ACL Reconstruction
Conditions
Keywords
ACL reconstruction, vertical jump test, return to play
Brief summary
Anterior cruciate ligament (ACL) injury is a common sports-related injury, particularly in sports that require extensive jumping and cutting movements. Although anterior cruciate ligament reconstruction (ACLR) surgery can restore knee stability, many athletes still face the risk of re-injury after returning to competition.Current return-to-play assessment relies primarily on single-plane horizontal hop tests and symmetry indices (LSI ≥ 90%); however, an increasing body of research suggests that these tests may not comprehensively reflect functional deficits in the vertical plane, repeated hopping, or high-intensity sport-specific activities.This study hypothesizes that incorporating multiple vertical jump tests-including single-leg vertical jumps and 10-second repeated vertical jumps-combined with advanced force plate analytics (such as Reactive Strength Index \[RSI\] and Time to Stabilization \[TTS\])-can more sensitively reveal residual neuromuscular control deficits following surgery. This approach would provide evidence-based guidance for return-to-play decision-making, thereby improving athletes' long-term athletic performance and safety.
Detailed description
This cross-sectional study compares biomechanical performance between ACLR athletes (\>6 months post-op) and healthy controls to evaluate whether vertical jump protocols reveal greater limb asymmetries compared to traditional horizontal hop tests. Following a 5-minute stationary bicycle warm-up and familiarization trials, participants perform four unilateral tasks on both limbs: Single-Legged Hop for Distance (SHD), Crossover Hop for Distance (CHD), Single-Legged Vertical Countermovement Jump (SLVJ), and 10-Second Repeated Single-Legged Vertical Jump (SLVJs). All tasks are performed with hands on hips to minimize compensatory motion. Three successful trials are recorded per limb per task with 3-minute rest intervals between sets. Trials are discarded if participants land on the contralateral limb, lose balance, or fail to land on the force plate. Vertical ground reaction forces are collected using a dual-force plate system (Hawkin Dynamics, 3rd Generation) at 1000 Hz. Data processing calculates Limb Symmetry Index (LSI), Modified Reactive Strength Index (RSI) from SLVJs as Jump Height divided by Movement Time, Time to Stabilization (TTS) defined as the duration for vGRF to stabilize within ±5% of body weight, and eccentric/concentric impulse.
Interventions
None listed
Sponsors
Kaohsiung Medical University
Study design
Observational model
CASE_CONTROL
Time perspective
CROSS_SECTIONAL
Eligibility
Sex/Gender
ALL
Age
18 Years to 35 Years
Healthy volunteers
Yes
Inclusion criteria
* 1.Age 18-35 years 2.Unilateral anterior cruciate ligament (ACL) rupture confirmed by magnetic resonance imaging (MRI) 3.Positive Lachman test grade ≥2 pre-operatively 4.Anterior cruciate ligament reconstruction (ACLR) using hamstring or gracilis autograft 5.Post-operative time ≥6 months 6.Completed rehabilitation program with clearance from orthopedic surgeon or physical therapist 7.Quadriceps strength symmetry index ≥90% .Elite athlete status (prior participation in national-level competitions)
Exclusion criteria
1. Other lower extremity injuries or pathologies (including other knee ligament injuries) 2. Contralateral lower limb injury within the past 3 months 3. Quadriceps strength symmetry index \<90% 4. Non-elite athlete status (no prior national-level competition participation) 5. Incomplete rehabilitation or lack of medical clearance
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Limb asymmetry index,LSI | At baseline (single testing session; no longitudinal follow-up) | Limb Symmetry Index (LSI) calculated as (\|Uninvolved limb value - Involved limb value\| / (Uninvolved limb value + Involved limb value)) × 100% for each of the four jump tasks: Single-Legged Hop for Distance (SHD), Crossover Hop for Distance (CHD), Single-Legged Vertical Countermovement Jump (SLVJ), and 10-Second Repeated Single-Legged Vertical Jump (SLVJs). LSI values will be compared between ACLR athletes and healthy controls to determine whether vertical jump protocols reveal greater limb asymmetries than traditional horizontal hop tests. Primary analysis will examine whether LSI differences in vertical jump tasks are statistically significantly lower (indicating greater asymmetry) than horizontal hop tasks, revealing residual neuromuscular deficits not detected by conventional return-to-play assessment. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Time to Stabilization (seconds) | At baseline (single testing session; no longitudinal follow-up) | Time to Stabilization (TTS) measured during the Single-Legged Vertical Countermovement Jump (SLVJ) task, defined as the time required for vertical ground reaction force (vGRF) to return to and stabilize within ±5% of the participant's body weight following landing. |
| Modified Reactive Strength Index | At baseline (single testing session; no longitudinal follow-up) | Modified Reactive Strength Index (mRSI) calculated as Flight Time(s) divided by Time to Take-off(s) for the 10-Second Repeated Single-Legged Vertical Jump (SLVJs) task. |
| Single-Legged Hop for Distance (centimeter) | At baseline (single testing session; no longitudinal follow-up) | Single-Legged Hop for Distance (SHD) measured as the maximum horizontal distance(centimeter) achieved during a single maximal hop on the tested leg, performed bilaterally. |
| Crossover Hop for Distance (centimeter) | At baseline (single testing session; no longitudinal follow-up) | Crossover Hop for Distance (CHD) measured as the total horizontal distance covered during three consecutive hops crossing a centerline, performed bilaterally with emphasis on stability and continuity. |
| Jump Height(meter) | At baseline (single testing session; no longitudinal follow-up) | Jump Height measured during the Single-Legged Vertical Countermovement Jump (SLVJ) and 10-Second Repeated Single-Legged Vertical Jump (SLVJs) tasks, calculated from the flight time (time from takeoff to landing) using force plate data. |
Countries
Taiwan
Contacts
Primary ContactTeng C Y Kaohsiung Medical University, Bachelor
Outcome results
None listed