Characteristics and proposed classification system of posterior pilon fractures

A systematic review of posterior pilon variant fractures

Posterior pilon variant ankle fractures (PPVF) are a unique subtype of posterior malleolar fractures which have been a source of controversy and confusion in recent years. There has not been a thorough literature review previously written on the topic. Database searches of PubMed and Embase were conducted from inception until June 2023. The key words included "pilon variant," "posterior pilon variant," and "posterior pilon" fractures. Outcomes were evaluated by union time, rates of delayed union, nonunion, malunion, and complication. A total of 15 articles relevant to surgical repair of pilon variant fractures were included in the literature review. The unique mechanism of injury has been reported to involve both rotational and axial forces, leading to involvement of the posterior and medial aspects of the distal tibia. Pilon variant fractures can be suspected by several characteristics on radiographs and have a high confirmation rate via CT images. Multiple systems have been proposed to classify this fracture pattern, but there is no consensus on the ideal classification system. Surgically, direct fixation has shown better short-term clinical outcomes versus indirect fixation or no fixation. PPVF have a distinct fracture pattern involving the posterior and medial columns of the distal tibial plafond, and results from a mechanism intermediate to rotational and axial forces. These fractures are more severe than tri-malleolar fractures due to increased rates of articular impaction and incongruity. Future classification systems should focus on joint surface area and the tibial pilon column involved to avoid confusion with less severe posterior malleolar fractures.

Three-Dimensional Heat Map: The OTA/AO Type 43C Pilon Fracture Lines Distribution

Background

This study aimed to create three-dimensional heat map and study the characteristic of fracture lines and represented fragments of OTA/AO type 43C pilon fractures.

Methods

CT scan was performed in105 fractures diagnosed with OTA/AO type 43C pilon fractures between January 2017 and December 2022. Three-dimensional pilon fracture maps were created and converted into fracture heat maps. CT scan graphic parameters including the fracture line height, α angle, β angle, the ratio of the area and size of bone fragment represented by the fracture line to the total articular surface were measured.

Results

The study included 105 patients with 91 males and 14 females. The fractures included C1 (n=16), C2 (n=23), and C3 (n=66). There was no statistically different among the most parameters except in the fracture-line height of the anterior fracture line (p=0.03) and the sagittal fracture line (p=0.02) between C2 and C3 pilon fractures. The average size of the anterolateral fragment, occupied approximately 13.5% of the articular surface area, was (11.5±2.8) mm × (20.5±6.3) mm with the average height of 29.8 mm. The average size of the posterolateral fragment, occupied approximately 13.0% of the articular surface area, was (15.7±4.6) mm × (19.3±4.0) mm with the average height of 19.1 mm.

Conclusion

This study demonstrates that the articular surface fracture lines in the C type pilon fracture are formed by fixed main fracture lines. The understand of morphological and distribution characteristics of the fracture lines and size of fragments in OTA/AO type 43C pilon fractures would help the surgeons take suitable approach and fixation.

Management of complex pilon fractures: Is it necessary to fix all the columns in AO/OTA type 43-C fractures?

INTRODUCTION

Surgical treatment of AO/OTA 43-C pilon fractures has not yet taken a standard form. We aimed to evaluate whether patients that appeared to be labelled as unsupported columns according to the four-column theory would affect long-term clinical and radiological outcomes.

MATERIALS AND METHODS

Patients with AO/OTA 43-C type who were treated surgically between January 2010 and December 2019 were included in the study. 53 fractures in 52 patients who received osteosynthesis were categorized based on the fixed columns. These groups were formed as fully supported columns (FSC- Group A), partly supported columns (PSC-Group B), Ankle range of motions (ROM), Burwell Charnley's reduction evaluation criteria, Kellgren-Lawrence ankle osteoarthritis staging system, and American Orthopedic Foot and Ankle Society (AOFAS) Scoring System, Olerud-Molander Ankle Score, Visual Analog Scale were used for evaluating radiological and functional outcomes.

