Intraarticular contact stresses with simulated ankle malunions

Open reduction and fixation does not improve short-term outcome of medium-sized posterior fragments in AO type B ankle fractures: one-year results of the POSTFIX randomized controlled trial

Aims

Guidelines for treatment of posterior malleolar fragments (PMFs) in trimalleolar fractures are scarce, mainly based on retrospective studies, and show varying advice. The need for fixation of smaller (< 25%) PMFs remains particularly controversial. This study aims to evaluate the superiority of fixation of medium-sized PMFs versus no fixation of the fragment.

Methods

A multicentre randomized controlled trial was conducted between January 2014 and January 2022 in two Dutch level 1 trauma centres (protocol registration: NCT02596529). Patients presenting with an AO-44-B3 fracture with a medium-sized (5% to 25%) PMF were 1:1 randomized online between open reduction and internal fixation (ORIF) (FIX) versus no fixation (NO-FIX) of the fragment. A total of 41 patients were allocated online to FIX via the posterolateral approach and 40 patients to NO-FIX. The primary outcome was functionality measured by the American Academy of Orthopaedic Surgeons (AAOS) questionnaire one year postoperatively. Secondary outcomes were osteoarthritis (OA) measured on radiographs and the Olerud and Molander ankle score, visual analogue scale pain, and EuroQol five-dimension questionnaire during follow-up. Quality of reduction was assessed by step-off on postoperative CT scan and radiograph. Complications were recorded.

Results

After one-year follow-up, no difference (p = 0.141) in AAOS was found after FIX (median 90 (IQR 68 to 95)) and NO-FIX (median 93 (IQR 85 to 97)). OA (≥ grade 2) was present in four (17%) of the cases after FIX and five (20%) after NO-FIX (p = 0.763). After one year, median pain scores were 20 (IQR 5 to 40) versus 10 (IQR 5 to 25) (p = 0.032), and perceived general median health scores were 80 (IQR 60 to 89) versus 83 (IQR 71 to 90) (p = 0.596) after FIX and NO-FIX, respectively. Postoperative step-off > 1 mm on CT scan was present in 56% after FIX versus 71% after NO-FIX (p = 0.193). Complication rates were 18% versus 5% (p = 0.071) after FIX and NO-FIX, respectively.

Conclusion

ORIF of medium-sized posterior fragments in AO type B trimalleolar fractures does not prompt superior functional or radiological results after one-year follow-up. Longer follow-up is needed to evaluate intermediate or long-term effects.

Weightbearing Computed Tomography Evaluation of Acute SER4a Ankle Fractures

BACKGROUND

Supination external rotation (SER) fibula fractures with abnormal medial clear space (MCS) on stress radiographs that normalizes with weightbearing radiographs, termed SER4a ankle fractures, pose a challenge in treatment decision making. This study aims to quantify differences in joint contact area, tibiotalar rotation, and translation using weightbearing computed tomography (CT) scans in SER4a ankle fractures.

METHODS

Between November 2022 and September 2023, patients presenting with isolated Weber B fibula fractures were evaluated for inclusion. Adult patients presenting within 10 days of injury with an SER4a ankle fracture, and no history of ankle fractures or surgery, were included. Ten patients were enrolled and underwent bilateral ankle weightbearing CT scans. Disior Bonelogic Software was used to quantify joint contact area, tibiotalar rotation, and translation, with the uninjured ankle serving as the control.

RESULTS

Ten patients (4 male, 6 female) with an average age of 51 years were included. The average MCS measured 2.5 mm (SD 0.36) on weightbearing and 5.7 mm (SD 0.67) on stress radiographs. The difference in joint contact area between injured and healthy joints was 12.2 mm2 (P = .085). Axial tibiotalar joint rotation averaged 6.6 degrees of increased external rotation on the injured extremity (P < .001). The mediolateral distance between the center of the tibial plafond and center of the talar dome was increased 1.0 mm in the injured extremity (P < .05).

CONCLUSION

In this study evaluating 10 patients with acute SER4a ankle fractures, no difference in joint contact area was found between individuals' healthy and injured ankles. However, differences in external rotation and lateral translation of the talus were observed on the injured ankle. The clinical effects of these tibiotalar rotational and translational changes are unknown.

CLINICAL RELEVANCE

This study provides insight regarding in vivo changes in 3-dimensional alignment of SER4a ankle fractures that may influence future management of these fractures.

Comparative finite element analysis of contact and stress distribution in tibiotalar articular cartilage: Healthy versus varus ankles

Background

The distribution of forces within the ankle joint plays a crucial role in joint health and longevity. Loading disorders affecting the ankle joint can have significant detrimental effects on daily life and activity levels. This study aimed to enhance our understanding of the mechanical behavior of tibiotalar joint articular cartilages in the presence of varus deformity using finite element analysis (FEA) applied to patient-specific models.

Methods

Two personalized ankle models, one healthy and another with varus deformity, were created based on CT scan images. Four static loading scenarios were simulated at the center of pressure (COP), coupled to the hindfoot complex. The contact area, contact pressure, and von Mises stress were computed for each cartilage.

Results

It was found that the peak contact pressure increased by 54% in the ankle with varus deformity compared to the healthy ankle model. Furthermore, stress concentrations moving medially were observed, particularly beneath the medial malleolus, with an average peak contact pressure of 3.5 MPa and 4.7 MPa at the tibial and talar articular cartilages, respectively.

Conclusion

Varus deformities in the ankle region have been consistently linked to elevated contact pressure, increasing the risk of thinning, degeneration, and eventual onset of osteoarthritis (OA), emphasizing the need for prompt interventions aimed at mitigating complications.

Hindfoot kinematics and kinetics - A combined in vivo and in silico analysis approach

BACKGROUND

The complex anatomical structure of the foot-ankle imposes challenges to accurately quantify detailed hindfoot kinematics and estimate musculoskeletal loading parameters. Most systems used to capture or estimate dynamic joint function oversimplify the anatomical structure by reducing its complexity.

RESEARCH QUESTION

Can four dimensional computed tomography (4D CT) imaging in combination with an innovative foot manipulator capture in vivo hindfoot kinematics during a simulated stance phase of walking and can talocrural and subtalar articular joint mechanics be estimated based on a detailed in silico musculoskeletal foot-ankle model.

METHODS

A foot manipulator imposed plantar/dorsiflexion and inversion/eversion representing a healthy stance phase of gait in 12 healthy participants while simultaneously acquiring 4D CT images. Participant-specific 3D hindfoot rotations and translations were calculated based on bone-specific anatomical coordinate systems. Articular cartilage contact area and contact pressure of the talocrural and subtalar joints were estimated using an extended foot-ankle model updated with an elastic foundation contact model upon prescribing the participant-specific rotations measured in the 4D CT measurement.

RESULTS

Plantar/dorsiflexion predominantly occurred at the talocrural joint (RoM 15.9±3.9°), while inversion/eversion (RoM 5.9±3.9°) occurred mostly at the subtalar joint, with the contact area being larger at the subtalar than at the talocrural joint. Contact pressure was evenly distributed between the talocrural and subtalar joint at the beginning of the simulated stance phase but was then redistributed from the talocrural to the subtalar joint with increasing dorsiflexion.

SIGNIFICANCE

In a clinical case study, the healthy participants were compared with four patients after surgically treaded intra-articular calcaneal fracture. The proposed workflow was able to detect small but meaningful differences in hindfoot kinematics and kinetics, indicative of remaining hindfoot pathomechanics that may influence the onset and progression of degenerative joint diseases.

Numerical simulations of the effect of lateral malleolus fracture malunion on ankle biomechanics: Different offset directions and offsets

INTRODUCTION

Ankle fractures account for approximately 10 % of all fractures. Approximately 5-68 % of patients with ankle fractures may suffer from malunion. Besides, suboptimal reduction of fracture fragments can affect the biomechanics of the ankle joint, ultimately leading to damage to the ankle joint. However, there are certain controversies over the conclusion of previous cadaveric studies.

METHODS

In this study, a three-dimensional model of the ankle joint was established based on CT image data. In addition, the effects of backward offset (1-2 mm) and outward offset (0.5-1 mm) of the fracture fragment on the contact area, contact pressure, and ligament force of the ankle joint were investigated via the finite element method. Moreover, lateral malleolus fracture malunion in five ankle positions (neutral, 10° dorsiflexion, 10° plantarflexion, 20° dorsiflexion, and 20° plantarflexion) was investigated.

