First MTP fusion- Revision with bone block and Wright Ortholoc plate

This clinical photograph shows a patient with bilateral failed silastic replacement.
Both great toes are hyperextended and during gait are in a non-functional position.
The patient has a degree of collapse at the medial column bilaterally and also transfer metatarsalgia.

The frontal image emphasises the defunctioned nature of both great toes and the bilateral pes planus

There are a number of things to note on the plain radiographs.
There seems to have been a very significant resection of the metatarsal head with very little of the 1st metatarsal head evident any longer. The void in the proximal phalanx will correspond to the silastic implant though it is significantly broader than the implant would be judging by the metallic colour.
There is also very evidence sclerosis around this cavity.
It is not possible to make out the position of the proximal silastic stem but again there is significant sclerosis in this part of the metatarsal head. Additional features which point toward some degree of infection are the periarticular cysts evident both sides of the joint.
The alignment of the metallic grommets suggest that neither of them are sitting well on the native bone, suggesting loosening.
(This is not the case demonstrated in the following technique)

The only incision to use in these revision cases is the one which has previously been used.
Placing further incisions parallel risks “tram lining” of the skin necrosis between the two surgical scars.
It is important that pre-surgery any scar hypersensitivity has been identified and already desensitised in an attempt to minimise rebound of hyperpathic-type symptoms or even regional pain syndrome.

The old skin incision is re-opened with sharp dissection and extended distally well beyond the inter-phalangeal (IP) joint.
The extensor hallucis longus (EHL) tendon needs to be adequately identified, mobilised and preserved.

Beneath the skin will be thick fibrosis and scar tissue and as far as possible the deeper tissue should be left attached to the skin to minimise the chance of devitalisation or cutaneous nerve injury.
It is however important to define the extensor tendon in which in this case is encased in thick fibrous tissue and a limited amount of dissection with tenotomy scissors is used just to gain appreciation of where it sits prior to proceeding with a more comprehensive mobilisation of the soft tissues with an inside knife.

The soft tissue flap being raised from the extensor mechanism with sharp knife dissection.

Deeper subperiosteally dissection is with the assistance of a sharp small periosteal elevator as well as an inside blade.
The exact dimensions and margins of the joint need to be defined dorsally, medially and laterally whilst preserving the plantar soft tissue envelope.
At this sort of early stage in dissection can be difficult to identify where the joint is and moving the MTP joint is a helpful manoeuvre.
In the vicinity of the joint one can see this image the whiter periarticular fibrosis that encapsulates the silastic replacement.

Further careful subperiosteal elevation proceeds both sides of the joint as described.

Small self-retaining retractors are useful but should be kept very much with their teeth in the deep soft tissues only. Regular periods of relaxation of these should be observed to minimise traumatising the soft tissue envelope.
In this image adequate subperiosteal exposure has occurred and the joint is not clearly seen.

With some flexion the joint starts to open dorsally.
Further intraarticular dissection and excision of the fibrosis is required to gain adequate access to the silastic which now needs to be removed.

Following further excision of the joint it opens easy to reveal the silastic. This interface between bone silastic had already been inspected and appears to be sound.

Removing silastic in part is generally easy though it may come out in several fragments.
If getting with other implants in particular press fit implants the work required to free them can be quite destructive. A set of small Lambottes osteotomes are essential.

A healthy looking silastic implant which has been easy to remove and in this case without grommets.

The entire silastic implant is removed. This is rotated through 180o compared to its implanted and functional position.

Multiple deep sort tissue samples should be taken both from the capsule and also from both sides of the joint.
There will likely be a biofilm and the bone itself will be sclerotic and also should be biopsied and sent for long microbiological culture.
The fibrosis surrounding the implant can be dense and it is important to be careful in terms of the plantar aspect of the joint were the flexor mechanism sits as well as the neurovascular bundles. This aspect of the joint should ideally be not breached.

Further sharp dissection around the joint to define precisely the bony margins of both sides of the joint.
The operation involves placing a bone block in to the gap created and it is important that the bone surfaces on both sides of the joint are appreciated and cut flush if they are not the bone block sits well and stably.

Both sides of the joint need to be carefully inspected and also debrided. Debridement is done using a curette, a 1.6mm K-wire and a wire driver and on occasion a fine bone burr is required if there is a significant amount of sclerosis.
Deep samples should be taken throughout.
The object of the next stage is to get back to healthy bleeding bone which will accept the bone block and also bone graft. It is important also to explore surgically the dimensions of both bones to ensure that any graft that is put in is going to be contained or if not pieces of cortical bone used to block any holes within the bone.

