Yes, there is treatment in physiotherapy without surgery if you start in time, depends on distruction of joint. If the pain is six months old apply heating over knee joint for 10-15 min, if it's below 6six months apply ice packs, they r available in pharmacy. He will get releif.
Next Steps
consult physio ASAP.
Health Tips
avoid cross leg sitting. use western toilet. avoid star climbing for some period.