Hi, thanks for writing to HCM.
As per the description, the dent in the knee cap could be a bucking of the outer cortex
of the patella
. This is not a serious condition and will usually resolve spontaneously within 3-4 weeks. No specific treatment is needed.
Apply ice or a cold
pack to the knee cap area for 15 to 20 minutes, 4 times a day for few days. Wrap the ice or cold pack in a towel. Do not apply the ice directly to your skin.
Hope this information is helpful. Good day