Pilon fracture refers to an injury caused by the talus striking the articular surface of the distal tibia, which is mostly caused by high-energy injuries such as high fall injuries and traffic injuries, and often leads to comminuted fractures of the distal tibia, metaphysis and weight-bearing surfaces. At present, for high-energy Pilon fractures, clinicians mainly adopt staged treatment, that is, the first stage uses external fixation to reconstruct the soft tissue, and the second stage uses open reduction and internal fixation to anatomically reduce the fracture. Staging treatment greatly reduces the occurrence of postoperative complications and greatly improves the prognosis of Pilon fractures.
At present, it has become a consensus to stage the treatment of high-energy Pilon fractures. Rüedi and Allgöwer et al. published a report on the good prognosis of surgical efficacy in patients with Pilon fractures, and proposed four treatment principles for Pilon fractures: restore fibular length; reconstruction of the articular surface; Bone grafting fills metaphyseal bone defects; The medial plate provides medial tibial support. This principle is still in use today. Due to the complexity and individual differences of Pilon fractures, the content of the four treatment principles has been continuously expanded, and many controversies have arisen among them, which are worthy of in-depth consideration by clinicians.
Clinical cases
The patient, a 47-year-old male, suffered a fall from a height, landed on both feet, and suffered pain, swelling, and deformity in both ankles after the injury, and a bone abrasion sensation could be detected. No chest and abdomen pain, no neck, chest and back pain. Physical examination showed no open wounds on both ankles and lower legs, marked swelling and tenderness, high skin tone, normal dorsalis pedis pulsation, sensation and active movement at the end of the limbs, and good blood supply.
【Question 1】What is the clinical diagnosis of this patient?
Idea 1:
The patient had pain, swelling, deformity, and limited movement of both ankles caused by severe violence from a fall from a height. The patient is found to be bipedal and a distal tibial ankle fracture is highly suspected, requiring further anterolateral ankle x-rays to confirm the diagnosis.
Knowledge points (clinical characteristics of Pilon fractures):
Fractures are diverse, with motor vehicle accidents and falls from heights being common forms of high-energy injuries, and low-energy injuries being sports injuries such as skiing and fall injuries. The main injury is comminuted fractures such as splitting and collapse of the weight-bearing articular surface of the distal tibia, which is caused by axial compression violence. Pilon fractures, whether open or closed, can cause severe soft tissue injury, which greatly interferes with the choice of treatment, the length of treatment, and affects the prognosis.
Idea 2:
Imaging examinations should be routinely taken on x-rays, and plain x-rays should include full-length radiographs of the injured calf, anterolateral and ankle acupuncture points centered slightly above the ankle joint surface, and external rotation at 45° if necessary. CT is the routine test for fractures involving the articular surface, and should include coronal, sagittal, and cross-sectional reconstruction, as well as three-dimensional reconstruction for severely comminuted fractures to determine the size and direction of displacement of the fragment.
Knowledge points (clinical classification of Pilon fractures):
At present, the AO/OTA classification of distal tibial fractures is commonly used in clinical practice. AO/OTA classification system: distal tibial fractures are divided into three types: A, B, and C.
1. Type A (Fig. 1) is an extra-articular fracture. A1 is a simple metaphyseal fracture. A2 is a wedge-shaped comminuted fracture at the metaphysis. A3 is a complex metaphyseal fracture.
Fig.1 Pilon fracture AO/OTA classification type A is an extra-articular fracture, which can be divided into three subtypes
2. Type B (Fig. 2) is a partial joint fracture, and the unfractured articular surface is still connected to the metaphysis and diaphysis. B1 is a simple split fracture of the articular surface. B2 is an articular surface cleavage compression collapse fracture. B3 is an articular surface comminuted compression collapse fracture.
Fig.2 Pilon fracture AO/OTA classification B is a partial intra-articular fracture, which can be divided into three subtypes
3. Type C (Fig. 3) is a complete intra-articular fracture in which all articular parts lose continuity with the metaphysis and diaphysis. C1 is a simple joint fracture without comminutement and compression with a simple metaphyseal fracture. C2 is a simple joint fracture with metaphyseal compression and comminuted fractures. C3 is a comminuted compression fracture of both the articular surface and the metaphysis.
Fig.3 Pilon fracture AO/OTA classification Type C is a complete intra-articular fracture, which can be divided into three subtypes through clinical classification, and the patient is currently considered to be diagnosed with bilateral Pilon fracture (AO/OTA classification is C3 type on both sides).
【Question 2】What are the treatment principles and key points of surgical treatment for Pilon fractures?
Idea 1:
Carefully read the patient's X-rays, the patient's bilateral Pilon fractures involved the articular surface, the joint collapsed obviously, and the fracture was displaced, and surgical treatment was required to restore the articular surface and reconstruct the fracture stability.
