Tibio-talo-calcaneal (TTC-Double ) fusion with Wright Valor nail

It is useful to mark out the tibial crest, tibial tuberosity, the ankle joint line, the medial and lateral malleoli all of which act as bony landmarks for the safe placement of the approach incision.

The limb is positioned as shown. Also shown on this image is the transfibular approach which is most often used particularly with severe deformity. The procedure can be done using arthroscopic techniques to prepare the surfaces :however in severe deformity this becomes quite difficult and time consuming to perform.

The transfibular approach is most often used particularly with severe deformity. It is also useful to note that the sural nerve travels posterior to this incision and the superficial peroneal nerve is anterior to it. The incision lies therefore in an inter-nervous plane and facilitates easy access to both ankle and subtalar joint. Additional smaller incision will be required on the medial aspect over the medial gutter both to prepare the joint and to resect part or all of the medial malleolus to medialise the axis of the talus and the os calcis. It is important to note that this step may be essential in almost all patients undergoing tibio-talo calcaneal fusion as the talocalcaneal axis lies lateral to the tibial axis and in order to position the nail accurately both within the talocalcaneal joint as also the ankle joint, such medialisation is almost inevitable.

A curvilinear incision is made on the lateral aspect of the hindfoot, the incision starts about 3 ½ inches above the tip of the lateral malleolus extending down to the tip between its anterior and posterior bolus and then curves forward along the superior aspect of the posterior subtalar joint extending towards the sinus tarsi. The incision can be extended to the base of the 4th metatarsal as necessary. The incision is deepened to the fibula and inferiorly extending in to the sinus tarsi lying superior to the peroneal tendons. Care is taken to dissect any aberrant nerve that might cross the path of this approach although this is rare. Care is to be taken to avoid laminating the layers and it is indeed safe to use an incision going through all layers to bone so as to avoid devitalising the tenuous subcutaneous layer. The incision is carried through distally to end at the sinus tarsi and also to incise the lateral capsule of the subtalar joint and eventually extending anteriorly enough to encounter the extensor digitorum brevis muscle which lies at the anterior end of this incision. At this level one can also expose the calcaneal cuboid joint if a pantalar fusion is being contemplated

The anterior and posterior flaps can now be raised subperiosteally from the fibula extending posteriorly to identify the posterior border of the lateral malleolus and anteriorly to first identify the syndesmosis and subsequently to extend subperiosteally on the anterior tibial surface and the ankle joint. If the plan is to use the fibula as a strut to buttress the lateral side of the fusion construct then care must be taken to ensure that there is a soft tissue hinge posteriorly which should include the calcaneal fibula ligament in the posterior tibio-fibular ligament so that vascularity can be maintained in this section of the fibula when used as a strut augmentation (RAF) for the fusion construct. If however it is planned to excise the fibula and use it as morselised bone graft, all the structures attached to the distal fibula can be dissected free.

The fibula is then dissected 3 ½ inches proximal to the lateral malleolar tip. A sagittal saw is used taking care to avoid damage to surrounding soft tissues structures. The fibula is then cut at the site of osteotomy at an angle of 45o to the horizontal aiming distally and medially bevelling it in such a fashion that there are no sharp spikes of fibula that present themselves to the skin. This gives an excellent view of the ankle and the subtalar joint. It is often useful to excise a centimetre of fibula at the osteotomy site so that it can be pulled downwards when used as an augmentation graft laterally.

It may be necessary to use an osteotome at the syndesmosis as often the syndesmosis is distorted with calcification and densely adherent to the incisura fibularis of the tibia . It is therefore useful to use an osteotome to prise apart the distal fibula from the tibia at this stage.

In this case a lateral fibular strut graft augmentation was preferred and therefore the distal fibula is hinged downwards on a soft tissue pedicle with a self-retaining retractor so as to allow unfettered access to the ankle and the subtalar joint.

The ankle joint surface can now be prepared on its lateral and central portions. It is often useful to distract the joint using a self-retaining retractor such as a Laminar spreader.

