Open femoral fracture bone defect treated with the Precice Bone Transport Nail (Nuvasive)

This is a 3D reconstruction of the initial trauma CT scan showing a multi-fragmentary mid-diaphyseal femoral fracture. There appears to be no vascular injury and the medially displaced fracture fragments are either through the skin or lying subcutaneously.

This image shows the long leg alignment coronal view. It demonstrates that the femur has been treated with an intramedullary nail and cement spacer where the loose femoral bone fragments have been debrided.
The tibia has been treated with an intramedullary nail and there is also a vertical shear fracture of the ipsilateral medial malleolus that has been treated with an antiglide plate.
From this image the overall length of the limb is measured from the centre of the femoral head to the centre of the talus (superior aspect). Also the lengths of the femurs and tibia are measured independently. The femur is measured from the centre of the femoral head to the centre of the femoral condyles at the knee. The tibia is measured from the centre of the tibial plateau to the centre of the tibial plafond.
The Precice Bone Transport Nail was not used as primary treatment because it is a special order implant in our hospital. The patient also requires counselling on the treatment options and what are the risks / benefits of this implant and this type of surgery.

The contralateral leg holding device is carefully positioned on the operating table, so that the gas strut does not block the path or view of the C-arm.The patient is positioned on the traction table in the usual position to perform a femoral nail. This means that the leg to be operated is attached to the traction boot and a post is placed into the table and between the patient’s thighs. When traction is applied to the traction boot, the post provides counter pressure against the ischium. The contralateral leg is placed into a leg holding device and the hip is flexed and abducted to move it out of the way of the C-arm. The patient’s torso is supine on the operating table however, for nailing, I like to move the shoulders towards the opposite side of the table. This gives the patient a posture similar to a banana and importantly provides a straight line trajectory with the anatomical axis of the femur (sometimes adding a little ipsilateral hip adduction also helps but can distort a fracture reduction). The patient’s arm on the ipsilateral side is flexed at the shoulder and elbow and placed on to their chest. This also helps maintain access to the femoral axis and we use a soft foam sling to hold the arm in this position (being careful to not put any pressure around the elbow medial epicondyle and ulnar nerve, as this can cause a palsy).
If you look carefully at the image, the leg holding device is attached on the proximal rail. This means that the gas strut doesn’t overhang the end of the table (i.e. distal to the yellow number 12 sticker). Also the piece of the table with the yellow number 12 sticker will need to be removed (this will be explained later in the technique), so it wouldn’t be possible if the leg holding device was attached to it.

Prior to prepping/washing the patient, the C-arm is used to check that the appropriate images/views can be obtained.

Before starting any operation, the skin overlying the operative site is washed with a detergent soap.
This step removes any natural skin oils or grease which could prevent the antiseptic from adequately penetrating the skin pores.

The whole leg is prepped with alcoholic chlorhexidine antiseptic.I routinely do a double prep and use a darker pink stained solution initially followed by a lighter pink / clear solution. I use the contrast in colours to be able to see that I have prepped the same area twice. Also I like to wash off the darker pink solution, as it is sometimes mistaken for cellulitis when seen in the post-operative period.

The exclusion drape is applied to the leg.If you look carefully, you may observe that a second adhesive plastic drape (Ioban) has been applied to the leg first. This allows the larger exclusion drape to stick to it much better than it does to the leg itself. A common problem with adhesive exclusion drapes is that when the C-arm is regularly going from an AP view to a lateral view, the drape comes off and detaches from the leg. By using this additional layer, it will remain in place throughout the whole operation.

The C-arm is used to plan and mark out the location of the bone defect and help identify which pre-existing surgical scars correlate with the in situ intramedullary nail.

An image intensifier (II) view showing the location of the bone defect. We need to first remove this bone cement and it was previously inserted from a medial approach (where the original wound was). We are planning to use a direct lateral approach and avoid the previous scar tissue and potentially distorted anatomy that may contain the neurovascular bundle.