RESULTS

The mean follow-up period was 72.6 (12-131) months. Mean age was 42.6 (18-76). Two groups were homogenously distributed in terms of age (p = 0.785), sex (p = 0.376), laterality (p = 0.732), smoking status (p = 0.488) and reduction quality. There was no difference in AOFAS score (p = 0.452), Olerud-Molander score (p = 0.354) and VAS scores (p = 0.589). TAS, TLS and TT angle measurements suggested no difference between groups (p = 0.493, p = 0.834, p = 0.577). There was no difference between groups in terms of infection (p = 0.734), malunion (p = 0.688) and arthritis (p = 0.483) CONCLUSION: We presented findings that contradicted the hypothesis positing the existence of four distinct columns in pilon fractures, as well as the notion that each fractured column requires support from distinct implants.

LEVEL OF EVIDENCE

Level III.

Open reduction and internal fixation for posterior pilon fracture: Transfibular approach versus posterior approach

BACKGROUND

For posterior pilon fractures, the posterior approach (PA) is widely used but has its limitations. The transfibular approach (TFA) has been adopted to treat posterior malleolar fractures for the advantage of direct visual confirmation of the reduction status intraoperatively, yet the report of its application on posterior pilon fractures is rare. This study aims to compare TFA with PA in terms of their corresponding reduction quality.

METHODS

Clinical data of 85 posterior pilon fracture patients treated via PA (n = 62) or TFA (n = 23) were retrospectively reviewed. Radiographic and clinical assessments, including articular step-off or gap, syndesmosis reduction quality, signs of ankle arthritis, the American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot score, visual analogue scale (VAS), ankle stability, and the active range of motion (ROM) of the ankle, were all evaluated by two readers independently.

RESULTS

The total incidence of step-off or gap ≥ 1 mm was significantly higher in the PA group (35.5%) than in the TFA group (8.7%, p = 0.015). In all the patients, step-off ≥ 1 mm was identified as an independent risk factor for the development of arthritis and a lower AOFAS score (p < 0.001). No significant difference was found in ROM and complication incidence between the two groups. Ankle instability was found in neither group during the follow-up.

CONCLUSION

TFA could offer a way to intraoperatively evaluate the reduction status with direct visual confirmation and, thereby, might improve the results of reduction for posterior pilon fractures.

LEVEL OF EVIDENCE

Level III.

Treatment outcomes of posterior pilon fractures using a simple single lateral approach via stretching fibular fracture line

Purpose

The aim of this study was to explore the treatment outcomes of a novel single lateral approach via fibular fracture line for patients with posterior pilon fractures.

Patients and methods

From January 2020 to December 2021, a total of 41 patients with posterior pilon fractures who received surgical treatment in our hospital were retrospectively reviewed. Twenty patients (Group A) were treated with open reduction and internal fixation (ORIF) via posterolateral approach. Twenty-one patients (Group B) were treated with ORIF using a simple single lateral approach via stretching fibular fracture line. Clinical assessments, including operation time, intraoperative blood loss, the American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot score, visual analogue scale (VAS), and the active range of motion (ROM) of the ankle at the final follow-up visit after surgery, were performed in all patients. Radiographic outcome was evaluated by using the criteria proposed by Burwell and Charnley.

Results

The mean follow-up time was 21 months (range 12-35). The average operation time and intraoperative blood loss in the Group B were significantly less than those in the Group A. Moreover, the AOFAS score and ankle ROM in the Group B were significantly higher than those in the Group A at the final follow-up visit. Eighteen cases (90%) in Group A and 19 cases (90.5%) in Group B achieved anatomical reduction of the fracture.

Conclusion

The single lateral approach via stretching fibular fracture line is a simple and effective technique for reduction and fixation of posterior pilon fractures.

Operative strategy for tri-malleolar ankle fractures with posteromedial plafond involvement: a review of sixty six cases

PURPOSE

We aimed to summarize the radiographic and clinical outcomes in various conditions of tri-malleolar ankle fractures (TMFs) with posteromedial (PM) plafond involvement (TMF + PM) and determine the factors affecting their subjective clinical outcomes.

