Altered Knee Loading Following Primary ACL Repair versus ACL Reconstruction

Evaluation of Lower Limb Asymmetry Index Based on the 30-Second Skater Squat Functional Test in Young Men

Introduction: Physical performance tests (PPTs) are used for the pre-season evaluation of athletes and to monitor and control the rehabilitation process. PPTs include single-leg jumps, single-leg squats, and balance tests. One of the physical fitness tests is the skater squat test. The 30 s skater squat functional test (SSFT) is used as one of the tests to assess fitness and symmetry in the lower limbs. The present study aimed to calculate and compare the asymmetry index using the 30 s skater squat functional test, the single-leg distance jump test, and the isometric measurement of knee joint extensor strength. Materials and Methods: The study examined 25 men aged 23 ± 3.17 years. The study used the 30 s SSFT, the single-leg long jump test (SLLJT), and an isometric dynamometer test to measure peak moment of force values for extensors of the knee using the JBA Zbigniew Staniak® measuring station ("JBA" Zb. Staniak, Poland). The statistical analysis of functional test results and iso-metric dynamometry results was based on correlation analysis. Results: There was a moderate correlation between 30 s SSFT and SLLJT (r = 0.540), and between SLLJT and measurements of peak moment of force of the knee joint extensors (r = 0.533). Conclusions: The asymmetry index calculated based on functional tests and peak moment of force of the knee extensors in a group of young men should not be used interchangeably. The asymmetry index calculated from the 30 s skater squat functional test detects greater differences in knee extensor strength than the ASI index calculated from the single-leg long jump test in a group of young male athletes. The practical significance of this study was that its results could play an important role in the training process and monitoring the return to sports after a possible injury.

Mechanical energy flow analysis in athletes with and without anterior cruciate ligament reconstruction during single-leg drop landing

Techniques that reduce mechanical energy have been linked to lower chances of experiencing an Anterior Cruciate Ligament (ACL) injury. Although there is evidence that movement patterns are altered in athletes who have undergone Anterior Cruciate Ligament Reconstruction (ACLR), energy transfer mechanisms have not been examined. This study aimed to compare energy flow mechanisms during single-leg drop landing between athletes with and without history of ACLR. A total of 20 female athletes were included in this study. Ten participants underwent ACLR 12 months ago (mean age, 21.57 ± 0.41 years) and 10 were healthy controls (mean age, 20.89 ± 0.21 years). Participants executed the single-leg drop landing (SLL) maneuver by descending from a 30 cm wooden box and landing on the tested leg on an embedded force plate. Information collected during the SLL trials was refined using rigid-body analysis and inverse dynamics within Nexus software, ultimately allowing construction of skeletal models of the athletes. Ankle and knee mechanical energy expenditure (MEE) was higher in the control participants during landing. However, the result for the hip MEE demonstrated that MEE of the control group was significantly lower compared with the ACLR group, but MEE of the control subjects was higher as compared to ACLR group (p ˂ 0.05). Results suggest the avoidant use of the quadriceps muscle post ACLR leads to knee-avoidant mechanics and loss of knee joint power generation during a SLL task.