Sarah,
There is nothing that states you can’t do both residency and fellowship, in fact, many of us do both. It is based on the number of approved positions and each speciality has determined what adequate support is and for Orthopaedics, it is as follows:
II.C. Program Coordinator
II.C.1. There must be a program coordinator. (Core)
II.C.2. The program coordinator must be provided with dedicated time and support adequate for administration of the program based upon its size and configuration. (Core)
II.C.2.a) At a minimum, the program coordinator must be provided with the dedicated time and support specified below for administration of the program. (Core)
II.C.2.b) Programs with an approved complement of 10 or fewer residents seeking to assign to the coordinator limited additional duties unrelated to program administrative needs must first obtain approval from the Review Committee. (Core)
Additionally, the above is based on support for ACGME accrediated programs, so additional support could be needed if you also manage non-accreditated programs, medical students etc.
Hope this helps some.
Have a wonderful day!
Cindy