Morphologic characteristics of the posterior malleolus fragment: a 3-D computer tomography based study

Analysis of the epidemiological characteristics of posterior malleolus fracture in adults

BACKGROUND

This study explores the latest epidemiological characteristics of posterior malleolus fracture and compares the epidemiological differences of posterior malleolus fracture in different periods, regions, and adult age groups.

METHODS

Clinical information of inpatients with posterior malleolus fracture in Shanghai Tongji Hospital and Karamay Central Hospital from January 2014 to February 2022 was reviewed and collected. The imaging data of patients were acquired using the Picture Archiving and Communication Systems. A statistical analysis was performed as to gender, current age, year of admission, injury mechanism, fracture type, and posterior malleolus fracture classification. Moreover, a comparative analysis was conducted on the injury mechanisms and morphological differences of posterior malleolus fracture at different periods, regions, and age groups.

RESULTS

A total of 472 patients (210 patients from Shanghai Tongji Hospital and 262 patients from Karamay Central Hospital) with posterior malleolus fracture and an average age of 48.7 ± 15.6 were included in this study. The peak of posterior malleolus fracture occurs in the age group of 50-59. The injury mechanisms mainly involve low-energy fall and sprain (411 cases, 87.1%), followed by traffic accidents (52 cases, 11.0%), and fall injury from height (9 cases, 1.9%). With aging, the number of fall and sprain cases increases and reaches the peak at the age of 50-59, followed by progressive decline. Traffic accidents presents a relatively flat small peak in the age group of 40-59. The number of cases according to different fracture types shows the following ascending order: trimalleolar fracture-supination external rotation (335 cases, 71.0%) > bimalleolar fracture (60 cases, 12.7%) > trimalleolar fracture-pronation extorsion (43 cases, 9.1%) > posterior malleolus + tibial shaft fracture (19 cases, 4.0%) > simple posterior malleolus fracture (15 cases, 3.2%). The numbers of cases corresponding to the Haraguchi I Type, II Type, and III Type of posterior malleolus fractures were 369 (78.2%), 49 (10.4%), and 54 (11.4%), respectively. The Tongji IIA Type represented the highest number of cases (249 cases, 52.8%), followed by the IIB Type (120 cases, 25.4%), I Type (54 cases, 11.4%), IIIB Type (36 cases, 7.6%), and IIIA type (13 cases, 2.8%). The trimalleolar fracture-supination external rotation, Haraguchi I Type and Tongji IIA Type of posterior malleolus fractures all presented an obvious peak of incidence in the age group of 50-59. However, no obvious statistical difference was observed in the injury mechanism, Haraguchi classification, and Tongji classification of posterior malleolus fractures among different years and regions in recent years (P > 0.05).

CONCLUSIONS

The injury mechanism of posterior malleolus fracture mainly involves low-energy fall and sprain cases. The trimalleolar fracture-supination external rotation, Haraguchi I type and Tongji IIA type of posterior malleolus fracture are predilection fracture types, and all present an obvious incidence peak in the age group of 50-59. Elderly patients have high risks of falling and their bones are more fragile, conditions which are potential risk factors of posterior malleolus fracture. Early positive control has important significance. This study provides references for relevant basic and clinical studies of posterior malleolus fracture.

Classifications of posterior malleolar fractures: a systematic literature review

INTRODUCTION

Complex ankle fractures frequently involve the posterior malleolus. Many classifications describing posterior malleolar fractures (PMF) exist. The aim of this study was to provide a systematic literature review to outline existing PMF classifications and estimate their accuracy.

METHODS

The databases PubMed and Scopus were searched without time limits. Only specific PMF classifications were included; general ankle and/or pilon fracture classifications were excluded. Selection and data extraction was performed by three independent observers. 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 110 studies with a total of 12.614 patients were included. Four main classifications were identified: Those describing the size of the posterior malleolar fracture (n = 66), Haraguchi (n = 44), Bartoníček/Rammelt (n = 21) and Mason (n = 12). The quality of the studies was moderate to good with a median Coleman-score of 43.5 (14-79) and a weighted median Coleman-score of 42.5 points. All classifications achieved a substantial to perfect score regarding the inter- and intraobserver reliability, with Mason scoring the lowest in comparison.

