Compartment fasciotomy and Hoffmann 3 spanning external fixator for open tibial fracture

The photo shows a limb with a traumatic wound on the antero-medial aspect. On close inspection, clues that this is an open fracture and communicating with the bone include continuous bleeding and fat globules mixed with the blood.
Prior to prepping the limb, it is washed with a detergent soap solution to remove any superficial debris or dirt. The soap also helps to remove the natural oils from the skin surface allowing the antiseptic to penetrate deeper into the skin pores.

The fracture level is determined with the C-arm and marked on the skin.Prior planning is essential in complex OrthoPlastic cases and the surgery should be performed with both a Consultant Orthopaedic Surgeon and Consultant Plastic Surgeon present throughout.
I recommend marking out the fracture anatomy on the skin surface and then planning your surgical incisions.

The inferior margin of the fracture is identified. Occasionally it is better to do this on the lateral projection depending on the obliquity of the fracture plane.

The wound is marked to indicate the zone for primary excision.A secondary area of contused skin is also marked, as this needs assessment and possible debridement. A common mistake is to do minimal wound margin excision and then when returning to theatre for definitive wound management, the borders have necrosed and further excision is required (and this sometimes delays definitive wound management e.g. if it is infected skin).

The medial arterial perforators are also marked to highlight their importance and avoid inadvertent injury.The BOA/BAPRAS BOAST guideline demonstrates that the medial perforators are at 5, 10 and 15cm from the medial malleolus.
The medial perforators arise from the posterior tibial artery and should be preserved if possible, as they may be necessary for a local soft tissue reconstruction flap. Often the perforator at 10cm is the most substantial and useful.
Refer to the BOA guideline associated with this technique.

The wound margin is excised first checking that the remaining skin margin is viable.The debridement is commenced in a systematic approach working from superficial to deep.
The obviously non-viable tissue is excised and the margins are assessed to ensure that they are bleeding and likely to recover.
The secondary margin indicates the area of skin that has been contused and may also evolve to be un-survivable and require excision.

The next layer to debride is the contaminated and exposed fat.The fat layer is debrided and exposed veins that are in the wound are tied off and removed.

The medial fasciotomy skin incision is made first incorporating the traumatic wound and is positioned 1-2cm posterior to the postero-medial border of the tibia.I recommend doing the fasciotomies early because it immediately decompresses the respective compartments and addresses the compartment syndrome. Also the surgical exposure is much better and therefore the surgical debridement will be easier to perform and more thorough. Prior to making the incision, first realign the limb and if possible, reduce the fracture.
Usually it is approximately 1 fingers width from the palpable posterior border. Occasionally in ACS the leg is too swollen making palpation of the bone very difficult. The incision should run from joint line to joint line. Mini-incisions are only suitable for chronic exertional compartment syndrome and in my opinion should be avoided.

Due to the venous hypertension, it is important to control the bleeding as you progress as it is often extensive. Here the long saphenous vein is being tied off at the distal end of the wound. Unfortunately the saphenous nerve is often not salvageable and the patients are left with a patch of numbness around the medial malleolus and dorso-medial foot.

The fascia of the superficial posterior compartment is released.The fascia is incised with a scalpel and the diathermy is used to promptly haemostase any bleeding vessels.
An alternative is to make an initial incision with a scalpel in the fascia and then use a pair or McIndoe scissors to release the fascia. If using scissors, first pass these proximally and distal underneath the fascia. This separates the fascia from the underlying muscle. Then cut the fascia using the scissors following the same path.

The medial fasciotomy wound length is checked by passing a finger under the fascio-cutaneous layer to ensure that it has adequately released the compartment.Often the wounds are not long enough and there is a tight band of fascia that encircles the limb like a tourniquet. This is why the mantra for wound length is from joint line to joint line.

