Distal radius fracture- Compound injury stabilised with Hoffman II External Fixator

This injury was sustained when a parachute collapsed 20 feet above the ground .
A PA view radiograph demonstrates an intra-articular distal radius fracture with disruption of the distal radio-ulnar joint (DRUJ) and a distal third ulna fracture.
I personally would not organise a CT at this stage, because my initial management would be a temporary external fixator. Once the wrist has been partially reduced a CT is much easier to interpret and helps plan the secondary reconstruction.

A lateral view radiograph demonstrates that the carpus is volarly translated in relation to the axis of the forearm.
A line can be drawn along the volar and dorsal cortices of the radius and the centre of rotation of the capitate should be in between the two lines.
Green’s Operative Hand Surgery. Sixth Edition: Chapter 17; Wolfe S, pp 577.

Before prepping the limb with antiseptic, it is pre-washed with soap to remove any grease/oil that would repel the water based antiseptic solution.It is open on the ulna side. Clinically the patient was neurovascularly intact prior to the operation (i.e. there was no motor or sensory deficit to the ulna, median or radial nerves).

After washing the forearm and hand the wound was inspected and any loose material removed.

The limb is prepared with antiseptic solution.I routinely use a double preparation of alcoholic chlorhexidine. The first batch has a dark pink stain and the second batch a much lighter pink stain. I use the contrast in colours between the skin and the dark pink stain to allow me to clearly see that the whole hand / arm has been painted with prep. The second batch of prep is used to ‘wash off’ the dark pink stain, so that it doesn’t leave the appearance of a cellulitic limb.
A cross-sectional survey of international orthopaedic surgeons found that 51.4% of responders would use either an alcohol based solution or added alcohol alone (when using more than one prep) in their preparation practices for open fractures.
Sprague et al. Large variations in the practice patterns of surgical antiseptic preparation solutions in patients with open and closed extremity fractures: a cross-sectional survey. Antimicrob Resist Infect Control. 2018 Nov; 29(7):148
In a separate prospective study of 6,959 consecutive spinal patients prepared with either chlorhexidine or iodine based solutions, there was no statistical difference in the incidence of surgical site infection.
Ghobrial GM et al. Preoperative skin antisepsis with chlorhexidine gluconate versus povidone-iodine: a prospective analysis of 6959 consecutive spinal surgery patients. J Neurosurg Spine. 2018 Feb; 28(2):209-214

My surgical plan was:
Debride the wound edges
Extend the wounds to allow further debridement
Assess and identify the injured structures
Formal debridement
Thorough wash with warmed saline
Liaise with Plastics to discuss wound management (they were present from the beginning of the case but it is after debridement that we decide how to proceed)
Apply the external fixator
Reduce the hand / carpus on to the forearm
Dress the wounds (simple dressing or Topical Negative Pressure – TNP)

Compound wound skin debridement, requiring the excision of the wound edges.I like to use a skin hook, as this tensions the skin and allows it to be cut cleanly (perpendicularly) with a scalpel.

Mark the planned incision, taking account of the surgical exposure required and also the location of any traumatic wounds.Each wound has now had its’ margin excised.
The next step is to plan how best to utilise the existing wounds and create an extensile approach. The vertical line of dots would represent a dorso-ulnar approach however, due to the the proximal wound, the apex of the skin flap would be too acute and potentially without an adequate blood supply. The curvi-linear dots connecting the wounds avoid this potential complication and also give better access to the volar compartment, where the neurovascular bundle can be accessed.
My recommendation is to always draw out your incision, as this allows you to change your mind.

A curvi-linear incision is centred over the ulna and connects the traumatic wounds.Blunt dissection is used to safely expose the bone and surrounding structures.
When raising any tissue flap, it is preferable to keep the flap as thick as possible to maintain the perfusion between the anatomic layers. There are perforating vessels that cross between the layers and if each layer is separately dissected out, then there is a risk that the collateral circulation may not be sufficient to maintain the perfusion of each layer.