CONCLUSIONS

None of the reviewed PMF classifications has been able to establish itself decisively in the literature. Most of the classifications are insufficient in terms of a derivable treatment algorithm or a prognosis with regard to outcome. However, as the Bartoníček/Rammelt classification has the greatest potential due to its treatment algorithm, its reliability in combination with consistent predictive values, its usage in clinical practice and research appears advisable.

Methods for Biomechanical Testing of Posterior Malleolar Fractures in Ankle Fractures: A Scoping Review

BACKGROUND

The treatment of posterior malleolar fractures (PMFs) is debated, including the need for surgery and method of fixation. Recent literature has suggested that fracture pattern, rather than fragment size, may be an important predictor for ankle biomechanics and functional outcome. Biomechanical studies have been conducted to provide evidence-based treatment on the effects of fracture and fixation on contact pressure and stability. The objective of this scoping review is to summarize the methodologies used in biomechanical studies on PMFs and assess whether they are sufficient to test the need for surgery and method of fixation.

METHODS

A scoping review of publications before January 2022 was performed. PubMed/Medline and Embase Ovid were searched for cadaver or finite element analysis (FEA) studies that created and tested the effects of PMFs in ankle fractures. Both cadaver and FEA studies were included. Data about fragment characteristics, mode of testing, and outcomes were charted by 2 persons from the study group. The data were synthesized when possible and compared.

RESULTS

We included 25 biomechanical studies, including 19 cadaver studies, 5 FEA studies, and 1 cadaver and FEA study. Aside from the fragment size, few other fragment characteristics were reported. Mode of testing varied with different loads and foot positions. Strong conclusions on the effects of fracture and fixation on contact pressure and stability could not be made.

CONCLUSION

Biomechanical studies on PMFs demonstrate wide variability in fragment characteristics and mode of testing, which makes it difficult to compare studies and draw conclusions on the need for surgery and method of fixation. Additionally, limited reporting of fragment measurements questions the applicability to clinical practice. The biomechanical literature on PMFs would benefit from the use of a standard classification and universal fragment measurements to match clinical injuries in future biomechanical studies. Based on this review, we recommend the Mason classification, which addresses the pathomechanism, and use of the following fragment measurements in all 3 anatomic planes when creating and describing PMFs: fragment length ratio, axial angle, sagittal angle or fragment height, and interfragmentary angle. The testing protocol needs to reflect the purpose of the study.

CLINICAL RELEVANCE

This scoping review demonstrates wide methodological diversity of biomechanical studies. Consistency in methodology should enable comparison of study results, leading to stronger evidence-based recommendations to guide surgeons in decision making and offer PMF patients the best treatment.

Effect of Posterior Malleolar Fixation on Syndesmotic Stability

BACKGROUND

Transsyndesmotic fixation with suture buttons (SBs), posterior malleolar fixation with screws, and anterior inferior tibiofibular ligament (AITFL) augmentation using suture tape (ST) have all been suggested as potential treatments in the setting of a posterior malleolar fracture (PMF). However, there is no consensus on the optimal treatment for PMFs.

PURPOSE

To determine which combination of (1) transsyndesmotic SBs, (2) posterior malleolar screws, and (3) AITFL augmentation using ST best restored native tibiofibular and ankle joint kinematics after 25% and 50% PMF.

STUDY DESIGN

Controlled laboratory study.

METHODS

Twenty cadaveric lower-leg specimens were divided into 2 groups (25% or 50% PMF) and underwent biomechanical testing using a 6 degrees of freedom robotic arm in 7 states: intact, syndesmosis injury with PMF, transsyndesmotic SBs, transsyndesmotic SBs + AITFL augmentation, transsyndesmotic SBs + AITFL augmentation + posterior malleolar screws, posterior malleolar screws + AITFL augmentation, and posterior malleolar screws. Four biomechanical tests were performed at neutral and 30° of plantarflexion: external rotation, internal rotation, posterior drawer, and lateral drawer. The position of the tibia, fibula, and talus were recorded using a 5-camera motion capture system.

RESULTS

With external rotation, posterior malleolar screws with AITFL augmentation resulted in best stability of the fibula and ankle joint. With internal rotation, all repairs that included posterior malleolar screws stabilized the fibula and ankle joint. Posterior and lateral drawer resulted in only small differences between the intact and injured states. No differences were found in the efficacy of treatments between 25% and 50% PMFs.