RESULTS

This model predicted an overall increased contact area in the ankle joint in patients with lateral malleolus fracture malunion compared with the normal ankle joint. The results demonstrated that the outward offset had a more significant effect than the backward one. The larger the dorsiflexion-plantarflexion angle, the more pronounced the effect of malunion. Further, an outward offset can cause the fibula to lose its function.

CONCLUSION

Post-traumatic osteoarthritis occurs under the action of unaccustomed cartilage forces due to altered tibial talar joint contact patterns, rather than increased contact pressure reported in previous studies. Malunion leads to an increase or decrease in force on the affected ligament, while the cause of malunion can be envisioned based on a decrease in the force on the ligaments.

Considerations with Fractures of the Posterior Malleolus in Ankle Fractures

Foot and ankle surgeons are commonly confronted with the surgical dilemma on when and how to best surgically address trimalleolar ankle fractures with a posterior malleolar component. This may involve either direct fixation of the posterior malleolus or indirect stabilization with the fixation of the medial and lateral malleoli and trans-syndesmotic fixation. Recently there has been a paradigm shift in the management of these injuries with a more thorough understanding of anatomy, stability, and long-term sequela of these injuries. This article aims to evaluate the current literature on posterior malleolar ankle fractures, approaches to fixing the posterior malleolus, and outcomes and complications of these procedures.

Evaluation of Contact Area and Pressure After Malreduction in Isolated Medial Malleolar Fractures With 2 mm of Displacement: A Cadaveric Study

This study was performed to evaluate the changes in contact area and pressure in the tibiotalar joint, with a 2 mm displacement after IMMF (isolated medial malleolar fracture). Ten cadavers with pairs were used to establish a situation in which IMMF occurred during ankle injury. We performed IMMF corresponding to types C and D of the Herscovici classification, and it was displaced by 2 mm. The normal group was defined as a normal tibiotalar joint, the TF (transverse fracture) group as a 2 mm transverse displacement corresponding to the Herscovici classification type C, and the OF (oblique fracture) group as a 2 mm oblique displacement corresponding to the Herscovici classification type D. We measured the contact area and pressure at the tibiotalar joint. The film was scanned and analyzed using the digital imaging software, Scion Image (Scion Crop. Frederick, MD). In normal group, the average contact area of the tibiotalar joint was 317 mm2 (IQR; interquartile range, 256; 347) and 308 mm2 (IQR, 262; 364), average pressure was 2.19 N/mm2 (IQR, 1.94; 2.27) and 2.15 N/mm2 (IQR, 2.06; 2.53). In the TF and OF groups, the average contact area of the tibiotalar joint decreased by 9% and 12%, respectively, and the average pressure increased by 8% and 14%, respectively. There was no statistical difference in peak pressure between the normal, TF, and OF groups. In the case of transverse and oblique fractures, a 2 mm displacement showed significant changes in contact area and contact pressure compared to the normal tibiotalar joint, but there were no significant changes pertaining to type, between the 2 fractures.

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.

Validation of a personalized ligament-constraining discrete element framework for computing ankle joint contact mechanics

BACKGROUND AND OBJECTIVE

Computer simulations of joint contact mechanics have great merit to improve our current understanding of articular ankle pathology. Owed to its computational simplicity, discrete element analysis (DEA) is an encouraging alternative to finite element analysis (FEA). However, previous DEA models lack subject-specific anatomy and may oversimplify the biomechanics of the ankle. The objective of this study was to develop and validate a personalized DEA framework that permits movement of the fibula and incorporates personalized cartilage thickness as well as ligamentous constraints.

METHODS

A linear and non-linear DEA framework, representing cartilage as compressive springs, was established, verified, and validated. Three-dimensional (3D) bony ankle models were constructed from cadaveric lower limb CT scans imaged during application of weight (85 kg) and/or torque (10 Nm). These 3D models were used to generate cartilage thickness and ligament insertion sites based on a previously validated statistical shape model. Ligaments were modelled as non-linear tension-only springs. Validation of contact stress prediction was performed using a simple, axially constrained tibiotalar DEA model against an equivalent FEA model. Validation of ligamentous constraints compared the final position of the ankle mortise to that of the cadaver after application of torque and sequential ligament sectioning. Finally, a combined ligamentous-constraining DEA model was validated for predicted contact stress against an equivalent ligament-constraining FEA model.

RESULTS

The linear and non-linear DEA model reproduced a mean articular contact stress within 0.36 MPa and 0.39 MPa of the FEA calculated stress, respectively. With respect to the ligamentous validation, the DEA ligament-balancing algorithm could reproduce the position of the distal fibula within the ankle mortise to within 0.97 mm of the experimental observed distal fibula. When combining the ligament-constraining and contact stress algorithm, DEA was able to reproduce a mean articular contact stress to within 0.50 MPa of the FEA calculated contact stress.

CONCLUSION

The DEA framework presented herein offers a computationally efficient alternative to FEA for the prediction of contact stress in the ankle joint, manifesting its potential to enhance the mechanical understanding of articular ankle pathologies on both a patient-specific and population-wide level. The novelty of this model lies in its personalized nature, inclusion of the distal tibiofibular joint and the use of non-linear ligament balancing to maintain the physiological ankle joint articulation.

[Translated article] Posterior malleolar fractures: Indications and surgical approaches

Posterior malleolus fractures are frequent injuries, present in 7-44% of all ankle fractures. The objective of this study is to review the evidence to indicate the fixation of this fracture and to choose the appropriate surgical approach. The classic indications for fixation were fragment size greater than 25-30% of the articular surface and displacement greater than 2mm. However, current evidence suggests that, rather than size, factors such as syndesmotic instability, intra-articular step-off greater than 1-2mm, plafond impaction and the presence of intercalary fragments should be considered. When comparing the different surgical approaches, the literature supports the use of posterior approaches and reserves the recommendation of the traditional approach for exceptional cases. For the treatment of this injury it is essential to know the anatomy of the ankle and to consider all the factors described above, in addition to the presence of concomitant injuries.

Posterior malleolar fractures: Indications and surgical approaches

Posterior malleolus fractures are frequent injuries, present in 7-44% of all ankle fractures. The objective of this study is to review the evidence to indicate the fixation of this fracture and to choose the appropriate surgical approach. The classic indications for fixation were fragment size greater than 25-30% of the articular surface and displacement greater than 2 mm. However, current evidence suggests that, rather than size, factors such as syndesmotic instability, intra-articular step-off greater than 1-2 mm, plafond impaction and the presence of intercalary fragments should be considered. When comparing the different surgical approaches, the literature supports the use of posterior approaches and reserves the recommendation of the traditional approach for exceptional cases. For the treatment of this injury it is essential to know the anatomy of the ankle and to consider all the factors described above, in addition to the presence of concomitant injuries.

Pre-and postoperative factors associated with functional outcomes in patients with posterior malleolar fractures

INTRODUCTION

Recent studies on posterior malleolar fractures mainly focus on the reduction quality and fixation of the posterior fragment since it contributes to ankle stability and articular congruency. However, the association of pre-and postoperative factors considering the whole ankle joint in postoperative functional outcomes remains unclear. Therefore, this study aimed to examine the association between pre-and postoperative variables for postoperative functional outcomes in patients with posterior malleolar fragments (classified as Haraguchi type I or II) and considered the association between reduction and fixation for small posterior malleolar fragments of less than 25% of the intra-articular surface.

METHODS

This multicenter retrospective cohort study included 110 adult patients who underwent internal fixation for ankle fractures with posterior malleolar fragments. The primary outcome was the American Orthopaedic Foot and Ankle Society (AOFAS) score 12-months postoperatively. As pre-and postoperative variables, the preoperative demographic data, radiographic findings, operative method, postoperative radiographic findings, and complications were evaluated. In addition, univariable and multivariable logistic regression analyses were conducted to examine the association between pre-and postoperative variables and AOFAS scores.

