Ankle and Subtalar (Double) Fusion using OrthoSolutions Oxbridge nail

The first incision made starts about 10cm above the ankle level, and extends below the ankle, curving forward at the tip of the fibula.

The incision is carried directly down onto the fibula (incising down to and through the periosteum), and for 1cm below, in line with the skin incision, into the sinus tarsi.

The periosteum is stripped backwards and forwards from the fibula exposing the bone, and protecting surrounding soft tissues.

The fibula is divided with an oblique cut above the level of the ankle joint with a sagittal saw.The soft tissues are protected by suitable retraction (these are not present in the photograph to allow good visualisation but should be used in practice). An oblique incision is made to avoid sharp subcutaneous bone surfaces which might arise with a square cut.
Surgical tip: if you predict that bone graft is going to be needed to fill any defects, cut your way up the fibula in multiple small slices (about 3-4mm) until you get to the level of the definitive cut. when you remove the slices, you get more good quality bone graft than if you morsellise the lower fibula later.

Sharp dissect off the fibulas soft tissue attachments, the interosseous membrane and lateral ankle ligaments, to allow its removal.
The ankle joint is thus exposed(A – with a periosteal elevator inserted to define it), as is the subtalar joint(B). The peroneal tendons (C)have been protected by retraction

The posterior subtalar joint is also mobilised – here again by inserting a periosteal elevator

The ankle joint is exposed, and surrounding nerves, vessels and tendons protected by inserting ring handled spikes carefully around the front and back of the tibia.
Take great care to keep the (blunt) tips of the spikes closely onto bone as they are passed.

The tibial and talar articular surfaces are are prepared. The key with whatever technique is used for preparation of the joint is that vascular, bleeding sub-chondral bone is exposed as well as that both joints are left in a functional position.With the spikes in place, cartilage is removed from the talus and tibia across their articulating surfaces.
These two surfaces must be congruently prepared whether using a flat saw cut or if kept convex and concave as with this technique.
Once the chondral lining is removed the subchondral bone needs to be exposed.
Surgical tip 1:take care to keep the incisions parallel with any deformity excised. It is always easy to make the osteotome cuts get shallower as the incision gets deeper. This will produce deformity. In this case cuts which are shallower on the deeper medial side will tend to cause valgus deformity.
Surgical tip 2: sometimes preparation of the tibia, causes a radiating crack across the whole of the tibia, through the medial malleolus. This is not critical, but extra care should be taken to avoid excessive medial displacement when positioning the foot later.

It is not possible to clear the anteromedial corner of the tibia, the medial malleolus, nor the medial aspect of the talus thoroughly through a lateral incision.
Using a blunt instrument passed across the ankle to the antero-medial corner, a second incision site is identified.

An antero-medial incision is made just medial to the tibialis anterior tendon.
A longitudinal incision is made down to show the upper surface of the medial talus (A), and the lower tibia (B) extending down to the medial malleolus.

Using a reciprocating saw a vertical incision is made into the tibia in line with the medial malleolus.This simply marks the medial extent of the distal tibial articular surface preparation.

Using an osteotome or saw, articular cartilage is removed from the talus (as shown), and the lateral (inner) aspect of the medial malleolus.

A laminar spreader is placed within the subtalar joint (alternatively a Hintermann wired retractor can be used) and the joint is cleared on both superior and inferior surfaces using an osteotome or high speed burr.

It is safest to complete the preparation of the medial side of the subtalar joint using an up-cutting spinal cutter. This minimises risk to the medial neurovascular bundle.
Both articular surfaces are re-examined to check they have been thoroughly and completely cleared. If any areas of sclerotic bone remain, they may be drilled with multiple holes to promote union.

The prepared joints definitively reduced. It is helpful to temporarily stabilise the prepared joints using stout K-wires, positioned to avoid the line of subsequent insertion of the intra-medullary K-wire and nail.
The most important thing about the reduction is to confirm that the foot will reduce to be below the leg, in correct alignment in all three planes.
An X-ray examination should be taken using an image intensifier to check that the ankle is reduced satisfactorily on AP and lateral views.
Technical tip: rotate the leg rather than the image intensifier. It takes a lot less time in an operation where there is always a bit of a rush to keep the tourniquet time down.