The first step is to remove the bone cement spacer and the skin is incised using a direct lateral approach.The direct lateral approach will go through: skin, fat, fascia lata, vastus lateralis. The incision is approximately 10cm in length and is in line with the femur. If you hold your left hand thumb and index finger in a C shape (see the photo), you can palpate the anterior and posterior borders of the femur. For the direct lateral approach, the incision is at the mid-point between the anterior and posterior borders of the femur.
Some surgeons prefer to use a sub-vastus approach however, I find this more awkward as the muscle falls under gravity into the surgical view and there are usually some perforating vessels that can retract behind the intermuscular septum attached to the linea aspera in the posterior compartment of the thigh and continue to bleed.

The pseudomembrane overlying the bone cement is incised and reflected.This pseudomembrane is used to prevent scar tissue from filling the bone defect void and to create a channel in which the transported bone segment can move.
If performing a Masquelet technique, this pseudomembrane is essential as it will contain the bone graft and act like the periosteum providing a blood supply to the graft.

Osteotomes are used to break up the bone cement spacer.The previously inserted bone cement has been carefully moulded around the outer cortex of the femur both proximally and distally. It is described as a ‘tulip’ shape as it is similar to the shape of the flower. This allows the newly formed membrane to be continuous with the existing periosteum.

Chunks of bone cement are removed using a Kocher forceps.I like the Kocher forceps as they have a large span and can grab large fragments. They are also toothed, so have a good grip on the pieces.

The bone ends are ‘squared off’ using an osteotome to create flat opposing surfaces for docking (at the end of the transport phase).The process where the two bone ends are brought together is called docking and is similar to a boat arriving at a harbour. When the proximal segment is transported down to meet the distal segment, the surfaces want to be complimentary so that the bone can unite over the greatest possible surface area. If the surfaces don’t match, then the bone may only unite in one area where it has achieved point contact and in effect ‘spot welds’. Unfortunately this spot weld may not be sufficiently strong to withstand the range of forces placed on the femur and may re-fracture in the future. Also the spot weld may allow sufficient movement to precipitate a hypertrophic nonunion (elephant foot appearance on x-ray) or the implant may eventually fail due to fatigue failure.
The bone ends should be inspected to ensure that the bone is alive and has a good blood supply. The bone end can be wiped with a clean dry swab (or gauze) and you are looking for punctate cortical bleeding. This is called the “Paprika sign” and indicates that the bone is well perfused. If the bone doesn’t bleed, then it needs to be resected in increments until bleeding bone is found.

Any remaining pieces of bone cement, bone or fibrous scar tissue are removed with bone rongeurs (nibblers).The idea here is to carefully remove the debris (bone cement, bone, fibrous tissue) but not to disrupt the pseudomembrane. Particularly when working on the medial side of the bone, great care is required, because you could inadvertently encounter the neurovascular bundle (femoral artery, femoral vein and saphenous nerve) which lies between the muscles; vastus medialis (antero-lateral in relation to the bundle), adductor longus (posteriorly) and sartorius (antero-medially).

The old incisions are used to access the locking bolts for the in situ intramedullary nail.In larger patients or where I’m struggling to get to the distal locking bolts, I often connect the previous stab incisions to create one single incision. This wound is usually large enough to create an adequate exposure and remove the locking bolts easily.

When removing any screw or locking bolt, it is essential that the screwdriver is correctly aligned with the locking bolt and is firmly seated. There are various tips and tricks and here are a few that I use:
If the screw head is full of scar tissue, it is possible to use the diathermy on coagulation to remove it.
It is also sometimes necessary to work circumferentially around the screw head in case it has been encased in scar tissue or bone. Sometimes using a periosteal elevator will help.
Place the screwdriver into the screw head, move the screwdriver up and down and side to side to build a mental image of where the centre point / axis of the screw is. When you move the screwdriver too much off axis, you will feel it tilt out of the screw head. Once you are in the central position, apply axial pressure (to keep it seated within the screw head) while rotating the screwdriver counter-clockwise.
An alternative is to use hammer blows to ensure the screwdriver is correctly seated in the screw head but be careful that you don’t embed the screw into the bone or below the bone surface.

