Over the years I’ve seen griplock injuries 2 or 3 times. Never to one of my own gymnasts, happily.
Grip lock is a … injury that rarely occurs in gymnastics …
Athletic trainers and therapists should become familiar with the cubital grip positions that place gymnasts at high risk for grip lock injury and carefully observe performances
on the high bar in men’s gymnastics …Grip lock injury may be prevented through education of gymnasts and their coaches …
Gymnastics Coaching.com 
This injury is becoming more and more frequent, sadly.
I always recommend my juniors and seniors to buy short handguards, possibly with buckles rather than straps.
What I fear is that we’d better switch to a slightly thicker bar. They should really consider making some experiments.
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