Knowledge Points (Therapeutic Principles):
1. Restore fibula length:
Restoration of fibular length allows for fixation of the lateral column and avoids varus and angulation; At the same time, it can be used as a reference for tibial fixation, which is conducive to restoring tibial length and rotational function. If the lower tibiofibular ligament is accompanied by injury, reduction of the fibula is also beneficial to the stabilization and recovery of the lower tibiofibular ligament, and the recovery of the lower tibiofibular ligament is beneficial to the reduction of the anterolateral and anteromedial bone fragments. However, there may be drawbacks if the fibula is fixed in the first stage, as the primary surgical approach may affect the choice of the secondary surgical approach, and the distance between the two incisions should be at least 7 cm in order to minimize the surgical treatment of the distal tibia intra-articular fracture with a skin bridge necrosis. Therefore, the lateral approach should be chosen to fix the fibula in the first stage, and the anterolateral approach should be avoided in the second stage to prevent the necrosis of the skin bridge.
The choice of primary or secondary fibular fixation depends mainly on the surgeon's technique and personal habits, and there is no significant difference in the prognosis of patients. If secondary fixation is chosen, anatomical reduction of the fibula is preferred, and in patients with comminuted fractures of the fibula, reduction of tibial fractures is preferred.
2. Reconstruction of tibial articular surface:
Patients with high-energy Pilon fractures often have severe intra-articular comminuted fractures, and the primary goal of intra-articular fracture treatment is to restore articular surface flatness and normal joint matching, and the quality of reduction is the prerequisite for functional recovery.
When reconstructing the tibial articular surface, the fibula and posterolateral bone block were first fixed through the posterolateral approach, and then the reduced posterolateral bone block was used as a reference, and the anterolateral and anteromedial bone blocks were reduced by direct view of the anterior approach, and the loss of the tibial articular surface was less than 2 mm after reduction. In this procedure, anatomical reduction of the posterolateral tibial fragment and fibula is a prerequisite for the continuation of articular surface leveling. The degree of loss of articular surface reduction was closely related to the radiographic findings of traumatic arthritis, but not to functional prognosis. Therefore, for high-energy Pilon fractures, the blind pursuit of articular surface reduction may lead to excessive incision, excessive dissection of soft tissue and periosteum, severe disruption of blood vessels, and increased operation time, thereby increasing the possibility of wound infection.
For patients with high-energy Pilon fractures and severe articular surface injury, it is still a challenge to effectively restore articular surface leveling and slow down articular cartilage degeneration. However, articular surface reconstruction with limited incision plus external fixator to restore tibial alignment and length seems to be a better choice.
3. Filling of metaphyseal bone defects:
High-energy Pilon fractures are often accompanied by metaphyseal bone defects, which can easily lead to nonunion. In the case of severe metaphyseal crushing, the articular surface must be reconstructed first, and then the articular surface must be fixed to the metaphysis with a dissecting plate to avoid shortening of the lower limbs and ankle valgus. For single-column comminuted metaphyseal fractures, a bone graft is usually not needed and only pulverized bone fragments are used. Traditional bone grafting (autologous cancellous bone grafting, structural allogeneic bone grafting, decalcified bone matrix, calcium-based bone cement) can be used when the metaphyseal is comminuted above double columns and the bone defect is less than 4 cm; When the bone defect is larger than 4 cm or combined with severe soft tissue injury, the first stage of bone transfer of the Ilizarov ring frame or the immobilization of the first stage of the external fixator can be used for flap transplantation, and after the soft tissue condition is improved, the second stage surgery can be performed to insert the bone filling through a small incision.
4. Tibia medial steel plate support:
The goal of surgical approach selection is to fully expose the articular surface with minimal soft tissue dissection. The anteromedial approach and the anterolateral approach are the most classic approaches, but the anteromedial approach is difficult to observe the anterolateral bone fragment during surgery, and the anteromedial approach has little soft tissue coverage, which is prone to postoperative wound rupture and exposed steel plates. Although the anterolateral approach can directly view the entire articular surface and has relatively more soft tissue coverage, there is a risk of injury to the superficial peroneal nerve, deep peroneal nerve, anterior tibial artery or vein, and its long incision increases the possibility of soft tissue infection and nonunion.
The optimal surgical approach requires a thorough understanding of column commination, metaphyseal commination, and articular surface, combined with soft tissue conditions and the ability of various bone plates to "trap" major fracture fragments. The placement of the medial steel plate is extremely important, it not only supports the medial tibia, but also effectively prevents varus, the effective fixation of the medial column reduces the incidence of nonunion in patients with Pilon fracture, and the medial column supports each other with the other three columns to form a stronger ankle joint, so the stable fixation of the medial column is essential to ensure that the patient starts functional exercises in time. Placement of the medial plate often requires limited incision or percutaneous insertion to prevent skin necrosis, especially in older patients.
