Context Due to the limitations of single-center studies in achieving appropriate sampling with relatively rare disorders multicenter collaborations have been proposed to achieve desired sampling levels. facility over a 1-mo period. Intervention Subjects were instrumented with 43 reflective markers to record 3D motion as they performed SLLs. During the SLL the athlete balanced on 1 leg dropped down off of a 31-cm-high box and landed on the same leg. Kinematic and kinetic data from both legs were processed from 2 trials across the 3 laboratories. Main Outcome Measures Coefficients of multiple correlations (CMC) were used to statistically compare each joint angle and moment waveform for the first 500 ms of landing. Results Average CMC for lower-extremity sagittal-plane motion was excellent between laboratories (hip .98 knee .95 ankle .99). Average CMC for lower-extremity frontal-plane motion was also excellent between laboratories (hip .98 knee .80 ankle .93). Kinetic waveforms were repeatable Divalproex sodium in each plane of rotation (3-center mean CMC ≥.71) while knee sagittal-plane moments were the most consistent measure across sites (3-center mean CMC ≥.94). Conclusions CMC waveform comparisons were similar relative to the joint measured to previously published reports of between-sessions reliability of sagittal- and frontal-plane biomechanics performed at a single institution. Continued research is needed to further standardize technology and methods to help ensure that highly reliable results can be achieved with multicenter biomechanical screening models. Keywords: ACL reinjury screening for injury risk multi-institution research biomechanics of rehabilitation Anterior cruciate ligament (ACL) injuries occur more frequently in adolescent and college female athletes than in their male counterparts in the sports of soccer and basketball.1 2 Those who suffer an ACL injury usually experience physical impairments such as effusion pain and decreased range of motion in the knee joint.3 Because of these impairments and Divalproex sodium the resulting loss of normal knee function individuals with ACL injury often elect to undergo surgery to reconstruct the injured ligament.3 However ACL-reconstruction Divalproex sodium (ACLR) surgery is not without secondary complications. For instance a recent study reported that 11% of the reconstructed ACL grafts did not last longer than 15 years.4 Moreover nearly one-third of athletes who return to their preinjury sporting activity will succumb to a second ACL injury 30 within the first 20 athletic exposures.5 6 In addition recent longitudinal studies reported a high incidence of premature osteoarthritis in those who experienced an ACL injury and underwent reconstructive surgeries.7 8 One of the commonly implemented return-to-sport guidelines after ACLR includes serial testing of muscle-strength symmetry single-limb hop and landing performance and patient-reported outcome measures.9-12 Specifically landing patterns during drop-landing tasks (both single- and double-leg) can discriminate between athletes who have undergone ACLR relative to uninjured peers.5 13 While strength symmetry and patient perception of function add important information to the clinical picture of each athlete single-leg hopping and landing tests effectively assess dynamic knee function before return to sport by quantifying dynamic limb-performance asymmetries. These tests may also have utility in identifying aberrant movement mechanics associated with risk of second ACL injury.16 17 These tests are easily implemented in clinical settings and commonly used to determine unilateral joint function and identify residual neuromuscular deficits (eg WASF1 side-to-side asymmetries) in patients after ACLR.14-16 The single-leg landing test (SLL) is commonly used in a clinical setting requires far less space than traditional hop testing lends itself to easy video recording in a clinical environment and may provide a better opportunity to assess the quality of movement that may be lacking in traditional models of functional testing.13 18 19 To examine the effectiveness of the traditional return-to-play guidelines and emergent evidence-based methods that can identify residual deficits in patients after ACLR there is a need to compile extensive data (ie determine the relevant criteria) as well as large numbers of study participants to.