Palpate the heel pad, and either in your mind, or with a marker pen draw a line between the centre of the heel at the back and the second toe.

Make a plantar skin incision along a line from the front of the heel pad, a third of the way towards the heel, in the line of the 2/3rd toes.
Sharp dissect the skin and then blunt dissect in the same line longitudinally through the fat with scissors. It is useful to carefully probe with the closed scissor tips once on the plantar aspect of the calcaneus to get an idea of its medial and lateral edges.
Technical tip: cut back towards the back of the heel, not forwards. This will keep the plantar nerve safer if you slip!

Load the 3.9mm wire onto the driver and advance it into the calcaneum, in the mid-point medio-laterally.
It is very important you drive the wire into the central calcaneum, at least 5 mm from both its medial or lateral walls, otherwise the reaming may breach the bony boundaries. As well as significantly destabilising the construct this risks damaging the medially placed plantar neuro-vascular bundle.
Feel your way to the lateral and medial borders by gently walking the wire along bone (don’t start the drill yet) and then settle about half way between them in the centre of the calcaneum.
Once the wire is passed, check it is central in the tibia on AP and lateral X-rays.
It is possible that if the reduction of the ankle and subtalar joints has been sub-optimal their position may need to be revisited and the surfaces recut to allow appropriate passage of this initial guide wire.
Most often the ankle/hindfoot is in slightly too much valgus and should be medialised by carefully removing more of the width of the medial malleolus or medial wall of the talus.

With practice initial guide wire placement becomes easier, but to begin with a guide is available (which works like an ACL guide). This is shown unassembled. It should be assembled before use. The target of the guide (A) is passed centrally on the talus, guide B is inserted into the heel wound, and the wire will reliably pass centrally (assuming the ankle and subtalar joints are anatomically aligned).
The guide is then dissembled and removed, before advancing the wire into the centre of the tibial surface under direct vision. Make sure the foot is in the correct position for fusion before advancing into the tibia, and make any positional adjustments before fixing the position when the wire passes into the tibia.
Once the wire is passed, check it is central in the tibia on AP and lateral xrays.
Drill a starting hole through the heel using the 8.0mm cannulated drill/starter reamer.

Once the guide wire is centrally placed and as far proximal as required (confirmed by image intensifier) over-ream using the 8mm cannulated starting reamer (shown here). This is advanced through the subtalar and ankle joints.Make sure the foot is held in the correct functional position for the fusion. This is at right angle to the tibia in the sagittal plane with no varus or valgus, nor equinus or calcaneus.
Advance the thick (3.9mm) wire, aiming it directly up the tibia in both planes.

The reamer is removed, the 3.9mm wire left and the clear exchange tube is introduced over the wire.

Holding the exchange tube in place, the 3.9mm wire is withdrawn. Then pass the 2.6 mm x 900mm olive tipped reaming wire up the exchange tube (olive end first).
Through all these manoeuvres, and throughout the rest of the operation the foot should be held in correct position.
If you don’t and ream with the foot in an incorrect position(usually equinus), then the foot will end up fixed in the wrong position.
Check that the wire has passed centrally up the tibia (using the image intensifier).

The reamers come as part of the Orthosoultions kit.
Start with the smallest size and ream using standard reaming technique under image intensifier guidance.
It is good practice not to ream the plantar soft tissues so ensure the reamer end has engaged with calcaneal bone before starting.

With the foot held in position (or K wired into position) progressively ream over the olive tipped wire in 0.5mm increments until you feel the reamer engage the cortex, or you have reamed to 13mm.
Technical tip 1: hold the guide wire in place while you withdraw each reamer. If you inadvertently pull the wire out, reintroduce it and check it is in the correct position before reaming again.
Technical tip 2:using a sterile marker pen, put a mark on the reamer shaft about 20cm from the cutting end. If you stop reaming when you see this at the level of the heel, allowing 2cm for the fat pad, you will know how far you have reamed.
Then select the correct diameter of nail. The nail comes in 10, 11 or 12 mm diameters. The diameter selected should be 1mm less than the maximum reaming diameter.
The nails come in 15 cm or 18 cm lengths. The 15cm long nail is the default length, with the 18cm used for special situations such as if there is a screw hole or old fracture near the end of the 15cm. The commonest size used is 15cm X 12mm.