CONCLUSION

Posterior malleolar screws resulted in higher syndesmotic stability when compared with transsyndesmotic SBs. AITFL augmentation provided additional external rotational stability when combined with posterior malleolar screws. Transsyndesmotic SBs did not provide any additional stability and tended to translate the fibula medially.

CLINICAL RELEVANCE

Posterior malleolar fixation with AITFL augmentation using ST may be the preferred surgical method when treating patients with acute ankle injury involving an unstable syndesmosis and a PMF ≥25%.

Direct Fixation of Fractures of the Posterior Malleolus Through a Postero-Medial Approach

Background and objective: Fractures of the posterior malleolus have long been neglected in the past. The decision for their fixation should be based on plain lateral radiographs. Recent studies have emphasized the important biomechanical function of the posterior tibial ridge. This has caused a trend towards more aggressive surgical treatment. The aim of this study was to present our experience with the direct fixation of complex ankle fractures engaging the posterior malleolus. We also tried to clarify the advantages and limitations of the posterior-medial surgical approach.

Materials and Methods: For a period of 1,5 years we have operated 14 patients with posterior malleolus fractures. Their average age was 51 years. Eight of the patients were male, the rest 6 were females. Fractures were classified according to Bartoníček classification system. All patients had type 3 fractures. Direct open reduction was performed in all cases. Posterior buttress plate was used for the fixation of the fracture. Bone grafting was found necessary in one case. Functional assessment was done according to the criteria of the AOFAS (American Orthopedic Foot and ankle score). Follow up was done for an average period of 10 months.

Results: All fractures united for an average period of 9 weeks (8-10 weeks). Six patients achieved an excellent functional result, 5 – a good one and 3 had an average result. The average AOFAS rating score was 84,02 (54-100). The average range of motion was 38° (15°-50°). There were no deep infections or septic arthritis. Three ankles had superficial skin necrosis that healed without any additional procedures. One patient had prolonged and substantial swelling of the leg, despite of the routine antithrombotic prophylaxis. Five patients needed their fibular plates removed due to local irritation.

Conclusion: The direct reduction and fixation of the posterior malleolus fractures allow anatomical restoration of the ankle mortise. This is a prerequisite for an optimal functional recovery and appears to be a safe treatment strategy.

Posterior Malleolar Fractures: A Critical Analysis Review

In patients with ankle fractures, the presence of a posterior malleolar fracture has a negative impact on the prognosis. Computed tomography (CT) scanning is essential for fracture classification and treatment planning, as the indication for surgery depends on the 3-dimensional fragment outline and displacement, incisura involvement, and the presence of joint impaction. Anatomic reduction of a posterior malleolar fragment restores the incisura, facilitating reduction of the distal part of the fibula, and it also restores the integrity of the posterior portion of the syndesmosis, reducing the need for additional syndesmotic stabilization. Direct open reduction and fixation of posterior malleolar fragments from a posterior orientation is biomechanically more stable and provides a more accurate reduction than does indirect reduction and anterior-to-posterior screw fixation. Intra-articular step-off of >=2 mm is an independent risk factor for an inferior outcome and the development of posttraumatic arthritis, irrespective of the fragment size.

Percutaneous posteroanterior screw fixation for Haraguchi type 1 posterior malleolar fracture in tri-malleolar fracture: Operative technique and randomized clinical results

PURPOSE

The study described a novel surgical treatment of Haraguchi type 1 posterior malleolar fracture in tri-malleolar fracture and patient outcomes at intermediate period follow-up.

METHODS

All patients from January 2015 to December 2017 with tri-malleolar fracture of which posterior malleolar fractures were Haraguchi type 1, were surgically treated in this prospective study. Lateral and medial malleolar fractures were managed by open reduction and internal fixation through dual incision approaches. 36 cases of Haraguchi type 1 posterior malleolar fractures were randomly performed by percutaneous posteroanterior screw fixation with the aid of medial exposure (group 1). And 40 cases were performed by percutaneous anteroposterior screw fixation (group 2). Clinical outcomes, radiographic outcomes and patient-reported outcomes were recorded.

