Hi, thanks for writing to HCM.
There is no way that your son has caused more damage to his MCL by just a movement of the knee joint.
Propably he could have stretched his MCL or anyother soft tissue
around the knee to produce pain. I personally feel that there is no need to panic.
Please follow the below mentioned measures -
* Rest to the injured part and don’t involve in activities which puts additional strain on the injured tissues.
* Ice packing should be applied for about 20 minutes once in every 2 hours.
* Use elastic compression bandage around the swollen area
& anti inflammatory medications as needed
If there is no symptom relief with the above, then an orthopedic surgeons consultation may be needed.
Hope this information is helpful. Good day