Single leg vertical jump performance identifies knee function deficits at return to sport after ACL reconstruction in male athletes

Abstract

ObjectivesVertical jump performance (height) is a more representative metric for knee function than horizontal hop performance (distance) in healthy individuals. It is not known what the biomechanical status of athletes after anterior cruciate ligament (ACL) reconstruction (ACLR) is at the time they are cleared to return to sport (RTS) or whether vertical performance metrics better evaluate knee function.MethodsStandard marker-based motion capture and electromyography (EMG) were collected from 26 male athletes cleared to RTS after ACLR and 22 control healthy subjects during single leg vertical jumps (SLJ) and single leg drop jumps (SLDJ). Performance outcomes, jump height and the Reactive Strength Index, were calculated. Sagittal plane kinematics, joint moments and joint work were obtained using inverse dynamics and lower limb muscle forces were computed using an EMG-constrained musculoskeletal model. Muscle contribution was calculated as a percentage of the impulse of all muscle forces in the model. Between-limb and between-group differences were explored using mixed models analyses.ResultsJump performance, assessed by jump height and Reactive Strength Index, was significantly lower in the involved than the uninvolved limb and controls, with large effect sizes. For the ACLR group, jump height limb symmetry index was 83% and 77% during the SLJ and SLDJ, respectively. Work generation was significantly less in the involved knee compared to uninvolved limb and controls during the SLJ (p<0.001; d=1.19; p=0.003, d=0.91, respectively) and during the SLDJ (p<0.001; d=1.54; p=0.002, d=1.05, respectively). Hamstrings muscle contribution was greater in the involved compared to the uninvolved limb and controls, whereas soleus contribution was lower in the involved limb compared to controls.ConclusionsDuring vertical jumps, male athletes after ACLR at RTS still exhibit knee biomechanical deficits, despite symmetry in horizontal functional performance and strength tests. Vertical performance metrics like jump height and RSI can better identify interlimb asymmetries than the more commonly used hop distance and should be included in the testing battery for the RTS.

Trunk Biomechanics in Individuals with Knee Disorders: A Systematic Review with Evidence Gap Map and Meta-analysis

“…5 A]). Very low-certainty evidence from 4 studies (312 participants) [ 109 , 110 , 118 , 122 ] showed no differences between groups for trunk flexion during jumping tasks (SMD = − 0.76; 95% CI = − 1.62 to 0.10; Z = 1.74, P = 0.08 [Fig. 5 B]).…”

Single leg drop jump performance identifies functional deficit in collegiate athletes who have returned to sports after ACL reconstruction: A case–control study

“…Two recent studies had a similar result with this study’s findings where there were significant differences between the involved and non-involved legs in JH and RSI during the SLDJ was shown in athletes after ACLR at the time to RTS and also athletes with knee injury in the final phase of rehabilitation prior RTS. [ 7 , 8 ]…”

“…[ 44 , 45 ] A recent study also show that athletes with significant asymmetries in SLDJ performance exhibited differences in knee work and kinematic and altered muscle coordination strategies between involved leg and non-involved leg after ACLR. [ 7 ] Asymmetries in limb performance during athletic tasks may be potential risk factors for lower extremity injury, particularly second ACL injury, and should be minimized prior to RTS following ACL reconstruction. [ 9 ] A previous study also found jump height and RSI asymmetry during the SLDJ were significantly correlated with 10 minutes, 30 minutes, and 505 change of direction (COD) performances, indicating that larger asymmetries are indicative of slower sprint and COD times.…”

“…Tests that measure lower limb power output and the reactivity of an athlete might be more useful to assess the physical and performance readiness to RTS. [ 7 ] Since RTS decisions are an important component of sports medicine practice and both researchers and clinicians have attempted to develop evidence-based models to facilitate positive outcomes, it is therefore apparent that assessment protocols, consisting of demanding and sensitive tests of neuromuscular function, are required to enable practitioners to make informed RTS decisions. [ 8 ] Hence, we wonder if single leg drop jump (SLDJ) can be an effective RTS testing since drop jump is a commonly used plyometric exercise or testing which rely on adequate development of critical motor abilities such as explosive strength and stretch shortening cycle (SSC) function.…”

How do the femoral anteversion angle and neck-shaft angle influence muscle forces and joint loading during walking?

“…Optimal ber lengths and tendon slack lengths of each muscle were optimized to t to the each scaled model using the Matlab tool developed by Modenese et al 32 . The maximum isometric force of each muscle was multiplied by two to allow the generation of realistic muscle activation waveforms with each model 33 , i.e. avoid plateaus of 100% muscle activation.…”