The fascia for the deep posterior compartment is incised.The medial fasciotomy first enters the superficial posterior compartment overlying the soleus muscle. Once the fascia overlying this is released, the fascia for the deep posterior compartment is then released (overlying the Flexor Digitorum Longus muscle).
The fascia for both the superficial and deep posterior compartments is attached to the postero-medial border of the tibia. The incision for the deep fascia is anterior to the neurovascular bundle (posterior tibial artery and tibial nerve) and posterior to the tibia. The muscle under this fascia is flexor digitorum longus.
When working proximally please be careful because there is a venous plexus at the soleus line/ridge which can bleed.

The picture shows the soleus muscle (SOL) from the superficial posterior compartment and the Flexor Digitorum Longus (FDL) from the deep posterior compartment.

With the medial fasciotomy complete, the bone is better exposed and can be thoroughly debrided.The periosteum that has been torn and exposed to the environment is excised.
Any loose fragments of bone that fail the ‘tug test’ are also removed.

Gandham S, Refolo M, Fischer B, Kerin C. The management of soft tissue injuries in open tibial fractures: the ‘soft tissue tug test’. Ann R Coll Surg Engl 2019; 101(5): 1-2.

The bone ends are delivered into the wound so that the medullary cavity can be accessed and curetted to remove any debris or fracture haematoma and lavaged.The fracture haematoma acts like a “chocolate agar” petri dish and is the perfect culture medium for any pathogenic contamination.

The wounds are irrigated with warmed saline to dilute and washout any contamination.
The FLOW study was a randomised control trial comparing high (>20 psi), low (5-10 psi) and very low pressure (1-2 psi) irrigation with either saline or a castile soap solution. They found that the rates of reoperation were similar regardless of irrigation pressure but that the soap group had a higher reoperation rate compared to the saline group. We therefore use warm saline with a high flow giving set and it’s under gravity pressure.
The amount of wash is dependent on the type and extent of contamination. It should be irrigated and if necessary, further debrided until the wound bed is clean and only healthy tissue remains.

The FLOW Investigators. A trial of wound irrigation in the initial management of open fracture wounds. N Engl J Med 2015; 373(27): 2629-41.

This image demonstrates just how extensive the internal degloving is and is often much larger than the skin wound would suggest.

The fracture is manually reduced to realign the limb and attention is turned to performing the second fasciotomy incision.The visible muscles are Soleus (SOL) which is in the superficial posterior compartment and Flexor Digitorum Longus (FDL) which is in the deep posterior compartment.

The lateral fasciotomy incision is sited 2cm anterior to the fibula, over the anterior compartment, and runs from joint line to joint line.Often in ACS the leg is too swollen to palpate the fibula and only the tibial crest is palpable. Therefore the incision is placed lateral to the crest approximately 2-3cm.

The incision is directly over the anterior compartment.

Again it is recommended to perform thorough haemostasis as you proceed.

Once through the skin and fat, the anterior compartment fascia will be visible.This is incised and often the muscle herniates through due to the underlying pressure.

The fascia overlying the anterior compartment is reflected laterally and separated from the underlying muscle as you work towards the fascial septum between the anterior and lateral compartments.The superficial peroneal nerve is at risk here, so it is worth taking the time to identify it and protect it. Unfortunately it is all too common for it to be injured.
The superficial peroneal nerve provides motor supply to the peroneus longus and peroneus brevis. It then pierces the fascia approximately 10-12cm proximal to the tip of the distal fibula and courses anteriorly to supply sensory nerve fibres to the antero-lateral distal leg and dorsum of the foot.

Here the superficial peroneal nerve can be seen (SPN) as it runs distally and pierces the fascia. Proximally it is between EDL and PB.
The muscles in the anterior compartment from left to right are; Tibialis Anterior (TA), Extensor Hallucis Longus (EHL), Extensor Digitorum Longus (EDL) and Peroneus Tertius (not visible).
The muscles in the lateral compartment are Peroneus Brevis (PB) and not visible is Peroneus Longus (PL). To help remember which is which, Brevis is adjacent to the Bone.

