Activation and torque deficits in ACL-reconstructed patients 4 months post-operative

Muscle Morphology Does Not Solely Determine Knee Flexion Weakness After Anterior Cruciate Ligament Reconstruction with a Semitendinosus Tendon Graft: A Combined Experimental and Computational Modeling Study

The distal semitendinosus tendon is commonly harvested for anterior cruciate ligament reconstruction, inducing substantial morbidity at the knee. The aim of this study was to probe how morphological changes of the semitendinosus muscle after harvest of its distal tendon for anterior cruciate ligament reconstruction affects knee flexion strength and whether the knee flexor synergists can compensate for the knee flexion weakness. Ten participants 8-18 months after anterior cruciate ligament reconstruction with an ipsilateral distal semitendinosus tendon autograft performed isometric knee flexion strength testing (15°, 45°, 60°, and 90°; 0° = knee extension) positioned prone on an isokinetic dynamometer. Morphological parameters extracted from magnetic resonance images were used to inform a musculoskeletal model. Knee flexion moments estimated by the model were then compared with those measured experimentally at each knee angle position. A statistically significant between-leg difference in experimentally-measured maximal isometric strength was found at 60° and 90°, but not 15° or 45°, of knee flexion. The musculoskeletal model matched the between-leg differences observed in experimental knee flexion moments at 15° and 45° but did not well estimate between-leg differences with a more flexed knee, particularly at 90°. Further, the knee flexor synergists could not physiologically compensate for weakness in deep knee flexion. These results suggest additional factors other than knee flexor muscle morphology play a role in knee flexion weakness following anterior cruciate ligament reconstruction with a distal semitendinosus tendon graft and thus more work at neural and microscopic levels is required for informing treatment and rehabilitation in this demographic.

Are lower limb symmetry and self-reported symptoms associated with functional and neuromuscular outcomes in Brazilian adults with anterior cruciate ligament reconstruction? A cross-sectional study

INTRODUCTION

After anterior cruciate ligament (ACL) reconstruction, determining readiness to return to participation is challenging. The understanding of which neuromuscular performance parameters are associated with limb symmetry and self-reported symptoms may be useful to improve monitoring the rehabilitation towards adequate decision-making to return.

OBJECTIVES

To compare the ACL-operated and injury-free lower limbs regarding functional performance; and to investigate whether lower limb strength and functional performance are associated with self-reported symptoms and functional lower limb symmetry.

METHOD

Thirty-four participants were included. Functional performance was assessed by using the Y-Balance test, Single-leg Hop, and Functional Movement Screen. An isokinetic dynamometer was used to evaluate the strength levels in open and closed kinetic chains. The functional lower limb symmetry was calculated considering the single-leg hop test results for each lower limb.

RESULTS

There were no differences in dynamic balance (Y-Balance) between the operated and injury-free limbs. The operated limb presented a worst performance in the single-leg hop. Self-reported symptoms prevalence and lower limb symmetry were associated with knee extension strength and functional performance (Y-Balance).

CONCLUSION

Individuals submitted to ACL-reconstruction presented worse functional performance in the operated limb compared to the injury-free limb. Both knee strength and dynamic balance were associated with limb symmetry and self-reported symptoms.

Dynamic Analysis of Vibration, Muscle Firing, and Force as a Novel Model for Non-Invasive Assessment of Joint Disruption in the knee: A Multiple Case Report

We present a new method for understanding knee pathology through non-invasive techniques. The combination of electromyography (EMG), vibroarthrographic (VAG), and force analysis in proposed to examine the force transfer between unhealthy and healthy knees. A multiple case report is presented to demonstrate the technique and its potential application for future study. The comparison of four individuals’ knee characteristics will be explained using this innovative methodology.