A curved osteotome or a Smillie knife is then used along with curette to take out remaining fragments of cartilage starting from posteriorly extending anteriorly forward on both the tibial and talar surfaces

After ensuring that all of the cartilage from the lateral central regions of the joint surfaces as far medially as possible have been extracted, a drill is then used to create multiple drill holes on both the talus and the tibia to open up the subchondral bone to allow bleeding to occur into the fusion site.

Care must also be taken to excise the anterior lip osteophytes from the distal tibial plafond as well as osteophytes on the talar neck as these will impede dorsiflexion and accurate plantigrade positioning of the ankle for fusion, and may lead to hinging of the ankle anteriorly and opening up of the joint space resulting in non-union

An osteotome can then be used to petal the tibial and talar articular surfaces in a criss cross fashion, cutting through the hard cortical bone to expose subchondral bone. If the bone is very hard then a burr could be used along with appropriate irrigation (to avoid thermal necrosis) to cut through into subchondral bone.

A Hintermann distractor is then used with pins in to the talus and the os calcis to distract the subtalar joint to expose the posterior and middle facets. I do not routinely expose the anterior facet unless it is planned to do a calcaneal cuboid fusion.

Osteotomes and drills are used to break into subchondral bone similar to as was done in the ankle joint.

The Hintermann distractor can also be used to distract the ankle joint providing 2mm wires are used to effect this distraction.

A medial incision has been used over the medial gutter first identifying the joint either with imaging identification or a needle. A 1 ½ inch incision is then made centred on the ankle joint at the anterior border of the medial malleolus.

Incision is deepened taking care to protect the saphenous vein and nerve.

The capsule is then divided and all osteophytes from the medial gutter and the adjoining anterior tibial plafond are excised. The cartilage now lining the articular surfaces of the medial third of the joint as well as the medial gutter are accessible for excision.

Any loose bits of cartilage are washed out.

Using similar methods the joint surface preparation of the ankle is completed.

An osteotome is used to excise medial portion including the articular surface of the medial malleolus . A similar preparation is made of the the medial surface of the talus that articulates with the medial malleolus. Both these areas are drilled and petalled as before.

Now the ankle is positioned so that the foot is plantigrade in 5o deg of plantarflexion and neutral in valgus/varus. One can factor in a valgus plantarflexion position of 5 deg however it is ideal to position the ankle at 90 deg both in the coronal and the sagittal plane. The position of the talus within the ankle mortise is less important than the position of the oscalcis in line with the tibial axis. This step is extremely important as it determines the eventual success of the fusion being positioned appropriately so that the patient can walk comfortably on it. This should be checked both on AP and lateral projections to confirm that the ankle is well positioned, the articular surfaces are well opposed and there is no residual deformity to correct as the nail is incapable of correcting the deformity. It merely holds the construct in the corrected position.

It is also useful at this stage to check the position of the talus in the mortise and to confirm that the talus is well medialised along with the oscalcis following excision of the medial malleolar portion. If necessary the whole of the medial malleolus can be excised to facilitate this medialisation. However it is desirable that some of the medial malleolus be maintained for added medial stability and to increase the surface area of fusion.

The whole construct in the corrected position is temporarily stabilised with 2 K-wires or Steinmann pins. These require to be so positioned that they do not obstruct the entry of the reamers and therefore it is ideal to place these as laterally and as medially as possible to avoid the reamer catching them on route. The ankle is then screened using image intensification to check the position of both the anteroposterior and lateral planes

It is now useful to engage in some surface marking to allow for insertion of the guide wire. Multiple attempts at insertion of the guide wire are to be avoided as there is the tendency for the guide wire to follow one of the previously drilled holes. After confirming the position of the construct once again with image intensifyer, the heel position which now should lie directly in the axis of the tibial sagittal plane is marked with a marker pen with a line longitudinally down the sole of the foot to bisect the heel in to two. This will serve as one of the landmarks to position the incision for the insertion site for the guide wire and subsequent insertion of the nail.

Similarly when viewing a lateral view on image intensification a guide wire is used on the lateral aspect of the tibia extending down on to the os calcis and using the marker and a further line is drawn to mark a longitudinal axis of the tibia in the coronal plane.

