Unplanned Movement Increases Risk of Knee Injury

Why are amateur athletes more prone to injury than professional athletes? One cause is, literally, unplanned movements versus planned movements while playing sports. Training and muscle memory, which professional athletes work at for years, create an economy and focus of movement which not only results in higher skill levels but also lower injury rates.

A new study looked at the role of unplanned movements as a contributing cause of sports injury and found that they result in higher knee abduction and tibial internal rotation moments and therefore increased risk for knee injury.

In the study, “Effect of unplanned athletic movement on knee mechanics: a systematic review with multilevel meta-analysis,” published online on August 3, 2021 in the British Journal of Sports Medicine, they compared the effects of pre-planned and unplanned movement tasks on knee biomechanics in uninjured individuals.

The systematic review with meta-analysis drew data from five databases including PubMed, Google Scholar, Cochrane Library, ScienceDirect and Web of Science which were all searched from inception to November 2020. All cross-sectional, (randomized controlled/non-controlled trials comparing knee angles/moments of pre-planned and unplanned single-leg landings/cuttings were included.

The researchers used a multilevel meta-analysis with a robust random-effects meta-regression model to pool the standardized mean differences of knee mechanics between pre-planned and unplanned tasks. They also examined the influence of possible effect modifiers in a moderator analysis.

Quality of evidence was assessed using the tool of the Grading of Recommendations Assessment, Development and Evaluation working group.

Overall, 25 trials with 485 participants were included. Quality of evidence was downgraded due to potential risk of bias such as confounding factors.

The research team found a pattern in the data which indicated that unplanned tasks resulted in significantly higher external knee abduction (SMD [standardized mean differences]: 0.34, 95% CI: 0.16 to 0.51, 14 studies) and tibial internal rotation moments (SMD: 0.51, 95% CI: 0.23 to 0.79, 11 studies). Furthermore, the team did not detect any significant between-condition differences for sagittal plane mechanics (p > 0.05).

The moderator analysis showed that increased abduction moments especially occurred in non-professional athletes (SMD: 0.55, 95% CI: 0.14 to 0.95, 5 studies).

“Unplanned movement entails higher knee abduction and tibial internet rotation moments, which could predispose for knee injury. Exercise professionals designing injury-prevention protocols, especially for non-elite athletes, should consider the implementation of assessments and exercises requiring time-constrained decision-making.”