Intramedullary nails are ideal for diaphyseal long bone fractures and mostly closed fractures are managed by reamed nails. Reaming is supposed to ensure thicker nails to be introduced that is better and stronger. Reaming also is supposed to provide interosseous bone grafts as reaming byproduct assisting Union of Fracture. However in open fractures reaming is withheld as it increases chances of prolonged surgery and chances if fat embolism syndrome. Intramedullary nail in emergency setting is thus a norm.

Reaming was also thought to interfere with intramedullary blood supply but no proven data is present till now.

I agree entirely with the considerations of Dr. Ganesh s Dharmshaktu. Reamed IN provide a stable osteosynthesis with some concerns - interference with endosteal blood supply and increased fat embolism rate, eventually also infection rate in open fractures.

Both devises are used for the fixation of long bones

Reamed

Mainly for closed fractures

Benefits: As the canal is conformed to accommodate a greater contact of the nail and the bone is achieved and this is adding to the fracture's stabilisation. On top of this the nail is wider and so the fixation more rigid. Working length as long as the direct contact of the nail to the bone. Reamings also are acting as bone graft in the area of the fracture. Earlier weight bearing.

Problems: There is the notion that reaming is destroying the intramedullary blood supply. There are papers that describing for or against this theory. Also high incidence of fat or pulmonary embolism is described but is linked mainly to time of fixation.

Un-reamed:

Mainly for open fractures.

Benefits: Fixation of the long bone without destroy further neither soft tissues (as the insertion of the nail requires smaller approach) or the intramedullary blood supply (as the damage and exposure of the bone and loss of soft tissues have disturbed the blood supply received from the periosteum).

Problems: Long working length as the fixation depends on the locking screws, unstable fixation. There is no presence of any "bone graft" as there are no reamings and still there is the risk of fat embolism linked with the time of operation and the "speed" of nail insertion into the canal.

There is a school of thoughts some surgeons follow; after soft tissue healing the un-reamed nail to be exchanged with a reamed so to achieve a better stability. There are surgeons against this practice though.

Mechanically,

reamed nail= thicker nail= more stability= early weight bearing..

Other concerns,

biological

I agree with all the above mentioned answers

Simply put dreaming allows the use of wider diameter IM nails in contrast to narrow nails used in the absence of reaming.

Consequently the fixation construct following use of wider diameter IM nails provides greater resistance against bending, torsional and compressing forces which theoretically reduces the risk of mechanical implant failure.