The lateral line is then extended in a linear fashion to bisect the line that divides the oscalcis in two on the sole of the foot. The interjection of these two lines is a focal point for replacement of the incision for nail insertion.The incision for this purpose should be about 2-3cm long and should be anterior to the calcaneal fat pad and 1cm lateral to this point of interjection to avoid injury to neurovascular structures. The skin is first divided and when using a cutting spread technique the oscalcis is reached. The soft tissues on the surface of the oscalcis are carefully elevated both medially and laterally. This allows the use of a McDonalds to tiptoe both medially and laterally to decide on the central position in the oscalcis to insert the guide wire. This can also be checked using image intensification using the image intensifier in the calcaneal axial mode.

Then using lateral anteroposterior and axial imaging the final position of guide wire entry is determined.The entry guide wire is then inserted to proceed down the centre of the oscalcis, the talus and the tibial medullary canal. The guide wire is advanced so that it is 2-3 cm longer than the desired length of the nail which is determined by the distance from the ankle fusion site of the isthmus of the tibia. Nail length is calculated to ensure that the proximal end of the nail ends distal to the narrow part of the isthmus of the tibia. The position of entry guide wire is checked in anteroposterior, lateral and calcaneal axial projections to ensure the entry guide wire is perfectly positioned as this determines the eventual position of the nail.

An entry reamer is then introduced through a tissue protector provided on the set. The entry reamer creates the nail’s distal diameter through the hindfoot. This is to ensure that the distal end of the nail which is wider than the proximal end can be seated snugly in the reamed hole provided by the entry reamer. As the 12mm diameter of the reamer is the same as that of the diameter of the distal end of the nail it is able to ensure a press fit in this region. It is important that at this stage the assistant can hold the position of the fusion construct in exactly the desired position.

The entry guide wire is then removed and replaced with a beaded guide wire which is introduced in the path created by the entry reamer and driven up the shaft of the tibia, this is checked with image intensifier to be in exactly the centre of the medullary canal of the tibia in both the anteroposterior and lateral projections. Them a 9mm flexible reamer head is attached with a self-retaining feature on to the flexible reamer shaft and this assembly is slid over the beaded guide wire. Reaming should proceed gently and it is advisable to use a large chest swab soaked in cold saline and wrapped around the distal tibia to ensure there is no thermal necrosis of tissue. This is particularly the case in very sclerotic bone particularly in young osteoarthritic patients or in post-traumatic situations. The depth to which the flexible reamers are used are determined by the length of the nail. The reamer shaft has laser markings which mark different lengths that the reamer has to be introduced into in order to correspond to available lengths of the nail which are 150, 200, 250 and 300mm. the range of flexible reamer heads are available in 0.5mm increment from 9mm to 12.5mm. It is recommended that the 9mm reamer head be used first and progressively increased by 0.5mm aliquots until the flexible reamer head diameter is 1mm larger than the desired nail diameter. If therefore 11.5mm nail was to be used the construct would have to be reamed to 12.5mm with the flexible reamer system. Image intensification is used to confirm the position when the beaded guide wires first introduced until the continued correct positioning of the guide wire prior to reaming. Following the use of the initial reamer the position is once again checked to ensure that the temporary wires holding the construct do not come in the way of the reamers. Aside from using the imaging intensifier to assess the diameter that is required to be reamed to, the chatter of the reamer against the cortex is also a useful method of assessing this desired diameter as it signifies the correct fit of the nail up against the cortex.

