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Bone and Spine

Orthopedic health, conditions and treatment

Intramedullary Nailing of Fractures

By Dr Arun Pal Singh

In this article
    • Biomechanics of Intramedullary Nailing
    • Advantages of Nailing over Plating
    • Indications for Intramedullary Nailing
    • Technique of Interlocked Intramedullary Nailing – General Points
      • Entry Point
      • Guidewire Insertion
      • Reaming
      • Fracture Reduction and Nail Insertion
      • Locking
      • Concept of Unreamed Nailing
    • Instrumentation for Interlocked Intramedullary Nailing
      • Guide wires
      • Reamers
      • Cross bolt guides
    • Universal Femoral Nail
    • Universal Tibial Nail
      • Shape
      • Holes
      • Bolts
    • Complications of Intramedullary Nailing

Intramedullary nailing of the bone involves the use of an intramedullary nail or rod to fix the fractured bone.

It is called intramedullary nailing because a metal rod forced into the medullary cavity of a bone to fix the fractures. Intramedullary nailing is commonly used to fix the long bone fractures. As of today, there are many types of nails available. Nails made for specific fracture patterns are also available now. For example Recon nail for fracture of the subtrochanteric region.

An intramedullary nail functions as a form of the internal splint which stabilizes long bone fracture with minimal damage to the surrounding soft tissues. Because they are sturdy and usually approximately round in shape, they withstand the heavy load of the body well in any direction, rather like the bone itself. Limbs with nailed fractures may be mobilized early after surgery with weight bearing before the bony union.

Küntscher nail has been used commonly but now is more of historical importance. It was a nail with triangular or cloverleaf cut-section without any locking mechanism. Gerhard Küntscher is credited with the first use of this device in 1939, during World War II.

Most of the modern nails come with a locking mechanism. Locking is a process of fixing the nail to the bone using premade holes in the nail both on the proximal and distal end of the nail for a stable fixation.

Nails which can be locked are called interlocking nails.

Nails are made of stainless steel and titanium

Locked intramedullary nailing is the standard today.

Modern nailing is a technique whereby the nail is inserted into the bone from one end whilst not disturbing the fracture site at all under an X-ray image intensifier.

Biomechanics of Intramedullary Nailing

The length of a nail that transmits the load from one main fragment of a fractured bone to the other is known as the working length. The stiffness of a nail in both rotation and bending is related inversely to its working length.

The longer the working length, the greater the relative movement between the main bone fragments.

Nails may be either solid or hollow. Solid nails are stronger than hollow ones of the same diameter simply because they have more metal for their volume.

Hollow nails are less stiff in bending than solid ones, although their stiffness may be altered by making the walls thicker or thinner. The thicker the wall the stronger and stiffer the nail.

The advantage of having a somewhat flexible nail is that it will have a little “give” in it on insertion which will make it easier to put in and will let the nail to deform slightly to conform to the natural shape of the bone. This slight flexibility does not affect the rigidity of the nail to support the broken bone.

Very stiff nails may damage the bone if there is any discrepancy between the nail of a shape and that of the bone.

Note: Nails are of a standard shape but people are not, even after reaming.

One way of reducing stiffness is to put a longitudinal slot in the wall of a nail. This makes it much more flexible but does so at the cost of it losing overall bending strength and torsional strength.

Nail design, like that of any engineering structure, is always a compromise between including as many desirable properties as possible whilst trying to keep undesirable properties to a minimum.

Nails are curved according to the bone involved and slotted along their length. The wall thickness of 1.2 mm and the slot give an optimal balance between strength and flexibility and permit good contact between nail and femur when the nail is not locked.

Advantages of Nailing over Plating

Intramedullary nail, biomechanically, offer several advantages over plate and screw fixation-

  • Intramedullary nails are subjected to smaller bending loads than plates and are thus less vulnerable to fatigue failure. This is because the intramedullary canal is closed to the central axis of the femur than the usual plate position on the external surface of the bone.
  • Intramedullary nails act as load- sharing devices in fractures that have cortical contact of the major fragments. If the nail is not locked at both the proximal and distal ends, it will act as gliding splint and allow continued compression as the fractures are loaded.
  • Stress shielding with resultant cortical osteopenia, commonly seen with plates and screws, is avoided with intramedullary devices.
  • Refracture after implant removal is rare with the use of intramedullary devices
  • The intramedullary implant does not usually require the extensile exposures required for plate application. With the use of image intensification, these devices can be implanted in a “closed” manner, without exposing the fracture site. These closed techniques result in low infection and high union rates, with a minimum of soft tissue scarring.

