These are very common injuries, especially during physical games and sports.
A sprain is when ligaments have been stretched, twisted or torn and often happens in the knees, ankles, wrists and thumbs. Symptoms can include tenderness/pain, being unable to use the joint normally or put weight on it, swelling and bruising.
Strains are when muscles stretch or tear and are common in the legs and back. Symptoms can include pain, swelling, bruising, spasms and temporary loss of function in the affected muscle.
Generally, a sprained joint should be moved as soon as it is not too painful, whereas a strained muscle should ideally be kept still for a few days.
Most sprains and strains can be cared for at home using PRICE therapy (protection, rest, ice, compression and elevation). Painkillers, such as paracetamol, can help and the affected body part will usually be back to normal within a few weeks.
You should take your child for medical advice if the pain is very severe, they cannot put any weight on the injured area, it gives way when they try to use it, the injury looks crooked/has unusual lumps or bumps (other than swelling) or there is numbness or coldness in any part of the area.