RESULTS

Twenty-four (21.8%) cases had postoperative complications. Univariate analysis showed that age was significantly according to AOFAS score-stratified groups in patients with Haraguchi type II fractures. Multivariable logistic regression analysis using bootstrapping in the Haraguchi type II group showed that postoperative complications were significantly associated with low AOFAS scores, indicating poor functionality. In both fracture types, postoperative complications had the highest odds ratio among the explanatory variables. In patients with small posterior malleolar fragments, fragment reduction, fixation, and ankle stability were not associated with AOFAS scores.

CONCLUSIONS

Our results suggest that postoperative complications were associated with AOFAS scores at postoperative 12 months in patients with ankle fractures with posterior malleolar fragments. In patients with small posterior malleolar fragments, reduction and fixation were not associated with AOFAS scores. Therefore, clinical decisions for posterior fragment fixation should be made based on the possible risk of complications related to the surgical procedures in addition to the posterior malleolar fragment size.

A new finite element model of intra-articular impacted fragment in posterior malleolar fractures: A technical note

Intra-articular impacted fragment (IAIF) was considered as the articular surface fragment resulting from impact and compressive forces. Malreduction of IAIF in posterior malleolar fractures was associated with the cause of talus subluxation and long-term arthritis. The effect of IAIF on ankle pressure and stress has not been studied, and it's difficult to do this in cadaver bone. So we established IAIF defect finite element model in posterior malleolar fractures and explored the effect of IAIF defect in ankle joint. We also discussed the relation between IAIF defect and post-traumatic arthritis.

Comparison of routine computed tomography and plain X-ray imaging for malleolar fractures-How much do we miss?

PURPOSE

Most patients with ankle arthrosis have a history of ankle fracture. Evaluation of malleolar fractures solely on X-ray may be insufficient to identify many pathologies that potentially contribute to ankle arthrosis, with a consequent poor prognosis. We investigated the pathologies that may be overlooked in malleolar fractures evaluated solely on plain X-ray.

METHODS

During 2012-2019, 65,479 patients attended our Emergency Department, of which 6508 complained of an ankle joint problem. X-rays indicated a fracture in 454 of these patients. Patients with isolated, simple fracture of the lateral or medial malleolus, or talus, or a history of surgery to this area were excluded; finally, 67 patients were enrolled (31 males, 36 females; mean age: 51,2 years (range: 9-83 years). Patients underwent X-ray imaging of both ankles in anterio-posterior, lateral, and Mortise views, as well as CT scans. Three independent observers with varied experience in diagnostic imaging (orthopaedic resident, experienced orthopaedic surgeon, and musculoskeletal radiologist) evaluated X-ray images blinded to CT scans. Their diagnoses were subsequently compared with CT findings.

RESULTS

Modeling results indicated that about 40% [95% CI: 32%, 50%] of pathologies may be overlooked based on X-ray evaluation, regardless of evaluator experience. The most frequently overlooked injuries were: Tillaux fracture, Pillon fracture, loose bodies and syndesmosis injury. All of that missed pathologies required dedicated treatment and could be easily missed with standard surgical approach.

CONCLUSION

Evaluation of malleolar fractures by X-ray only inevitably results in overlooking of many pathologies, despite the clinician's experience. Routine CT scan can help to improve the accuracy of diagnosis, and thereby reduce the risk of ankle osteoarthrosis.

Anatomic Structures at Risk During Posterior to Anterior Percutaneous Screw Fixation of Posterior Malleolar Fractures: A Cadaveric Study

Background. There are no established guidelines for fixation of posterior malleolus fractures (PMFs). However, fixation of PMFs appears to be increasing with growing evidence demonstrating benefits for stability, alignment, and early functional outcomes. The purpose of this study was to determine the risk to anatomic structures utilizing a percutaneous technique for posterior to anterior (PA) screw fixation of PMFs. Methods. Percutaneous PA screw placement was carried out on 10 fresh frozen cadaveric ankles followed by dissection to identify soft tissue and neurovascular structures at risk. The distance from the guidewire to each anatomic structure of interest was measured. The correlation between the mean distances from the guidewire to each structure was calculated. Results. The sural nerve was directly transected in 1/10 specimens (10%) and in contact with the wire in a second specimen (10%). There was a significant correlation between the proximity of the guidewire to the apex of Volkmann's tubercle and its proximity to the sural nerve. The flexor hallucis longus (FHL) muscle belly was perforated by the guidewire 40% of the time but was not tethered or entrapped by the screw. Conclusions. Percutaneous PA screw placement is a safe technique which can be improved with several modifications. A mini-open technique is recommended to protect the sural nerve. There may be potential for tethering of the FHL with use of a washer or large screw head. Risk to the anterior and posterior neurovascular bundles is minimal.Levels of Evidence: Level V.

Prognostic value of the Haraguchi classification in posterior malleolar fractures in A0 44-C type ankle fractures

BACKGROUND AND PURPOSE

Incidence of posterior malleolar fractures (PMFs) associated with ankle fractures is historically based on plain radiographs. Several classification systems for PMF are currently in use, but the reliability of the Haraguchi classification is not reported. The aim of this diagnostic cohort study was to assess incidence of PMF in patients with AO 44-C fractures, and test the reliability of the Haraguchi fracture classification based on CT. In addition, to evaluate the clinical outcome in patients with PMF.

METHODS

210 patients with an AO 44-C type fracture treated with syndesmotic fixation between 2011 and 2017 were included. Presence of PMF was registered, morphology was assessed and classified according to the Haraguchi classification. Interobserver agreement for the Haraguchi classification was evaluated. Patient assessment was conducted at 6 weeks, 6 months, 1 and 2 years. The American Orthopaedic Foot & Ankle Society Ankle-Hindfoot Score (AOFAS) was the primary outcome measure. Secondary outcome measures included presence of osteoarthritis.

RESULTS

125 of 210 patients (60%) had a PMF. 34% of the PMFs were missed on plain radiographs compared to CT. The interobserver agreement was 0.797, (95% CI: 0.705 to 0.889, p < 0.001), for the Haraguchi classification. The 2-year follow-up rate was 86%. Haraguchi type II fractures had a lower AOFAS compared with the no-fracture group at 6 weeks (mean difference -7.5 (95% CI; -15.0 to -0.2), p = 0.04) and 6 months (mean difference -8.4 (95% CI; -15.3 to -1.5), p = 0.01). Presence of osteoarthritis was higher in patients with Haraguchi type II PMF compared to the no PMF group, this finding was not significant (relative risk (RR) 1.6(95% CI 1.1 to 2.4, p = 0.059)).

CONCLUSIONS

Plain radiographs underestimated PMF. Patients with a Haraguchi type II fracture had a poorer outcome measured by the AOFAS score compared to no PMF up until 6 months. Classification of PMF according to the Haraguchi classification was reliable.

External Validation of the Radiographic Investigation of the Distal Extension of Fractures Into the Articular Surface of the Tibia (RIDEFAST Study)

OBJECTIVE

To test the external validity of the fracture to plafond (FTP-length of fracture/distance to plafond) ratio to rule out distal intra-articular fractures (DIA) in distal tibial shaft fractures at an independent tertiary trauma center.

DESIGN

Retrospective cohort study.

SETTING

Two Level 1 trauma centers.

PATIENTS

Two hundred seventeen patients with a distal tibial shaft fracture in the model cohort and 146 patients in the validation cohort.

INTERVENTION

Radiographic measurements to calculate FTP ratio.

MAIN OUTCOME MEASUREMENTS

Calibration plots, area under receiver operating characteristic curve (AUC), and decision curve analyses to evaluate the external validity of FTP ratio to determine DIA.

RESULTS

The AUC for the anteroposterior (AP) FTP ratio was 0.83 [95% confidence interval (CI) 0.78-0.88] in the model data set and 0.86 (95% CI 0.80-0.91) in the validation data set. The AUC for the lateral FTP ratio was 0.82 (95% CI 0.77-0.87) in the model data set and 0.82 (95% CI 0.75-0.88) in the validation data set. The previously established AP FTP cutoff ratio of 0.61 had a 94% negative predictive value in the model cohort and a 100% negative predictive value in the validation cohort.

CONCLUSION

The FTP ratio is an effective and externally validated screening tool to rule out DIA in distal tibia shaft fractures.

LEVEL OF EVIDENCE

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

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.

