601 EP001 – The differences between the injured and non-injured limb performance in several lower limb tasks for ACLR athletes: 6 months post-operative

Background Most rehabilitation programs use some testing to determine the readiness to return-to-sport; however, it is important to determine what the pass criteria is. One of the most common return-to-sport criteria is the limb symmetry index (LSI). Objective To investigate the differences between injured and non-injured leg in ACLR across these tests, hop, 2-D FPPA, balance, force generation, and isokinetic muscle tests, also to describe reference values for the LSI for hop and isokinetic testing. Design Differences study Setting At Salford University labs Participants 29 ACLR highly athlete (6–9 post-operative), 16 males and 13 females (age27.4±2.5years; height171±3.8cm; and mass74.6±4.07kg). Interventions Five tests on each leg: Hop tests: Two tests were applied using a tape measure: the horizontal hop for distance and crossover hop test. Knee valgus angle tests: Two tests were applied using 2D capturing: the horizontal hop for distance and squat test. Balance tests: Three tests were applied using Kistler Force Plate: straight leg, bent leg, and hop for distance balance test. Force test: One test was applied using FT 700 Power Cage: an isometric mid-thigh clean pull. Isokinetic muscle testing: Two tests were applied using Biodex System 4: quadriceps and hamstring muscle tests. Main Outcome Measurements Hop: the maximum point reached. Knee valgus angle: FPPA of the knee valgus in maximum knee flexion position. Balance: postural sway in straight and bent leg tests, while time to stability in hop land test. Force: maximum RFD, peak force, and impulses from 0–300ms. Isokinetic muscle testing: peak torque, peak torque to body weight, and work to body weight. Results Differences found between the injured and non-injured legs in hop tests and isokinetic testing. Symmetry between limbs didn't exist in both tests Conclusion One leg's performance cannot define the other The existing return-to-play criteria appears to be insufficient