This image demonstrates that the muscle has been badly damaged and it wasn’t visible from the medial incision.
To assess the muscle viability it can be assessed using the 4 Cs:
Colour – it should be pink and healthy and match the surrounding uninjured muscles.
Consistency – not waxy or ‘stewed’
Contractility – contracts when pinched with forceps
Capacity to bleed – capillary bleeding when cut
When working behind the bone, be aware that the posterior tibial artery and tibial nerve are in close proximity. Importantly it’s very easy to damage a deep vein which often bleeds extensively.

When performing a surgical debridement I recommend having both a monopolar and bipolar diathermy.
The monopolar diathermy is useful for dissecting but when trying to haemostase the muscle, it causes it to recoil and contract. A bipolar diathermy will allow you to haemostase the muscle without it retracting.

With both fasciotomies complete, it can be seen that even by the end of this part of the operation, the muscle injuries have continued to evolve and it would not be possible to close the wounds.
This clearly demonstrates that if the fasciotomies had not been performed, then the development of ACS was imminent.

This has to take into account what the definitive fixation will be, as well as the existing soft tissue injury and the fracture configuration. The majority of diaphyseal tibial fractures will be treated with an intramedullary nail, so the half pin positions want to be away from where the locking bolts will be sited.
Prior to making any incisions for the external fixator, it has to be planned where the half pins will be sited.
Diaphyseal tibial fractures are usually stabilised with 2 half pins proximal and 2 half pins distal to the fracture.
Proximal third tibial fractures are best treated by spanning the knee. This is because there is often insufficient bone in the proximal tibia segment to site the half pins, such that they do not negatively impact the definitive fixation i.e. the half pin position is where a tibial nail locking bolt would be sited. Also you want to avoid the primary zone of injury where possible to help protect the soft tissues.
For this fracture pattern, we will site 2 half pins in the distal femur, 1 half pin in the proximal tibia and 2 half pins in the distal tibia.

The skin incision for a half pin is approximately 1cm long and the first is placed over the antero-lateral distal femur.I prefer to do an oblique incision, as this gives two planes of movement should I need some adjustment of the pin position / angle. I also only incise the skin and deep dermis. I prefer to avoid a ‘stab’ incision down to the bone as I’m concerned that a sharp scalpel can inadvertently cause injury to a vessel.

Once through the skin, use blunt dissection to perforate the muscle fascia and create the half pin tract down to the bone.The scissors will easily perforate the fascia and then I use them to feel the bone. When satisfied that you are in the correct position, I open the scissors and withdraw them in one movement so that they open up the track to the maximum diameter. I don’t like to close the scissors while still in the patient, because something could have fallen in between the scissor blades.
The plane you are aiming for is between the quadriceps anteriorly and the ilio-tibial band laterally, and proximal enough to avoid the knee joint capsule. The supra-patellar pouch of the knee joint capsule extends approximately 2 fingers breadth proximal to the superior pole of the patella.
The leg is rotated so that the patella is facing forward and the plane / angle for half pin approach is at 45 degrees (see the angle of the scissors in the photo).

The half pin is connected to the drill brace assembly prior to insertion.The drill brace assembly has a removable handle. One end accommodates 5mm half pins and the other end is for 4mm half pins.
There is no indication for hydroxyapatite (HA) coated half pins in a temporary external fixator.

To identify the best place to insert the first half pin; hold the half pin and drill brace assembly in one hand and gently feel for the crest of the bone.With the other hand, gently stabilise the half pin at the skin level. By making a smooth and slow transverse movement of the half pin, while it is up against the bone, you will be able to feel the contour of the bone. When the half pin is at the crest of the bone, if you insert the pin here, you should be perpendicular to the bone and less likely to skid off.

