Monitoring Cortical and Neuromuscular Activity: Six-month Insights into Knee Joint Position Sense Following ACL Reconstruction.
Aglaja Busch, Lorena R R Gianotti, Frank Mayer and 1 others
PMID 39502546WHAT IT FOUND
After ACL reconstruction, knee position sense accuracy, quadriceps muscle activity and brain activity in the ACL group did not differ from healthy controls over time, except an isolated frontal brain activity result.
Key findings
01Knee joint position sense absolute angular error showed no statistically significant differences between ACL patients and healthy controls across measurement time points or between involved and non-involved limbs.
02Normalized surface EMG activity of the vastus medialis, vastus lateralis and rectus femoris during extension to the target angle showed no statistically significant differences between groups, time points or limbs.
03EEG power showed no statistically significant differences for frontal theta, frontal beta-1, parietal alpha-2, central beta-1, central beta-2, parietal beta-1 or parietal beta-2, apart from a significant frontal beta-2 comparison.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
The researchers did not calculate the required sample size in advance, and the study used 20 participants per group, so it may miss modest differences. Rehabilitation after surgery was usual care and not controlled; frequency, content and independent training varied between participants. Pain was higher around the first measurement in the ACL group, which could influence position sense, muscle activity and brain activity. The test used only one target angle and a seated, open-chain movement, so it may not reflect weight-bearing or functional movement. The test has a minimal detectable change of 6.8°, and a difference of more than 5° has been proposed as clinically meaningful. One participant could not perform the first test, and data from one non-involved limb at the first measurement and one block at the third measurement were excluded for technical issues. Healthy controls were measured once, so the study cannot show how controls would have performed over the same period.
Declared interests
The authors report no conflicts of interest.
The easy way to misread this
Do not read the isolated frontal beta-2 result as evidence that ACL reconstruction causes a clinically important brain change. The main knee position sense outcome showed no difference from controls, and the paper does not show that this finding matters for function or injury risk.