Pertrochanteric hip fracture(A3) stabilised with proximal femoral nail (Synthes short TFNA)

Pre-operative AP pelvis xray showing an extra capsular pertrochanteric fracture. The fracture extends to involve the lateral wall (1.). As an extracapsular fracture with an intact blood supply to the femoral head fixation rather than joint replacement is indicated however the lateral buttress required for controlled collapse of a sliding hip screw is deficient and an intramedullary device is preferred for this fracture pattern (AO-OTA A3 fracture).

The patient is positioned on the traction table.The injured leg is placed on traction with the foot in the boot attachment and additionally secured with crepe bandage and adhesive dressing (1.). The uninjured leg is positioned with the hip flexed and abducted in the table attachment shown, this keeps the leg out of the way of the image intensifier during the procedure.

Image intensifier is used to check the fracture reduction prior to prepping the limb.The fracture is reduced with longitudinal traction to restore limb length and internal rotation to a neutral alignment (patella facing vertically). The reduction is checked on image intensifier, if the reduction is not satisfactory adjustments can be made to the traction however one must be prepared to perform an open reduction if satisfactory alignment cannot be achieved closed. Varus malreduction is a common cause of fixation failure and must be avoided.
Open reduction, when required can be achieved by extending the incision around the fracture site. Often the proximal fragment is flexed by psoas and the distal segment sags posteriorly. Reduction can be achieved with Hey-Groves clamps around the fracture (although this may impede implant positioning) or with careful placement (under image guidance) of an elevator over the anterior femoral neck to control flexion. In fractures with more distal extension into the subtrocahanteric region open reduction can be achieved by placing a cable around the fracture fragments.

The limb is prepped and draped from the iliac crest to the knee.I do not use the ‘pole’ to hold the surgical drapes. After skin preparation I apply an Ioban drape over the surgical field and then place the standard DHS drape over this (the Ioban helps the DHS stick and prevents it coming away from the limb intra-operatively), the DHS drape is then placed over the top of the injured limb.

The uninjured side is covered with a sterile Mayo cover and the image intensifier draped. This method reduces the risk of the drapes being pulled off the leg by an unsterile image intensifier arm as it is positioned during the operation.

The instrumentation for the Synthes TFNA is shown.
This tray includes the optional awl for identifying the entry point (1.) and the initial reamer for opening the proximal tibia (2.).

This tray has the instruments for introducing the nail including the slap hammer and attachment (1.), nail introducer (2.) and the extension jig for the proximal screw or blade and distal locking screw for short nails (3.).

the final tray contains the instruments for the locking bolts; trocars and drill bits (3.); depth gauge (2.); screwdrivers (1.).

It is helpful for nailing cases to use image intensifier to mark up the greater trochanter and incision position- this will ensure accrurate placement of the incision making finding the entry point for the nail far easier and avoiding problems later in the procedure.

The incision is made 3cm proximal to the greater trochanter in the longitudinal axis of the femur.The incision only needs to be large enough to insert the nail and jig.

After sharp dissection through the fascia large scissors are used to divide the abductor muscle in the line of the fibres and the entry point of the nail is identified by palpating the greater trochanter with the tip of the scissors, this position is confirmed with image intensifier.

The initial 3.2mm guidewire is now placed on the entry point.In fragility fractures the wire can normally be placed by hand using the universal chuck. the entry point on the AP view is at or just lateral to the tip of the greater trochanter as shown. In this instance reduction has been achieved indirectly with longitudinal traction and internal rotation on the traction table. As noted above if satisfactory closed reduction cannot be achieved (restore length, correct varus, good contact fracture fragments) then an open reduction should be performed.

On the lateral view the guidewire should be central within the femoral canal. In this case the entry point and wire position are a little posterior which can result in issues achieving a good position of the blade in the femoral head later in the procedure, in this instance the position was considered acceptable- as can be seen later a satisfactory position of the blade in the femoral head was achieved although the blade sits posteriorly in the femoral neck due to the slightly posterior entry point.

The wire is now in position and can be seen to be aligned with the axis of the femur marked on the thigh (1.).

A soft tissue protector is placed over the guidewire to prevent damage to the soft tissues around the hip with reaming.

The proximal femur is opened with the initial reamer (12.5mm) passed over the 3.2mm guidewire via the soft tissue protector.This should be done under imaging and care taken not to propagate the fracture into the greater trochanter or penetrate the femur medially. The TFNA is specifically designed for use in fragility fractures (proximal design, radius of curvature, distal taper and blade for proximal hold), further reaming is very rarely indicated in these patients with osteoporotic bone- the intramedullary canal is invariably capacious enough for the nail to be inserted without difficulty.