A curette being used to clear fibrous tissue and get back to subchondral bone within the proximal phalanx.
Not all cases are suitable for one stage bone block fusions.
In the presence of overt infection a similar level of debridement is required but should be allied with an appropriate amount of anti-bacterial wash such as a diluted hydrogen peroxide and copious pulsed lavage prior to using an antibiotic laden cement spacer.

The soft tissue envelope has a tendency to retract so estimation of the bone block size should not be made without the tissues distracted.

The Wright Ortholock plate of appropriate length is now inserted. The fact these plates that are pre-contoured is very helpful at this point.

The polyaxial guide is useful after the initial screw has been inserted to ensure that there are enough options in terms of angulation of the screws that all three holes can be used without any fear of the screws impinging on each other and therefore compromising the length of the screws used. There is a 30 degree arc that can be employed using the polyaxial guide.

With an appropriate amount of distraction the size of the required bone block can be estimated.
You will note that the self-retaining retractors are still in the wound. These tend to have a fore-shortening effect on the soft tissues and should be removed before the final measurement is taken. By taking the retractors out there will certainly be another 0.5cm or so of additional length that is required in this case.

The cavitated nature of the proximal phalanx can be seen here following the initial debridement. Once this K-wire has been used to drill widely in to the cavity and open out the subchondral bone any sclerosis should be back to bleeding bone.

Any areas of abnormally thickened bone are drilled including cortical bone as shown here.

Following both sides of the joint having been prepared similarly the area is washed copiously and then packed with diluted aqueous soaked swabs.

The foot is then wrapped with sterile crepe and the tourniquet deflated whilst the attention is turned to the next stage which is harvesting the iliac crest bone graft.

The iliac crest bone block is taken from the ipsilateral side.
This has been prepped at the same time as the foot and there is no further tie spent there for draping.
The iliac crest has been marked with a surgical marker so the draping can be done accurately.

The skin is pulled up or down over the iliac crest and then the incision is directly down on to the iliac crest.
The purpose of moving the soft tissue up or down is so that the incision does not sit directly over the bony prominence but above or beneath it which makes it less likely that this will cause an irritation with the wearing of undergarments or any type of waistband.
The subcuticular fat here is very vascular and you should be prepared for this. A bipolar diathermy is usually what is required to control bleeding.

A blunt swab-type dissection can be used once the fat is split to reveal beneath it the deep fascia overlying the iliac crest.

An index finger is inserted over the pelvic rim and sharp knife dissection is used in the mid-point of the iliac crest to incise its periosteum which can then be carefully mobilised both medially and laterally using a large round nosed periosteal elevator as well as careful subperiosteal dissection.

A pair of self-retaining retractors are very useful to place appropriate tension on the fat layer.
The iliac crest can be seen centrally. The fat needs to be blunt dissected off the deep fascia overlying the bone to define the outer and the inner table of the iliac crest.

Swabs of an appropriate size are walked down the outer and inner table of the pelvis for a limited amount. During this stage there is usually a fair amount of venous ooze and these are useful to keep the field bloodless. Superiorly the surgeon can place a Homan’s type retractor for an assistant to hold and this needs to be closely and carefully applied to the inner table of the iliac crest. Inferiorly, as can be seen here, a sharp round nosed periosteal elevator is being used to strip the muscle from the outer table of the iliac crest to define the areas for osteotome cutting.

The length of iliac crest required is now being measured. It is good practice not to take the anterior superior iliac spine and enough of this should be left anteriorly. Posteriorly the quality of the bone tends to diminish as the iliac crest narrows. It is usually possible to harvest 3cm or potentially 4cm if required from this area. This volume of graft is not required for a bone block distraction fusion of the great toe however.

A large Hibs osteotome or large Lambotts osteotome is used to cut the the bone graft. The cut starts on the outer table and is progressed carefully towards the inner table. Two vertical incisions are thus progressed, one at the anterior extent of the graft and one at the posterior extent of the graft. Both these need to be extended down on the outer table by 1.5-2cm depending on the height of graft required.

These two vertical cuts are then joined by a further cut on the outer table that runs from the anterior osteotome cut to the posterior osteotome cut.
Whilst making the three preceding cuts the inner table needs to be reached but not necessarily breached. Once these three surfaces have been cut the inner table will normally yield simply by elevating the handle of the osteotome. This will result in a cracking sensation and the graft very visibly mobilising. This step is being show here.

