Please don't make him afraid.Half the ortho problems are relieved by rest and immobilisation.I'd advise him to consult an orthopedic if the problem is not relieved by 1-2 days rest.Strains are more common than tears.barmyarmy said:You could either have damaged the miniscule cartelidge or if you're really unlucky one of the ligaments - most likely anterior or posterior cruciate ligaments.
You'll need an arthoscopy if you have