Davide Santon was in Rome having his medical ahead of a transfer to Napoli on Monday, but apparently issues arose that has the move in doubt. Instead of finalizing the transfer, Napoli and Inter Milan are instead in a holding pattern until they can come to a conclusion.
The nature of the problem that the medical brought up hasn't been reported yet, though it's worth noting that Santon has had multiple knee problems throughout his career, one of which required a surgery and then additional treatment after a setback. If that's what's causing this new issue, if it looks like Santon's knee will be a long-term problem, then it's definitely worth Napoli taking a step back to re-evaluate the transfer, starting with a reported additional medical to take place on Tuesday.
Right now, Napoli are believed to be talking with Inter about options should they decide to go ahead with the transfer. What those options entail depend on how Napoli feel about the results of Tuesday's additional tests. They could take the existing €6 million transfer that's been agreed and re-structure the fee to be much more bonus-heavy, giving Inter a smaller guarantee and recouping the rest of the fee through playing time related bonuses. Alternatively, Napoli could agree to take Santon on loan with a small fee up front, and a purchase clause for the remainder if they decide he's worth keeping.
Of course, Tuesday's re-evaluation could go sideways and lead Napoli to abandon the whole thing. That would be unfortunate as Santon seemed like a good depth option for Napoli, but it'd be better than signing on a player who's going to be an injury problem, especially as he'd be replacing a guy in Christian Maggio who had perennial injury woes.