. For the ACL injured group, the peak knee extensor moment observed both pre and post-surgery was significantly lower when compared to the controls. The EMG results showed minimal differences. In conclusion, at 10 months post-surgery, the FL was performed significantly faster and the movement time was comparable to that of the controls. While the perceived knee function and activity level improved post-surgery, the knee joint biomechanics were unchanged. This may reflect that knee joint function was not fully restored.

Variation in Gastrocnemius and Hamstrings Muscle Activity During Peak Knee Flexor Force After Anterior Cruciate Ligament Reconstruction With Hamstring Graft: Preliminary Controlled Study

“…Alkjae r et al in 2020 [5] performed an EMG analysis of the different muscles of the knee in patients who had undergone ACL reconstruction during a front knee lunge. This study reports a significant increase in medial gastrocnemius activity during a front cleft in subjects operated on 10 months ago for ACL reconstructive surgery compared to a healthy control group.…”

“…All of these studies [4,5,9] focus on the observation of muscle activity in the muscles involved in knee function during functional tests that solicit the neuromotor agility of participants. The present study makes it possible to show that, the increase in the activity of hamstring muscles on the one hand and of the medial gastrocnemius on the other hand, is also present during a pure force test.…”

“…For the test group, one patient had been operated on for an ACL reconstruction with hamstring graft 12 weeks before the study, one patient 16 weeks before and 2 patients 24 weeks before participating in the study. For both groups, the subjects were selected according to inclusion and exclusion criteria based on the literature, making it possible to limit the biases linked to differences between the subjects as well as to standardize the study population [4,5] .…”

“…On the other hand, some authors use functional tests [4,5,9] which could be more relevant for the normalization of gastrocnemius. Another method considered may be to normalize the signal directly using as a reference value the peak of muscle activity during the test exercise [10,13].…”

Variation in Gastrocnemius and Hamstrings Muscle Activity During Peak Knee Flexor Force After Anterior Cruciate Ligament Reconstruction With Hamstring Graft: A Preliminary Controlled Study

“…This modification can have an important functional role; these two muscle groups have the same function in the knee's neuromotor control and the protection of the ACL. Thus, a change in the proportional activity of the flexor muscles of the knee after such a surgical intervention could lead to an alteration in the active capacities of the patients, which may result in the long term in consequences in terms of sports performance as well as the risk of injury [4,5]. To better understand if there is a phenomenon of modification of these muscles' activity patterns, this study aims to compare the hamstrings and gastrocnemius muscles' electromyographic activities during a knee flexion movement between an operated for ACL reconstruction with hamstring graft and a healthy control population.…”