The Valor hind foot fusion nails are offered in both left and right orientation, left being golden in colour and the right is silver in colour. This orientation of the nail accounts for the unique screw trajectories that have been created in the nail for appropriate use. This includes the trajectory of the calcaneal locking screw which is aligned 7o lateral to the sagittal plane to track the slight angulation in the calcaneal neck. As the various screws follow different trajectories the hind foot fusion nails also come with their own dedicated connectors which are colour coded appropriately according to their orientation. Prior to assembling the nail on to the targeting jig it is essential to verify the positioning of the pre-loaded internal compression screw at the distal end of the nail. Silicone plugs which are present at the compression slot at the ends of the nail are removed, the location of the internal compression screw is then identified within the nail. The correct position of the internal compression screw is adjusted until the top of the screw is flush with the distal end of the oblong compression slot. A 4mm Hex screwdriver is used to adjust the position of the internal screw until the desired position is achieved. If it is felt that compression was already achieved by digital methods and held by the use of a temporary wires or if it was felt that the bone is too soft to hazard the risk of compression and fracture then the internal compression screw can be removed prior to attachment of the nail to the targeting device. It is easier to undertake this manoeuvre prior to attachment of the nail as after insertion this becomes a much more difficult proposition. The thumb screw is then pushed upwards toward the proximal end of the nail to extend the connector screw in to the distal threads of the nail. It is of note that the Valor nail is to be attached to the appropriately colour coded connector by aligning 3 prongs on the connector to 3 slots at the distal end of the Valor nail. The connector screw is then advanced using the thumb wheel on the connector in to the threads cut in to the distal end of the nail. An Allen key (a tightening bar) is also available to achieve this satisfactorily and to tighten the thumb screw. The connector is to be tightened until there is no looseness felt in this connection. Any looseness is likely to result in inaccurate targeting of the screws through the jig. It must not be over-tightened as it is a struggle to remove it at the end of the procedure if too tight. It may also cause damage to the tightening assembly.
The targeting guide is the assembled. The subtalar out of the guide is first attached on to the main targeting guide with the thumb screw completely retracted and the angle faces of the outrigger facing downwards. The outrigger is then slid on to the targeting guide first horizontally and then vertically. The top of the guide is aligned with a marker on the targeting guide and when these line up the thumb screw is used to tighten the outrigger to the targeting guide.
The targeting guide is then connected to the nail connector by sliding the connector on to the large cylindrical peg at the base of the targeting guide. This has got a self-locking mechanism and by rotating the targeting guide until it clicks this mechanism is activated. The targeting guide is now checked for any looseness or mal-positioning. By inserting static or dynamic guides into the appropriate holes the guide should sit exactly over the corresponding hole on the nail. It is also advisable to further check this by inserting a drill through the guide into the nail to ensure that when the nail is inserted the drill is going to enter the requisite hole.
The connector has the numbers 1, 2 and 3 printed at its distal end to signify the guides’ relative position when aligned with the arrow on the targeting guides’ base. These numbers will ensure the proper alignment of the various screws into the nail and the trajectories are sequentially created by pulling the quick trigger positioning system at the base of the targeting guide and rotating the guide. For example position 1 is achieved by rotating the assembly so that the printed number 1 on the connector aligns with an arrow on the targeting jig. The alignment of the targeting jig with the nail is again checked by using guide sleeves and drills to ensure that the drills actually pass through the requisite hole in the nail.

The main jig assembly should be on the medial side of the fusion construct. With the nail and the jig thus positioned the nail is advanced over the beaded guidewire and into a reamed canal. It is advisable to gently toggle the nail and push it in to the canal and to only use the slap hammer when manual pressure alone is inadequate to seek the final couple of centimetres of nail at its distal end going to the press fit design of the canal and the nail. A radiographic marker is the presence of this single posterior notch at the junction of the nail with its connector. The nail should be impacted after removal of the beaded guide wire until the notch at the nail connector interface is countersunk at least 5mm past the plantar cortex of the oscalcis. This will ensure that compression will not pull the nail out of the cortical border and the trajectory of the calcaneal screw compression screw before compression lies in the subchondral region of the subtalar joint. This is the case if internal compression screw is to be used. It is extremely important to confirm that the compression screw slot does not lie over the arthrodoesis site for fear of introducing the calcaneal compression screw into the arthrodoesis site at the subtalar level.

The rotation orientation of the targeting jig is next checked before the insertion of the proximal locking screws. This is of paramount importance as the rotational alignment of the jig prior to proximal locking ensures the successful trajectory of the rest of the screws. In particular it is essential that the calcaneal locking screw trajectory runs through the long axis of the os calcis. The subtalar screws’ positioning should be at the junction of the posterior aspect and the lateral aspect of the calcaneal tuberosity. If placed too laterally the tendency is for the drill to skid off the cortical surface whereby affecting the eventual trajectory of the screw and the possibility of missing its appropriate hole.

