In theory, there shouldn't be major problems. Recognising times for your specialist training depends somewhat on the Landesärztekammer you register with on your return. In general, jobs of less then 6 months will not be recognised. Jobs in Accident and Emergency (A&E) can be difficult as there is no comparable speciality in Germany. Non-Training posts can cause problems, too. GP-Training is still a problem because the training structure and contents are so different in both countries.

It might well be necessary that you have to work for some months on a lower level when returning to Germany to get to know the system (coding, dealing with insurances, etc.)