RESULTS

Seventy-six patients with mean follow-up of 30 months were included. There were no significant differences in the mean operation time (81.0 ± 11.3 vs. 77.2 ± 12.4), ankle function at different periods of follow-up, range of motions and visual analog scale (VAS) at 24 months between the two groups (p > 0.05). However, the rate of severe post-traumatic arthritis (Grade 2 and 3) and the rate of step-off rather than gap in radiological evaluation were lower in group 1 than that in group 2 (p < 0.05).

CONCLUSION

Using our surgical technique, more patients had good outcome with a lower rate of severe post-traumatic arthritis, compared with the group of percutaneous anteroposterior screw fixation. Percutaneous posteroanterior screw fixation can be a convenient and reliable alternative in treating Haraguchi type 1 posterior malleolar fracture.

Comparison of radiographs and CT features between posterior Pilon fracture and posterior malleolus fracture: a retrospective cohort study

OBJECTIVES

This study explored the morphological differences between posterior Pilon fracture and posterior malleolus fracture from radiographs and CT to provide detail for diagnosis and treatment of them.

METHODS

Radiographs and CT imaging data of 174 patients with distal posterior tibial fractures who were treated from January 2013 to January 2019 were retrospectively analyzed. Based on the operation and imaging examination, the fractures were classified into posterior Pilon fractures and posterior malleolus fractures. Radiographic parameters including the width, height, depth, α angle, β angle, γ angle, fragment area ratio 1 (FAR1), δ angle and fragment area ratio 2 (FAR2) of ankle mortise were measured.

RESULTS

There were 96 posterior Pilon fractures (Type I: 30, Type II: 22 and Type III: 44) and 78 posterior malleolus fractures (Type I: 40 and Type II: 38). The ankle depth, α angle, γ angle, FAR1 and FAR2 of posterior Pilon fractures were larger than these of posterior malleolus fractures (p < 0.05). In addition, FAR1 and FAR2 of Type II and Type III posterior Pilon fractures were significantly larger than these of Type I (p < 0.05). FAR1 and FAR2 of Type I posterior malleolus fractures were significantly smaller than these of Type II (p < 0.05).

CONCLUSION

Radiographs combined with CT analysis is an effective method to accurately distinguish morphological features between posterior Pilon fracture and posterior malleolus fracture.

ADVANCES IN KNOWLEDGE

Radiographs combined with CT distinguished the fracture of posterior malleolus and posterior Pilon rapidly and accurately, instead of operation.

Finite element analysis of the effect of sagittal angle on ankle joint stability in posterior malleolus fracture: A cohort study

OBJECTIVE

Aim of this study was to establish three-dimensional finite element model of the posterolateral-oblique type of posterior malleolus fracture with different sagittal angle and to explore the effect of sagittal angle on ankle joint stability.

METHODS

CT data of ankle were collected from a normal male volunteer.Established finite element model of the normal ankle and verified its reliability. Five posterior malleolus fracture models with different sagittal angles were established. Finite element analysis(FEA)was carried out to simulate the conditions of vertical loading in neutral position with a total weight of 600 N.Recorded the data and did statistical analyses.

RESULTS

(1) The contact area was 483.55 mm2 and the maximum contact stress was 3.793 MPa in the model of the normal ankle joint. (2) There was a positive correlation between the sagittal angle(SA)and the contact area(CA)(r = 0.925,P < 0.05). Regression equation was CA = 316.755 + 1.749* SA. The correlation between the sagittal angle and the maximum contact stress(MCS)was negative (r = -0.988,P < 0.01). Regression equation was MCS = 5.214-0.018*SA. There was a negative correlation between the sagittal angle of fracture and relative displacement(RD)(r = -0.950,P < 0.05). Regression equation was RD = 1.388-0.009*SA.

CONCLUSION

The greater the sagittal angle of fracture was, The more stable the ankle joint was. The sagittal angle of fracture could be used as a relative index to reflect ankle stability for posterior malleolus fracture.

The risk of violating the posterior malleolar fracture when nailing the ipsilateral concomitant spiral distal tibial fracture

Background

For a distal tibial spiral fracture combined with a non-displaced posterior malleolar fragment (PMF), we proposed a hypothesis that the treating surgeon could assess the size of the PMF to determine the need for stabilizing that structure first before rodding the tibia.