There are two proximal locking options available, a static and a dynamic compression screw. The static screw is able to resist rotational and axial translation of the screw whilst the oblong dynamic compression slot allows either for static locking or dynamic locking of the nail. For dynamic locking the screw is inserted in to the proximal end of the oblong slot and for dynamic locking it is inserted at its distal end. It is recommended that both screws are used for locking proximally as this gives the surgeon the option of dynamising the construct post-operatively by removing the proximal static screw. This will allow axial compression as the patient weight bears on the construct. Nail lengths of 200mm and over have got a second proximal freehand locking screw hole which is static.

The positioning of the dynamic locking can be confirmed by using the dynamic drill guide in the oval proximal compression slot marked DYN on the targeting jig. By using the round static guide tube in to the proximal static hole of the targeting jig a static screw can then be inserted. After sliding the drill guide in to the appropriate slot the definitive drill guide is then inserted into the outer guide tube and screwed into position. An entry trocar is now available to mark an incision point on the skin which is made with a knife and a haemostat is used to open and strip the periosteum in this region. The trocar is then gently impacted on the cortex to make a starting point for the drill to prevent the drill skidding off a hard cortical surface. The short drill is now inserted in to the drill guide and both cortices of the tibial shaft are drilled. This is checked with anteroposterior and lateral image intensification. The drill is withdrawn after reeling off the depth gauge markings of the drill at the end of the drill tube. Image intensification will ensure that the drill tube is sitting on the cortex of the bone so as to not miss-record these depth gauge markings on the drill. The drill and the inner drill guide is removed from the outer drill guide and the desired length of screw is inserted in to the outer drill guide.

With a star driver attached to a quick connect handle the screw is advanced through the nail and on to engage with the opposite cortex. The position is then checked with image intensification. Repeat the procedure for the proximal dynamic screw insertion.

The jig must now be adjusted to place the transfer calcaneus screw for the purposes of internal compression. The quick trigger at the base of the targeting jig is activated to disengage the connector from the targeting jig. The targeting jig arm is then rotated to the lateral side of the foot until it clicks in to place and the assembly is aligned in position 2. The targeting jig connection must be secure and must be re-tightened with the Allen key as required.

The dynamic outer guide is now inserted in to the oblong slot marked ‘comp’ which is located near the middle of the targeting jig arm and adjust the length of the dynamic guide tube with the ‘comp’ markings at the bottom of the compression slot. If compression is deemed to be unnecessary this calcaneal transfer screw will be locked by the internal compression screw therefore orientate the dynamic guide tube at the top of the compression slot with the lock markings for locking of the calcaneal screw. By doing this the facility for internal compression will be abolished. Similar to the proximal locking procedure the steps of inserting definitive drill guide in to the outer drill guide, the use of the trocar, marking and making an incision, using the trocar to create a starting dent on the lateral wall of the oscalcis is performed. Both cortices of the oscalcis are drilled with a short drill. It is essential to stop as soon as the distal cortex is broached for fear of damage to the flexor hallucis/flexor digitorum/neurovascular bundle structures. The appropriate screw length is defined and inserted. The position of the transverse calcaneal screw is checked with image intensification to ensure that it does not protrude on the medial side.

The 4mm Hex driver is then inserted through the distal end of the targeting assembly through the nail and advanced until the screwdriver engages in to the internal compression screw that has been prepared prior to insertion of the nail. Up to 5mm of compression can be achieved and 3mm at a bare minimum in order that the posterior to anterior calcaneal locking screw can be satisfactorily inserted. The internal compression screw advances through the Valor nail interfering and pushing the transverse calcaneal screw forcing it to the subchondral region of the posterior facet of the subtalar joint creating compression at both the subtalar and the ankle joints. Sufficient compression distance can be also determined by the position of the laser mark on the 4mm Hex driver at the end of the targeting jig.

If the desired compression is not achieved then the compression screw will obstruct the path of the posterior to anterior calcaneal locking screw. Further attempts should be made to continue compressing with a 4mm Hex driver until the clearance and the required compression is achieved.
When first engaged in to the compression screw the hole of this laser mark is visible and as the compression screw is tightened this laser mark will disappear in to the targeting jig.
If the internal compression screw cannot be advanced any further and the trajectory of the calcaneal locking screw has been blocked there are three options available to try and achieve this if possible.
1. To re-position the transferors calcaneal screw after retraction of internal compression screw, then re-positioning the dynamic guide tube in the locked position so that no compression can be achieved.
2. Internal compression screw can be removed after disconnecting the connector from the nail then reconnect to the nail and continue to calcaneal locking screw insertion. This manoeuvre also will result in low compression.
3. If some compression is desired it is possible to abandon the attempts to use a posterior to anterior calcaneal screw but to use the subtalar compression screw as a locking screw to prevent rotary displacement of the nail. This should only be used as a last resort when other manoeuvres fail.