The main ways to rebuild the inner column are screws, rebuilding steel plates, and locking steel plates. The use of screws reduces the irritation of the soft tissues and reduces the dissection of the soft tissues, which reduces the disruption of the blood supply to the distal tibia and facilitates fracture healing. However, the screws are not strong enough to allow for early postoperative weight bearing, increasing the incidence of complications due to prolonged bed rest. The strong fixation provided by the reconstructed plate can ensure early postoperative functional exercises, however, the thickness of the plate can irritate the thin soft tissues of the medial malleolus, leading to postoperative infection, nonunion of fractures, and delayed union. Locking the plate can better maintain the alignment of the articular surface and tibial shaft in patients with osteoporosis, but due to the physiological curvature attached to the medial column, the position of the nail hole is not flexible, which increases the difficulty of surgery in patients with comminuted fractures. Therefore, for patients with medial column crushing, locking steel plates can be used, while for patients with large medial column bone blocks without obvious comminutement, 1/3 tubular steel plates or reconstructed steel plates can be used.
Idea 2:
The patient's surgical treatment strategy and surgical plan were formulated. Due to the obvious swelling of the soft tissues of the ankle joint, it is not suitable for the treatment of early fracture open reduction and internal fixation. After the consultation, calcaneal traction, lower limb elevation, swelling reduction, and hyperbaric oxygen therapy were performed, and there were no tension blisters on the skin, and after the swelling fully subsided 12 days after the injury, open reduction of bilateral Pilon fractures, double plate fixation of the distal tibia, and artificial bone grafting were performed, and there were no complications after surgery (Fig. 4).
Fig.4 X-ray reexamination after bilateral Pilon fracture showed that the articular surface morphology was restored
Knowledge points (minimally invasive treatment of tibial Pilon fracture using double reverse traction technique):
For Pilon fractures without neurovascular injury, minimally invasive surgery is recommended as the preferred procedure. The patient's surgical position was supine, and bone traction was performed at the tibial tuberosity and calcaneus respectively, and the double reverse traction reduction device was connected to perform double reverse traction. After traction to tense calf muscles, C-arm perspective:
(1) After double reverse traction, most of the distal tibial fracture fragments can be completely reduced due to the traction and squeezing of muscles and ligaments. Using MIPO technology, the distal tibia plate was minimally inserted for final fixation.
(2) If the articular surface of the distal tibia still collapses after double reverse traction, the bone window is opened at the junction of the anterior and middle 1/3 of the medial surface of the medial tibia 6~8cm above the medial malleolus, and the top rod is used for pressure reduction, and bone grafting is carried out in the bone defect area caused by the collapse of the articular surface, until the articular surface is flattened, and then MIPO technology is applied to minimally invasively insert the distal tibial bone plate.
(3) If the articular surface of the distal tibia is still widened after traction and compression reduction and bone grafting, Zhang's compression bone plug can be applied to compress the widened articular surface under continuous traction of double reverse traction to restore the width of the distal tibial articular surface (Fig. 5).
Fig.5 Reduction of Pilon fracture using double reverse traction reducer
summary
A high-energy Pilon fracture is a very complex and difficult fracture to manage, and staging treatment may be the gold standard for management. The Rüed-Allgöwer principle remains valid when determining treatment, but clinicians need to individualize their approach to the patient's situation, taking into account the following:
(1) It is very important to reconstruct the length of the fibula, if the fibula is severely comminuted and fractured, the tibial articular surface should be reduced first, and the primary or secondary fibula fixation has no significant impact on the prognosis of the patient.
(2) Articular surface reconstruction is also important, but it is not the only factor affecting functional prognosis, and the soft tissue conditions and metaphyseal comminutement should be considered at the same time, and the recovery of lower limb alignment and the stable fixation of fracture may be more important.
(3) Bone defect filling is not necessary, and the appropriate plan needs to be selected according to the length of metaphyseal bone defect and soft tissue conditions.
(4) Medial column stabilization plays an important role in limiting ankle varus, and in high-energy complex Pilon fractures, a single plate cannot be used to "capture" the anterolateral bone fragment and the anteromedial bone fragment, and double plate fixation is required.
(5) The development of anterolateral variable angle plates may become a breakthrough in the treatment of high-energy Pilon fractures with a single incision.
bibliography
[1] Li Han, Kong Weijie, Hao Haihu. International Journal of Orthopedics,2024,45(01):1-4.)
[2] Orthopedics. Author:Zhang Yingze,Weng Xisheng. Publisher: People's Medical Publishing House. Online:2022-06-01. ISBN：9787117327442.
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