CASE 59 PILON FRACTURE

1. Describe the radiographs pictured above.

These are AP and lateral radiographs showing a comminuted and displaced pilon fracture. There is articular impaction and comminution, as well as metaphyseal comminution, as is typical with most pilon fractures.

2. What is the typical mechanism of injury?

The mechanism of injury is axial load. They are usually sustained as a result of a high-energy injury, commonly after a fall from height or a motor vehicle accident.

3. How would you manage this injury initially?

This is a high-energy injury with the potential for other life- or limb-threatening injuries. I would manage this patient in the emergency department as per ATLS guidelines with concurrent assessment and treatment using an ABCDE approach. The limb itself must be carefully inspected and assessed for the degree of soft tissue injury as this will be the deciding factor in how to manage the fracture initially.

After sufficient analgesia, I would perform a circumferential examination of the limb, looking for any evidence of open injury and documenting the degree of skin damage, contusion or fracture blistering. A thorough neurovascular examination should be performed. This would include palpation of the posterior tibial artery and dorsalis pedis artery, as well as an examination of the capillary refill to ensure an intact vascular supply, followed by examination of the five nerves to cross the ankle joint: superficial and deep peroneal nerves; tibial nerve (which branches into the medial and lateral plantar nerves to supply the sole); sural nerve and the saphenous nerve.

Any skin tenting or impending breaches would be managed emergently with a closed reduction under sedation in the emergency department. Compartment syndrome is less common in pilon fractures than tibial shaft fractures but would require a high index of suspicion to ensure early recognition.

Assuming that this is an isolated injury, a closed reduction would be performed prior to placing the patient into a plaster of Paris backslab for immobilisation, pain relief and limb/fracture alignment. The hindfoot should be aligned with the tibia and any rotational deformity corrected.

4. Would you want any further investigations prior to determining your treatment of choice?

A CT scan would allow for better visualisation of the fracture configuration, partic- ularly the intra-articular component, and is vital for preoperative planning. If these are greatly displaced, a CT scan following spanning external fixation is generally more useful.

5. How can one classify such injuries?

There is no commonly accepted classification for intra-articular fractures of the dis- tal tibia. Two classification systems that can be applied include the AO classification or the Ruedi and Allgower classification.

The former system allocates 4-3 to the distal tibia (four for tibia and three for the distal portion). 43A fractures are extra-articular and therefore not true pilon fractures as the plafond is unaffected. 43B refers to partial articular fractures and 43C refers to complete articular fractures. C type fractures are further subdivided into C1 (simple articular), C2 (simple articular, complex metaphyseal) and C3 (com- plex articular, complex metaphyseal).

The latter classification system is divided into types I, II or III. Type I is an undis- placed pilon fracture, type II is a fracture with significant joint incongruity but without comminution, and type III is a comminuted intra-articular fracture.

6. What are the common intra-articular fragments associated with a pilon fracture?

These are

1. 1. – Anterolateral fragment (Chaput fragment). This is the attachment of the anterior inferior tibiofibular ligament
   2. – Posterolateral fragment (Volkmann fragment). This is the attachment of the posterior inferior tibiofibular ligament
   3. – Medial malleolus. This is the attachment of the deltoid ligament
   4. – Die punch fragment. This is the central articular fragment which lacks soft tissue attachment and therefore cannot be reduced by ligamentotaxis. It can prevent reduction and must be addressed by direct visualisation. These frag- ments vary in size and number depending on the degree of comminution.

7. How would you manage this after an initial closed reduction in the emergency department, assuming it’s a closed and neurovascularly intact injury?

The treatment of pilon fractures is complex and many different treatment options are described, both for initial management and definitive management.

If the patient is fit for surgical management and has a displaced fracture, I would discuss operative treatment with the patient. However, there is controversy regard- ing the timing of surgery for these complex, high-energy, intra-articular injuries. One must decide between a ‘span and scan’ method of treatment or early ORIF. In the former, a spanning external fixator is applied to the affected limb prior to obtain- ing a CT scan and planning for conversion to ORIF once swelling has subsided, the soft tissue envelope is healthy, and there is no evidence of pin site infection.