Materials and methods

Fifty 3-D models (22 females) of combined distal tibial and posterior malleolar fractures from one trauma center were reconstructed. In each case, a virtual tibial intramedullary nail (vIM nail) with three distal anteroposterior (AP) locking screws (S₁₃, S₁₅ and S₃₇, the number indicating the distance from the screw to the nail tip) were inserted into the center of the tibial canal and ended on top of the distal tibial physeal scar. Contact between the screws and the PMF was defined as causing PMF displacement. The relationship between PMF secondary displacement and traumatic anatomic factors (the fragment area and height of the PMF) was explored. Then, the parameters were justified by analyzing intraoperative radiographs of 35 cases treated by nail with single locking screw (S₁₅) design.

Results

In the analog experiment, multiple logistic regression analysis revealed that the height of the PMF could confidently predict the risk of fragment displacement (S₁₃: odds ratio [OR] 1.18, 95% confidence interval [CI] 1.06–1.32; S₁₅: OR 1.15, 95% CI 1.05–1.27). Regarding the height of the PMF, the receiver operating characteristic established a cut-off value of 31.2 mm for preliminary fixation of the fragment with 88.89% sensitivity and 88.89% specificity. In the operation group the nail stopped on the top of distal tibial physeal scar, no PMF secondary displacement occurred when the PMF height was less than 31.2 mm. However, the incidence of secondary displacement was 93.33% when the height of the PMF exceeded 31.2 mm.

Conclusion

When the distal tibial physeal scare was set as the limit of nail insertion depth, the height of the PMF could be used as a reliable reference predicting the risk of PMF secondary displacement caused by distal anteroposterior locking screw.

Morphological characteristics of the posterior malleolar fragment according to ankle fracture patterns: a computed tomography-based study

Background

The posterior malleolar fragment (PMF) of an ankle fracture can have various shapes depending on the injury mechanism. The purpose of this study was to evaluate the morphological characteristics of the PMF according to the ankle fracture pattern described in the Lauge-Hansen classification by using computed tomography (CT) images.

Methods

We retrospectively analyzed CT data of 107 patients (107 ankles) who underwent surgery for trimalleolar fracture from January 2012 to December 2014. The patients were divided into two groups: 76 ankles in the supination-external rotation (SER) stage IV group and 31 ankles in the pronation-external rotation (PER) stage IV group. The PMF type of the two groups was assessed using the Haraguchi and Jan Bartonicek classification. The cross angle (α), fragment length ratio (FLR), fragment area ratio (FAR), sagittal angle (θ), and fragment height (FH) were measured to assess the morphological characteristics of the PMF.

Results

The PMF in the SER group mainly had a posterolateral shape, whereas that in the PER group mainly had a posteromedial two-part shape or a large posterolateral triangular shape (P = 0.02). The average cross angle was not significantly different between the two groups (SER group = 19.4°, PER group = 17.6°). The mean FLR and FH were significantly larger in the PER group than in the SER group (P = 0.024, P = 0.006). The mean fragment sagittal angle in the PER group was significantly smaller than that in the SER group (P = 0.017).

Conclusions

With regard to the articular involvement, volume, and vertical nature, the SER-type fracture tends to have a smaller fragment due to the rotational force, whereas the PER-type fracture tends to have a larger fragment due to the combination of rotational and axial forces.

Biomechanical Study of Screw Fixation and Plate Fixation of a Posterior Malleolar Fracture in a Simulation of the Normal Gait Cycle

BACKGROUND

Fixation of posterior malleolar fractures with plates or screws is under debate. A fatigue loading system and a spatial motion capture system were used in this study to evaluate a posterior malleolar fracture model.

METHODS

Thirty-six below-knee specimens with a single posterolateral fragment (Haraguchi I) type posterior malleolar fracture models were randomly divided into 2 groups. Two parallel-placed 3.5-mm partially threaded titanium alloy screws were used in Group A to fix the fractures, while anatomical plates were used in Group B. According to the ratio (S) of the area between the fracture and the total articular surface, each group was subdivided into 3 subgroups. In group A1 and B1, S=1/4; in A2 and B2, S=1/3; and in A3 and B3, S=1/2. To simulate the gait cycle, each specimen was subjected to mechanical loading in 4 different ankle positions. A fatigue loading system was used for repeated loading. A spatial motion capture system was used to measure the displacement in the final loading stage.