To insert the half pin, first rotate the drill brace anticlockwise to create a notch in the bone surface.If you start by rotating the drill brace clockwise, the half pin often ‘wanders’ off the bone. By rotating it anticlockwise, it maintains its position and doesn’t slip. I routinely do 4-5 full revolutions while applying gentle axial pressure.
When using the drill brace you must ensure that the pin is kept in perfect alignment and doesn’t wobble, otherwise it will slip. The half pins are self-drilling, self-tapping and once the thread engages it will advance at the thread pitch (approximately 1mm) for every full rotation.

The depth of the half pin insertion is checked with the image intensifier.As you advance the half pin, it should get harder to rotate and advance as it encounters the opposite cortex. At this point, if you do 5 full rotations, the half pin should advance sufficiently to go through the cortex and have threads engaged with it.

The image intensifier and leg/half pin are rotated so that they are perpendicular to one another and the pin depth is checked.
The half pin should be inserted so that the self-drilling self-tapping portion is just through the far cortex and the half pin threads are engaging.

The second half pin is inserted using the 5-hole pin clamp to help position and direct it.The 5-hole pin clamp is loosely applied to the first half pin using hole 1 and the assistant holds it in place. The second half pin is inserted through the pin clamp using hole 5 to maximise the distance between the half pins.
The half pin is first gently placed against the skin to identify where to make the skin incision and then removed. Then using the previously described technique, the skin incision and half pin track are created. The half pin is then re-inserted through the pin clamp and into the track. The crest of the bone is identified and the half pin is inserted.

After checking the proximal two half pins are the correct depth, the 5-hole pin clamp is fastened to the half pins.At this stage you need to check that the clamp has sufficient space beneath it, in case the soft tissues swell and impinge on it. The pin clamp has 7mm square bolts which are tightened with the 7mm T-wrench.
The two bolts on the side are used to clamp the half pins and the two bolts on the top are used to clamp the posts (either angled or straight). This segment of the external fixator is now complete.

The next “block of bone fixation (distal tibia) is planned using exactly the same process.
The half pin location is planned factoring in:
The location of the joint
The fracture pattern
The soft tissue injury and fasciotomies
The anticipated definitive fixation
The safe corridors for half pin placement are shown in the next slide.

This diagram is from the Hoffmann 3 surgical technique.
It illustrates the safe corridors for half pin placement depending on the cross-sectional level of the leg. Each corridor and half pin position is dictated by the adjacent structure at risk e.g. neurovascular bundle. It also tries to avoid tethering too much muscle, as this can be painful when the muscle contracts and moves relative to the half pin. Too much muscle movement around a half pin is also associated with soft tissue irritation and infection.

The skin incision is made for the distal tibial half pins is in a safe corridor between directly anterior and directly medial (approximately between 9 o’clock to 12 o’clock).This is due to the cross sectional shape of the distal tibia and the surrounding structures at risk, in particular the neurovascular bundles.

The distal tibia half pins are inserted and are attached to another 5-hole pin clamp.The half pins are inserted at approximately a 30 degree angle from the vertical, with the foot pointing forward, into the subcutaneous border of the tibia.

Finally a 5th half pin is inserted into the proximal tibia fragment because when the quadriceps contracts this would displace the fracture reduction.The distal femur pins are positioned so that they don’t tether the quadriceps muscle. Occasionally if they are placed directly anterior through the quadriceps it causes scarring within the muscle which the patient experiences as knee stiffness.
Although the leg would be partially stabilised by constructing a frame from distal femur to distal tibia, it wouldn’t control the proximal tibia segment which would move on contraction of the quadriceps. There is also some laxity within the knee joint that contributes to the proximal segment instability, so by placing a single half pin into this piece of bone, it controls and prevents that movement.

With all of the half pins sited, the frame is constructed by attaching the posts to the pin clamps.The posts are available as angled or straight. In general I prefer the angled ones so that the frame is closer to the limb and this increases the frames’ stability.

The connecting rods are measured using the trials on the set.The green rods are trials and should not be used for definitive frame construction. They are used to select the correct rod length.

