Does prior concussion lead to biomechanical alterations associated with lateral ankle sprain

Key points

1. 01Concussion may leave lingering movement-control deficits that are thought to raise the risk of later lower-limb injuries such as lateral ankle sprain (LAS) and anterior cruciate ligament (ACL) injury.
2. 02Recent concussion (within 2 months) was associated with decreased postural stability (g=0.34) and slower locomotion-related performance (g=0.26), both small effects linked to ankle sprain risk.
3. 03About 2 years after concussion, individuals showed altered frontal plane kinetics (g=0.41) and sagittal plane kinematics (g=0.30, a more erect landing posture), both linked to ACL injury risk.
4. 04Adding cognitive demands to jump-landing tasks affected frontal plane kinematics (p=0.009), suggesting dual-task testing may better expose ACL-relevant changes.
5. 05The injury link is inferred from biomechanics rather than measured injury rates, and most ACL-related data came from cross-sectional studies.

How it was conducted

Design

Systematic review and meta-analysis of observational studies (PROSPERO CRD42021248916)

Search

Five databases (Web of Science, Scopus, PubMed, SPORTDiscus, CINAHL) searched April 2023

Participants

27 studies, 1,544 participants (concussion n=757, non-concussion n=787); mostly young (<25 years) active or student-athletes

Intervention

Comparison of biomechanics with vs without concussion history (or before vs after concussion) during balance, gait, and jump-landing tasks, with and without cognitive demands

Analysis

Random-effects models with Hedges g, heterogeneity by Cochran Q and I2, NIH quality tool, moderator analyses, Egger regression for publication bias

What they found

• 27 studies, 1,544 participants (concussion n=757, non-concussion n=787).
• Recent concussion (within 2 months): decreased postural stability (g=0.34, 95% CI 0.20 to 0.49, p<0.001) and slower locomotion-related performance (g=0.26, 95% CI 0.11 to 0.41, p<0.001), both associated with lateral ankle sprain risk.
• About 2 years post-concussion: altered frontal plane kinetics (g=0.41, 95% CI 0.03 to 0.79, p=0.033) and sagittal plane kinematics (g=0.30, 95% CI 0.11 to 0.50, p=0.002), both associated with ACL injury risk.
• Cognitive demands affected frontal plane kinematics (p=0.009) but not sagittal plane kinematics or locomotion performance.
• NIH quality scores ranged from 5 to 9; publication bias was detected for the postural-stability (LAS) construct (p=0.008).

Limitations

• Effects are small, and grouping diverse outcomes into constructs may obscure which specific variables drive injury risk.
• ACL-related constructs had few studies and small samples and were predominantly cross-sectional, so causation cannot be established.
• Included participants were mostly young active or student-athletes, limiting generalizability to other ages and activity levels.
• The English-only search and publication bias in the postural-stability construct may bias estimates.

Why it matters

For patients

After a concussion, your balance and landing mechanics can stay subtly altered for a long time, which may raise the chance of an ankle or knee injury when you return to sport.

For clinicians

Consider screening balance, gait, and especially dual-task jump-landing mechanics before return-to-play, since cognitive load helps reveal ACL-relevant frontal plane changes.

For readers

Concussion is associated with measurable, injury-risk-related movement changes, but the link to actual injuries is inferred, not demonstrated.