What is wrong with this sentence? Although they seemed inflamed, the site of the previous craniectomy seemed free of defect.

3 answers

To what does "they" refer? I don't see any plural word to which it could refer.
craniectomy sounds weird.

I'll have to go with this.
Although they seemed inflamed, the site of the previous craniectomy seemed free of defect.What type of agreement error in a sentence is this?