A Novel Approach to the Assessment of Limb Loading Symmetry in Adolescent Athletes with and without a History of Ankle Sprains Prior to an ACL-R.

OBJECTIVES: The limb symmetry index (LSI) is commonly used for return-to-sport decisions but focuses primarily on the knee, neglecting intralimb compensations at the ankle and hip. We aimed to evaluate the effectiveness of using energy absorption contributions (EAC) to assess joint loading asymmetry (LSI EAC ). This approach was compared with the conventional method of joint moment analysis in adolescent athletes with and without prior ankle sprains before anterior cruciate ligament reconstruction (ACL-R) and in healthy controls.

METHODS: Thirty-nine adolescent athletes were divided into three groups: 13 healthy controls, 13 with ACL-R (ACLR), and 13 with a history of ankle sprains prior to ACL-R (ACLR-LAS). All participants completed isokinetic quadriceps strength testing at 60 deg·s -1 and a bilateral jump-landing task. LSI was calculated using joint moments at peak knee flexion and EAC from initial contact to peak knee flexion during landing. EAC was expressed as a proportion of total energy absorption across all joints.

RESULTS: Significant three-factor interactions were found between groups, joints, and the LSI metric. Only LSI EAC identified significant joint loading asymmetry at the hip, knee, and ankle in the ACLR-LAS group compared with healthy controls. LSI EAC also detected significant differences at the knee between the ACLR and ACLR-LAS groups.

CONCLUSIONS: The LSI EAC approach effectively identified joint loading asymmetries across lower extremity joints in the ACLR-LAS group, highlighting compensatory interjoint patterns that traditional LSI metrics may overlook. These findings support the need for more comprehensive return-to-sport assessments.