As a catcher, he did his best to keep his head and neck attached when players charged home plate.

Can someone tell me the function of past participle ‘attached’?
I know the two functions of participle; either adjectival or adverbial.
Which function does it do here?
Does it modify verb or noun?

Also, is it object complement in structural-function wide?

As a catcher, he did his best to keep his head and neck attached when players charged home plate.

I would called this an adjective for two reasons:

First, the verb keep is often followed by adjectives (keep calm, keep silent, keep still). It’s like the verbs remain and seem in this sense.
Second, attached describes the condition of the head and neck.

And, yes, I would say that it’s an object complement.

Thank you very much.