Tibial Pilon Fractures





KEY FACTS





  • The tibial pilon fracture is a rare, yet devastating injury.




    • Despite the best treatment, patients sustaining high-energy pilon fractures generally do not return to their previous state of general health or function.



    • After recovery from pilon fractures, many patients continue to have debilitating pain and ankle stiffness.




  • Pilon fractures can occur from both low- and high-energy mechanisms.



  • The pilon fracture usually has an anterolateral (Chaput) fragment and a posterolateral (Volkmann) fragment.




    • Fragments usually remain attached to the distal fibula segment by the anterior and posterior tibiofibular ligaments.




  • Initial management of pilon fractures depends as much on the soft tissue as the bony injury.




    • Understanding the soft tissue injury accompanying pilon fractures is of utmost importance for providing optimal treatment while minimizing complications.




  • Indications for closed reduction and cast treatment of pilon fractures are limited.




    • Pilon fractures treated with a cast have led to poorer outcomes than those managed operatively.




  • Surgical timing and type of fixation utilized is largely dictated by the condition of the soft tissues.




    • Surgical options include the following: Bridging external fixation, external fixation with limited internal fixation, nonspanning external fixation ± limited internal fixation, and staged open reduction and internal fixation.




  • Complications following surgical management of pilon fractures, particularly wound breakdown, were historically common.




    • Wound complications can be minimized with appropriate treatment strategies and soft tissue handling.




  • Other common complications seen following treatment of tibial pilon fractures are arthrofibrosis and posttraumatic arthritis.






Pilon fracture map.

Primary fracture lines of 40 OTA-type 43C3 fractures are shown. Fracture lines were mapped from axial CT cuts 3 mm above the plafond after an external fixator had been applied. Appreciate the consistent Y pattern creating 3 main articular fragments.







Pilon comminution pattern.

Impaction most commonly occurs at the dome between the 3 main fracture fragments. Anterolateral comminution is commonly encountered with high-energy fractures. Collectively, these 2 maps aid the surgeon in predicting necessary surgical tactics and approaches.








Arbeitsgemeinschaft für Osteosynthesefragen/OTA pilon fracture classification system is shown.








Axial CT shows fracture lines dividing the plafond into 3 major fragments: Anterolateral, posterior, and medial. There are also multiple small, comminuted fragments. Sclerosis is due to impacted bone fragments/trabeculae. The small flake of bone medially is consistent with flexor retinaculum avulsion. (From DI: MSK Non-Trauma.)






TERMINOLOGY


Definitions





  • Pilon is a French term used to describe a fracture of the distal tibia usually characterized by high-energy traits, including dissociation of the articular surface from the tibia shaft.




    • Destot coined the term pilon, as he thought that the distal tibial metaphysis resembled a pharmacist’s pestle.




  • Plafond is also a French term, described by Bonin, referring to the distal tibial articular surface as the roof (ceiling) of the ankle joint.





Anatomy


Normal Anatomy





  • At the level of the ankle, the distal tibia is intimately associated with the fibula through strong ligamentous attachments.




    • The attachments are as follows:




      • Anterior inferior tibiofibular ligament



      • Posterior inferior tibiofibular ligament



      • Interosseous ligament



      • Inferior transverse ligament





  • The articular surface of the distal tibia is concave in both the coronal as well as the sagittal plane.



  • The talus has the opposite geometry of the tibial plafond and therefore serves as a perfect template for assessing articular reduction of the distal tibia.



  • The concave tibial plafond provides ~ 40% more posterior than anterior coverage.



Fracture Anatomy





  • The pilon fracture usually has an anterolateral (Chaput) fragment and a posterolateral (Volkmann) fragment, which usually remain attached to the distal fibula segment by the anterior and posterior tibiofibular ligaments.



  • In the vast majority of pilon fractures, the fracture lines propagate from the fibular incisura laterally in the shape of a Y to exit anterior and posterior to the medial malleolus.



  • Comminution, which frequently occurs with high-energy pilon fractures, is most typically located in the anterolateral and central regions of the plafond.



Surrounding Soft Tissue Anatomy





  • There simply is not a lot of soft tissue around the distal tibia, as compared to more proximal parts of the leg.




    • There is no muscle tissue to “cushion” or protect the bone if skin is injured.




  • The tendons of the anterior compartment, the dorsalis pedis artery, and the superficial and deep peroneal nerves can be encountered with anterior exposures at the level of the ankle joint.