METHODS

Radiographic and clinical findings of 66 patients who underwent operative treatment for TMF + PM were retrospectively reviewed. The patients were classified into three groups according to the PM fracture line location. Type I fractures were defined when the PM fracture line extended medially beyond the PM corner of the distal tibia while type II fractures were those in which the PM fracture line was located laterally to the PM corner. Type III fractures were defined as medial malleolar avulsion fractures when the PM fracture integrated into the medial malleolus. Clinical outcomes were evaluated using a subjective rating scale (excellent, good, fair, poor, and bad). Satisfactory results were defined as excellent, good, and fair. Factors affecting satisfactory clinical outcomes were assessed using a binary logistic regression analysis. Independent variables included demographic, fracture-related, and operation-related factors and radiographic measurements at the final follow-up.

RESULTS

Satisfactory clinical outcomes were observed in 74.2% of the total patients; of these patients, 75.7% (28/37), 76.5% (13/17), and 66.7% (8/12) had type I, type II, and type III fractures, respectively. The binary logistic regression analysis revealed that age at the time of operation, number of incarcerated fragments (IFs), type of IFs, and postoperative articular step-offs (mm) were related to subjective clinical outcomes (all P < 0.05). A positive value for post-operative articular step-offs represented distal migration of the posterior malleolar fragments. The odds ratios for older age, increased numbers of IFs, rotated IFs, and positive articular step-offs were 0.936, 0.116, 0.020, and 0.295, respectively.

CONCLUSION

Because TMF + PM is highly unstable, a delicate approach is needed according to each patient's fracture condition. Although it is best to reduce the fractured articular surface, a negative step-off, rather than a positive step-off, would be more likely recommended if accurate reduction is impossible. This could be applied to manage IFs, especially when the IFs are rotated. Dimpling of the articular surface induced by the removal of a small IF was not related to unsatisfactory clinical outcomes.

The Intercalary Fragment in Posterior Malleolus Fractures: Characterization and Significance

Methods of fixation in ankle fractures involving the posterior malleolus have become increasingly scrutinized. With the increase in computed tomography (CT), an intercalary fracture fragment (ICF) adjacent to the posterior malleolus has been oft described. Treatment of the ICF remains controversial and the purpose of this study was to evaluate radiographic and clinical outcomes in patients who had direct reduction and fixation of this fragment compared to those where the ICF was not fixed. This retrospective study included 249 trimalleolar and posterior pilon ankle fractures grouped into those who had the ICF reduced and fixed (n = 74) and those where the ICF was not directly addressed (n = 175). CT scans were evaluated for size and location of the ICF. Demographic, radiographic and intraoperative variables were collected and analyzed. The group which had the ICF reduced and fixed had decreased Kellgren-Lawrence scores (p = .001). There was also a higher rate of repeat surgery in the group who had the ICF fixed, although not meeting statistical significance. There were no differences in size or location of the ICF fragment between groups. We did identify similarities with other studies in regard to size and posterolateral location of the ICF between groups. However, based on worsening radiographic outcomes of the group where the ICF was reduced and fixed, we do not necessarily recommend universal treatment of this fragment. The surgeon's goal should always be a concentric articular reduction and treatment of the ICF should be considered on a case-by-case basis.

[Established classification systems of posterior malleolar fractures : A systematic literature review]

BACKGROUND

Posterior malleolar fractures are found in almost 50% of all ankle fractures. The high clinical relevance of these joint fractures is explained by the significantly worse clinical and functional outcome. There is still a lack of unified opinion regarding the classification and treatment of these fractures.

OBJECTIVE

The aim of this article is to provide a systematic literature review of clinical studies that investigated posterior malleolar fractures and classified them using one of the three established classifications according to Haraguchi, Bartonicek/Rammelt, or Mason.

MATERIAL AND METHODS

PubMed was searched without time limits. The systematic literature search was performed according to the current criteria of Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA). The methodological quality of the included studies was quantified using the modified Coleman score.

