Hello. Thanks for asking from HCM.
I can understand your concern. Linear
skull fracture heals on its own. Usually depressed fracture needs surgical management. In your friend's case, you should find out the cause. If
head injury has occurred long time ago and it has still not healed, look for any pus collection/wound over it/some discharge containing bone pieces coming through it. If any of above signs present, then
consult doctor. He might need surgical cleaning of wound along with antibiotic course.
If injury is less than 6 months old and he is having no complaint other than headache, then no need to worry. The fracture will heal in some time. The tissue around fracture can be scar tissue suggesting healing.
I hope now you can correlate.
For skull
bone fracture healing, nothing much is required. Just eat healthy diet and avoid further injury at same site. Plaster is not needed, as skull bones are immobile.
Thanks. Hope it will help you. Take care.