A haemostat or clip placed under the head of the locking bolt will help it reverse out of the bone.

Next the bone defect is measured to ascertain that the current gap matches the pre-operative plan.This is to ensure it correlates with your pre-operative plan and matches the proposed amount of bone transport.

A unicortical plate is applied to one side of the bone defect.The plate is held freehand against the equator/midline of the bone. It is carefully positioned both proximally and distally so that at least 2 holes are over good quality bone. The drill guide is screwed into the locking side of the combi-hole on the plate. The holes for 3.5mm locking screws are drilled with the 2.8mm drill bit. They are only unicortical and we don’t want the screw tip to enter the medullary cavity, as this may interfere when we ream the canal.

The hole depth is first measured with a depth gauge and this will be different to your usual technique, as you won’t pass through the medullary cavity (because the nail is in the way) and then through the opposite cortex where you’d normally hook the toe of the depth gauge. The depth gauge is inserted into the drill hole and it may hit the nail. The outer sleeve of the depth gauge is pushed down into the plate hole and the depth is read (you may need to deduct a couple of millimetres so that the screw doesn’t enter the medullary cavity). The locking screws are inserted with the torque star head screwdriver.

A laminar spreader is inserted into the bone defect and the bone defect gap is increased to match the planned amount of correction.In this patient we had decided that the femur was slightly shorter than her contralateral femur and the patient reported that she felt more balanced with an additional 1cm Coleman block placed under the ipsilateral foot. Coleman blocks are pieces of wood that have different thicknesses. These are placed under the patients’ affected limb and the thickness is increased until the patient reports that they feel balanced and the examiner feels the pelvis is level.
The patient reported no rotational problem with the limb and this was confirmed on clinical examination.

The patient was positioned on the traction table, so in addition to the laminar spreader, the traction table was used to help increase the length of the femur.
The image intensifier image demonstrates a pair of forceps have been placed into one of the previous distal locking bolt holes and that the distal locking nail hole appears to have moved proximally in relation to the forceps. In actual fact the distal femur has moved more distally in relation to the nail and thus the length of the femur has increased.

The remaining holes on the unicortical plate (on the side not previously secured) are drilled using the 2.8mm drill.To select the appropriate sized plate, I measured the bone gap and added the extra 1cm of length correction that we were going to add. I then selected a plate length that would leave at least 2 plate holes lying over good quality bone both proximally and distally.

The remaining unicortical screws are inserted using the torque star head screwdriver.

The purpose of the unicortical plate is to maintain the femurs correct length, alignment and rotation, so that when the intramedullary nail is removed, it doesn’t change position. The plate does not need to be stronger than a small fragment locking compression plate (LCP) because it is only temporary and the forces being applied to it, are only the weight of the leg. Even in a larger patient with a heavier leg, a unicortical small fragment LCP should be sufficient for this purpose.

The end cap for the intramedullary nail is removed using a T40 cannulated star head screwdriver.The old scar is incised and often it is necessary to make this incision longer than the previous one used for the nail insertion. Once through the skin, the fat is split in line with the skin incision and you are working in an oblique direction toward the tip of the greater trochanter (i.e. at 45 degrees in the same horizontal plane angled distally). The hip abductor muscles are next encountered. The tensor fascia lata should be anterior and the hip abductors are gluteus medius and gluteus minimus and these insert into the proximal femur. First I palpate the greater trochanter and work out where the midline is. I then like to bluntly insert a pair of Mayo scissors through the muscle fibres of gluteus medius and gluteus minimus. The scissor blades are fully opened and pulled backwards towards the skin surface creating a tract. The reason for using blunt dissection is that the superior gluteal artery has a deep branch that lies on the undersurface of the gluteus medius muscle which I’m trying to prevent injuring.
The in situ intramedullary nail is a Synthes Lateral Femoral Nail (LFN). The T40 screwdriver is cannulated, so it is sometimes helpful to use a 3.2mm guidewire that is placed into the end cap and helps guide the screwdriver in.