The Nail alignment shaft (A) is mounted within the outrigger arm (B) and secured with the locking collar (C).The nailing jig is now assembled in preparation for the Orthosolutions Oxbridge nail.

The locking collar is tightened with a spanner.

There is a choice of compression devices .
The heel plate bone compression nut (A) is usually used, but in cases of severe osteoporosis, when compression against the calcaneum may cause collapse of bone, a different device (B – the soft tissue device) may be used, which compresses externally against the heel fat pad.

The heel plate bone compression nut is attached by screwing it onto the nail alignment shaft.
Whichever one is chosen, it is threaded onto the nail alignment device and threaded right down onto the jig, but only finger tight.

The impaction cap (A) is selected.

The retaining clip (A) is selected which fits into a slot on either side of the jig (B) to secure the impaction cap.

The cap is then secured once the retaining clip is inserted.

The alignment jig bolt (A) is then passed through the impaction cap and into the nail alignment shaft.

Select the correct diameter of nail. The nail comes in 10, 11 or 12 mm diameters. The diameter selected should be 1mm less than the maximum reaming diameter.The nails come in 15 cm or 18 cm lengths.

The nail (A) is attached to the jig by screwing the alignment jig bolt (B) onto the proximal end of the nail.
Make sure the nail is fully engaged on the alignment shaft. There is an inset into the nail which engages the shaft.

The position when engaged is shown here.

Finally tighten the alignment jig bolt(A) through the impaction cap using the small spanner head (B) which is an integral part of the large spanner.

Finally tighten the alignment jig bolt (through the impaction cap) using the small spanner head (which is an integral part of the large spanner).

Finally check that the holes on the jig and nail line up correctly, by inserting the jig guide tube with a drill through the appropriate holes in the outrigger.
Check each of the holes to be used.

The alignment jig trocar is inserted into the alignment jig guide tube before placing them through the jig and trialling with the 4.0 mm drill through the nail.

A lever underneath the outrigger (A) allows the outrigger to rotate around the long axis of the nail once pressed.
Use this to rotate the nail 180 degrees to check the medial holes also align correctly through the nail once the lateral position has been checked.
Also rotate the jig back 90 degrees to check the antero-posterior holes are also correctly aligned.

The nail is inserted over the wire (with the outrigger placed medially) and introduced into the heel.
The wire its olive tip are both smaller than the central hole up the nail, so this can be withdrawn later.

The heel incision may need enlarging slightly to allow passage of the bone compression device through the skin.
Technical tip: either enlarge the incision behind the nail, or, if it it must be enlarged in front, then cut backwards onto the nail. You are less likely to inadvertently damage the lateral plantar nerve that way.

Take a lateral image intensifier view of the heel. You will see a notch on the introducer which lies 5mm distal to the end of the nail (on the introducer). Advance the nail until this point lies level with the inferior calcaneum.
The tip of the nail now lies 5mm proximal to the inferior calcaneum, and will lie flush once the compression is applied.
Check the position of the nail with the image intensifier in both planes. The seating of the nail is best confirmed on the lateral image.
Technical note 1: it is permissible to gently tap the impaction cap with a hammer or mallet when inserting, but do so with great caution. If you are having problems inserting the nail, first withdraw it, make sure the nail is 1mm less in diameter than the reamed width, and if necessary ream another 0.5mm. The hammer is only used to finely impact small distances to get the positioning of the marker correct. If it is used to overcome tightness,it may produce a fracture around or at the tip of the nail.
Technical tip 2: NEVER hammer the side arm. This is very strong but can still distort. If it does, all the screw holes will be malaligned with the jig.

The olive tipped wire should be withdrawn completely

The rotational position of the nail should be adjusted to allow appropriate location of the proximal cross-screws on the subcutaneous border of the tibia. Make a stab skin incision and advance the trochar and guide onto bone.
Having chosen this position medially it is worth swinging the outrigger jig laterally also to ensure an appropriate position is also possible for lateral locking.
Insert the drill guide and trocar into the appropriate holes.
The dynamic holes are used unless there a specific reason, such as a gap at the arthrodesis site with non-structural bone graft inserted.