Reconciliation Between Lateral X-ray and Axial Computed Tomography Regarding Posterior Malleolus Fracture Anatomy and Medial Malleolus Involvement: A Pilot Study

Configuration of a posterior malleolus fracture has significant variation based on mechanism of injury and concomitant ankle injuries. Radiographs obtained during early workup of ankle trauma play a pivotal role in closed reduction, surgical planning and preoperative management. Preoperative computed tomography helps distinguish fracture pathoanatomy. The purpose of this study is to relate measurements from traditional lateral radiographs with measurements on axial computed tomography. Imaging from a total of 22 patients treated at our institution from January 2008 to 2018 were evaluated. Two raters measured posterior malleolus fracture height and articular surface length on lateral radiographs, as well as medial-lateral width and anterior-posterior depth on axial computed tomography using calibrated imaging software. Posterior malleolar fractures with medial extension were recorded. Pearson correlations were calculated for all pairwise combinations of measurements. Lateral height and axial width were positively correlated. There was found to be an association between taller lateral height, and separately, wider axial width with presence of medial extension. Based on the correlations found between the measurements as well as the independent associations found with presence of medial extension, we suggest posterior-medial incision be evaluated as a potential approach in taller fractures as noted on lateral radiograph.

Comparison of Different Magnitudes of Applied Syndesmotic Clamp Force: A Cadaveric Study

Overcompression of the ankle syndesmosis was once thought to be improbable. Recent studies using computerized tomography (CT) however, have demonstarted otherwise; raising pertinent questions regarding the factors associated with and consequences of syndesmotic overcompression. The purpose of the present study was to directly compare different magnitudes of applied clamp force on the coronal reduction of ankle syndesmosis. Eight through-the-knee cadaveric specimens were obtained. Fiducial cannulated screws were placed in the tibia and fibula to standardize placement of the reduction clamp's tines. CT scans were obtained as baseline controls, followed by destabilization of the syndesmosis. Reductions were then performed using a clamp equipped with an inline load cell, and objective forces (60, 80, 100, 120, 140, and 160 N) applied sequentially to each of the specimens. The syndesmosis was fixed with a single quadricortical screw, and CT were scans repeated. Applied clamp forces of 60 and 80 N resulted in lateral fibular displacement and undercompression (42.9% and 57.1%, respectively), whereas forces of 140 and 160 N resulted in medial fibular displacement (p = .011 and p = .001) and overcompression (100%). The smallest mediolateral displacements were observed with 100 and 120 N, respectively. Malreduction assessment with CT was superior to traditional radiographs [r(54) = 0.22; 95% confidence interval -0.04 to 0.45; p = .101]. In our cadaveric model, an applied clamp force of 100 N most effectively mitigated iatrogenic coronal syndesmotic malreduction from under- or overcompression. Although additional research is warranted, based on the data, inherent variabilities in the applied clamp force by surgeons appear to contribute to the unacceptably high coronal syndesmotic malreduction rate.

Anatomic Analysis of a Percutaneous Fixation Technique for the Posterior Malleolus Using Posterior-to-Anterior-Directed Cannulated Screws: A Cadaveric Study and Technique Description

BACKGROUND

Posterior malleolus fractures are traditionally managed with open reduction and internal fixation or percutaneous anterior-to-posterior screws. We present a third option using a percutaneous technique for the placement of posterior-to-anterior-directed screws. An anatomic safety analysis is done using cadaveric specimens.

METHODS

Using 15 embalmed specimens (10 F and 5 M), a guidewire was placed using the described technique. The posterolateral ankle was dissected to evaluate for damage to vulnerable structures including the sural nerve, peroneal artery, and flexor hallucis longus/flexor digitorum longus/peroneal/Achilles tendons. The distance from the sural nerve and peroneal artery was measured to the guidewire at its nearest point. The tendons were evaluated for traumatic piercings.

RESULTS

The sural nerve had a mean distance to wire of 5.3 mm (range 0 to 12) and the peroneal artery had a mean distance to wire of 5.7 mm (range 2 to 13 mm) with no traumatic piercings of either structure. The flexor hallucis longus/flexor digitorum longus/peroneal/Achilles tendons had no traumatic piercings.

CONCLUSION

This percutaneous technique provides a safe alternative to the standard open and traditional percutaneous techniques. It has limited application and is suitable for noncomminuted minimally displaced posterior malleolus fractures and those with fragile tissues where the morbidity of the soft tissue exposure outweighs the benefit of an open reduction.

[Fracture of the posterior malleolus : A paradigm shift]

Ankle fractures with involvement of the posterior malleolus have a poor prognosis. The traditional concept of addressing the posterior fragment as the final step in the surgical reconstruction depending on the fragment size manifest in the lateral X‑ray, does not do justice to the anatomic and biomechanical relevance of the posterior malleolus. Intra-articular step-offs and fragment displacement ≥ 2 mm, impacted intercalary fragments, involvement of the fibular notch and instability of the syndesmosis, represent parameters relevant for the surgical reconstruction and the functional and radiomorphological outcome independent of fragment size. A valid assessment of these parameters can only be achieved via computed tomography (CT) including multiplanar 2D and 3D reconstruction. This is the foundation for the classification of posterior malleolar fractures according to Bartoníček et al., it forms the basis of the preoperative analysis of the fracture components and represents a decision-making tool for the indications for surgery. The individual fracture pattern guides the selection of the suitable approach or a combination of approaches and the surgical strategy. Making use of the posterior approaches enables the surgeon to have a direct view of the fracture components of the posterior malleolus as a precondition for an anatomic reduction. This central surgical step is frequently done as the first measure of the surgical reconstruction of the ankle joint. Furthermore, direct reduction and posterior stabilization is more accurate and stable than indirect reduction from an anterior approach with indirect fixation using lag screws. An additional temporary transfixation of the tibiofibular syndesmosis is often dispensable.

Strategies to Avoid Syndesmosis Malreduction in Ankle Fractures

Nearly half of surgically treated ankle fractures may have associated syndesmotic disruption, and the quality of reduction has been shown to affect functional outcomes. Malreduction ranges from 15% to 50% in the literature, and achieving anatomic reduction remains a significant challenge, even for experienced surgeons. Keys to success include having a stepwise plan and an understanding of reliable fluoroscopic parameters to help achieve reduction in both the coronal and sagittal planes. This article summarizes the literature on syndesmotic reduction and provides the authors' preferred technique using fluoroscopy.

Clinical and radiological mid- to long-term results after direct fixation of posterior malleolar fractures through a posterolateral approach

BACKGROUND

Direct fixation of posterior malleolar fractures has been shown to lead to higher accuracy of fracture reduction compared to an indirect anterior to posterior fixation but lacks long-term clinical results. This study shows the mid- to long-term clinical and radiological outcome after direct fixation of the posterior malleolus through a posterolateral approach.

MATERIALS AND METHODS

Thirty-six patients with an ankle fracture including a posterior malleolar fragment (23 × AO-44C, 12 × AO-44B, 1 × unclassifiable) treated with direct fixation of the fragment through a posterolateral approach were retrospectively evaluated. There were 24 females (67%) with a mean age of 63 (range 34-80) years and a BMI of 28 (range 19-41) kg/m² at the time of surgery. An initial fracture-dislocation was seen in 67%. The clinical outcome was assessed with the Visual Analog Scale (VAS, 0-10 points) and the American Foot and Ankle Society (AOFAS, 0-100 points) score. Posttraumatic osteoarthritis was recorded with the Van Dijk Classification (grade 0-III). Subgroup analyses of patient- and fracture-associated risk factors (age, BMI, smoking, fracture-dislocation, postoperative articular step-off) were assessed to reveal possible negative prognostic predictors.

RESULTS

After a mean follow-up of 7.9 (range 3-12) years, the median VAS was 1 (IQR 0-2) point, and the median AOFAS score was 96 (IQR 88-100) points. Ankle range of motion measurements showed a significant, but clinically irrelevant, difference in plantar- and dorsiflexion between the affected and unaffected ankle. 92% of the patients were very satisfied or satisfied with the postoperative course. 89% had no preoperative signs of ankle osteoarthritis. Osteoarthritis progression was seen in 72%, with 50% showing grade II or III osteoarthritis at the final follow-up. No significant negative prognostic factors for a worse clinical outcome could be detected.

