Biomechanical Markers of Forward Hop-Landing After ACL-Reconstruction: A Pattern Recognition Approach.

Area of Science:

• Biomechanics
• Orthopedic Surgery
• Rehabilitation Science

Background:

• Anterior cruciate ligament reconstruction (ACLR) may lead to long-term knee-joint health issues due to persistent biomechanical alterations.
• Understanding these changes is crucial for optimizing patient recovery and preventing secondary injuries.
• Landing biomechanics after ACLR are complex and require advanced analytical methods for accurate characterization.

Purpose of the Study:

• To characterize biomechanical differences during the single-leg forward hop landing phase in individuals post-ACLR using pattern recognition.
• To identify known and novel biomechanical adaptations in ACLR patients compared to healthy controls.
• To detect subtle indicators of landing instability in the ACLR group for improved return-to-sport evaluations.

Main Methods:

• Utilized experimental data from 66 individuals 12-24 months post-ACLR and 32 controls.
• Employed a musculoskeletal modeling pipeline to compute joint angles, moments, and muscle forces.
• Applied pattern recognition techniques to waveform data, transforming them into principal components (features) for distinguishing between groups.

Main Results:

• Identified 10 main distinguishing features between ACLR and control landing biomechanics.
• Confirmed known alterations: reduced knee flexion, lower knee extensor moments, and decreased vasti, rectus femoris, and hamstring forces.
• Discovered novel adaptations: smaller ankle plantar flexor moment, lower soleus forces, altered knee rotation, hip rotation, and knee abduction moments, alongside subtle instability indicators in knee, hip, and lumbar movements.

Conclusions:

• Pattern recognition effectively identified known and novel biomechanical differences in individuals post-ACLR.
• Subtle aberrations in knee, hip, and lumbar kinematics and kinetics indicate landing instability in the ACLR group.
• These findings can enhance rehabilitation strategies and return-to-sport assessments for ACLR patients.