Unscrew the trocar from the guide and replace it with the drill guide.
Drill through the tibia using the shorter drill, being careful not to ver-penetrate the lateral cortex.
Check with the image intensifier that the drill has just passed the lateral cortex and measure the screw length off the markings on the drill.
To make life easy, leave this shorter drill in place while you insert a second cannula and trocar at the second medial drill site on the outrigger, and repeat the process of passing the drill sleeve and drilling, this time using the longer drill.
This way you use the stability of the first drill to ensure easy and accurate drilling of the second drill hole.
Technical tip 1: If in doubt, go up one screw length. The screws are flat headed. This means they can be introduced from medial to lateral without the screwhead being palpable. The lateral end will be buried in the muscle mass, so being a few millimetres too long will not matter.
Technical tip 2:If you can’t drill across, think whether you’ve remembered to remove the wire!

The drill sleeve is unscrewed from the cannula and the screw inserted down the cannula and through the drill hole.
The screwdriver has a small plastic lug on its side near the tip, and this should ensure that the screw doesn’t inadvertently drop of , detach etc. However still be careful not to drop the screw, and keep moderate pressure on the screw whilst tightening it to keep contact.
Repeat this procedure for the second proximal screw.

Then tighten up the heel plate bone compression nut, using the large spanner, to obtain joint compression. At this stage you should insert any bone graft into the joints to be fused.
As you sit facing the sole of the foot, this means rotating the nut clockwise.

Tightening the compression nut.

Advance the nut along its thread until you feel compression at the arthrodesis sites, or until you have advanced the compression device about 10mm.
Then take a lateral image, using the image intensifier, and check two things .
Firstly check that the compression device is not advancing into the calcaneum, if it is stop compressing.
Secondly see where the notch on the jig lies.
With ideal compression it will come to lie about 5mm below the calcaneum.
As compression is applied the nail If it isn’t this far advanced, and it’s not too difficult to advance the spanner further, continue advancing until the notch lies 5mm below the calcaneal cortex.

Press the rotation lever and rotate the outrigger beneath the heel until it is located laterally.

Insert two lateral to medial cross-screws, one in the talus, one in the calcaneus.A check is made using the trochar and cannula, to see where the lateral holes now lie.
Having checked this earlier before the proximal locking was started there should be no reason that good bony purchase is not possible with these cross screws.
It is not useful to pass a screw across the ankle or subtalar joints.
The jig is designed to ensure that at least one lateral to medial screw can be passsed, and often two can.
Use two if possible.

The same technique (and drill) is used for the lateral screws as for the proximal screws.
It is sensible to screen the drill in its passage to prevent drilling through the medial cortex more than necessary.

The most proximal lateral screw is well seated in the talus but using this hole on the jig(34) would result in an intra-articular calcaneal screw. The hole one inferior (marked 23) will therefore be used.

Then the jig is rotated to be behind the foot, for insertion of the posterior screwScrew insertion can often be performed by rotating the hip and leg, and if the foot hangs over the edge of a large bowl, the drilling and screw insertion is possible. If, as in this case, the patient’s hip is stiff, the leg has to be elevated – which is more awkward.
Pass a guide through one of the posterior holes in the jig and take an X-ray to see where this lies. Typically one posterior screw will lie entirely within the calcaneum, and usually only this screw is inserted.

Check X-rays are then taken to confirm position of all screws, the fusion site and the tip of the nail (to exclude proximal fracture).The technique of making a skin incision, using the drill guides etc is the same as before, and a long posterior – anterior screw inserted.

Optional step: the OrthoSolutions set contains a further adjustable outrigger, which can be attached to the main jig, in order to pass an accessory screw (MISA screw) from distal to proximal, obliquely in front of or behind the nail.
This is very rarely used, but if it is, then the safest position for such a screw is passing from lateral to medial, in front of the screw.

The alignment jig bolt is removed, using the small spanner (on the side of the larger one) which once done allowing the jig to be removed from the implanted nail.The jig is rotated back to either side, to allow the assistant to put the leg down on the bowl.

Optional step: a metal end cap is available to screw into the lower end of the nail. This is useful to prevent ingrowth of bone, which is troublesome in the (rare) event that the nail has to be removed / exchanged.
Finally the wounds are all sutured, taking care to close the main incisions in layers to close any dead space which will allow haematoma formation.
A below knee backslab, cast, boot or brace is applied.