CONCLUSION

Direct fixation of posterior malleolar fractures through a posterolateral approach showed good clinical mid- to long-term results with a high satisfaction rate but substantial development of posttraumatic ankle osteoarthritis. Further studies should include CT analysis of the preoperative fracture morphology and even, perhaps, the postoperative reduction accuracy to evaluate the benefit of posterior malleolar fracture reduction in preventing ankle osteoarthritis in the long term.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for authors for a complete description of levels of evidence.

Ankle joint re-balancing in the management of ankle fracture malunion using fibular lengthening: prospective clinical-radiological results at mid-term follow-up

PURPOSE

An unsatisfactory reduction and internal fixation of an ankle fracture can result in an alteration of the anatomical axes and distribution of the load on the ankle, with consequent development of chronic pain and articular degeneration. The aim of this study is to evaluate the results of the articular re-balancing with realignment and lengthening of the fibula in case of malunited distal fibular fractures.

METHODS

A review of prospectively collected data was performed for all patients with a diagnosis of malunion of the fibula and underwent ankle joint re-balancing with fibular lengthening. Twenty-three patients, with a mean age of 39.4 ± 13.1 years, have been evaluated using radiographic parameters, American Orthopaedic Foot and Ankle Surgeons ankle-hindfoot, Ankle Activity scale, and SF-36 score at six, 12, 24, and 36 months post-operatively.

RESULTS

All cases treated showed at follow-up the osteotomy healed in good correction of the deformities. Clinical scores showed a clear improvement: final 36-month mean AOFAS was 74.0 ± 8.9 point, final 36-month mean HALASI score was 4.9 ± 0.9 points, 36-month follow-up SF-36 score showed an average score of 73.2 ± 10.7 points. Pre- and post-operative radiographic parameters have been registered and described.

CONCLUSIONS

The ankle joint is a complex structure, and even minor changes of the structure of this joint can significantly compromise its functionality. Ankle joint re-balancing is an effective surgical procedure in case of fibular malunion. This procedure, in patients carefully selected, could procrastinate more disabling surgical procedure, as arthrodesis or prosthesis.

A patient-specific numerical model of the ankle joint for the analysis of contact pressure distribution

A patient-specific numerical model of the ankle joint has been developed using open-source software with realistic material properties that mimics the physiological movement of the foot during the stance phase of the gait cycle. The patient-specific ankle geometry has been segmented as a castellated surface using 3DSlicer from the computed tomography image scans of a subject with no congenital or acquired pathology; subsequently, the bones are smoothed, and cartilage is included as a uniform thickness extruded layer. A high-resolution Cartesian mesh has been generated using cfMesh. The material properties are assigned in the model based on the CT image Hounsfield intensities and compared to a sandwich-based material model. Gait data of the same subject was obtained and used to relatively position the tibia, talus, and calcaneus bones in the model. The stance phase of the gait cycle is simulated using a cell-centred finite-volume method implemented in open-source software OpenFOAM. The predicted peak contact pressures occur in the range of 4.85-5.53 MPa with average pressures in the range of 1.56-1.95 MPa, and the contact area ranges between 429 and 707.8 mm² for the entire stance phase with the mid-stance phase predicting the maximum contact area. These predictions are in agreement with results from the literature. The effect of arthritis on the contact characteristics of the ankle joint has also been examined. A concentrated increase in pressure was predicted that could be manifested as pain, thereby leading to reduced motion in the ankle. The model, with continued development, has the capability to understand the effect of joint degradation and furthermore, could help provide a tool to predict the efficiency of therapeutic surgical procedures as well as guide the development of next generation ankle prostheses. The work would be made available in the University College Dublin depository (https://github.com/laxmimurali/anklejoint) as well as research gate once the article has been published.

Early Corrections after Failed Ankle Fracture Fixation

Even minor residual fragment malpositioning after internal fixation of ankle fractures is associated with a worse prognosis. Frequent causes for non-anatomical reduction are fibular shortening due to comminuted fractures or poor bone quality, translational or rotational malpositioning of the distal fibula within the tibial incisura with unstable syndesmosis injuries, and inadequately addressed bony avulsions of the tibiofibular syndesmosis. After operative treatment of fracture dislocations with syndesmotic fixation, in case of complex fracture pathoanatomy, and with suspected non-anatomic reduction in postoperative radiographs, computed tomography imaging of both ankles should be performed. Correction of relevant malreductions should be performed as early as possible in order to speed up rehabilitation and to avoid late sequelae due to a load shift or instability in a weight-bearing joint.

An extended discrete element method for the estimation of contact pressure at the ankle joint during stance phase

Abnormalities in the ankle contact pressure are related to the onset of osteoarthritis. In vivo measurements are not possible with currently available techniques, so computational methods such as the finite element analysis (FEA) are often used instead. The discrete element method (DEM), a computationally efficient alternative to time-consuming FEA, has also been used to predict the joint contact pressure. It describes the articular cartilage as a bed of independent springs, assuming a linearly elastic behaviour and absence of relative motion between the bones. In this study, we present the extended DEM (EDEM) which is able to track the motion of talus over time. The method was used, with input data from a subject-specific musculoskeletal model, to predict the contact pressure in the ankle joint during gait. Results from EDEM were also compared with outputs from conventional DEM. Predicted values of contact area were larger in EDEM than they were in DEM (4.67 and 4.18 cm², respectively). Peak values of contact pressure, attained at the toe-off, were 7.3 MPa for EDEM and 6.92 MPa for DEM. Values predicted from EDEM fell well within the ranges reported in the literature. Overall, the motion of the talus had more effect on the extension and shape of the pressure distribution than it had on the magnitude of the pressure. The results indicated that EDEM is a valid methodology for the prediction of ankle contact pressure during daily activities.

Functional Outcomes of Isolated Infrasyndesmotic Fibula Fractures

Background:

Ankle fractures are among the most common injuries encountered by orthopedic surgeons, with an incidence ranging from 71 to 187 per 100 000 people. Few studies have reliably investigated injuries involving isolated fractures of the distal fibula below the level of the ankle syndesmosis. Therefore, this study details on the patient-reported outcomes of nonoperatively managed isolated infrasyndesmotic fibula (ISF) fractures with a minimum 3-year follow-up.

Methods:

A retrospective population-based cohort study was undertaken across all emergency departments serving a major urban population. Among 159 consecutive patients meeting inclusion criteria, 108 agreed to participate. Clinical information, functional outcomes, and radiographic measurements were collected from electronic medical records and 3 validated outcome measures: the American Academy of Orthopaedic Surgeons (AAOS) Foot & Ankle Scale (FAS), the AAOS Shoe-Comfort Scale (SCS), and a general questionnaire.

Results:

An incidence of 22 ISF fractures per 100 000 people/year was found with FAS (91.2 ± 12.9) and SCS scores (76.8 ± 27.7), similar to reported population norms. Approximately 40% of patients (n = 43) reported continuing symptoms including pain (81.8%), stiffness (68.1%), and/or instability (39.0%). Less than 13% (n = 14) reported “severe” disabilities, and no patients required operative intervention within the follow-up period. Less-favorable outcomes were reported among work-related injuries, female patients, and “avulsion-type” fractures less than 10 mm in height (P < .01). No relationships were identified between age, degree of articular-incongruity, fracture-displacement, and self-reported outcomes.

Conclusions:

The majority of patients with nonoperatively managed ISF fractures reported good-to-excellent early functional outcomes. Less-favorable outcomes were reported among work-related injuries, female patients, and “avulsion-type” fractures.

Level of Evidence:

Level III, comparative series.

Posterior Malleolar Fracture Morphology in Tibial Shaft Versus Rotational Ankle Fractures: The Significance of the Computed Tomography Scan

OBJECTIVE

To compare posterior malleolar fracture morphology in ankle fractures compared with those with tibial shaft fractures.

SETTING

Level 1 trauma center.

DESIGN

Retrospective cohort study.

PATIENTS/PARTICIPANTS

Fifty-four patients with tibial shaft fractures and 61 patients with ankle fractures.

MAIN OUTCOME MEASUREMENTS

Posterior malleolar fractures in ankle fractures versus tibial shaft fractures were classified by type and pathomorphology analyzed.

RESULTS

Posterior malleolar fractures were significantly larger when associated with tibial shaft fractures (32% cross-sectional area) as compared to ankle fractures (15% cross-sectional area) (P < 0.001). The distribution of posterior malleolar fracture type differed between tibial shaft fractures and ankle fractures. In addition, 47% of the type II posterior malleolar fractures in tibial shaft fractures had an additional fracture line oriented in the sagittal plane, a fracture pattern unique to these injuries that were not observed in the ankle fracture cohort.

