Hand Call Schemes
Emergency hand call is a perpetually thorny issue, because hand call can be fairly demanding, and because it is common for surgeons who would not consider themselves qualified to take emergency hand call to nonetheless perform elective hand surgery. Generally, the pool of those taking call is taken from both orthopaedic and plastic surgeons. There are many existing schemes, and many hospitals rotate between different solutions depending on the exact numbers of those available and willing to take call. Here are common setups I have seen:
Type No formal call schedule
Description Coverage determined on the fly by the emergency room doctor
Advantages No maintenance
Disadvantages Unpredictable. May not be able to provide coverage. Emergency room may be told by all potential surgeons that they are not available or that the problem is out of their level of expertise. Hand specialists in the area wind up being on 24/7/365 "backup" call.

 
Type Dealer's Choice
Description Hand cover is provided either by the person on call for orthopaedics or by the person on call for plastics, to be determined by the emergency room physician as to whether the problem is more "bone" or "soft tissue".
Advantages In theory, provides full cover. Spreads the burden of call the most widely. Typically used when no smaller group wishes to claim all call, and there is no organized refusal to take hand call.
Disadvantages 1. Unpredictable. May not be able to provide coverage. Emergency room may be told by both ortho and plastic surgeons that the problem, such as a mangled hand, is out of their specialty. 
2. May not provide consistent community standard of care, especially if certified hand surgery specialists take some of the call.
3. Inequities: Orthopods get all the closed fractures; Plastics get all the tendon injuries and all infections.

 
Type Alternate Night
Description Hand cover is provided either by the person on call for orthopaedics or by the person on call for plastics, to be determined by the date, day of the week or similar - for example, odd days: hand goes to Orthopaedics, even days: hand goes to Plastics.
Advantages In theory, provides full cover. Spreads the burden of call the most widely. Typically used when no smaller group wishes to claim all call, and there is no organized refusal to take hand call.
Disadvantages May not provide consistent community standard of care, especially if certified hand surgery specialists take some of the call.

 
Type Dedicated: Softball
Description Hand cover is provided by a group of surgeons who specialize in hand, take all comers, and determine the call schedule internally. "Hand" is defined as beginning at the distal forearm, radiocarpal joint, carpus, or carpometacarpal level, depending on the wishes of the group taking call. Call schedule is not tied to other triage, such as operating room privileges, elective referrals by the hospital, triage within an orthopaedic group, etc. 
Advantages In theory, provides the best qualified cover. Typically used when 3 or more hand specialists are on staff. Takes hand call burden away from relatively less qualified surgeons.
Disadvantages Places the full burden of call on a smaller group of surgeons. Because of frequent nighttime calls, burnout more likely. Elective hand cases are skimmed by those not taking call, leaving the more demanding problems for those who do. 

 
Type Dedicated: Hardball
Description Hand cover is provided by a group of surgeons who specialize in hand, take all comers, and determine the call schedule internally.  "Hand" is defined as beginning at the distal forearm. Those taking all the call also negotiate for exclusive rights to elective hospital hand referrals and to hand privileges in the hospital operating room. This includes all hand surgery, including that for carpal tunnel, trigger finger, deQuervain's, etc. 
Advantages In theory, provides the best qualified cover, maximizes referral stream. Typically used when 3 or more hand specialists are on staff. Takes hand call burden away from relatively less qualified surgeons.
Disadvantages Places the greatest burden of call on a smaller group of surgeons. Because of frequent nighttime calls, burnout more likely.