There are two different types of couplings on the set. A pin-to-rod coupling and a rod-to-rod coupling.
On the pin-to-rod coupling, one end is grey/grey and one end is green/grey. They can accommodate half pins with diameters 4/5/6mm and rods with diameters 5/8/11mm.
On the rod-to-rod coupling, both ends are green/grey. They can accommodate rods with diameters 5/8/11mm.

The couplings are loosened and snap on to the half pin (5mm) and connecting posts (11mm).

The 11mm rod is snapped into the coupling and loosely tightened with the T-Wrench.If you don’t loosely tighten them, when you apply traction to complete the reduction, the rod / half pin pops out of the coupling. If you tighten them too much, you cannot adjust the reduction.

The tibial fracture is first appropriately reduced and stabilised before spanning across the knee with connecting rods.The best and most stable frame shape is a triangle, so always try and make this shape where possible.
A classic exam question would be, what are the factors that influence frame stability? I prefer to use a systematic approach to answering this question and work from the bone sequentially through the frame:
Fracture reduction (most important)
Half pin material (titanium vs stainless steel)
Half pin diameter (increasing diameter is more rigid)
Number of half pins (more points of fixation = more stable construct)
Half pin position (near / far construct)
Multi-planar half pins are better than mono-planar fixation
Distance of coupling / pin clamp from the bone
Rod diameter
Rod material
Number of rods (doubled up parallel rods are stiffer)
Frame shape

The frame is extended to span the knee by connecting the half pin clamp posts to the tibial frame using 11mm rods and rod-to-rod couplings.It’s not obvious from the photo, but the knee should have approximately 10 degrees of flexion. This relaxes the tension on the tibial nerve and common peroneal nerve. I like to use a sterile gown pack placed under the knee to permit a little bit of flexion.

The fracture reduction is checked with the image intensifier.

The reduction doesn’t need to be anatomical as it is not the definitive fixation. However, it should realign the limb and reduce any significant tension on the soft tissues. Importantly the limb should be stable so that the patient can comfortably move around their bed without causing too much pain from fracture movement.

The frame stability should be tested by lifting the leg by the heel, and separately by the frame itself, to check that the fracture has been adequately stabilised.If the fracture displaces, then you need to reassess your frame by first checking all of the couplings are tight and then considering whether the frame construction needs supplementation.

Once reduction is conformed using II, the couplings are definitively tightened using the 7mm spanner.The spanner has a longer lever arm than the T-wrench, so it allows you to make the couplings tighter.

The skin is cleaned of blood and then the VAC dressing foam is pressed on to the wounds to create an ink blot template of the wound shape.

The foam is cut to match the wound shape and size.

The wound base is covered with a non-adherent dressing prior to applying the foam.
This prevents the soft tissues from sticking to the foam.

A separate strip of foam is used to bridge the two wounds so that a single VAC machine can be used.

The foam is held in place using sheets of self-adhesive clear plastic.
When applying the self-adhesive plastic, you must take great care to prevent any creases from forming as these will cause an air leak.
The limb should be dried prior to application and if necessary, further strips of self-adhesive plastic can be applied along each edge of the sheet of plastic, to ensure an airtight seal.
Once all of the plastic is in place, a pair of scissors is used to create a hole where the VAC connector pad will be applied.

The suction is used to remove the bulk of the air from the dressing, prior to applying the VAC connector pad.
This avoids a rate limiting step, as the VAC machine takes a long time to remove this volume of air.

The connector pad is applied and connected to the VAC machine.
The VAC machine is set initially to continuous suction, so that if there is a leak, it will alarm. If it does alarm, then you have to identify where the problem is. It is usually a crease or around a half pin. Sometimes you can see that one area of the dressing isn’t as suctioned as the rest, giving a clue that there is a leak nearby.

Finally the half pins are dressed using chlorhexidine soaked gauze and plastic half pin dressing washers.These keep the gauze in situ and allow light pressure to be applied to the skin to prevent any haematoma forming around the half pin. A haematoma could get infected and lead to a pin tract infection.