  • The tendinous and neurovascular structures are covered proximally by the investing fascia of the anterior compartment and distally by the extensor retinaculum.



  • The superficial peroneal and saphenous nerves are superficial to the fascia.




    • The superficial peroneal nerve pierces the fascia of the lateral compartment ~ 12 cm proximal to the ankle joint en route to provide sensation to a majority of the dorsum of the foot.




  • Anterolateral exposures for pilon fractures risk injury to the superficial peroneal nerve.



  • The dorsalis pedis and deep peroneal nerve are at risk with an anterior exposure.




    • They run together in the pericapsular fat between the extensory digitorum and extensor hallucis longus tendons.






Understanding Injury


Context and Mechanism





  • The tibial pilon fracture is a rare yet devastating injury.



  • Despite the best treatment, patients sustaining high-energy pilon fractures generally do not return to their previous state of general health or function.




    • After recovery from pilon fractures, many patients continue to have debilitating pain and ankle stiffness (Babis et al 1997, Sands et al 1998, Pollak et al 2003).




  • Fortunately, pilon fractures compose a minority of tibia or lower extremity fractures, occurring in ~ 7% and 1% of all cases, respectively.



  • Pilon fractures can occur from both low- and high-energy mechanisms.




    • Low-energy fractures typically occur due to rotational forces imparted to the distal tibia.



    • High-energy fractures are generally due to axial force that drives the talus into the tibial plafond, causing an “implosion” of the articular surface.




  • In the most severe plafond fracture patterns, the articular segment is fractured into numerous pieces with certain segments driven proximally into the metaphysis, creating marked joint incongruity and associated metaphyseal defects.



  • An associated fibula fracture is often present in pilon fractures.



  • The most common fracture pattern occurs with the ankle in dorsiflexion (i.e., the foot on the brake pedal during a motor vehicle accident).




    • When the ankle is dorsiflexed at the time of injury, pilon fracture patterns involve the anterior articular surface of the tibial plafond.




  • Central articular (implosion) injury is the result of an axial load on the foot in neutral position.



  • A severely traumatized soft tissue envelope accompanies the higher energy pilon fractures.




    • Although many pilon fractures are open injuries, closed fractures have significant soft tissue compromise as well.




  • Initial management of pilon fractures depends as much on the soft tissue as the bony injury.




    • Understanding the soft tissue injury accompanying pilon fractures is of utmost importance for providing optimal treatment while minimizing complications.




Classification





  • Classification systems have been developed to stratify both severity of fracture pattern and soft tissue injury.



  • Although the Arbeitsgemeinschaft für Osteosynthesefragen (AO)/Orthopaedic Trauma Association (OTA) classification system is the most widely accepted fracture classification system, the Ruedi-Allgower system is the classic fracture scheme often known and used for this injury throughout the world.



  • Ruedi-Allgower type 1 fractures are minimally displaced cleavage fractures, in contrast to type 2 injuries, which are displaced. Type 3 injuries portend the worst prognosis as a consequence of articular comminution and metaphyseal impaction.



  • Moderate interobserver reliability makes the AO/OTA system reliable for classifying pilon fractures (Swiontkowski et al 1997).




    • The distal tibia is designated as #43 (4 = tibia, 3 = distal segment).



    • The fractures are divided into types and further into groups then subgroups.




  • 43C patterns are high-energy injuries with a compromised soft tissue envelope.




    • Irreversible damage to the articular cartilage, and at times the soft tissues, occurs at the time of injury.




  • Soft tissue injury has been standardized using the method of Tscherne for closed fractures and the Gustilo-Anderson classification for open injuries.




    • The Tscherne scheme has 4 grades of increasing severity for soft tissue injury in closed fractures.




      • Tscherne grades 0 and 1 have negligible soft tissue injury and superficial abrasions/contusion, respectively.



      • Type 2 Tscherne injury describes advanced muscle contusion and deep, potentially contaminated abrasions.



      • Pilon fractures with extensive crush, degloving, or vascular injury are considered type 3.




    • The most widely accepted open fracture classification is credited to Gustilo and Anderson.




      • Gustilo type 1 open fractures are generally clean with a < 1-cm skin laceration.



      • Type 2 open fractures have more extensive soft tissue injury with minimal to moderate crushing, typically with a laceration > 1 cm.



      • Open pilon fracture with extensive soft tissue injury and a severe crush component are graded as type 3.




        • Type 3A open fractures have adequate soft tissue coverage over the fracture.