Unfortunately the end cap doesn’t attach to the screwdriver so it is fairly common for it to fall off in the soft tissues and have to be retrieved with another instrument (e.g. Kocher forceps).

The extraction screw for the LFN is attached to the nail.It’s important to do this step prior to removing the last proximal locking bolt. If you don’t, when you try and tighten the extraction screw on to the nail, the nail may rotate within the femur. The extraction screw is tightened with the 11mm combination wrench. The hammer guide is then attached to the extraction screw.

The proximal nail locking bolts are now removed.Here we’ve used gentle hammer blows against the back of the screwdriver to ensure that the screwdriver is firmly seated and centred within the locking bolt head.

Once all of the locking bolts have been removed from the nail, it is removed from the femur.If you are unfamiliar with the LFN, when it is originally inserted the nail jig is in the 12 o’clock position and as the nail advances down the femur, it gradually rotates due to the shape of the nail and anterior bow of the femur. Here you can see that the proximal locking bolt holes are angled upwards and the nail is rotating as it is withdrawn.
If the nail is difficult to remove, the hammer guide extension can be screwed on to the extraction screw and the combined hammer can be used to apply gentle blows.
If the nail is still difficult to remove, then you must stop and ensure that all locking bolts have been removed e.g. using the image intensifier. Alternatively I have seen cases where a broken locking bolt becomes lodged in the nail hole and acts like a barb on a hook and prevents the nail from being removed. To address this problem, the broken piece of locking bolt should be pushed through the nail hole and either retrieved from the opposing side of the femur or by creating a cortical window in the bone to retrieve it.

The guide wire for the Reamer Irrigator Aspirator (RIA) 2 is inserted into the femur. The guide wire should be central within the distal femur on both an AP and lateral image intensifier view. We have chosen to use the RIA 2 due to the fact that the previous injury was an open injury and we want to debride the medullary cavity of any fibrous scar tissue and lower the risk of there being any possibility of developing an infection (although clinically this patient had no symptoms, signs or investigations that were concerning).

Prior to reaming, the femur is measured to determine the correct nail length and diameter.When determining the correct nail size, it is always good to check the previous operation record. In this case, the LFN was 9mm x 380mm. Therefore the previous surgical team will have reamed the femur to 11.5mm i.e. 1.5mm greater than the nail diameter.
According to the Precice Bone Transport Nail surgical technique there are 3 diameters of nail available for the femur but due to the transport segment in the nail, this creates a weaker area and therefore only certain amounts of load / weightbearing can be permitted:
10.0mm nail – 25lbs / 11kg
11.5mm nail – 190lbs / 91kg
13.0mm nail – 250lbs / 114kg
Ideally we would have liked to use the 11.5mm diameter nail and this would have allowed our patient to full weightbear. However, this would require reaming to 13.5mm as the surgical technique recommends reaming to 2.0mm greater than the nail diameter.
The final aspect to note is that due to the transport mechanism the nail has to be straight. This means that after nail insertion, the femur which would normally have an anterior bow, has to have a slight apex posterior deformity of a few degrees so that the nail will fit. Clinically this deformity is negligible and is in the plane of the joints so will be well tolerated.

The RIA 2 is assembled.The sterile packaging is helpfully annotated with a diagram that clearly shows how to assemble the device. It can be used as a standalone reamer with only the irrigation attached or it can be connected to suction to aspirate as well. Finally the graft filter for bone harvesting or specimen collection can be attached to the aspiration port and suction.
See step 4 in the picture, the Aspiration port is marked with a letter “A” and the irrigation tube connects to the port marked with a letter “I”.

The RIA 2 is now assembled and ready to have the cutting reamer head attached. Note the irrigation set is on the left of the image and has a blue tube clamp and the aspiration set is on the right of the image and has a red tube clamp.