For the ‘span and scan’ approach, I would insert two tibial shaft half pins (away from the zone of injury). I would incise the skin then spread the soft tissues bluntly down to bone. I would use a sharp drill bit with a sleeve and irrigate whilst pre- drilling the cortex to avoid heat damage, before finally inserting the appropriate pin using a sleeve. This would be followed by the calcaneal transfixion pin into the calcaneal tuberosity, from medial to lateral, to protect the NV structures behind the medial malleolus. To prevent an equinus deformity of the ankle, a single 4 mm pin can be inserted into the base of the first metatarsal. I would connect these pins using clamps and rods to reduce the fracture and maintain that ankle at 90 degrees.

Ultimately, the decision between early ORIF and ‘span-and-scan’ depends on a multitude of factors, the most important of which are the state of the soft tissues, the mechanism of injury, the patient’s physiological age and co-morbidities, and the availability of expertise to treat this complex injury.

The principles of the definitive surgery are to restore anatomical reduction of the articular surface, reconnect the articular surface to the metaphysis, and then the metaphysis to the diaphysis, whilst protecting the soft tissue envelope. ORIF as both initial and definitive management requires an honest assessment of the state of the soft tissues.

My favoured approach for ORIF of a pilon fracture is the anteromedial approach. It is the workhorse approach to the ankle as it’s extensile and can be used for future surgery such as potential ankle fusion or ankle arthroplasty.

In some cases, a posterolateral approach to the tibia is required initially where there is a displaced posterior malleolus fragment. The patient is placed prone and the internervous plane between FHL (tibial nerve) and the peroneal tendons (super- ficial peroneal nerve) is utilised to expose, reduce and buttress the fragment. The posterior malleolus fragment can then be used as the keystone for reconstruction through an anteromedial approach. If required, the fibula may be reduced and fixed through this same incision.

8. Can you describe the anterior approach to the ankle and how you would reduce and fix the fracture?

The patient is placed supine with a pneumatic thigh tourniquet. An incision is placed just medial to the tibialis anterior, starting approximately 10 cm proximal to the ankle joint and extending over the ankle joint towards the second ray. The extensor retinaculum is incised and the tibialis anterior tendon sheath is kept intact to minimise wound problems. The plane between EHL (medially) and EDL (later- ally) is identified. The NV bundle (anterior tibial artery and deep peroneal nerve) lies between these two tendons just proximal to the ankle and is behind EHL at the level of the ankle joint. EHL and the NV bundle are retracted medially and EDL is retracted laterally. The ankle joint capsule is incised in line with the incision and the full width of the ankle joint can be exposed by subperiosteal dissection.

The fracture is opened to expose the die punch fragment which must be reduced and held to the posterior malleolus to prevent it from blocking reduction of the main fragments. The remaining fragments are provisionally fixed to the posterior malleo- lus with K-wires and clamps, before fixing these definitively with a site-specific lock- ing plate. My preference is for an anterolateral plate, as opposed to an anteromedial plate over which there would be little soft tissue coverage.

Where there is difficulty reducing the fracture fragments, application of a dis- tractor can help with visualisation of the articular surface and may also align several of the major articular fragments. One Schanz pin is placed into the talus and the other into the tibia.

9. What other options exist for definitive management of pilon fractures?

An external fixator or circular frame may be used. However, there is a higher rate of mal-union associated with external fixator use and the inability to reduce the die punch fragment leads to less anatomical reconstruction of the articular surface. However, clinical trials have failed to show conclusive superiority of ORIF or external fixation.

10. How would you manage a fibular fracture associated with a pilon fracture? Fibular fractures associated with pilon-type injuries to the distal tibia can be man- aged in a number of ways. They can be managed conservatively, reduced and fixed with a view to helping re-establish lateral column length or the fibula can be taken as bone graft used to augment external fixation.

A retrospective case control study from a level-one trauma centre in the United States could find no significant difference in outcomes among three groups: Fibular fixation, no fibular fixation, no fibular fracture. The only difference was that the group who underwent fibular fixation had a statistically higher rate of metalwork removal.

11. What are the complications of this injury when managed operatively?

Starting with early complications, these would include wound dehiscence and infec- tion, particularly in open fractures or where the state of the soft tissue envelope is