CONCLUSIONS

Posterior malleolar fracture morphology varied significantly between tibial shaft fractures and rotational ankle fractures. Posterior malleolar fractures in tibial shaft fractures were over twice the size of posterior malleolar fractures that occur with rotational ankle fractures and more likely to involved the medial malleolus. This information emphasizes the importance of recognizing that large posterior malleolar fractures are associated with tibial shaft fractures.

LEVEL OF EVIDENCE

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Screw Fixation of the Posterior Malleolus Fragment in Ankle Fracture

BACKGROUND

This study aimed to evaluate the outcomes of ankle fractures with posterior malleolus fragments (PMFs) involving <25% of the articular surface treated with or without screw fixation.

METHODS

Among patients with ankle fractures and PMFs who underwent surgery between March 2014 and February 2017, 62 with type 1 PMFs involving <25% of the articular surface were included. Of these 62 patients, 32 underwent screw fixation for PMFs and lateral and/or medial malleolar fracture fixation (group A) and 30 underwent internal fixation for malleolar fractures without screw fixation for PMFs (group B). Ankle joint alignment and fracture healing were measured using plain radiography and computed tomography (CT). Clinical outcomes were determined using the American Academy of Orthopaedic Surgeons Foot and Ankle Questionnaire, Short Form-36, and American Orthopaedic Foot & Ankle Society Scale.

RESULTS

Nonunion was not noted in either group. However, we detected union with a step-off of 2 mm or more in 2 cases from group B. With regard to ankle joint alignment, 1 case in group A and 3 cases in group B showed mild asymmetry of the medial and lateral clear spaces on CT at 12 months. Clinical outcomes at 6 and 12 months after surgery were better in group A than in group B.

CONCLUSION

Screw fixation of PMFs was effective for fracture healing and maintaining ankle alignment. Additionally, it improved short-term clinical outcomes, which we believe was due to stabilization of ankle fractures with PMFs involving <25% of the articular surface.

LEVEL OF EVIDENCE

Level II, prospective comparative study.

Screw fixation of the syndesmosis alters joint contact characteristics in an axially loaded cadaveric model

BACKGROUND

The purpose of this study was to quantify the effects of rigid syndesmotic fixation on functional talar position and cartilage contact mechanics.

METHODS

Twelve below-knee cadaveric specimens with an intact distal syndesmosis were mechanically loaded in four flexion positions (20° plantar flexion, 10° plantar flexion, neutral, 10° dorsiflexion) with zero, one, or two 3.5-mm syndesmotic screws. Rigid clusters of reflective markers were used to track bony movement and ankle-specific pressure sensors were used to measure talar dome and medial/lateral gutter contact mechanics.

RESULTS

Screw fixation caused negligible anterior and inferior shifts of the talus within the mortise. Relative to no fixation, mean peak contact pressure decreased by 6%-32% on the talar dome and increased 2.4- to 6.6-fold in the medial and lateral gutters, respectively, depending on ankle position and number of screws.

CONCLUSIONS

Two-way ANOVA indicated syndesmotic screw fixation significantly increased contact pressure in the medial/lateral gutters and decreased talar dome contact pressure while minimally altering talar position.

Negative prognostic factors in surgical treatment for trimalleolar fractures

PURPOSE

Trimalleolar fractures are a common injury of the ankle that require surgical treatment to obtain an anatomic reduction of both malleoli and stabilization of the syndesmosis. This study aims to report the outcomes of surgical treatment for trimalleolar fractures, identifying the risk factors determining a worse result.

MATERIALS AND METHODS

Between January 2013 and December 2016, 48 patients with trimalleolar fracture treated with open reduction and internal fixation were retrospectively analyzed. The mean age was 44.69 years, and average body mass index (BMI) was 29.04. According to the Danis-Weber classification, 30 (62.5%) fractures were type B and 18 (37.5%) were type C. Clinical and radiographic evaluations at 3, 6, and 12 months were assessed. The functional results of Visual Analogue Staircases and Olerud-Molander (O&M) ankle score were reported.

RESULTS

No significant difference was found among the size of the PM in patients with and without ankle dislocation (p = 0.364). Therefore, there is no correlation between the size of the posterior fragment and the ankle dislocation and the size of the posterior malleolus and syndesmosis stability (p = 0.328). Age over 61 years, BMI > 40, ASA > 1, type C fracture, and fracture dislocation were considered as negative prognostic fractures.

CONCLUSIONS

Surgical treatment for trimalleolar fractures needs accurate preoperative planning. Age over 61 years, BMI > 40, ASA > 1, type C fracture, and fracture dislocation were considered as negative prognostic fractures.

Persistent postoperative step-off of the posterior malleolus leads to higher incidence of post-traumatic osteoarthritis in trimalleolar fractures

BACKGROUND

Traditionally, size of the posterior fragment is considered the most important indicator for fixation in trimalleolar fractures. It remains unclear which factors contribute to worse functional and radiological outcome. This study was designed to determine predictors for the development of posttraumatic osteoarthritis and worse functional outcome in trimalleolar fractures.

METHODS

This retrospective cohort study evaluated outcomes of 169 patients with a trimalleolar fracture treated between 1996 and 2013 in a level-1 trauma hospital in the Netherlands after a mean follow-up of 6.3 (range 2.4 to 15.9) years. The average fragment size was 17%. Twenty patients had a posterior fragment smaller than 5% of the intra-articular surface, 119 patients a fragment of 5-25% and 30 patients a posterior fragment larger than 25%. In total, 39 patients (23%) underwent fixation of the posterior fragment.

RESULTS

Clinical union was achieved in all 169 patients. The median AOFAS score after follow-up was 93 (interquartile range 76-100) and the median AAOS score was 92 (interquartile range 81-98). A persistent postoperative step-off larger than 1 mm was found in 65 patients (39%) and osteoarthritis was present in 49 patients (30%). Higher age and postoperative step-off > 1 mm were independent, significant risk factors for the development of osteoarthritis. Osteoarthritis and BMI were independent, significant risk factors for worse functional outcome.

CONCLUSION

It is advisable to correct intra-articular step-off of intraarticular posterior malleolar fragments to reduce the risk of developing osteoarthritis and, consequently, the risk of worse functional outcome after long-term follow-up.

LEVEL OF EVIDENCE

Level IIB.

In defence of the posterior malleolus

The posterior malleolus of the ankle is the object of increasing attention, with considerable enthusiasm for CT scanning and surgical fixation, as expressed in a recent annotation in The Bone & Joint Journal. Undoubtedly, fractures with a large posterior malleolar fragment that allow posterior talar subluxation from the mortise are served better by fixation. However, in all other situations, the existing literature does not support this widespread change in practice. The available biomechanical evidence shows that the posterior malleolus has little part to play in the stability or contact stresses of the ankle joint. Radiographic studies have not shown that CT scanning offers helpful information on pathoanatomical classification, case selection, or prognosis, or that scanning improves the likelihood of an adequate surgical reduction. Clinical studies have not shown any improvement in patient outcome after surgical fixation, and have confirmed that the inevitable consequence of increased intervention is an increased rate of complications. A careful and thoughtful evaluation of indications, risks, and benefits of this fashionable concept is required to ensure that we are deploying valuable resources with efficacy, and that we do no harm.

Cite this article: Bone Joint J 2018;100-B:566–9.

Radiographic Investigation of the Distal Extension of Fractures Into the Articular Surface of the Tibia (The RIDEFAST Study)

OBJECTIVE

To determine whether radiographic measurements are predictive of involvement of the distal tibia articular surface in tibial shaft fractures.

DESIGN

Retrospective review.

SETTING

Academic Level-I trauma hospital.

PATIENTS

Two-hundred seventeen patients with tibial shaft fractures distal to the isthmus (OTA/AO: 42-A1-3; 42-B1-3; 42-C1-3; and 43-A1-3).

INTERVENTION

Analysis of anteroposterior (AP) and lateral radiographs. The following parameters were measured: (1) angle between the predominant fracture line and the plane of the tibial plafond (α-angle), (2) length of the shaft fracture, (3) distance from the most inferior extent of the shaft fracture to the tibial plafond (DTP), (4) width of the tibial plafond, (5) width of the tibial isthmus, (6) ratio of fracture length to DTP (FTP), and (7) fibular fracture distance.