The appropriately sized RIA 2 reamer head is selected and attached to the reaming shaft.The size selected in this case was 12.0mm, so that it was 2.0mm greater than the selected Precice Bone Transport Nail (10.0mm) and 0.5mm greater diameter than the previously reamed channel for the Lateral Femoral Nail (LFN).
On the image, the holes marked “A” are where the irrigation fluid emerges and the holes / flutes marked “B” are where the bone marrow, morselised bone and debridement are aspirated.
An important development of the RIA 2 compared to its’ predecessor version (RIA) are that the reaming heads are changeable and can be increased in 0.5mm increments from 10.0mm to 18.0mm.

The RIA 2 is inserted into the proximal femur.The reaming does not commence until the sharp reamer head is safely within the bone. Also the irrigation fluid is kept off until the RIA 2 is in the bone otherwise, the fluid goes everywhere. Just before the reaming commences, the blue tube clamp is released to commence the irrigation and the suction is switched on (if not already).

When approaching the bone defect with the RIA 2 it is important to stop reaming. If you observe the image, the guide wire is slightly eccentric within the medullary cavity and it is possible to eccentrically ream at this level due to the reamer head being so sharp.
For the proximal fragment one method is to hold the guide wire centrally with a Kocher forceps. I also recommend passing the reamer across the defect and checking that the wire / head are central in the distal fragment before recommencing the reaming.

The RIA 2 is passed into the distal femur so that the whole bone has been reamed to the appropriate diameter.An image intensifier view will confirm that the reamer has reached the knee. Also the guide wire has a ball nose to restrict how far the reamer can safely advance.
During the reaming process you should observe blood and bone debris coming into the suction and graft filter.

Within the graft filter there is a fine mesh lining that retains the bone graft and debris while allowing the excess blood and irrigation fluid to pass through. In this case we aren’t planning to use this material but it demonstrates the fibrous tissue membrane that has lined the medullary cavity around the previous LFN.

The next step is to carefully plan the location of the osteotomy.On the preoperative radiographs and in collaboration with the implant supplier, you will plan where to place the osteotomy. If you look at the diagram, the location for the osteotomy is marked with an “A”. If using a shorter nail, the area in which to accommodate the osteotomy is narrower than if you are using a longer nail.
Also if the defect is greater than 70mm, then it will be necessary to use the proximal transport segment and then perform a secondary procedure to move the transport segment locking bolt from the proximal section to the distal section. Therefore doing 30mm of transport and then moving the bolt to the distal section to continue transporting up to a further 70mm.
In this case we are using a 380mm nail and the defect is less than 70mm, the osteotomy must be located between the distal locking bolt of the proximal group (marked 42mm) and the end of the proximal transport segment (marked 75mm + 30mm). Therefore the window for the osteotomy is only 63mm but needs to be sufficiently far away from either locking bolt in case the osteotomy line propagates.
Image reproduced with permission from the manufacturer’s surgical technique.

A metal ruler is measured and a clip applied at the level of where the osteotomy is planned.

Using the C-arm the ruler is placed over the proximal femur and the osteotomy level is identified.In this case we are using a 380mm nail and the defect is less than 70mm, therefore the osteotomy must be located between the distal locking bolt of the proximal group (42mm from the greater trochanter) and the end of the proximal transport segment (105mm from the greater trochanter). Therefore the window for the osteotomy is only 63mm but needs to be sufficiently far away from either locking bolt in case the osteotomy line propagates. We therefore planned the osteotomy to be mid-way between the distal locking bolt of the proximal group and the end of the proximal transport segment (i.e. 42mm + 30mm = approximately 72mm from the greater trochanter). The skin is marked at this level.

A small incision is made that is large enough to gain access to the bone and insert a drill guide and drill bit.The drill guide is essential as it prevents any soft tissues from wrapping around the drill bit and also helps maintain the drill bit’s exact position on the bone.