RESULTS

Despite the limited sample size and relatively low power, no significant difference was observed between A1 and B1, A2 and B2, and A3 and B3 in all 4 ankle positions after repeated loading.

CONCLUSION

For a Haraguchi type I posterior malleolar fracture with an average height of 19 mm, fixation with a posterior malleolar anatomical plate failed to demonstrate a stronger strength than 2 parallel-placed 3.5-mm partially threaded screws, which indicates that plates may not be absolutely necessary for standard rehabilitation after posterior malleolar internal fixation.

CLINICAL RELEVANCE

These findings may help guide surgeons with regard to fixation requirements for posterior malleolar fractures.

[Pilon fractures : Review of diagnostics and classification]

Intraarticular fractures of the distal tibia (pilon fractures) are rare injuries and today they occur mostly in traffic accidents and falls from a great height. There are simple fractures in the context of low-energy traumas, as well as complex comminuted fractures in high-energy traumas. Besides the clinical examination, plain radiographs and computed tomographic scans are diagnostic prerequisites. The aim of the diagnostic process is to clearly identify and classify the fracture before appropriate treatment is initiated. The systems used to classify the displaced distal pilon fractures are supposed to ensure the three-dimensional assessment of the fracture and provide high inter- and intra-observer agreement. In addition to the classification of Rüedi and Allgöwer, the classification of pilon fractures has been carried out using the AO classification.

The Role of Computed Tomography in Surgical Planning for Trimalleolar Fracture. A Survey of OTA Members

OBJECTIVE

Does the additional information provided by computed tomography (CT) alter surgeons' treatment plans for trimalleolar ankle fracture?

DESIGN

Prospective.

SETTING

Electronic survey.

PATIENTS/PARTICIPANTS

Members of the OTA.

INTERVENTION

Compare management of trimalleolar ankle fracture before and after CT.

MAIN OUTCOME MEASUREMENTS

Compare types of fixation used, indication for fixation, and approach need for fixation before and after CT.

RESULTS

Overall, OTA members' operative technique changed in 430 of the 1710 (25.1%) cases after review of the CT images. Of the 430 observations in which the operative technique was altered, the surgeon had initially stated that they would not have requested a CT in 51.2% incidences. When analyzing if CT affected whether or not operative fixation was indicated, a total of 16.3% responses changed. Surgeons were significantly more likely to change from no fixation to fixation (11.5%) than vice versa (4.8%) after reviewing CT imaging. A total of 17.8% of responses changed operative approach after reviewing the CT; 11.7% changed to open reduction internal fixation, whereas 6.1% changed away from open reduction internal fixation.

CONCLUSION

A consensus on the ideal treatment of trimalleolar fractures remains elusive, evidenced by a high variation in treatment preference, both before and after CT review. Our results demonstrate with the additional information delineated on CT, a surgeons' operative plan, technique, and approach often change. With greater than 25% of respondents changing their treatment strategy after seeing CT imaging, radiographs alone limited surgeon understanding of fracture pattern. Because of difficulty understanding the posterior fracture fragment, we recommend preoperative CT on all trimalleolar fractures.

LEVEL OF EVIDENCE

Diagnostic Level V. See Instructions for Authors for a complete description of levels of evidence.

Comparison of the direct and indirect reduction techniques during the surgical management of posterior malleolar fractures

Background

The optimal method for the reduction and fixation of posterior malleolar fracture (PMF) remains inconclusive. Currently, both of the indirect and direct reduction techniques are widely used. We aimed to compare the reduction quality and clinical outcome of posterior malleolar fracture managed with the direct reduction technique through posterolateral approach or the indirect reduction technique using ligamentotaxis.

Methods

Patients with a PMF involving over 25% of the articular surface were recruited and assigned to the direct reduction (DR) group or the indirect reduction (IR) group. Following reduction and fixation of the fracture, the quality of fracture reduction was evaluated in post-operative CT images. Clinical and radiological follow-ups were performed at 6 weeks, 3 months, 6 months, 12 months, and then at 6 month-intervals postoperatively. Functional outcome (AOFAS score), ankle range of motion, and Visual Analog Scale (VAS) were evaluated at the last follow-up. Statistical differences were compared between the DR and IR groups considering the patient demographics, quality of fracture reduction, AOFAS score, and VAS.