        • Type 3B are usually contaminated with extensive periosteal stripping and bone exposure necessitating flap coverage.



        • Open fractures with vascular injury requiring repair along with extensive soft tissue compromise are considered type 3C.






Evaluation





  • In view of the fact that most pilon fractures usually occur as the result of violent trauma (i.e., motor vehicle accident), associated bodily injuries must be considered in the work-up of these patients.



  • Examination should document the presence of both closed and open soft tissue injury as well as location and extent of lacerations, abrasions, and contamination.



  • A systemic motor and sensory examination is warranted in addition to documentation of distal pulses.



  • Leg compartment syndrome should be diagnosed based on clinical examination and confirmed if necessary with compartment pressures.



  • Radiographs are critical for characterization of the bony injury and joint position and must include an ankle anteroposterior, mortise, and lateral view.




    • Traction views may be valuable for further characterization of the pilon fracture.




  • Computed tomography (CT) examination is best delayed until restoration of length in shortened fractures because ligamentotaxis helps to better approximate fragments closer to their native position, making interpretation easier.



  • Initial splinting in the emergency room decreases further soft tissue trauma, and fracture dislocations should be reduced with adequate anesthesia to restore joint alignment.



  • Open wounds are covered with moist gauze, and antibiotic and tetanus protocols are employed.



Historical Discussion





  • Ruedi and Allgower revolutionized the management of pilon fractures after reporting their operative strategy in 1969.



  • The series reported by Ruedi and Allgower described superior outcomes after formal open reduction and internal fixation (ORIF) in their patient population with few major complications.



  • The operative principles described by the AO group for operating pilon fractures serves as a working paradigm for ORIF of these injuries.




    • Principle 1: Length and rotation is restored by ORIF of the fibula.



    • Principle 2: Anatomical reconstruction of the articular surface of the tibial plafond is performed after the acute phase of the injury.



    • Principle 3: Metaphyseal bone defects are bone grafted to buttress the articular surface.



    • Principle 4: Buttressing of the tibial metaphysis is then required while connecting the articular block to the diaphysis.




  • These principles (perhaps with #3 optional), restoration of articular surface, realign joint surface to shaft, then bridge metaphyseal comminution with fixation, can be applied to any periarticular fracture.



  • The results of the classic study from the Swiss AO group could not, however, be reproduced by all surgeons.




    • Reports describing ORIF of tibial pilon fractures revealed a concerning complication rate with higher energy pilon fractures, including wound problems, deep infection, nonunion, and malunion (McFerran et al 1992, Teeny and Wiss 1993).




  • Recognition of a different category of higher energy pilon injuries emerged, which was quite different than those treated by Ruedi and Allgower, who treated lower energy injuries primarily in healthy skiers: So-called “boot top injuries.”



  • New research was undertaken to determine the best way to manage higher energy fractures of the tibial plafond in response to the higher rates of infection.



  • External fixation alone became popular for managing complex pilon fractures associated with both closed and open compromised soft tissue envelopes.




    • The rate of deep infection decreased with external fixation, however, at a cost.



    • The quality of reduction with external fixation alone was suboptimal, leading to poor outcomes secondary to joint arthrosis.




  • Initial external fixator constructs spanned the ankle joint until fracture union, resulting in unacceptable ankle stiffness.



  • Small wire epiphyseal-diaphyseal ring fixators were then employed to treat pilon fractures to allow for early ankle motion in an effort to minimize long-term ankle stiffness.



  • Limited ORIF to improve articular reductions without formal operative exposures was then employed to supplement external fixation strategies.



  • Unsatisfied with the limitations of external fixation strategies, including compromised articular reduction, pin tract complications, and patient dissatisfaction, new strategies to allow for ORIF were investigated.



  • Protocols developed to enhance soft tissue recovery prior to definitive operative fracture fixation, including greater waiting time for such recovery, became the mainstay.



  • A common modern algorithm is to apply a spanning external fixator to maintain length urgently following injury.




    • Once the swelling has peaked and regressed 1-3 weeks after injury, open reduction of the tibia (and fibula) can be performed with removal of the temporary external fixator.




  • Some surgeons have found that immediate (within a few hours of injury) open reduction, prior to significant swelling, can be performed safely.




    • There may be some benefits to this technique with possibly less swelling and stiffness.



    • This is still an emerging technique, and the risk of opening a pilon fracture during the initial stages of swelling could be devastating.



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Oct 29, 2019 | Posted by in ORTHOPEDIC | Comments Off on Tibial Pilon Fractures
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