The osteotomy level is very carefully drilled.There is a specific technique for successfully performing an osteotomy:
Ideally a brand new sharp drill bit should be used
The correct level must be identified
The drill bit must be perpendicular to the bone
The bone is drilled either on high speed with pauses to allow cooling (i.e. pulsed) or on low speed (so that you don’t generate too much heat and burn the bone)
The same entry hole in the near cortex is used to drill the second / third / fourth holes in a fan shape perpendicular to the long axis of the bone. The near cortex hole will be slightly larger due to the multiple passes of the drill bit.
Once satisfied that the far cortex has been drilled multiple times and is perforated like the serrations on a stamp, you then use an osteotome.
Thankfully the neurovascular bundle is not a deep structure at this level and is more superficial than the bone. It lies in an antero-medial position in relation to the bone.

Select an osteotome that is not too narrow and not too wide (usually the same width as the bone) and is sharp.
Align the osteotome using the C-arm and ensure it is truly perpendicular and follows exactly the same path as the drill holes.
Rotate the osteotome blade so that it is perfectly aligned with the C-arm x-ray beam (appears narrower) and perpendicular to the bone.
Using gentle hammer blows advance the osteotome but always checking it is following the correct path and not rotating.
To remove the osteotome from the bone, wiggle it in the same plane as the osteotomy (i.e. up and down). Don’t lever in the horizontal plane otherwise the bone will shatter.

Once satisfied that the osteotome passes easily (front, back and centre) and just enters the medial tissues, use a spanner on the osteotome handle to gently rotate it.Rotating the osteotome will cause the osteotomy to open up.

Check radiographically that the osteotomy is mobile and opens up.Technically this step is called a corticotomy because you are only supposed to cut the bone cortex and leave the cancellous medullary bone intact. However, I’ve never been able to understand how you access the far cortex without the osteotome passing though the medullary cavity.
The osteotome is actually the same width as the femur, so that when you rotate it with the spanner, one side edge applies pressure to the anterior cortex and the other edge of the osteotome applies pressure to the posterior cortex of the femur. Thus causing the osteotomy to open and the distance between both cortices (proximally and distally) to increase.

Next connect the Precice Bone Transport Nail to the Guide Arm Assembly.The nail is attached using the Implant Locking Rod and tightened with the ball hex driver.

To test the nail alignment with the insertion handle, the drill bit is inserted through a drill guide, through a guide tube.The drill bit is passed through the drill guide and should be centred and concentric with the corresponding locking bolt hole in the nail (i.e. not touching the nail at all).

The transport segment is checked to ensure that the locking bolt holes are both in the correct position and not obscured by the transport slot bridge.In our case we will be doing no more than 70mm of transport, so the locking bolt holes should be at the bottom of the short transport segment (marked C) and at the top of the long transport segment (marked D). We will be putting a transport segment locking bolt through the hole marked “E”. The holes marked A and B are the oblique proximal locking bolt holes for the nail.

The Precice Bone Transport Nail is inserted into the femur.I prefer to use a “no touch technique” with the nail and will put on fresh gloves and avoid touching the implant. I also avoid touching the nail against the patient’s skin as the most common type of orthopaedic infection is a Staphylococcus which is prevalent on the skin.

The proximal locking bolt holes are drilled using the guide arm assembly and drill guides.The nail height is first checked to ensure that it isn’t prominent and sticking out of the femur and that the transport section is in a good position in relation to the osteotomised bone. Once satisfied the first proximal locking bolt can be drilled with the 5.0mm step drill bit.

The drill bit is calibrated so when you are just about to drill through the second cortex, stop and measure the depth from the side of the calibrated drill bit.The C-arm image shows the drill bit has just passed through the second cortex and that the drill sleeve is appropriately down on the near cortex. If you don’t check that the drill sleeve is in the correct position, you will get an incorrect measurement and the screw will be too long.