Results

Totally 116 patients were included, wherein 64 cases were assigned to the DR group and 52 cases were assigned to the IR group. The quality of fracture reduction was significant higher in the DR group (P = 0.038). In the patients who completed a minimum of 12 months’ follow-up, a median AOFAS score of 87 was recorded in the DR group, which was significantly higher than that recorded in the IR group (a median score of 80). The ankle range of motion was slightly better in the DR group, with the mean dorsiflexion restriction recorded to be 5.2° and 6.1° in the DR and IR group respectively (P = 0.331). Similar VAS score was observed in the two groups (P = 0.419).

Conclusions

The direct reduction technique through a posterolateral approach provide better quality of fracture reduction and functional outcome in the management of PMF over 25% of articular surface, as compared with the indirect reduction technique using ligamentotaxis.

Trial registration

NCT02801474 (retrospectively registered, June 2016, ClinicalTrails.gov).

Posterior Malleolar Fractures: Changing Concepts and Recent Developments

Injuries to the posterior malleolus are of prognostic relevance in ankle fracture-dislocations. The three-dimensional outline of the fragments as reflected by computed tomography classification, involvement of the fibular notch, and the presence of intercalary fragments seem to be of greater therapeutic relevance than the size of the fragment and amount of the articular surface involved. Operative treatment aims at reconstruction of the posterior tibial plafond, the fibular notch, and the integrity of the posterior inferior tibiofibular syndesmosis. Direct open reduction and fixation of posterior malleolus fragments via posterior approaches is biomechanically more stable than indirect reduction and anteroposterior screw fixation.

Articular Gap and Step-off Revisited: 3D Quantification of Operative Reduction for Posterior Malleolar Fragments

OBJECTIVES

Despite advanced imaging techniques, classic measurements of fracture reduction have not been revisited to date. The purpose of this study was to evaluate the reliability of innovative measurement techniques to quantify operative fragment reduction of posterior malleolar fractures by quantification of three-dimensional computed tomography (Q3DCT).

METHODS

Twenty-eight ankle fractures including a posterior malleolar fragment (AO/OTA type 44) were evaluated using 2DCT and Q3DCT to postoperatively quantify fragment reduction. "Classic" maximum gap and step-off of the posterior fragment were measured on 2DCT and Q3DCT. In addition, 2 innovative Q3DCT parameters were introduced and their reliability was tested using intraclass correlations (ICCs): gap surface (mm) and multidirectional 3D-displacement (mm).

RESULTS

"Classic" measurements showed a median maximum step-off of 1.1 mm [interquartile range (IQR) 0.0-1.8 mm] on 2DCT versus a median step-off of 0.6 mm (IQR 0.0-1.1) on Q3DCT. Median maximum gap was 1.2 mm (IQR 0.0-3.8) on 2DCT, and its equivalent on Q3DCT showed no median displacement. Q3DCT measurements revealed a median gap surface of 14.5 mm (IQR 4.7-30.0) and a median multidirectional 3D-displacement of 0.7 mm (IQR 0.0-1.1). Interrater reliability of these new Q3DCT parameters of displacement was excellent (ICC 0.92, 95% CI 0.79-0.98) for gap surface and good (ICC 0.64, 95% CI 0.28-0.88) for 3D-displacement.

CONCLUSIONS

Q3DCT is a reliable and promising technique for postoperative evaluation of fracture fragment reduction. In addition to "classic" gap and step-off measurements, we propose to explore total gap surface and 3D-displacement as innovative radiographic measurements in future clinical studies.

LEVEL OF EVIDENCE

Diagnostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Modified posteromedial approach for treatment of posterior pilon variant fracture

Background

Posterior pilon variant fracture is a recently described posterior malleolus fracture characterized by the involvement of both posterolateral and posteromedial malleolar fragment. The associated surgical approach remains controversial. The aim of this study was to present the application of modified posteromedial approach in the treatment for posterior pilon variant fracture.

Methods

Sixteen patients were identified with posterior pilon variant fractures. All fractures were operated via modified posteromedial approach. Fragment length ratio, area ratio and height were measured as morphologic assessments. The clinical outcome was evaluated with American Orthopaedic Foot & Ankle Society ankle-hind foot score and visual analogue scale. Radiological images were evaluated using osteoarthritis-score.