The short TFNA comes in 3 lengths (170, 200, 230mm) and 4 diameters (9-12mm). In our unit we only stock 200mm- shorter nails may lack stability and longer ones risk creating a stress riser between the tip of the nail and the anterior femoral cortex. In most cases 10 or 11mm diameter nails are sufficient. The shorter lengths of nail are straight as here, longer nails (235mm and above) have a radius of curvature of 1m to avoid the distal tip of the nail contacting the anterior femoral cortex and creating a stress riser which could result in peri-implant fracture. For similar reasons the tip of the nail is tapered and there is only a single distal locking bolt. Proximally the nail has a 15.6mm diameter for good proximal hold. Various blade angles are available (125-135 degrees) to match proximal femoral anatomy and neck shaft angle- as noted previously care needs to made to avoid varus malreduction which risks implant failure.
In preparation for nail insertion, the nail (1.) is connected to the insertion arm (2) and the connecting bolt (3.) placed in the proximal end.

The selected nail is now connected to the introducer.The connecting bolt is now tightened with the 8mm hexagonal screw driver (1.).

Prior to implanting the nail it is checked to ensure that the introducing arm is correctly attached and that the aiming jig for the proximal blade will pass through the nail.
The aiming arm (1.) is connected to the nail introducer and then the trocar for the blade (2.) is inserted. The trocar should click into place was it is seated in the aiming arm.

A 3.2mm wire or a drill bit is then passed down the trocar, correct positing of the aiming arm is conformed if the wire passes through the nail as shown (1.).

The 3.2mm guidewire is now removed and the nail inserted.The nail is gently introduced into the proximal femur, it is often possible to position the nail by hand.

If necessary gentle hammer blows may be used on the driving cap attachment (1.) to fully seat the nail- excessive force should be avoided, if the nail is not advancing as anticipated check that it is not caught on the fracture or abutting a cortex.
Very occasionally it is not possible to insert the nail due to a tight canal, in these cases the nail should be removed and the proximal femur carefully reamed to 1.5mm greater than the nail diameter.

Once the nail is positioned the helical blade is inserted.The nail position is checked on image intensifier. on the AP view it needs to be positioned such that the blade will be positioned within the centre of the head, this position is determined by the depth of the nail. Nail depth can be assessed by checking the position of the slot for the blade trocar on the introducing handle relative to the femoral neck- the slot should be aligned to allow the blade to be positioned in the centre or slightly inferiorally in the femoral neck. If the slot is not aligned with the centre of the femoral neck then the nail can be advanced or withdrawn until it sits properly.
Lateral alignment can be judged from the initial lateral xrays- the position of the traction post relative to the femoral neck gives an indication of the femoral neck anteversion and the nail can be positioned to correlate with this – in this instance the nail is rotated to give around 10 degrees of anteversion. Rotation is altered by moving the introducing handle up or down, moving it down will increase the anteversion and moving it upwards increase the retroversion, in most instances 10-20 degrees of anteversion is required.
The trocar for the blade is inserted in the jig (1.) and a skin incision made in line with this (2.). A further incision is made in the fascia and then the muscle divided with scissors- this dissection should follow the oblique path of advancement of the trocar rather than being perpendicular to the limb.
The trocar is now clicked into the jig (3.) and loosely tightened with the turning sleeve (4.) until the tip of the trocar is touching the femur on the AP xray.

A 3.2mm guidewire is now advanced via the trocar (1.).On the AP and lateral views we are aiming to the wire in the centre of the femoral neck. If the position is not correct then the wire is removed, the nail repositioned and the wire re-advanced. The ideal position in centre-centre on AP and lateral views, slightly inferior (AP) and posterior (lateral) is however acceptable as this will still position the blade in good bone. High or anterior positions of the wire/blade are not acceptable as this has a high risk of blade cut out and fixation failure.

On this image the trocar can be seen abutting the lateral femoral cortex (1.), the guidewire is positioned slightly inferiorally in the neck (inferior is safe compared to superior).

On the lateral view the wire entry point is slightly posterior, secondary to a slightly too posterior original nail entry point, however the blade will be in the centre of the femoral head ensuring good stability.

These images from another case shows a well positioned guidewire that is centre/centre on lateral and AP imaging- this is the ideal position although posterior (lateral view) and inferior (AP view) are acceptable.

The wire is advanced to within a few mm of the subchondral bone and then the depth measured (1.).The depth is measured directly from the scale, 5-10mm is subtracted from the measured depth, we are aiming for a tip-apex distance of approximately 20-25mm. The blade has a single diameter but is available lengths from 70-130mm.
The tip apex distance (TAD) is the distance from the tip of the blade to the apex of curvature of the femoral head, the value is the sum of the distances on the AP and lateral views. Baumgarten showed that a TAD of less than 25mm reduced the risk of cut out of sliding hip screws and similar principles are applied to implants using helical blades.