The proximal locking bolt is inserted using the ratcheting straight screwdriver.The locking bolt is first placed on to the cannulated screwdriver and then the screw capture rod is passed into the screwdriver and the locking bolt head. The screw capture rod is tightened by hand and when the locking bolt is secure, the ratcheting straight screwdriver handle is attached to the cannulated screwdriver.
The locking bolt is inserted through the guide tube and down to the bone. It is manually inserted and depending on the bone hardness, its’ position should be periodically checked with the image intensifier to ensure it isn’t embedding below the near cortex surface. Once satisfied that it is down, the ratcheting straight screwdriver handle is removed and the screw capture rod is released. Final tightening can be performed with the solid 3.5mm hex head screwdriver.

Locking bolts tend to break and fail in their mid-portion where they make contact with the nail. This manufacturer has tried to prevent locking bolt failure by only having threads in the region of the near and far cortices. The rest of the locking bolt is smooth and this therefore means that the core diameter of this section of the screw is equivalent to the thread diameter and is therefore stronger in the mid-portion.

The distal locking bolts are inserted using a free hand technique.The first step is to ask the radiographer to make the holes “round” i.e. a perfect circle. The hole should be first centred on the image and then the C-arm base wheels should be locked. The C-arm should be advanced so that it is almost touching the non-sterile aspect of the leg. This will both magnify the hole and also create sufficient room for you to work in.
If the hole is narrow / elliptical side-to-side, then the C-arm horizontal plane rotation is adjusted. If the hole is narrow / elliptical top-to-bottom, then the C-arm is rotated in the vertical plane. There is also a magnification option on some C-arms which can be helpful.
Once satisfied with the hole shape, a scalpel is used in combination with the C-arm to position the skin incision. The fascia is perforated with a clip or my preference is to use McIndoe scissors (because they are narrower and have a longer body).
The 5mm step drill bit is placed on the bone surface and carefully repositioned with the aid of the C-arm until it is concentrically overlying the nail hole. Once it is in the correct position, the power tool should be brought into alignment with the x-ray beam, so that the drill bit is directly over the nail hole and has the correct trajectory.

The power tool is uncoupled from the drill bit and its’ relationship to the distal locking nail hole is checked with the image intensifier.In this nail, the tolerance (i.e. gap) between the nail hole diameter and the locking bolt is much less, so accuracy is essential because the locking bolt cannot pass through the nail hole on a slight angle, it has to be perpendicular to the nail.
In standard nails, if you hit the nail and don’t immediately fall into the nail hole, then don’t panic! If the drill bit is overlying the nail hole by more than 50% then this can be salvaged. If you hold the drill bit with a Kocher forceps and angle the tip towards the hole under image intensifier guidance, then with gentle hammer blows the drill bit can be advanced into the hole. Once in the nail hole, the power tool is reconnected and the far cortex is drilled.

Once both cortices of the distal locking have been drilled, the C-arm is used to confirm that the drill bit correctly goes through the nail hole and hasn’t missed.If there is any doubt then a Kocher forceps or the finger/thumb aperture of any instrument (e.g. scissor handle) can be used to angle the drill bit so that it is aligned with the x-ray beam. The drill bit should disappear or overlap with the nail and it shouldn’t be seen either anterior or posterior to the nail.

The distal locking bolts are measured using the depth gauge.A common mistake is for the depth gauge outer sleeve to get caught on the ilio-tibial band fascia and therefore give an incorrect locking bolt length.

The distal locking bolts are inserted with the 3.5mm hex ratcheting screwdriver.To recap: the locking bolt is first placed on to the cannulated screwdriver and then the screw capture rod is passed into the screwdriver and the locking bolt head. The screw capture rod is tightened by hand and when the locking bolt is secure, the ratcheting straight screwdriver handle is attached to the cannulated screwdriver.

The final locking bolt to insert is the one for the transport segment.Although we had checked that we could obtain a C-arm view at this level at the start of the operation, we found that we didn’t have enough room between the C-arm and the patient’s leg, so were unable to get the drill into the correct position.
We realised that due to the proximal position of the transport segment, we would have to remove another piece of the operating table (see photo – piece marked with a yellow 12). Once this piece was removed, the C-arm was able to advance and create sufficient room on the sterile side of the leg.
We also tried abducting the leg (before removing the additional piece of the table). This didn’t help as the transport segment hole is so proximal within the femur that the table was still getting in the way.

