Pilon Fractures
Tibial pilon fractures represent 1% of all lower limb fractures. They usually result from high-energy trauma and are associated with significant soft tissue injuries. They may also occur after a low-energy twisting injury in the presence of osteoporotic bone.
Mechanism
Pilon fractures are usually caused by a combination of axial and torsional forces following a fall from height or road traffic collisions. An axial load drives the talar dome into the distal tibia with the ankle position influencing the pattern of injury. The fibula, fractured in the majority of cases, is important in understanding the mechanism of injury and as a reference during surgical fixation to help determine correct limb length, alignment, and rotation.
Commonly seen fracture fragments in plafond are defined by the ligamentous attachments around the ankle; posterolateral (Volkmann’s), anterolateral (Chaput), and medial (Deltoid) fragments.
Soft tissue envelope around the distal tibia is thin and constrained, and the majority of the blood supply is supported by an anastamotic network of extra-osseous vessels from the posterior tibial and anterior tibial arteries. Therefore these fractures require careful attention to the soft tissue envelope for the timing and method of surgical fixation.
Classification
Ruedi and Allgower classification (based on the degree of articular comminution)
Type I - undisplaced cleavage fractures
Type II - displaced fracture fragments with minimal comminution
Type III - high degree of comminution and displacement
AO Classification (described as 43)
Type A - extra-articular
Type B - partial articular
Type C - total articular
CT Classification
Topliss, Jackson and Atkins used CT scans on 126 consecutive pilon fractures. Their study offered a CT-based classification of fracture pattern variability. They classified fracture patterns as either ‘sagittal’ or ‘coronal’, based on the main fracture line from the axial CT cuts at the plafond level.
Assessment
Plain radiographs, obtained initially and after provisional reduction, and a CT scan after initial stabilisation, are essential to fully understand the anatomy of fracture and formulate an adequate preoperative plan (span, scan and plan approach). Soft tissues should be assessed carefully for swelling, blisters, puncture wounds and degloving.
Tornetta et al. correlated radiographs and CT scans in 22 (82%) patients with pilon fractures. Based on the CT findings, they altered their surgical approach in 64% of their patients.
Management
Non-operative management is reserved only for low-energy, undisplaced articular fractures and patients who carry high risks of surgery (significant medical co-morbidities, low physical demands with an acceptable alignment of the fracture).
Surgical Management
Emergency Management
In case of a low-energy rotational injury without soft-tissue compromise, it is usually safe to immobilise the extremity in a cast and plan for an early ORIF.
High-energy pilon fractures usually are treated in two stages. Emergency management of closed fractures includes reduction of displaced fracture and temporary stabilisation with a bridging external fixator until soft tissues settle down (10-14 days) to allow definitive fixation (span, scan and plan approach, as above).
Two major objectives in the management of these injuries include restoration of the articular surface and preservation of the soft tissue envelope to optimise osseous healing and minimise complications. Open fractures are managed as per BOAST guidelines. Multiply-injured patients are assessed and managed as per ATLS principles.
The timing of fibular fixation is controversial, as an acute inappropriate incision placement for fibular fixation (to restore the length along with a bridging external fixator) can compromise subsequent approaches.
Definitive Management
When soft tissue swelling and blisters settle, definitive fixation is undertaken. It is vital to understand the fracture anatomy before planning surgery through adequate imaging.
Multiple options are described for definitive fixation of pilon fractures, but there is no level I evidence for their optimal management.
Surgical Approaches
The distal tibia can be approached through different surgical intervals depending on the presence of an open wound, residual fracture blisters and the location of key fracture fragments.
The anteromedial, anterolateral, anterior, lateral, posteromedial and posterolateral approaches have been described and used depending on the above factors and surgeon’s preference.
There is no single surgical technique for these fractures and a step-wise reduction of fracture fragments, attempted restoration of the joint surface with K-wires, followed by stable internal fixation is performed.
Open Reduction and Internal Fixation
The restoration of the articular surface normally starts by opening the more anterior articular fragments to visualise the central and posterior fragments.
The individual articular fragments are reduced from posterior to anterior, with provisional reduction performed with K-wires, and definitive fixation with two or three screws.
When the articular reduction is achieved, multiple anatomical low profile locking or non-locking plates are available to connect the articular fragment to the tibia.
As a general rule, fracture patterns that end with valgus failure and lateral compression (coronal patterns) are better fixed with anterolateral plating. Fracture patterns that end with varus angulation of the tibia with lateral tension failure and compression of the medial side (sagittal patterns) are better stabilised with medial buttress plates.