Once the tricortical graft is mobile there will be soft tissue attachments that needs to be sharp dissected off it to allow it to be delivered. It needs to be carefully held with a Kocher’s as shown here and immediately put safely in to a kidney dish or similar receptacle.

The defect created can be seen. Point A and B mark the respective anterior and posterior aspects of the cut.

Generous amounts of bone wax should be placed on the cut bone surfaces. A finger should be moved around the donor site to ensure no sharp spicules of bone are left and these can be smoothed down at this stage.

A single deep grain is placed and closure then is in layers and ensuring haemostasis with bipolar diathermy as the cavity is closed.

The right Ortholock fusion plates.
These are sided left and right.
Each side has a 0o, 5o and 10o dorsiflexion version plate and each plate is sided either small or large.
In addition (and seen centrally placed) are long revision plates and there are also standard revision plates which are seen at the top of the tray.
The screw options are locking and non-locking for each of the holes.
Each plate has at least one proximal oblong shaped hole to allow generation of compression.
The set comes with two diameters of screws and each of these diameters fit with each of the plate options present.
The screw pitch and thread diameter of the 3.2mm screws makes this ideal for the type of inadequate bone that can exist in these revision cases.
The fact that there are locking options of the screws also makes this a versatile plate to use for this revision indication.
Finally the fact that the plate comes already pre-contoured is useful as when the plate is applied to the toe and bone graft this is not often inherently stable of its own accord and the pre-contouring assists this step of the operation.

Both sides of the arthrodesis site are again inspected for any bone fragments and the margins of the joint identified.

Further smoothing off of bone both sides of the arthrodesis to produce flat reciprocal surfaces to accept the tricortical bone graft.

The bone graft is inspected.
It is key that it is handled stably and I tend to always place it in to a swab and be very measured about where it is moved to and from. Ideally it should not be moved on to the floor.
The graft will be inserted with its own superior surface superior. The inferior surface is cancellous bone where the graft has been detached from the iliac crest. There are frequently spicules of bone here that need to be smoothed down and sometimes the whole inferior surface needs to be chamfered back if it is deeper than the space in which it will sit.

There are two ends to the tricortical graft and generally the broader end should sit next the metatarsal head and the smaller end to the base of the proximal phalanx.

The graft is measured again according to the previous dimensions noted. It can also be offered up now directly to the MTP cavity for a visual check before it is modified.
It is useful to take an extra amount of tricortical graft which can then be removed (as is being shown here) and morcellised.
What this slide also shows is one form of natural selection for orthopaedic registrars/residents. A straightforward way to cut the bone graft is to hold it carefully in a large swab between thumb and index finger and cut towards it with a power saw shown here. Though probably not in keeping with any health and safety policy anywhere a surgeon should not perform this manoeuvre without cutting the ends of their fingers off probably should not be involved in orthopaedics.

The excess tricortical graft that has been removed is now broken down in good sized fragments to pack in to the cavities and the metatarsal and proximal phalanx.

The graft needs to be well impacted.

The tricortical graft is now inserted in to the gap.
This is definitely not a point in the operation if you want to drop the graft on the floor. The foot should be well located on the table and with plenty of sterile field beneath the foot should the worst happen. You may wish to insert this whilst controlling it with a Kocher’s (as shown in the next slide).
An additional manoeuvre which needs to be performed then is not yet shown here is that the self-retaining retractors are removed to provide as much slack as possible in terms of the soft tissue envelope. The previous measuring and trialling manoeuvre should mean that the block should now fit well.
How much the toe is lengthened by the bone block is determined very much by the soft tissue envelope and how much distraction is tolerated.
I have not found the need to let the tourniquet down to assess vascular status if the normal tissue tension is respected.

The self-retainers have been reinserted again and the bone block is being manoeuvred in to a better alignment using the Kocher’s forceps. An assistant is useful during this manoeuvre to put some distraction on the great toe to ease manoeuvring of the bone block.

The stability of the construct should be tested and specifically the bone to bone contact looked at on both sides of the bone block not just dorsally but also through the superior to inferior extent of the graft medially and laterally.
This current position is relatively unstable and careful control should be maintained by the surgeon of the digit and inserted bone block.

This demonstrates the 10o dorsiflexion angle plate being offered to the first ray. It is held closely approximated to the graft and bone and best guess made as to whether this is a functional position of the hallux. With this 10o dorsiflexion plate this is not the case.