The quick trigger is activated again to disengage the connector and the jig is now rotated and locked behind the heel in position 3 for the insertion of the posterior to anterior calcaneal locking screw. The targeting device should be tight and if necessary re-tightened with the Allen key. The static outer guide is inserted into the slot marked ‘calc’ of the targeting jig. The inner drill guide is then inserted and screwed into the outer drill guide. The entry trocar is again used to create an incision and the entry trocar is gently tapped to create a starting point for drilling.

The drill is used in this region to peck drill through the oscalcis with a long drill. This is to ensure that the drill does not skid off the hard posterolateral cortex of the calcaneal tuberosity. The drill is advanced under image intensification in the lateral position through the nail stopping just short of the calcaneal articular surface of the calcaneal cuboid joint in the anterior section of the oscalcis.

The drill and the inner drill guide are removed after the appropriate screw length has been determined. The screw is then inserted from posterior to anterior under image intensification guidance to ensure accurate placement of the screw. It is essential that this screw be screwed in flush with the calcaneal surface to avoid irritation inside footwear. The position of the final construct is then checked with image intensification.

The connector is then disengaged from the Valor nail by unscrewing the thumb wheel on the connector using the Allen key. The quick trigger is activated and the connector is removed from the main targeting guide and sliding the connector upwards. The outrigger is then detached by loosening the thumb screw and sliding up and outwards. The end cap is then inserted into the distal end of the Valor nail by using the 4mm Hex driver and screwing into the internal distal threads of the nail.
If it is thought necessary to use a subtalar compression screw the static outer -guide is inserted into the appropriate hole (left or right on the targeting guide outrigger) the inner drill guide is then inserted into the tube and screwed into position. The entry trocar is similarly placed into the drill tube to mark an incision point. An incision is then made, the trocar is used to make a starting point of the calcaneal cortex. This step is especially important for the placement of the subtalar screw as the drill has a propensity to slide off the posterolateral cortex of the oscalcis. The long drill is used to drill through the oscalcis into the talus until it breaches the far cortex of the talus the screw length is determined and the screw is inserted to ensure compression of the subtalar joint.

In this particular instance the RAF fibula strut augmentation technique has been used. I release the tourniquet at this stage to confirm that the vascular structures are uninjured. It is important particularly in severely deformed ankles when the position of the vascular structures particularly medially might be abnormal and susceptible to injury.

The medial half of the osteotomised lateral malleolus is excised using a saw. The lateral surface of the fusion construct is also prepared using a saw to freshen up the surface to fix the fibula on to.

guide wires for cannulated screws inserted

Two cannulated partially threaded screws are then used one anterior and one posterior to the nail as appropriate to secure the fibula on to the lateral side of the fusion construct.

I also aspirate bone marrow from the os calcis which is then injected into the fusion interfaces for further osteoinductive augmentation.

I also aspirate bone marrow from the os calcis which is then injected into the fusion interfaces for further osteoinductive augmentation.

The deep fascia is closed over the fusion construct with interrupted 2:0 Vicryl and the skin is closed with interrupted Vicryl rapide.

A plaster backslab is then applied with the foot in the neutral position after 30ml of Chirocaine is infiltrated into the various wounds for post-operative pain relief.

Pre-op Xray showing a significant valgus ankle and hindfoot deformity.
In these cases a CT is often helpful to clarify at which joints the deformity sits, and give a more comprehensive idea of which joints are effected by arthritc change, particularly into the midfoot, often difficult to assess on plain films.

Pre-op lateral shows degenerate change at both the ankle and subtalar joints, but doesn’t give an idea of the deformity.

Post-op AP view showing correction of deformity, nail and the fibula strut graft.

Post-op lateral view showing excellent alignment and bone contact and nail placement.