Read on Twitter
This study has been making the rounds a bit on ACL twitter.
After a careful read, I'd like to give my thoughts...
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After a careful read, I'd like to give my thoughts...
/thread
Knee valgus is a common theme of debate among ACL folk. Is it a risk factor? Should we even bother screening for it?
(For the sake of discussion, let's not mention that ACL injury is extremely complex and predicting this injury off single factor(s) is likely problematic)
(For the sake of discussion, let's not mention that ACL injury is extremely complex and predicting this injury off single factor(s) is likely problematic)
One thing that stood out to me immediately is that 1 day of screening was used to collect data and subsequently predict ACL injury. That's "OK" for a season-long injury risk study, but this tracked injuries for 8 YEARS.
The authors fail to provide much injury tracking details...
The authors fail to provide much injury tracking details...
Motor performance will certainly change due to growth, maturation, and S&C training.
Cross-sectional injury prediction is certainly a limitation in many studies, but extending this to multiple years is reaching here IMO.
Cross-sectional injury prediction is certainly a limitation in many studies, but extending this to multiple years is reaching here IMO.
Another thing that stood out was a lack of description on the standardization of 2D analyses. How far were the athletes from the camera? Was this the same for every athlete?
This is important because estimating joint centers is quite challenging and parallax errors could arise.
This is important because estimating joint centers is quite challenging and parallax errors could arise.
The figures leave me a little leery relating to the above point. These athletes look like they're being analyzed from different distances and viewpoints.
The hip joint center estimations don't seem great. 2D analysis takes a lot of practice!
The hip joint center estimations don't seem great. 2D analysis takes a lot of practice!
This study employed multiple "teams" of analysts.
Team 2 performed much worse. In clinical practice, anything <0.75 is considered poor. These reliability values were found at initial contact, which is when most ACL injuries occur...
Team 2 performed much worse. In clinical practice, anything <0.75 is considered poor. These reliability values were found at initial contact, which is when most ACL injuries occur...
Something else to keep in mind. Knee valgus without a high knee moment is not really a risk factor for injury.
Stand up and "kiss your knees" together. Without the accompanying moment, the ACL is not really under any sort of strain.
Stand up and "kiss your knees" together. Without the accompanying moment, the ACL is not really under any sort of strain.
Knee moments are likely more predictive than knee valgus angles.
While I do like this study from a clinician-friendly perspective, I would have liked to see the authors comment on some of their methodological considerations / limitations.
While I do like this study from a clinician-friendly perspective, I would have liked to see the authors comment on some of their methodological considerations / limitations.
Bottom line: ACL injury is way more complex than assessing athletes dropping off a standardized box and completing a standardized task.
If that were so, I'd likely be looking for new work!
If that were so, I'd likely be looking for new work!
