Intramedullary rod
Encyclopedia
An intramedullary rod, also known as an intramedullary nail (IM nail) or inter-locking nail or Küntscher nail, is a metal rod forced into the medullary cavity
of a bone
. IM nails have long been used to treat fractures
of long bones of the body. Gerhard Küntscher
is credited with the first use of this device in 1939, during World War II
, for soldiers with fractures of the femur
. Prior to that, treatment of such fractures was limited to traction
or plaster
, both of which required long periods of inactivity. IM nails resulted in earlier return to activity for the soldiers, sometimes even within a span of a few weeks, since they share the load with the bone, rather than entirely supporting the bone.
, radius
and ulna
nails, Rusch nails etc.
Steel
continues to be the material of choice for these nails, owing to its strength, but more recently titanium
has gained popularity due to its advantages over steel. However the biggest problem with the earlier designs was the failure to prevent collapse or rotation in inherently unstable fractures. This was addressed by the introduction of the concept of 'locking' of the nails using bolts on each end of the nail, leading to emergence of locked IM nailing, which is the standard today.
Medullary cavity
The medullary cavity is the central cavity of bone shafts where red bone marrow and/or yellow bone marrow is stored; hence, the medullary cavity is also known as the marrow cavity...
of a bone
Bone
Bones are rigid organs that constitute part of the endoskeleton of vertebrates. They support, and protect the various organs of the body, produce red and white blood cells and store minerals. Bone tissue is a type of dense connective tissue...
. IM nails have long been used to treat fractures
Bone fracture
A bone fracture is a medical condition in which there is a break in the continuity of the bone...
of long bones of the body. Gerhard Küntscher
Gerhard Küntscher
Gerhard Küntscher was a German surgeon who inaugurated the intramedullary nailing of long bone fractures, a process that was first performed in November 1939 at the University Department of Surgery in Kiel...
is credited with the first use of this device in 1939, during World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
, for soldiers with fractures of the femur
Femur
The femur , or thigh bone, is the most proximal bone of the leg in tetrapod vertebrates capable of walking or jumping, such as most land mammals, birds, many reptiles such as lizards, and amphibians such as frogs. In vertebrates with four legs such as dogs and horses, the femur is found only in...
. Prior to that, treatment of such fractures was limited to traction
Traction (orthopedics)
In orthopedic medicine, traction refers to the set of mechanisms for straightening broken bones or relieving pressure on the spine and skeletal system.There are two types of traction: skin traction and skeletal traction....
or plaster
Plaster
Plaster is a building material used for coating walls and ceilings. Plaster starts as a dry powder similar to mortar or cement and like those materials it is mixed with water to form a paste which liberates heat and then hardens. Unlike mortar and cement, plaster remains quite soft after setting,...
, both of which required long periods of inactivity. IM nails resulted in earlier return to activity for the soldiers, sometimes even within a span of a few weeks, since they share the load with the bone, rather than entirely supporting the bone.
Design
The earliest IM nails were triangular or 'V' shaped in cross-section. Later they were modified to their present and more rotationally stable clover-leaf shape. Several modifications and shapes were introduced subsequently for various bones such as V-nails for tibiaTibia
The tibia , shinbone, or shankbone is the larger and stronger of the two bones in the leg below the knee in vertebrates , and connects the knee with the ankle bones....
, radius
Radius (bone)
The radius is one of the two large bones of the forearm, the other being the ulna. It extends from the lateral side of the elbow to the thumb side of the wrist and runs parallel to the ulna, which exceeds it in length and size. It is a long bone, prism-shaped and slightly curved longitudinally...
and ulna
Ulna
The ulna is one of the two long bones in the forearm, the other being the radius. It is prismatic in form and runs parallel to the radius, which is shorter and smaller. In anatomical position The ulna is one of the two long bones in the forearm, the other being the radius. It is prismatic in form...
nails, Rusch nails etc.
Steel
Steel
Steel is an alloy that consists mostly of iron and has a carbon content between 0.2% and 2.1% by weight, depending on the grade. Carbon is the most common alloying material for iron, but various other alloying elements are used, such as manganese, chromium, vanadium, and tungsten...
continues to be the material of choice for these nails, owing to its strength, but more recently titanium
Titanium
Titanium is a chemical element with the symbol Ti and atomic number 22. It has a low density and is a strong, lustrous, corrosion-resistant transition metal with a silver color....
has gained popularity due to its advantages over steel. However the biggest problem with the earlier designs was the failure to prevent collapse or rotation in inherently unstable fractures. This was addressed by the introduction of the concept of 'locking' of the nails using bolts on each end of the nail, leading to emergence of locked IM nailing, which is the standard today.