The anatomy is carefully dissected out and identified, revealing the tract created by the bone as it punctured the skin. This wound is now ready to be deeply debrided and the bone ends delivered, curetted and washed.The loose bone in the ulnar sided wound, was actually from the distal radius metaphysis.
All wounds were connected creating a large skin flap that could be reflected to allow adequate access to the volar compartment, this is so that the tract where the distal radius perforated the ulnar sided skin can be fully explored, debrided and washed out.
Just below the Langenbeck retractor, the median nerve can be seen.
On the ulnar side of the wrist, the muscle / tendon to identify is the Flexor Carpi Ulnaris (FCU). On the radial and deep side of this, the ulnar artery and nerve can be found. Within the distal forearm, the ulnar artery is superficial to the ulnar nerve (and the artery is slightly more radial than the nerve).
In any open wrist injury with ulnar nerve symptoms, then you should also suspect and rule out an ulnar artery injury. I think it is important to explore these structures as part of my routine practice, as partial injuries cannot be excluded and it is easier to do it now versus return later and dissect through scar tissue.

The wound is irrigated with 3-6 litres of warmed sterile saline after being deeply debrided.
The FLOW study concluded that the use of low pressure to irrigate wounds may decrease the re-operation rate for infection, wound healing problems, or nonunion.
FLOW investigators. Fluid lavage of open wounds (FLOW): a multicenter, blinded, factorial pilot trial comparing alternative irrigating solutions and pressures in patients with open fractures. J Trauma 2011 Sep; 71(3): 596-606.

The tourniquet is deflated to ensure that adequate haemostasis has been achieved.

A joint decision is made between the orthopaedic and plastics teams regarding the appropriate wound management strategy.
On this occasion the decision was to close the wound after debridement and washout.
Applying a TNP dressing and returning to theatre in 48-72 hours may result in skin edge retraction and a higher chance of requiring a skin graft.

Plan external fixator pin placement taking into account the fracture location, the anatomic structures at risk and the future open approach.The zone of injury is identified with the aid of a C-arm.
The axis of the proximal radius and index metacarpal are marked using fluoroscopy.

When applying an external fixator, you must think about the next possible operation. If this case is going to be definitively treated with a plate, then the pin sites need to be far enough away, so that previously compromised soft tissue does not form part of the second surgical field.

Use skin incisions big enough to insert both half pins through. The superficial radial nerve is at risk from this procedure, so using an adequate sized incision lowers this risk.The superficial radial nerve runs on the deep border of the brachioradialis muscle and radial to the radial artery.
By placing two mini Hohmann retractors either side of the radius, this helps to stabilise the bone and also safely retract the soft tissues (brachioradialis and superficial radial nerve are taken dorso-radial and the radial artery is taken volar-ulnar). This exposes the fibres of Pronator Teres (PT) inserting on to the dorso-radial aspect of the radius. It is not necessary to release all of PT and a few fibres can be released at the exact point that the half pin is to be inserted.

The Hoffman half pins are inserted directly into the bone, or a pilot hole can be drilled initially. Initial placement is into the radius.The half pins are self drilling and self tapping however, I often find that they ‘walk’ themselves off the bone (despite doing multiple anti-clockwise revolutions first).
I therefore use a 2mm drill to create a pilot hole, which I feel gives me more control of the insertion point and angle of insertion.
I like the half pins to be inserted at approximately 45 degrees to the direct dorsal / direct lateral plane. This means that if you decide to return to theatre for a definitive open reduction internal fixation, then the fixator can be left in situ and it helps facilitate the reduction. Placing it directly dorsal prevents you from supinating the forearm. Placing it directly lateral can leave hardware overlying the lateral radiographic view.

The half pin is inserted by hand using the pin driver. I would caution against trying to insert a half pin on power, as it’s very easy to wrap up the soft tissues or ‘walk off’ the bone and plunge into the forearm.
If the entry point is eccentric on the bone, then you won’t get the second cortex of resistance, as you have missed the medullary space. Care must therefore be taken with the insertion point and also the depth that the half pin is advanced to.