Indications for Intramedullary Nailing

Femur and tibia are bones where nails are most commonly and successfully used. The ideal indications for nailing are:

  • Transverse and short oblique fractures of the tibial and femoral shafts.
  • Comminuted fractures of tibia and femur, provided cross locking facilities are available.
  • Pathological fractures
  • Delayed or non-union of femur or tibia.
  • Selected open fractures

In children, as the nail may damage growth plates and should be avoided.

Technique of Interlocked Intramedullary Nailing – General Points

Illustration showing intramedullary nailing in femur
Illustration showing intramedullary nailing in femur
Image credit: rob.cs.tu-bs.de

 

Entry Point

Nails are inserted at the one end of the bone, generally, proximal end into the intramedullary cavity, travel across the fracture site to reach the other end.

This point where nail enters the bone is called the entry point. In femur, this is piriformis fossa or tip of the greater trochanter.

Initially, a small hole is made using a bone awl or drill and gradually enlarged with reamers to accommodate the nail diameter.

Guidewire Insertion

Guide wires are thin wires which are inserted in the intramedullary canal after initial entry point is made with awl or drill.

The guide wire is pushed into the medullary cavity through the entry hole made. Its position is ascertained by C-arm image intensifier.

Guide wires are passed through fracture fragments till the other end of the bone is reached.

Reaming

Using cannulated reamers, the intramedullary cavity is reamed to increase the size of the cavity.  Reamers could be manual or power reamers. The reaming is done over the guide wire which guides the reamer and protects it from getting astray in the bone.

Reamer is passed over the guide wire

Depending on the final reamer size allowed by bone, the diameter of the nail is chosen which generally is smaller by one size.

For example, if we can ream till size 11mm, the desired nail size would be 10mm in diameter.

It is pertinent that the fracture fragments should be aligned while reaming is done.

Fracture Reduction and Nail Insertion

Nail over guide wire

After length and diameter of the nail is determined, the nail is assembled with its inserting jig and inserted over the guide wire [in case of hollow nails, in solid nails guide wire needs to be removed before nail insertion.]

The nail could also aid in the reduction of the fracture.

Locking

Interlock nails have two holes at either end. A hole is drilled into the bone at the right angle to the nail. It passes through the hole in the nail and then drills the opposite cortex. When a bolt is passed through this, it engages cortices on either side while engaging the nail hole too, thus locking nail and bone together.

An interlock nail with bolts passed through the slots

The introduction of paired holes which align at right angles to the long axis of a nail permits cross locking to give axial and rotational stability.

Holes may be round, as they are usually at the distal end, to accommodate a screw or bolt. The holes are slightly bigger than the thread diameter of either bolt to allow smooth gliding through the nail.

Following image illustrates the concept of dynamization very well.

Mechanism of Dynamization when locking is done through dynamic slots. With loading, the screw allows play and bone fragments get approximated
Mechanism of Dynamization when locking is done through dynamic slots. With loading, the screw allows play and bone fragments get approximated, Image Credit: AO

Some proximal holes may instead be oval-shaped slots. This permits slight axial movement of the bone but still prevents rotation.

This allows increased bone contact during loading and encourage callus formation and rapid healing. The process is called dynamization.

Proximal locking is achieved by passing bolts through the aligned holes across the nail guided by a jig which attaches into the top of the nail.

Locking in the distal screw holes of the nail is achieved under X-ray image intensification.

Routine removal of screws later in fracture treatment to ensure dynamization is seldom necessary as the natural flexibility of the nail is sufficient to stimulate callus formation.

Concept of Unreamed Nailing

Some authors contend that reaming damages the interior blood supply of the bone. If a fracture is extensive and there is a lot of soft tissue damage, there is a risk that the outer blood supply will also be impaired. At best this will delay healing and at worst may lead to bone death.

By using a smaller solid nail, reaming may be avoided.

The concept of an undreamed nail as a way of stabilizing open fractures in cases where such severe damage to the blood supply is a distinct possibility is now being actively explored.

Instrumentation for Interlocked Intramedullary Nailing

Nail and bolts constitute the implants. Nails of all sizes should be kept on the table for a particular case. Preoperative length could be measured by measuring the contralateral bone length.

Each nail has its own instruments and these are generally not interchangeable. Major instruments are as below

Guide wires

Guide wires of interlocked nailing

A guide wire is used to provide an initial crossing of the fracture site after the medullary canal of the fractured bone has been opened. It provides alignments and is essential to facilitate the passage of the reamers.

