An intramedullary rod, also known as an intramedullary nail (IM nail) or inter-locking nail or Küntscher nail (without proximal or distal fixation), is a metal rod forced into the medullary cavity of a

bone A bone is a rigid organ that constitutes part of the skeleton in most vertebrate animals. Bones protect the various other organs of the body, produce red and white blood cells, store minerals, provide structure and support for the body, an ...

. IM nails have long been used to treat fractures of long bones of the body.

Gerhard Küntscher Gerhard Küntscher (6 December 1900 – ) was a German surgeon who inaugurated the intramedullary nailing of long bone fractures. Biography Küntscher was born in Zwickau, Germany. Küntscher invented what is known as the Küntscher nail, an ...

is credited with the first use of this device in 1939, during

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the World War II by country, vast majority of the world's countries—including all of the great power ...

, for soldiers with fractures of the

femur The femur (; ), or thigh bone, is the proximal bone of the hindlimb in tetrapod vertebrates. The head of the femur articulates with the acetabulum in the pelvic bone forming the hip joint, while the distal part of the femur articulates wit ...

. Prior to that, treatment of such fractures was limited to traction or

plaster Plaster is a building material used for the protective or decorative coating of walls and ceilings and for moulding and casting decorative elements. In English, "plaster" usually means a material used for the interiors of buildings, while "r ...

, 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. The oldest intramedullary nail was found in the left knee of a

mummy A mummy is a dead human or an animal whose soft tissues and organs have been preserved by either intentional or accidental exposure to chemicals, extreme cold, very low humidity, or lack of air, so that the recovered body does not decay fu ...

named Usermontu, the remains of an Egyptian man from more than 3,500 years ago. Researchers believe the pin was inserted after the man's death, but before his burial.

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 tibia,

radius In classical geometry, a radius ( : radii) of a circle or sphere is any of the line segments from its center to its perimeter, and in more modern usage, it is also their length. The name comes from the latin ''radius'', meaning ray but also the ...

and

ulna The ulna (''pl''. ulnae or ulnas) is a long bone found in the forearm that stretches from the elbow to the smallest finger, and when in anatomical position, is found on the medial side of the forearm. That is, the ulna is on the same side of t ...

nails, Rusch nails etc. Although stainless steel was used for older IM nails,

titanium Titanium is a chemical element with the Symbol (chemistry), symbol Ti and atomic number 22. Found in nature only as an oxide, it can be reduced to produce a lustrous transition metal with a silver color, low density, and high strength, resista ...

has several advantages, including lower mechanical failure rates and improved biocompatibility. A more significant problem with earlier designs was their failure to prevent collapse or rotation in inherently unstable fractures. This was addressed by the introduction of the concept of 'locking' the nails, where bolts on each end of the nail fix it to the bony cortex, preventing rotation among the fragments. This led to the emergence of locked IM nailing, which is the standard today. The extension mechanism of intramedullary can be of two types: ratcheting, such as in the Bliskunov, Albizzia, and the Internal Skeletal Kinetic Distractor (ISKD, removed from market in 2015) nails; and rotating spindle, as in the Fitbone, Phenix, PRECICE, and PRECICE 2 nails.

Complications

At a median 14 years after tibial nailing of isolated tibial fractures, patients' function is comparable to population norms, but objective and subjective evaluation shows persistent

sequelae A sequela (, ; usually used in the plural, sequelae ) is a pathological condition resulting from a disease, injury, therapy, or other trauma. Derived from the Latin word, meaning “sequel”, it is used in the medical field to mean a complicati ...

which are not insignificant. One potential complication of intramedullary nailing after a fracture is ''bone malrotation'', where the broken bone is fixated out of alignment and heals incorrectly, causing a rotated limb. Lower screws holding intramedullary rods can sometimes cause limited dorsiflexion as a result of damage and subsequent healing and fibrotic developments around that area. If the bone breaks more medially, there is scope to position the nails further from the ankle joint which would prevent/reduce this dorsiflexion loss.

References

External links

* {{Authority control Orthopedic implants German inventions of the Nazi period 1939 in science 1939 in Germany

Design

Complications

See also

References

External links