The C-arm is carefully adjusted to give the perfect circle view.

The 3.5mm step drill bit is used for the 3.5mm locking bolt in the transport segment.The process of positioning the drill bit over the locking bolt hole is repeated so that it is concentric with the nail hole.

The transport segment locking bolt is measured with the depth gauge.

The 3.5mm transport segment locking bolt is inserted.The locking bolts come in 5mm increments, so it may be necessary to leave the head slightly off the near cortex so that the threaded portion has adequate purchase in both the near and far cortices.

The unicortical plate is removed as the bone transport nail will now maintain the length, alignment and rotation.The screws are removed with the 3.5mm star head screwdriver.

A non-absorbable suture is inserted in the distal thigh and this overlies the magnet within the bone transport nail.To locate the magnet, it is 43mm from the distal tip of the nail. The C-arm is used with a metal ruler that is held with a Kocher at 43mm. The end of the ruler is held over the tip of the nail and the skin marked accordingly.

Prior to wound closure the nail mechanism is checked by placing the External Remote Controller (ERC) in a sterile bag and over the nail magnet.The ERC will take approximately 5 minutes to open a 1-2mm gap at the osteotomy site.
An important point to note is that the ERC will not be able to control the magnet if the distance from the skin surface to the magnet is greater than 51mm so this must be considered prior recommending this treatment option.

The transport mechanism is tested by saving a C-arm image prior to switching on the ERC and then a second image is taken at the end of the transport programme. Both images are then compared to see if the osteotomy gap has increased.This is an essential step and also confirms that the ERC has been programmed to transport in the correct direction.
If you look back through the slides, you’ll note that the last II image had a smaller osteotomy gap.

Another method to test if the transport mechanism is working, is to repeat the lateral image of the transport segment and the proximal screw hole should now appear as an ellipse as it has moved distally and behind the transport segment bridge.

All of the wounds are thoroughly irrigated to remove any haematoma or bone swarf that could precipitate an infection.

The wounds are closed in layers and dressings applied.

Bone transport should commence 5-7 days after the surgery.
The image shows the nonabsorbable suture that has been used to demonstrate where to place the ERC in relation to the nail magnet.

The ERC is very heavy and should be held with 2 hands at all times. The machine is connected to a base unit which is set with the transport prescription and then locked so that it cannot be inadvertently altered.

On top of the ERC is a small window which should be positioned directly over the nonabsorbable stitch. When in the correct position, the machine is started and it will make a whirring noise.On the base unit, the display will show the amount of travel. When the correct amount of travel has been reached, the machine is switched off.
A typical transport programme would be 1mm per day and usually done in 0.25mm increments (i.e. 4x times / day).

The graphic shows the migration of the transport segment from proximal to distal. The femur maintains its’ length but the transport segment moves causing distraction osteogenesis proximally and then it docks distally, closing the bone defect gap. The transport segment is moved by applying the ERC over the magnetic mechanism in the distal portion of the nail (43mm from the nail tip).
Image reproduced with permission from the manufacturer’s surgical technique.

The patient should be seen every 2 weeks with radiographs at each appointment to ensure that the transport is following the agreed plan.
This x-ray shows that the proximal osteotomy gap is being distracted and the distal bone defect gap is getting smaller as the transport segment of bone is moving distally.

The radiographs need to be reviewed to ensure:
The transport segment is moving
The transport locking bolt is moving away from the nail transport slot bridge
The regenerate is forming nicely at the osteotomy site and isn’t consolidating too quickly
The bone defect gap is decreasing and isn’t prematurely uniting
The implant isn’t deforming or failing

The patient should have regular physiotherapy to ensure that the joints do not become stiff or lose any of their range of motion.
As the transport segment approaches the distal segment, it must be observed for signs of union as sometimes an additional ‘docking’ surgery is required to help stimulate the bone to unite.