MAIN OUTCOME MEASURE

Distal intra-articular involvement (DIA).

RESULTS

A total of 217 patients were identified, 56 (26%) with DIA. The FTP ratio as measured on both the AP (odds ratio: 8.20, confidence interval, 4.26-17.22, P < 0.0001) and lateral radiographs (10.00, 4.78-23.23, <0.0001) was the most effective screening measurement for DIA. AP and lateral FTP ratios of 0.224 and 0.255, respectively, achieved a negative predictive value of 100%, eliminating the need for computed tomography in 16%-23% of injuries.

CONCLUSION

Involvement of the distal articular surface in patients with distal tibial shaft fractures is significantly associated with fracture geometry and pattern. The FTP ratio may be used as an effective screening tool to rule out of intra-articular involvement.

LEVEL OF EVIDENCE

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

Impact of Computed Tomography on Operative Planning for Ankle Fractures Involving the Posterior Malleolus

BACKGROUND

The purpose of this study was to (1) Determine the effect of computed tomography (CT) on identification of fractures involving the posterior malleolus, (2) determine its effect on operative indications, and (3) determine its effect on the overall operative plan.

METHODS

Patients with ankle fractures involving the posterior malleolus were identified. Only injuries with complete preoperative plain radiographs and a CT scan were included. Spiral tibia fractures and pilon variants were excluded. The plain radiographs were deidentified, randomized, and presented to 3 orthopedic surgeons. They were asked 3 questions: (1) Is this fracture simple or complex? (2) Does the injury require direct visualization and reduction? and (3) How would you position the patient and approach the fracture? The same process was repeated for the CT scans. A total of 376 posterior malleolus injuries were identified and 25 met the inclusion criteria.

RESULTS

A complex fracture pattern was identified on 44% of plain radiographs and 56% of CT scans. The surgeons chose to operate in 84% of cases based on plain radiographs and 92% of cases based on CT scan. The observers changed their operative approach or positioning 44% of the time after reviewing CT images. The interobserver and intraobserver correlation coefficients were moderate.

CONCLUSION

The use of CT scan changed operative positioning and approach in 44% of cases. There was no significant change in characterization or operative indications when comparing plain radiographs to CT scan. CT scan may be a valuable tool in the management of ankle fractures involving the posterior malleolus.

LEVEL OF EVIDENCE

Diagnostic Level III, comparative series.

Posterior malleolus fractures

The posterior malleolus component of a fracture of the ankle is important, yet often overlooked. Pre-operative CT scans to identify and classify the pattern of the fracture are not used enough. Posterior malleolus fractures are not difficult to fix. After reduction and fixation of the posterior malleolus, the articular surface of the tibia is restored; the fibula is out to length; the syndesmosis is more stable and the patient can rehabilitate faster. There is therefore considerable merit in fixing most posterior malleolus fractures. An early post-operative CT scan to ensure that accurate reduction has been achieved should also be considered.

Cite this article: Bone Joint J 2017;99-B:1413–19.

Effect of Complete Syndesmotic Disruption and Deltoid Injuries and Different Reduction Methods on Ankle Joint Contact Mechanics

BACKGROUND

Syndesmotic injuries can be associated with poor patient outcomes and posttraumatic ankle arthritis, particularly in the case of malreduction. However, ankle joint contact mechanics following a syndesmotic injury and reduction remains poorly understood. The purpose of this study was to characterize the effects of a syndesmotic injury and reduction techniques on ankle joint contact mechanics in a biomechanical model.

METHODS

Ten cadaveric whole lower leg specimens with undisturbed proximal tibiofibular joints were prepared and tested in this study. Contact area, contact force, and peak contact pressure were measured in the ankle joint during simulated standing in the intact, injured, and 3 reduction conditions: screw fixation with a clamp, screw fixation without a clamp (thumb technique), and a suture-button construct. Differences in these ankle contact parameters were detected between conditions using repeated-measures analysis of variance.

RESULTS

Syndesmotic disruption decreased tibial plafond contact area and force. Syndesmotic reduction did not restore ankle loading mechanics to values measured in the intact condition. Reduction with the thumb technique was able to restore significantly more joint contact area and force than the reduction clamp or suture-button construct.

CONCLUSION

Syndesmotic disruption decreased joint contact area and force. Although the thumb technique performed significantly better than the reduction clamp and suture-button construct, syndesmotic reduction did not restore contact mechanics to intact levels.

CLINICAL RELEVANCE

Decreased contact area and force with disruption imply that other structures are likely receiving more loads (eg, medial and lateral gutters), which may have clinical implications such as the development of posttraumatic arthritis.

3-D computer modelling of malunited posterior malleolar fractures: effect of fragment size and offset on ankle stability, contact pressure and pattern

BACKGROUND

The positioning of the fracture fragment of a posterior malleolus fracture is critical to healing and a successful outcome as malunion of a posterior malleolar fracture, a condition seen in clinical practice, can affect the dynamics of the ankle joint, cause posterolateral rotational subluxation of the talus and ultimately lead to destruction of the joint. Current consensus is to employ anatomic reduction with internal fixation when the fragment size is larger than 25 to 33% of the tibial plafond.

METHODS

A 3-dimensional finite element (FE) model of ankle was developed in order to investigate the effect of fragment size (6-15 mm) and offset (1-4 mm) of a malunited posterior malleolus on tibiotalar joint contact area, pressure, motion of joint and ligament forces. Three positions of the joint were simulated; neutral position, 20° dorsiflexion and 30° plantarflexion.

RESULTS

Compared to the intact joint our model predicted that contact area was greater in all malunion scenarios considered. In general, the joint contact area was affected more by section length than section offset. In addition fibula contact area played a role in all the malunion cases.

CONCLUSIONS

We found no evidence to support the current consensus of fixing posterior malleolus fractures of greater than 25% of the tibial plafond. Our model predicted joint instability only with the highest level of fracture in a loaded limb at an extreme position of dorsiflexion. No increase of peak contact pressure as a result of malunion was predicted but contact pattern was modified. The results of our study support the view that in cases of posterior malleolar fracture, posttraumatic osteoarthritis occurs as a result of load on areas of cartilage not used to loading rather than an increase in contact pressure. Ankle repositioning resulted in increased force in two ankle ligaments. Our finding could explain commonly reported clinical observations.

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.

Medium-sized posterior fragments in AO Weber-B fractures, does open reduction and fixation improve outcome? the POSTFIX-trial protocol, a multicenter randomized clinical trial

BACKGROUND

Guidelines for treatment of the posterior fracture fragment in trimalleolar fractures are scarce and show varying advices. Did the increasing size of the posterior fragment seem to relate to worse outcome in the past, nowadays this has changed to the amount of dislocation of the posterior fragment post-operatively. Despite many retrospective cohort studies and some prospective cohort studies, no consistent guideline could be derived from the current literature.

METHODS

The POSTFIX-study is designed as a multicenter randomized clinical trial to analyse the effects of anatomical reduction and fixation of the posterior fragment in AO 44-B3 fractures with medium-sized posterior fragment. A total of 84 patients will be included and online allocated to either anatomical reduction and fixation of the posterior fragment via the posterolateral approach (n = 42) or no fixation of the posterior fragment (n = 42). The concomitant fractured medial and lateral malleoli are treated according to the AO-principles. Functionality of the ankle as measured by the AAOS-questionnaire (American Association of Orthopaedic Surgeons) 1 year post-operatively was set as primary outcome. Main secondary outcome measures are the AAOS-questionnaire 5 years postoperatively and osteoarthritis as measured on plain radiographs 1 year and 5 years post-operatively. The Olerud and Molander score, the AOFAS-score, the VAS-pain, the Euroqol-5D and Range of Motion by physical examination will also be evaluated during the follow-up period.

DISCUSSION

The POSTFIX-trial is the first high quality multicenter randomized clinical trial worldwide to analyse the effects of anatomical fixation of the posterior fragment in trimalleolar fractures. New guidelines on anatomical reduction and fixation of the posterior fragment can in future be based on the results of this trial.

TRIAL REGISTRATION

This trial is registered on ClinicalTrials.gov with reference number: NCT02596529 . Registered 3 November 2015, retrospectively registered.

