Hmmm...well since both joint reconstruction and Pediatric Ortho require Ortho residency and likely some Trauma call (even as an attending), I suspect that the time off issue is not as lenient as you might suspect. Even as a orthopod in private practice, you have to share call with your partners and often orthopedic injuries happen after hours. Patients who have joint reconstruction can still call you after hours with questions, although the surgeries aren't usually emergent.
For surgical specialties, the traditional best lifestyle choices are Derm, Ophtho, Uro, ENT and Plastics. All will still require some call and various amounts of Trauma/in house call if you are affiliated with an academic medical center.
Hope this helps.