RESULTS

A total of 27 studies with a total of 2220 patients were included in this systematic literature review. Trimalleolar fractures showed a significantly less favorable prognosis than other ankle fractures. The quality of reduction was the most important prognostic factor for the clinical outcome.

CONCLUSION

None of the three classifications examined has become established in the literature. Most of the classifications are weak or should not be used with respect to a derivable treatment algorithm or a prognosis with respect to the outcome. Only the classification according to Bartonicek/Rammelt is suitable to become established in the literature and in clinical practice due to its derivable treatment algorithm.

Characteristics and classification of medial malleolar fractures

AIMS

The morphology of medial malleolar fracture is highly variable and difficult to characterize without 3D reconstruction. There is also no universally accepeted classification system. Thus, we aimed to characterize fracture patterns of the medial malleolus and propose a classification scheme based on 3D CT reconstruction.

METHODS

We retrospectively reviewed 537 consecutive cases of ankle fractures involving the medial malleolus treated in our institution. 3D fracture maps were produced by superimposing all the fracture lines onto a standard template. We sliced fracture fragments and the standard template based on selected sagittal and coronal planes to create 2D fracture maps, where angles α and β were measured. Angles α and β were defined as the acute angles formed by the fracture line and the horizontal line on the selected planes.

RESULTS

A total of 121 ankle fractures were included. We revealed several important fracture features, such as a high correlation between posterior collicular fractures and posteromedial fragments. Moreover, we generalized the fracture geometry into three recurrent patterns on the coronal view of 3D maps (transverse, vertical, and irregular) and five recurrent patterns on the lateral view (transverse, oblique, vertical, Y-shaped, and irregular). According to the fracture geometry on the coronal and lateral view of 3D maps, we subsequently categorized medial malleolar fractures into six types based on the recurrent patterns: anterior collicular fracture (27 type I, 22.3%), posterior collicular fracture (12 type II, 9.9%), concurrent fracture of anterior and posterior colliculus (16 type III, 13.2%), and supra-intercollicular groove fracture (66 type IV, 54.5%). Therewere three variants of type IV fractures: transverse (type IVa), vertical (type IVb), and comminuted fracture (type IVc). The angles α and β varied accordingly.

CONCLUSION

Our findings yield insight into the characteristics and recurrent patterns of medial malleolar fractures. The proposed classification system is helpful in understanding injury mechanisms and guiding diagnosis, as well as surgical strategies. Cite this article: Bone Joint J 2021;103-B(5):931-938.

Mechanism of posterior malleolar fracture of the ankle: A cadaveric study

Objectives:

Ankle fracture treatment involves reduction of the bone fragments and stabilization of the joint by reversing the mechanics of injury. For posterior malleolar fracture however, the true mechanism is not understood, leading to a lack of consistent guidance on how to best treat this injury.

Methods:

Fifteen cadaver ankles were subjected to fracture loading that replicated the Lauge-Hansen pronation-external rotation mechanism. An axial load was applied to each specimen, which was mounted on a materials testing machine, and the foot was rotated externally to failure. Digital video cameras recorded the failure sequence of specific anatomic structures.

Results:

Posterior malleolar fracture occurred in 7 specimens. Of these, 1 was an intra-articular fracture, another was a fracture involving the entire posterior tibial margin consisting of 2 fragments: that of the posterior tubercle and that of the posteromedial margin of the tibial plafond, with the former judged to be a consequence of avulsion by the posterior inferior tibiofibular ligament and the latter a consequence of axial loading from the talus. In the remaining 5 specimens, the posterior malleolar fracture was a small extra-articular avulsion fracture.

Conclusions:

Fractures at the posterolateral corner of the distal tibia were shown to be avulsion fractures attributed to the posterior inferior tibiofibular ligament and produced by external rotation of the talus. A fracture involving the entire posterior tibial margin consisting of 2 fragments can be produced by a combination of avulsion by the posterior inferior tibiofibular ligament and axial loading from the talus.