A reamer (1.) is now advanced over the wire to open the lateral cortex.The reamer has a ‘stop’ on it so it will only advance just beyond the lateral cortex. Further reaming is not required in osteoporotic bone- the blade is designed to compact the bone as it is introduced enhancing hold in the proximal femur.

The blade (1.) is connected to the introducer (2.).

The blade is now mounted on the insertion handle, the handle contains a connecting bolt which is tightened by turning the screw at the opposite end of the handle.

The blade is inserted over the guidewire and seated with hammer blows.

As the blade advances it rotates around the wire.

The blade is advanced until the yellow line on the introducer and the yellow line on the trocar are aligned (1.). The blade is designed to compact the osteoporotic cancellous bone in the femoral head as it advances and thereby increase it’s hold in poor quality bone- these implants should not be used in young, healthy bone.

This image from another case shows a well seated helical blade. The tip apex distance is satisfactory (1.) and the blade sits within or just proud of the lateral cortex (2.) to achieve good hold here.
The tip apex distance is the sum of distances from the tip of the blade to the apex of the femoral head on both the AP and lateral views. This should be less than 25mm to ensure the blade achieves good hold in the femoral head- Baumgarten showed that this reduced the risk of femoral head cut out with sliding hip screws.

The nail contains a locking mechanism to lock the blade in place. To tighten the locking bolt inside the nail against the blade a flexible screwdriver (1.) is inserted into the end of the nail – this will fit through the nail insertion jig. The screwdriver is turned until the bolt is fully tightened. In this position the blade is statically locked. In some fracture patterns it may be desirable to allow some controlled collapse of the fracture against an intact lateral wall (eg A2 fractures) and in this situation the blade can be dynamically locked by turning the screwdriver back anti-clockwise for 1/2 turn after the bolt is fully tightened.

For short nails distal locking can be performed via the nail introducer extension.
The trocar for the 5mm locking bolt is pressed against the skin to mark the incision site (1.).

A skin incision is then made over this mark for the distal locking bolt (2.), the incision should be just large enough to allow the trocar to be passed.

The incision is continued through fascia and muscle.The drill trocar (1.) is then introduced, via the jig, and pushed down onto the lateral femur ensuring it contacts bone.

A 4.2mm drill bit is then used to drill make a hole in the distal femur through the slot in the nail.The screw depth can be measured directly from the markings on the drill bit (as long as the trocar is properly seated on the bone and the drill bit is just beyond the far cortex- I check this on xray).

A 5mm screw is inserted via the trocar and tightened in place- this screw is functioning as a bolt and does not need to be excessively tightened, doing so may create a stress riser at the distal end of the nail.

The end cap (1.) is now inserted.This can be inserted over a 3.2mm wire (2.). End caps come in 0, 5, 10 and 15mm lengths (length that protrudes proximal to the nail). Ideally the nail/end cap should sit just above the greater trochanter to provide some hold here and increase the stability of the construct. The 0mm end cap can, if desired, be inserted via the nail introducer.
In general I do not use end caps for intramedullary nailing however for these nails the end cap serves two purposes. Firstly it prevents bone ingrowth into the internal screw mechanism for locking the blade in position which would otherwise prevent nail extraction were it needed. Secondly the end cap can be used to lengthen the nail proximally to ensure good fixation in the greater trochanter – part of the ‘3 point fixation’ when nailing proximal femoral fragility fractures.

Here we have removed the nail introducer. The 3.2mm wire is placed in the proximal end of the nail (confirmed on xray) and the end cap can then be tightened in place without fear of it disappearing into the soft tissues around the proximal femur.

Final xrays are taken.On the AP view the position of the blade is seen to be sitting slightly inferior however there is a satisfactory tip-apex distance (20-25mm for blade implants). There is a concept of 3 point fixation when nailing proximal femoral fractures which confers optimal stability- good fixation in the head as confirmed by tip-apex distance (1.), hold on the lateral cortex with the blade slightly prominent (2.) and hold in the greater trochanter by the proximal end of the nail/end cap (3.).
The fracture is still on traction and is slightly distracted, however we have locked the blade in ‘dynamic’ mode which allows it to slide within the nail and as the patient walks the fracture will compress.

On the lateral view of the hip, although the entry point is slightly posterior and the blade sits posteriorly in the neck it is seen to be central within the femoral head.

Distally the locking bolt position is comfirmed as passing through the nail and the tip of the nail is checked to ensure it does not contact the anterior cortex- this would increase the risk of a peri-implant fracture.

Wounds are now closed in layers.The fascia is closed with heavy vicryl. Skin is closed with an absorbable subdermal suture.

Simple dressings are applied.A pressure dressing is useful over the proximal incision where there may be some ooze from the proximal femur.