Once one half pin is satisfactorily sited, the 4 hole pin clamp is used to determine the correct position for the next half pin in the radius.The 4 hole pin clamp is loosely applied to the half pin and a second pin is passed through the clamp and on to the bone. This can either be inserted by hand using the pin driver, or alternatively the insertion point can be noted and a pilot hole drilled.
The 4 hole pin clamp will accept half pins with either 3mm or 4mm diameters but all pins held by the one clamp must have the same diameter.

A fluoroscopic image demonstrates that the pins have been sited appropriately.

Half pins are inserted through the clamp into the index metacarpal.Attention is turned to the index metacarpal and the process repeated.
I’ve used a single incision to ensure that any terminal branches of the superficial radial nerve are carefully retracted and not cut, which could lead to a painful neuroma. The tendons have also been safely moved to one side.
The image shows another technique which I use when the pilot hole has to be precisely positioned. If the pilot hole were at the wrong spacing or angle for the clamp, then when the clamp is tightened on to the half pin, it could stress the metacarpal and cause a fracture.
The half pin is held within the clamp and the point where it touches the metacarpal is marked with a sterile marker pen. A pilot hole is then drilled at this level and in the centre of the bone (with care taken to match the angle of the previous pin).

The 4 hole pin clamps are securely fixed to the half pins at both sites and at a level that will allow for any swelling and also access to the arm for bandages.The 30 degree angled posts are then inserted into the 4 hole pin clamp and secured.

The frame is loosely constructed with two rods between the clamps. The rod to rod coupling is used to connect the 30 degree angled posts to the 5mm radiolucent connecting rods. These are loosely tightened to prevent them from snapping off the rods but not too tight so as to prevent any movement.
The fracture is then manipulated under fluoroscopy until an adequate reduction has been achieved.
Techniques to achieve fracture reduction include:
Direct longitudinal traction
Ulnar deviation to restore the radial inclination
Using a bandage / bump under the distal forearm to restore the volar tilt
Supinating / pronating the forearm or hand to restore the rotational alignment
The couplings are then definitively tightened before the traction and reduction manoeuvre is released.

The fracture is manipulated and reduced under fluoroscopy and then the frame is securely tightened to maintain the fracture reduction. This fracture configuration has an intra-articular die punch component.
It should be noted that an indirect reduction relies upon ligamentotaxis. Ligamentotaxis will only reduce fracture fragments that have a soft tissue attachment, therefore it is not possible to reduce a die punch injury using this technique alone.
The radius is still short but for a temporary reduction this is adequate. Also over-distraction of the radio-carpal joint can lead to increased stiffness and precipitate a complex regional pain syndrome (CRPS).
The purpose of the temporary fixator is to correctly align the hand with the forearm and provide enough stability for the soft tissue injury to recover.
This is not the definitive fixation in this case.

The lateral fluoroscopic image demonstrates that the volar translation of the carpus has been corrected and the hand is in alignment with the forearm.
The half pin in the index metacarpal is also not too long.
Once satisfied with your reduction, I recommend that you systematically go round each coupling and double check the tightening. It is often possible to improve it.

A single incision has been used to insert each pair of half pins so it is necessary to close the skin between the pins.I prefer to use a horizontal mattress stitch, as it everts the wound edges nicely.

At the end of the procedure, the previous wound is checked to ensure that there is no evidence of compartment syndrome i.e. the forearm is grossly swollen and the stitches are bursting.

The wounds are dressed with a non-adherent dressing.

The pin sites are also covered with a non-adherent dressing.
The traumatic wound is then covered with a C-view dressing.

The pin sites are covered with alcoholic chlorhexidine soaked gauze and then clips are added to the pins to keep pressure on the dressings.The purpose of the clips is to prevent any haematoma forming around the pin sites which could become infected.
There are lots of different ways to dress a pin site but the general principle is to keep them clean and prevent haematoma formation around the pin that could become infected.

The forearm is dressed with wool and you’ll remember that we discussed the distance of the external fixator construct from the forearm previously, this is to allow the easy passing of dressings underneath it (but not at the expense of fracture stability).

Finally a bandage is applied and this is to allow some moderate compression and prevent a haematoma formation.It also helps to support the soft tissues and reduce their movement and thus enable the swelling to resolve quicker.