Posterior Malleolus Fractures

Posterior malleolus fractures vary in morphology. A computed tomography scan is imperative to evaluate fragment size, comminution, articular impaction, and syndesmotic disruption. Despite an increasing body of literature regarding posterior malleolus fractures, many questions remain unanswered. Although, historically, fragment size guided surgical fixation, it is becoming evident that fragment size should not solely dictate treatment. Surgical treatment should focus on restoring ankle joint structural integrity, which includes restoring articular congruity, correcting posterior talar translation, addressing articular impaction, removing osteochondral debris, and establishing syndesmotic stability.

Buttress Plating Versus Anterior-to-Posterior Lag Screws for Fixation of the Posterior Malleolus: A Biomechanical Study

OBJECTIVES

The preferred method of fixation for posterior malleolus fractures remains controversial, and practices vary widely among surgeons. The purpose of this study was to compare anterior-to-posterior (AP) lag screws with posterior buttress plating for fixation of posterior malleolus fractures in a human cadaveric model.

METHODS

Posterior malleolus fractures involving 30% of the distal tibial articular surface were created in 7 pairs of fresh frozen cadaveric ankles. One specimen in each pair was randomly assigned to fixation with either 2 AP lag screws or a one-third tubular buttress plate without supplemental lag screws. Each specimen was then subjected to cyclic loading from 0% to 50% of body weight for 5000 cycles followed by loading to failure. Outcome measures included permanent axial displacement during each test cycle (axial displacement at no load), peak axial displacement during each test cycle (axial displacement at 50% body weight), load at 1-mm axial displacement, ultimate load, and axial displacement at ultimate load.

RESULTS

The buttress plate group showed significantly less peak axial displacement at all time points during cyclic loading. Permanent axial displacement was significantly less in the buttress plate group beginning at cycle 200. There were no significant differences between the 2 groups during load-to-failure testing.

CONCLUSION

Posterior malleolus fractures treated with posterior buttress plating showed significantly less displacement during cyclical loading compared with fractures fixed with AP lag screws. Surgeons should consider these findings when selecting a fixation strategy for these common fractures. Further research is warranted to investigate the clinical implications of these biomechanical findings.

Experimental strain analysis on the entire bony leg compared with FE analysis

The present study addresses the question of evaluating, by combining both experimental and numerical approaches, the stress/strain distribution within a complete model of the entire lower bony chain. With this purpose an experimental model and a complete 3D finite element one were realised. A load of 700 N has been applied at the top of pelvis and the feet were rigidly fixed. Obtained results reveal interesting consequences deriving by taking into account the complete bony chain; it is possible to get information on load sharing between bones, location of high strain concentrations, and bone relative motion.

Foot-ankle simulators: A tool to advance biomechanical understanding of a complex anatomical structure

In vitro gait simulations have been available to researchers for more than two decades and have become an invaluable tool for understanding fundamental foot-ankle biomechanics. This has been realised through several incremental technological and methodological developments, such as the actuation of muscle tendons, the increase in controlled degrees of freedom and the use of advanced control schemes. Furthermore, in vitro experimentation enabled performing highly repeatable and controllable simulations of gait during simultaneous measurement of several biomechanical signals (e.g. bone kinematics, intra-articular pressure distribution, bone strain). Such signals cannot always be captured in detail using in vivo techniques, and the importance of in vitro experimentation is therefore highlighted. The information provided by in vitro gait simulations enabled researchers to answer numerous clinical questions related to pathology, injury and surgery. In this article, first an overview of the developments in design and methodology of the various foot-ankle simulators is presented. Furthermore, an overview of the conducted studies is outlined and an example of a study aiming at understanding the differences in kinematics of the hindfoot, ankle and subtalar joints after total ankle arthroplasty is presented. Finally, the limitations and future perspectives of in vitro experimentation and in particular of foot-ankle gait simulators are discussed. It is expected that the biofidelic nature of the controllers will be improved in order to make them more subject-specific and to link foot motion to the simulated behaviour of the entire missing body, providing additional information for understanding the complex anatomical structure of the foot.

The healing stages of an intramedullary implanted tibia: A stress strain comparative analysis of the calcification process

AIMS

The extended usage of unreamed tibial nailing resulted in reports of an increased rate of complications, especially for the distal portion of the tibia. Unreamed nailing favours biology at the expense of the achievable mechanical stability, it is therefore of interest to define the limits of the clinical indications for this method. Extra-articular fractures of the distal tibial metaphysis, meta-diaphyseal junction, and adjacent diaphysis are distinct in their management from impaction derived ''pilon'' type fractures and mid-diaphyseal fractures. The goals of this work were to gain a thorough understanding of the load-sharing mechanism between unreamed nail and bones in a fractured tibia. With this purpose a complete model of the human leg was realised, simulating a mid-diaphyseal fracture, classified as A2 type 1, according to the AO classification. The analysis of the entire chain allows to have a complete picture of the stress distribution and of the most stressed bones and soft tissues, but, more importantly can overcome problems connected with boundary conditions imposed at single bony components.

METHODS

Model consists of six bony structures: pelvis, femur, patella, fibula, tibia, and a simplified lump of the feet, configured in a standing up position. Their articular cartilage layers, were simulated by 3D membranes of opportune stiffness connecting the different segments. Moreover an unreamed intra-medullary nail Expert Tibial Nail (DePuy Synthes(®)) stabilized the fractured tibia. A load of 700 N has been applied at the top of pelvis and a part the feet, at the tip, was rigidly fixed. Five different contact interfaces have been imposed at the different bony surfaces in contact.

RESULTS

Three different conditions were analysed: the initially healthy tibia, the A2 type 1 fractured tibia with the Expert tibial nail implanted, and the follow up stage after complete healing of tibia. Non-linear finite element analysis of the models were performed with Abaqus version 5.4 (Hibbitt, Karlsson and Sorensen, Inc., Pawtucket, RI) using the geometric non linearity and automatic time stepping options.

CONCLUSION

The obtained results reveal interesting consequences deriving by taking into account how the stress shielding can influence the integrity and resistance of bones, in order to identify the mechanical reasons for the unfavourable clinical results, and to identify borderline indications due to biomechanical factors. The evolution of treatment options for these fractures has been closely linked to developments in implant technology and surgical technique. Further developments in this area, particularly with respect to minimally invasive plating techniques and nail design are ongoing.

Long-term functional and radiographic outcomes in 243 operated ankle fractures

BACKGROUND

Large comparative studies that have evaluated long-term functional outcome of operatively treated ankle fractures are lacking. This study was performed to analyse the influence of several combinations of malleolar fractures on long-term functional outcome and development of osteoarthritis.

METHODS

Retrospective cohort-study on operated (1995-2007) malleolar fractures. Results were assessed with use of the AAOS- and AOFAS-questionnaires, VAS-pain score, dorsiflexion restriction (range of motion) and osteoarthritis. Categorisation was determined using the number of malleoli involved.

RESULTS

243 participants with a mean follow-up of 9.6 years were included. Significant differences for all outcomes were found between unimalleolar (isolated fibular) and bimalleolar (a combination of fibular and medial) fractures (AOFAS 97 vs 91, p = 0.035; AAOS 97 vs 90, p = 0.026; dorsiflexion restriction 2.8° vs 6.7°, p = 0.003). Outcomes after fibular fractures with an additional posterior fragment were similar to isolated fibular fractures. However, significant differences were found between unimalleolar and trimalleolar (a combination of lateral, medial and posterior) fractures (AOFAS 97 vs 88, p < 0.001; AAOS 97 vs 90, p = 0.003; VAS-pain 1.1 vs 2.3 p < 0.001; dorsiflexion restriction 2.9° vs 6.9°, p < 0.001). There was no significant difference in isolated fibular fractures with or without additional deltoid ligament injury. In addition, no functional differences were found between bimalleolar and trimalleolar fractures. Surprisingly, poor outcomes were found for isolated medial malleolar fractures. Development of osteoarthritis occurred mainly in trimalleolar fractures with a posterior fragment larger than 5 %.

CONCLUSIONS

The results of our study show that long-term functional outcome is strongly associated to medial malleolar fractures, isolated or as part of bi- or trimalleolar fractures. More cases of osteoarthritis are found in trimalleolar fractures.