Functioning of Rods and Nails

//Functioning of Rods and Nails

Functioning of Rods and Nails

Different types of orthopedic Implants have been designed for placement in the intramedullary canal of bones, ranging from Kirschner’s nails to the femoral nails. One can usually classify these devices by whether intramedullary reaming is essential prior to placement of the device or not. With the first nails placed down the femoral shaft, the medullary space first had to be reamed out so that the large nail wouldn’t shatter the bone as it is hammered down the shaft. However, reaming is an invasive process, and can compromise the already tenuous blood supply of the medullary space. Reaming can also lead to thermal osteonecrosis, especially if the medullary canal is small, a tourniquet is used while reaming, or there is marked soft tissue injury. If intraosseous pressure becomes elevated at the time of reaming, fat emboli to the lungs are possible. For these reasons, a different variety of un-reamed Implants have been developed. The Rush rod has a chisel-like tip, and is commonly used for fibular shaft fractures, and sometimes in other tubular bones as well.

Another type of un-reamed nail is Ender’s nail. These nails also have a chisel-like end. These nails are generally used three or four at a time and pushed through a cortical hole up or down the shaft of the bone and across the fracture under fluoroscopic control.

The odds-on favorite nowadays for fracture fixation of the tibial or femoral shaft is a reamed or un-reamed nail. These nails allow early weight-bearing and can be placed with closed technique, which avoids damage to soft tissue and to the muscular and periosteal blood supply. If the fracture is transverse and otherwise uncomplicated (not comminuted, rotated or too near the end of the bone), the nail may be placed on its own. However, interlocking screws are very commonly added both distally and proximally to provide stability in cases of comminution, and to prevent rotation of the fracture fragments and shortening of the bone. When these bone screws are used, the nail is commonly known as an “interlocking nail”.  These are available from different Orthopedic Implant manufacturers in India.

Subtrochanteric fractures are a particularly difficult type of fracture to treat, they act very differently from an intertrochanteric fracture. In the latter fracture type, a dynamic hip screw (DHS) can be used to just provide angular support. Longitudinal support by the DHS isn’t as important in this fracture type since the ends of the bone tend to impact against each other in a stable way. Subtrochanteric fractures, on the other hand, put a lot of stress on a DHS, especially along with the side plate. Due to this reason, special nails such as the gamma nail and the Proximal Femoral Nail (PFN) have been developed. These orthopedic devices are much stronger devices than the DHS and offer a much shorter moment arm for rotational forces to act upon than the DHS.  On the minus side, these nails are also more invasive.

By |2019-07-09T08:12:26+00:00April 27th, 2019|Categories: Orthopedic|Tags: , |0 Comments