Rupture: not as obvious as you’d think!
Complete hamstring avulsions — that is, complete ruptures of muscles where they attach to bones — are not necessarily obvious. According to O'Laughlin et al, they “can be difficult to diagnose acutely due to swelling and patient guarding, which may mask a visibly palpable defect and lead to delays in diagnosis.” Yikes!
In this case study, the only diagnosis was “hamstring pain” for several days, before the avulsion was finally confirmed by MRI, and surgically repaired on day 13. It’s not hard to imagine cases where the diagnosis would have taken much longer — too long.