The 5o plate however provides a better and entirely functional position when offered up to the toe.
This is the time also to decide on the length of the plate. It is evident here that there is not much room for manoeuvre with skirting the native bone/bone block interface on both sides but there is just about adequate clearance.
The alternative is to upsize to one of the two sizes of revision plates that exist in the set.

With the plate kept insitu and the bone block under compression from the pressure exerted on the distal phalanx an assessment is made of the ultimate functional position of the first ray by offering it up with the ankle in a neutral position to a flat foot plate. In this case the sterile top of the Ortholock screws.
The 1st MTP should be fused in a position that allows the IP joint to sit at best just slightly off a flat surface and extend beyond this easily. This is demonstrated in this image.

Easy contact is demonstrated here between the distal phalanx and the flat surface with the toe held in a reduced position.

This is an image taken from a separate bone block procedure. In this case once inserted the position of the hallux is too plantarflexed. This is evident from the clinical picture.

A wedge of bone needs to be chamfered from one side of the block to extend the toe and bring it in to a more functional position. The amount shown here would be too much to take in the first instance and is for purposes of illustration only. A relatively small amount should be chamfered initially and position of the toe reassessed on each occasion.

In preparation for the plate the dorsal aspect of the bone block and first ray are burred back to an entirely flat surface and any prominences is removed.

The tray of Ortholock instruments.
There are three different types of guides labelled. 1 are the locking guides and these are differentially sized for the 3.5 or 2.7 screws. The guide labelled 2 is for use in the compressive holes on the proximal limb of the plate and again is sized appropriately according to the screws. The guide labelled 3 is the poly-axial guide , allowing the angle of insertion of the locking screw to be varied by up to 30 degrees. In the foreground are the screws and these come as either 2.7mm or 3.5mm diameters. Both sizes either come as simple cortical or locking varieties.

This is the 3.5 mm locking guide and is colour coded.
Locking screws are particularly useful when fixing through bone in these type of revision cases where there are large cavities which will be packed with graft and offer little purchase and potentially even cortical fixation is going to be poor.

Attention is paid to positioning the plate so that all holes sit on viable bone. There are guide pins available to temporarily fix the plate to the bone but if there is a lack of inherent stability as there is with a bone block then these tend to get in the way of controlling the position of the plate relative to the bone which is straightforward enough using an orthopaedic thumb.
Attention needs to be paid to ensuring that the thread engages correctly and the guide locks fully. This step must not be forced and you should ensure that both sets of threads are clear of any bone swarf. It is not bad practice to lavage these threads before engaging them. If these threads are not properly engaged when the hole is drilled this will mean that the locking head will sit proud potentially causing irritation and not finding as much stability as it might. Under these circumstances it is possible to simply to remove the locking screw and insert a cortical screw with a head. The holes in the plate accept both.
The 3.5mm locking screw requires a 2.8mm drill.

The polyaxial guide is designed for use with the locking screws and therefore a 2.8mm drill would normally be used.

With two screws in the distal phalanx attention is now turned to the proximal fixation.
The guide being used here is for the non-locking cortical screw and a drill hole has been placed at the most proximal extent of the hole with the guide engaged in the hole. This is to allow compression to be generated using AO principles of the head engaging with the screw hole geometry and sliding distally thus producing compressive force.
A 2.5mm drill is used for this hole.

The compressive cortical screw is angled slightly distally and the guide is placed initially perpendicular to the long axis of the plate.

The cortical screws are driven home whilst the position of the plate is still carefully controlled.
To generate compression bi-cortical fix is required. When fixing through an effective bone cavity (as is the case once an implant has been removed) it can be on occasion be difficult to find the plantar exit point of the drill hole and some trial and error may be required to locate this.

Again the functional position of the hallux is checked with respect to the foot plate.

A locking screw is now inserted in to the proximal part of the plate. This is drilled as before using a 2.8mm drill.

The position of fixation is checked using image intensification and screws are re-tightened at this stage. The bone to bone contact is also checked and if graft will require interface this can now be added though following a good compressive force generated by the plate none is required.

The polyaxial guide is once again used and the third screw inserted in to the distal part of the plate.

The locking screw being driven home.

A final screw needs to be inserted in to the proximal half of the plate and this again will be using the poly-axial guide.
The final screw positions are checked with the image intensifier and adjusted as required.

The soft tissue tensions are checked over the plate and closure will be with a subcuticular closure.