If the pain is mostly underneath the cap it says that the joint line pain would be there. Pain at the joint line is the result of a collateral ligament or meniscus problem (or both) until proven otherwise. Anterior knee pain can also be due to Patello-femoral syndrome.
When did his pain begin, what was he doing at the time, and what were the initial symptoms?
Does he experience any grinding, locking, catching, or giving way of the knee?
Are there any positions that make his knee more or less comfortable?
Has he tried anything to help his pain and, if yes, has that been successful?
Has he ever had surgery on his knee? Does he have any hip or ankle pain?
His other symptom of stabbing and aching pain suggests that he might be having nerve compression either at the lower back or at the level of knee.
Keep us posted with your answers.
The pain started 2005, he was splitting up fighting kids and lifted one up and felt a twist.
Experiences locking when knee is tensed
if its 'Cracked' it feels more comfortable, onces pain starts it stiffens and aches for around 24 hours
ibuprofen gel and tablets don't work. Doc suggested anti-inflammation tablets but they didn't work.
No Surgery, no other pains in hip or ankle.
As I said in my earlier post the symptoms seems to be like your friend is having meniscus injury. The other symptom of locking is characteristic of meniscus injuries and osteochondritis dissecans (meniscus injuries are much more common than osteochondritis dissecans).
Has he consulted any doctor so far? If so, which one?
Has any imaging study been done like x-ray or MR study of knee?
I think he is having meniscus injury and you need to get x-rays done.
Keep me posted if you have any queries regarding the management and whom to approach.