There are two types of the guide wire, each with a different diameter.

One of the wires has a blunt bulbous tip so that reamers cannot pass beyond the end of this guide wire. It is called beaded guide wire. [Shown in the image above]

Beyond the bulbous stop, the guide wire is slightly bent to 15 degrees. By rotating it during the insertion process a degree of manipulative control may be achieved when trying to cross the fracture site.

The second wire has no bead at the tip and inserted after reaming before the actual insertion of the nail as otherwise, the nail may snag on the bulbous tip when the guide wire is extracted.

In the femur, the thin guide wire is 3mm in diameter and the thicker one 4mm. not that in the tibial set the bulbous tipped and plain ended guide wires are both 3mm in diameter.

Reamers

Reamers for interlocking

There are two sorts of reamers with different cutting ends.

The first reamer of 9mm diameter has a front cutting end to force an initial passage down the medullary canal of the bone.

The rest of the reamers are side cutting and are used to widen the pilot hole. They come in o.5mm increments and because they are side cutting will get jammed unless used sequentially without missing out any steps.

Flexible shafts are constructed of wound coils of wire and are designed to rotate only in one direction. Under no circumstances should they be reversed or the wire will uncoiled.

Cross bolt guides

Also proximal cross bolts can be placed without the image intensifier using an outrigger jig.

The distal holes positions can vary as the nails tend to twist slightly. The holes, therefore, will not always be in the expected plane.

C-arm image intensifier is required for distal holing [Some nail companies do provide jig which may often produce the desired results]

Universal Femoral Nail

It is called universal to indicate that the nail can be used unblocked and has a side to side symmetry so that it may be used in either the left or the right femur.

Proximally, there is one hole and another slot, providing an ability to lock in static [using round hole] or dynamic [using slots]

The nail has a “cloverleaf” cross-section which maintains good contact with the bone whilst preventing excessive nail distortion when twisted.

The nail comes in different outer diameter from 9mm to 13mm.

The wall of the nail is The wall is 1.2mm thick which balanced strength and flexibility

There is a continuous longitudinal slot that makes the nail flexible and deformable enough to make contact with the bone.

The upper end has a conical “female” threads in it to accommodate a conical “male” threaded bolt, used to attach the insertion and extraction devices

The nail has a curvature which corresponds to part of the circumference of a circle which has a radius of 1500 mm, which reflects the average shaped femur.

Universal Tibial Nail

Universal Tibial Nail

It is also called universal for the same reasons as described for the femoral nail.

It has a different overall shape and a range of dimensions that are slightly different from the femoral nail.

Shape

The tibial nail has a bend one-third of the length of the nail so that the nail can be inserted from a point on the anterior surface of the tibia behind and slightly to one side of the patellar tendon. It is called Herzog’s notch or bend.

The entry canal, on average, makes an angle of eleven degrees with the tibial medullary canal. This is the angle built into the shape of the nail.

Holes

The holes in the universal tibial nail differ from those in the femoral nail in that there are three holes at the bottom, two orientated in the coronal plane and one in the sagittal plane. Some nails also come with three proximal holes.

Bolts

For tibial nails size 8 mm, the bolts are smaller in size. These bolts are 3.9 mm as compared to 4.9 bolts used for bigger tibial and femoral nails.

Complications of Intramedullary Nailing

  • Compartment syndrome
  • Infection
  • Implant Failure
    • Fractures near metaphyses
    • Smaller diameter nail used
    • Early weight-bearing
  • Shortening
    • Often due to dynamic interlocking with excessive weight-bearing
    • Limb length inequality < 1.2 cm – no intervention
    • Higher values may need corrective measures
  • Malunion
    • Malrotation> 10 degrees
    • Varus/ valgus angulation > 7 degrees
    • Anteroposterior angulation > 10 degrees
  • Heterotopic Ossification
  • Soft tissues irritation over entry points  [usually longer sized nail]

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Filed Under: General Ortho

About Dr Arun Pal Singh

Arun Pal Singh is an orthopedic and trauma surgeon, founder and chief editor of this website. He works in Kanwar Bone and Spine Clinic, Dasuya, Hoshiarpur, Punjab.

This website is an effort to educate and support people and medical personnel on orthopedic issues and musculoskeletal health.

You can follow him on Facebook, Linkedin and Twitter

Reader Interactions

Comments

  1. Parveen says

    September 7, 2016 at 8:14 pm

    Thank you for such detailed information about this subject. Some of it is too over my head. My interest is due to my little one breaking two bones.