Results

According to the radiological measurements, the average fragment length ratio of posteromedial and posterolateral fragment was 25.3 and 31.5 % respectively. All fractures healed within a mean period of 13.1 weeks without malalignment or articular step-off. Fourteen patients were followed up, and all achieved good or excellent ankle function. The average score of American Orthopaedic Foot & Ankle Society and visual analogue scale at rest, motion and weight bearing walking was 85.6 and 0.25, 0.81, 1.31 respectively.

Conclusion

Modified posteromedial approach provides an alternative surgical treatment for posterior pilon variant fractures, and the short-term outcome was good.

Electronic supplementary material

The online version of this article (doi:10.1186/s12891-016-1182-9) contains supplementary material, which is available to authorized users.

Early Weightbearing After Operatively Treated Ankle Fractures: A Biomechanical Analysis

BACKGROUND

No consensus exists regarding the timing of weightbearing after surgical fixation of unstable traumatic ankle fractures. We evaluated fracture displacement and timing of displacement with simulated early weightbearing in a cadaveric model.

METHODS

Twenty-four fresh-frozen lower extremities were assigned to Group 1, bimalleolar ankle fracture (n=6); Group 2, trimalleolar ankle fracture with unfixed small posterior malleolar fracture (n=9); or Group 3, trimalleolar ankle fracture with fixed large posterior malleolar fracture (n=9) and tested with axial compressive load at 3 Hz from 0 to 1000 N for 250 000 cycles to simulate 5 weeks of full weightbearing. Displacement was measured by differential variable reluctance transducer.

RESULTS

The average motion at all fracture sites in all groups was significantly less than 1 mm (P < .05). Group 1 displacement of the lateral and medial malleolus fracture was 0.1±0.1 mm and 0.4±0.4 mm, respectively. Group 2 displacement of the lateral, medial, and posterior malleolar fracture was 0.6±0.4 mm, 0.5±0.4 mm, and 0.5±0.6 mm, respectively. Group 3 displacement of the lateral, medial, and posterior malleolar fracture was 0.1±0.1 mm, 0.5±0.7 mm, and 0.5±0.4 mm, respectively. The majority of displacement (64.0% to 92.3%) occurred in the first 50 000 cycles. There was no correlation between fracture displacement and bone mineral density.

CONCLUSION

No significant fracture displacement, no hardware failure, and no new fractures occurred in a cadaveric model of early weightbearing in unstable ankle fracture after open reduction and internal fixation.

CLINICAL RELEVANCE

This study supports further investigation of early weightbearing postoperative protocols after fixation of unstable ankle fractures.

Anatomy and classification of the posterior tibial fragment in ankle fractures

INTRODUCTION

The aim of this study was to analyze the pathoanatomy of the posterior fragment on the basis of a comprehensive CT examination, including 3D reconstructions, in a large patient cohort.

MATERIALS AND METHODS

One hundred and forty one consecutive individuals with an ankle fracture or fracture-dislocation of types Weber B or Weber C and evidence of a posterior tibial fragment in standard radiographs were included in the study. The mean patient age was 49 years (range 19-83 years). The exclusion criteria were patients below 18 years of age, inability to provide written consent, fractures of the tibial pilon, posttraumatic arthritis and pre-existing deformities. In all patients, post-injury radiographs were obtained in anteroposterior, mortise and lateral views. All patients underwent CT scanning in transverse, sagittal and frontal planes. 3D CT reconstruction was performed in 91 patients.

RESULTS

We were able to classify 137 cases into one of the following four types with constant pathoanatomic features: type 1: extraincisural fragment with an intact fibular notch, type 2: posterolateral fragment extending into the fibular notch, type 3: posteromedial two-part fragment involving the medial malleolus, type 4: large posterolateral triangular fragment. In the 4 cases it was not possible to classify the type of the posterior tibial fragment. These were collectively termed type 5 (irregular, osteoporotic fragments).

CONCLUSION

It is impossible to assess the shape and size of the posterior malleolar fragment, involvement of the fibular notch, or the medial malleolus, on the basis of plain radiographs. The system that we propose for classification of fractures of the posterior malleolus is based on CT examination and takes into account the size, shape and location of the fragment, stability of the tibio-talar joint and the integrity of the fibular notch. It may be a useful indication for surgery and defining the most useful approach to these injuries.