Antigen test recommended. Infection not possible
I appreciate your concern for your would be sex partner.
As you said the dancer not necessarily HIV positive woman.
I hope that these girl would have their inner wears during dancing.
Even if it is not so, she would not have a dribbling discharge while dancing. If so, then she would not have opted to dance on that day.
Just a casual contact of knee near the external genitals of a lady is not infectious even in presence of an injury
on your knee.
You just forget that incident.
If you have lot of tension in mind regarding this, then it is ideal for you to go for a HIV test
. P24 Antigen test, DNA PCR test or any combo/duo
(both antigen and antibody) tests are recommended for you to know your HIV negative status earlier by 2- 4 weeks.