Controversy exists regarding fibular fixation in pilon fractures. Ruedi and Allgower recommended fixing the fibula first to restore the length of the lateral column, followed by the rest of the fracture fixation. However, in cases of severe fibular comminution, restoring the length is difficult. In case of using an anterolateral approach, care should be taken to leave at least 6 cm skin bridge from the fibular incision.
Lee et al. found a lower rate of malunion and ankle arthrosis in 6 years of follow-up when the fibula was fixed with plating compared to pin fixation. Rouhani et al. and Williams et al. found no clinical difference at 6-month and at 2-year follow-ups, respectively, in patients treated with ankle-bridging external fixation, with or without fibula plating. The plating group suffered more wound complications, and the non-plating group had more incidence of angular malunion.
External Fixation with or without Limited ORIF
Indications for an external fixation include severely comminuted fractures, large articular fragments reducible by ligamentotaxis, open fractures with significant soft-tissue injury or contamination and patients with co-morbidities. This can be utilised with or without a limited ORIF.
Different configurations of external fixators can be used; however, most surgeons recommend at least two or three pins proximal to the fracture, inserted from different directions with a cross-braced frame, and at least two or three tensioned 2 mm wires in the articular portion.
Many authors have reported the results of external fixation with limited ORIF to be comparable with ORIF alone. A meta-analysis by Wang et al., including the results of 9 studies (498 fractures), comparing these two techniques, reported that the rates of non-union, malunion, delayed union, infection, subsequent arthrosis and chronic osteomyelitis were comparable between groups.
Pin-site infection has been reported to be a serious complication with prolonged external fixation. It can be controlled and managed with an integrated multidisciplinary approach. Deep infection rates vary significantly in the literature and are biased by a higher proportion of open injuries treated definitively with external fixation.
Papadokostakis et al. reviewed the merits of spanning versus non-spanning frames and found, in their systematic review, that the overall deep infection rate with non-spanning frames was 2.7% and in the spanning group was 3.9%.
McDonald et al. retrospectively reviewed 13 pilon fractures, treated with non-bridging three-ring circular frame, with a minimally invasive approach to articular reduction. Eleven fractures healed by 16 weeks. There was one delayed union that required bone grafting and one non-union treated with an arthrodesis. There were no deep infections.
Watson et al. reviewed 107 pilon fractures treated according to a staged protocol. Forty-one patients had ORIF with minimal incisions and low-profile implants, with most cases managed within 5 days of presentation. Sixty-four patients underwent limited internal fixation of the articular fragments through small incisions and fine wire external fixation as definitive management. For the type C fractures in both groups, there was a significantly higher rate of complications including non-union, malunion and wound complications. Some would argue that internal fixation when performed within 5 days of injury might have accounted for the higher complication rate, but this group was selected on the basis of the less severe soft tissue injuries.
Pilon Fractures Treatment Algorithm (Reproduced with permission, Jacob et al. Management of high-energy tibial pilon fractures, Strat Traum Limb Recon (2015) 10:137–147)
Outcomes
The outcomes of surgically treated pilon fractures frequently depend on the associated injury to, and management of, the soft tissues and accuracy of the articular reduction. Pollak et al., in a retrospective study, reported that 43% of previously working patients were unemployed after suffering the injury and 68% of individuals attributed their situation to sequelae of their fractures. Rates of delayed union and non-union increase with fracture severity and soft tissue injury, especially open fractures, but were quoted to be around 5%.
Sands et al. reported similar outcomes. Another very important finding was that clinical results usually deteriorate with time, and the incidence of post-traumatic arthritis significantly increases over time.
Sirkin et al., in their landmark paper that popularised the staged approach to the management, found that in their closed group of pilon fractures (29 patients), 5 patients developed wound-related problems, which did not escalate to deep infection. One patient developed a chronic discharging sinus that resolved with fracture consolidation and metalwork removal. The open fracture group (17 patients) had two late deep infections and one patient had a below knee amputation.
Using a two-stage minimally invasive technique, Borens et al. reported on 17 patients with good to excellent radiographic results, using low-profile non-locking plates, at 17-month follow-up, although 41 % had developed moderate arthritis by that stage.
Blauth et al. compared three methods of treatment in a cohort of 51 patients with 47 type C fractures. Twenty-eight patients were treated with one-stage articular reduction and bridging external fixation. Fifteen were treated with primary plate fixation, and eight patients had a two-stage minimally invasive intervention, with application of a medial plate when the soft tissues had recovered. The latter option yielded the best results although two comparative groups used in their study, are not considered as reliable management options anymore.
References
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