These are issues that the RRC, ACGME and ABOS all deal with and frankly there are no known metrics at this time - in other words, is there a "magic number" of tibial nails that we should have our residents do to become proficient? As you probably can guess, all of the governing organizations are hesitant to ever put absolute numbers for fear of the medico-legal ramifications.
That being said, however, when the RRC performs a site visit and reviews the resident's operative case log there are certain "red flags" for which the alarm may sound -- first, is insufficient surgical volume (less than 1200 CPT codes for a graduating resident) but interestingly the second red flag is excessive surgical volume (no real number attached to this) where there appears to be too much surgery and not enough "other" including clinic time, research time, etc...
The programs you cited, however, (Penn, HSS, Mass Gen) are all outstanding programs not just academically but in training their residents to be outstanding orthopaedic surgeons (both in the OR and in the office). From those programs, residents can then get outstanding fellowships to further enhance their surgical and clinical acumen in the subspecialty of their choice.
The majority of graduates now are pursuing fellowships usually not because they feel deficient in any areas but instead to become leaders in a field (either in their community or in academics). In summary, if you only look at surgical volume in isolation you probably should consider broadening your scope in the final analysis.
wnl