  2. Dr Arun Pal Singh says

    September 10, 2016 at 7:15 am

    Sorry to hear that. What is the injury? Treated or yet to be?

  3. Cathy Servante says

    September 28, 2017 at 12:57 am

    My friend broke her femur and had surgery including an intramudellary nail. She’s getting pain near her knee and has been told it’s due to the nail size-apparently there’s a choice of two and she had the larger so it’s rubbing on muscle-does this make sense?

  4. Dr Arun Pal Singh says

    September 28, 2017 at 12:30 pm

    Cathy,

    Please share some details.You need to elaborate on the issue. I am not able to deuce much.

    Thanks.

  5. Kathy Koops says

    June 27, 2019 at 12:36 am

    My husband had an air compressor tank explode and his right lower leg took the brunt of the blast. Both the femur and tibia were fractured and were sticking out the side of his leg. He developed compartment syndrome while in the ER. They took him to surgery and cut his leg open 6″ on one side and the full length of his calf muscle on the other side. They put a rod in the full length of his femur with a screw at the top by the knee and a screw at the bottom by his ankle. The accident happened 11/9/18. It took the sutured incision and where the bones stuck out of the leg almost 7-1/2 months to finally scab over so all wounds were closed. My husband was walking without support from a cane, but he limped quite bad and would have to rest his leg every 2-3 hours of being on his feet. About 6 weeks ago he started complaining that his shin hurt real bad where the bones had broken. At his doctor appointment he was told that he had not only bent the top screw, but it was broken. Two weeks later he underwent surgery to remove the top and bottom screw as they were concerned that the bones had not healed together. They decided to do the dynamization process to compress the bones. Since they took the screws out, my husband is in a tremendous amount of pain and can’t walk without crutches again. As of yesterday, 6/26/19, he has been getting a sharp shooting pain that starts at the bottom of his foot and goes all the way up to his butt. He said yesterday he almost fell because it came on so quickly and the pain was so extreme. He called his doctor and he is basically telling him to ‘suck it up’ and deal with it. Is this kind of pain normal during the dynamization process? If so, how long will this go on? It has been almost 8 months and my husband is getting very frustrated and is losing his patience because he is now so limited in what he can do again. Any inuformation you can provide on this subject would be greatly appreciated.

  6. Arun Pal Singh says

    July 3, 2019 at 1:10 pm

    Kathy,

    After a fracture, the most important thing we are interested in is if a fracture has united. Because you did not mention about fracture femur, I have to ask if it has united.

    The tibial fracture has not united and dynamization has been done for the same. Please read the following article for more on dynamization.

    Dynamization of nail/
    The dynamization is painful because fracture fragments collapse on to each other when the weight is borne. But the pain is restricted usually to the fracture region.

    If the femoral fracture is united, a pain from foot to hip asks for ruling out any spinal cause of pain [symptoms sounds more like sciatica]. But this is just conjecture because I deduce from whatever you tell me. Your treating physician is in a better place to guide you.

    I am not sure if dynamization at this stage is helpful though it does not mean that it cannot be done at this stage.

    I hope the bone unites because if it does not, you are probably staring at another surgery which would involve exchange nailing and bone grafting.

    But after dynamization, it is pertinent to wait for 6 weeks at least.

    All the best.

  7. yoni says

    October 16, 2019 at 2:05 pm

    I had broken my two tibia last August. There was a closed bilateral tibial fracture . Doctors made Intramuscular nailing on my legs . Now I am in 5th week of my fracture. I haven’t any pain . But there is mild arthritis like pain on my two knees. I can move my leg range of motion . But I cant walk. What are the specific cares for it ?How do I know If have complications ?How long does it take to heal my fracture . Thank you.

  8. Arun Pal Singh says

    October 18, 2019 at 3:37 pm

    Yoni,

    The entry point of the nail is at the upper end of leg. There could be discomfort on moving for some time. It would take around 8-12 weeks for fractures to unite if everything goes normal.

    Rest of the questions would be best answered by your treating doctor.

    I hope that helps.

  9. Badr says

    April 22, 2020 at 6:12 am

    My father is being told to undergo this procedure due to a tumor that is growing in the thigh causing him pain! However he does not have a visible fracture so the point they say is to stabilize the thigh from causing pain! Do share your expert opinion does this even make sense?

  10. Dr Arun Pal Singh says

    April 23, 2020 at 6:59 pm

    The procedure is contemplated when the bone gets weakened and could fracture. You can ask your doctor about the details and why of the procedure.

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