A radiographic evaluation of the tibiofibular syndesmosis

Fibular Malunion: Diagnosis, Treatment, and Prevention

Malunions of the fibula are caused by malreduction during initial surgical management or the result of nonoperative treatment of an unstable ankle fracture. They can cause significant changes in loading of the ankle and subsequently lead to arthritic changes. Timely recognition of abnormal anatomy and corrective osteotomy yields favorable results. The current review addresses the anatomy and biomechanics of the ankle and the effects of a malunited fibula fracture. The radiological workup is discussed as well as the technique of the osteotomy. Last, the authors highlight the expected outcome and possible complications for an optimal informed consent of the patient.

Long-term Clinical Outcomes After Syndesmosis Fixation With K-wires in Ankle Fractures With Syndesmotic Instability

Background

Syndesmotic instability is a significant concern in the management of unstable ankle fractures, occurring in approximately 10% to 13% of these cases. Early recognition and stabilization of syndesmotic injuries are essential to ensure optimal long-term outcomes. Several techniques are currently in use, often involving complex procedure and/or costly devices. Our study presents a syndesmosis fixation technique using K-wires that is both simple and cost-effective.

Methods

This is a retrospective single-center case series. Three hundred seventy-seven ankle fractures with intraoperative syndesmosis instability and subsequent syndesmosis fixation with a K-wire were treated between 2002 and 2012. Of the 377 patients, 51 died and we were able to obtain long-term questionnaire completions from 94 patients (29% of presumed living patients), with a mean follow-up of 10.6 ± 3.0 years.

Results

The mean age was 46.6 ± 18.5 years; 42% were Danis-Weber type B and 58% type C fractures. Syndesmosis fixation failure was observed in 9 (2%) patients, and 5 (1%) patients had K-wire displacement without loss of syndesmosis reduction. The Manchester-Oxford Foot Questionnaire (MOXFQ) was obtained 10±3 years after surgery. The mean MOXFQ pain score was 25.9 ± 25.4, the mean functional score was 18 ± 24.8, and the mean social score was 13.7 ± 22.2.

Conclusion

We report long-term (10.6 ± 3 years) functional outcomes using a validated patient-reported questionnaire in patients who underwent syndesmosis fixation with 2 K-wires for unstable ankle fractures. In the subset of patients we were able to find in follow-up, we found low rates of syndesmosis fixation failure, low pain scores, and excellent functional outcomes. The availability and low cost of these implants make this technique an accessible and cost-effective solution to consider for syndesmosis fixation.

Level of Evidence

Level IV, retrospective case series.

Subtle Syndesmotic Instability

Latent or subtle syndesmotic instability is defined as an injury to the syndesmosis which is not apparent on static radiographs of the ankle. Syndesmotic injuries have also been referred to as high ankle sprains. Injury to the syndesmosis typically occurs with collision sports and often involves an external rotation force to the ankle. Diagnosis can be delayed because of negative initial imaging studies. Physical examination tests including the external rotation test, proximal squeeze test, and fibular shuck test can assist in the diagnosis. Advanced imaging modalities such as MRI and weight-bearing CT have been studied and can provide prognostic indications for management, although arthroscopic stress evaluation remains the benchmark for diagnosis. Both surgical and nonsurgical management techniques have been described, which can assist patients in returning to their preinjury level of function.

Syndesmosis Injury Contributes a Large Negative Effect on Clinical Outcomes: A Systematic Review

INTRODUCTION

The literature largely addresses questions of diagnostic accuracy and therapeutic accuracy. However, the magnitude of the clinical impact of syndesmosis injury is commonly described in intuitive yet qualitative terms. This systematic review aimed to quantify the impact of syndesmosis injury.

METHODS

Published clinical outcomes data were used to compute an effect size reflecting the impact of syndesmosis injury. This was done within the clinical contexts of isolated syndesmosis injury and syndesmosis injury with concomitant ankle fracture. Clinical outcomes data included Olerud-Molander (OM) and American Orthopaedic Foot and Ankle Society (AOFAS) scores, visual analog scale for pain, and days missed from sport competition. Parametric data were compared with Student t tests. Effect size was computed using Cohen's d.

RESULTS

In ankle fracture patients, syndesmosis injury demonstrated a large effect size for OM (d = 0.96) and AOFAS (d = 0.83) scores. In athletic populations without concomitant ankle fracture, syndesmosis injury demonstrated a large effect size on days missed from competition (d = 2.32).

DISCUSSION

These findings confirm the magnitude of the negative impact of syndesmosis injury in athletic populations with isolated injury and in ankle fracture patients. In ankle fracture patients, this large negative effect remains despite surgery. Thus, syndesmosis repair may not fully mitigate the impact of the injury.

LEVELS OF EVIDENCE

Level III: Systematic review.

Functional Syndesmotic Widening: A Case Report and Literature Review

Injury to the distal tibiofibular syndesmosis can be a diagnostic challenge in the absence of advanced imaging. We report a case of a 21-year-old male patient who sustained an ankle injury and demonstrated radiological evidence of syndesmosis widening on plain radiographs. He underwent endobutton fixation which resulted in anterior subluxation of the talus and difficulty in ankle dorsiflexion. This is the first case report in the literature of a functional syndesmotic widening and the subsequent sequelae when subjected to a stabilisation procedure. The previously reported risk factors were inconsistent with our patient's demographics of a young, previously obese adult. We postulate that his childhood morbid obesity likely contributed to the functional widening of his ankle syndesmosis.

Image Rotation Alters Apparent Fibula Length: An Evaluation of Talocrural Angle, Shenton Line, and Dime Sign

BACKGROUND

Fibula shortening can compromise ankle stability and force transmission, thereby impacting clinical outcomes. Because radiographs depict 3-dimensional anatomy in 2 dimensions, accurate radiographic assessment of fibula length is a commonly encountered clinical challenge. The talocrural angle (TCA), Shenton line, and dime sign are useful parameters of fibula length. Yet, the impact of 3-dimensional limb positioning on these radiographic parameters is not established.

METHODS

Bone models were constructed from CT scans of 30 lower limbs. Fibula length was computationally manipulated, and digitally reconstructed radiographs were generated reflecting 1-degree increments of sagittal and axial plane rotation of each limb for each fibula length condition. The TCA was computationally measured on each image. The presence of an aligned mortise view, intact Shenton line, and intact dime sign was assessed by 2 observers.

RESULTS

The mean TCA, which was 78.0 (95% CI ± 1.6) degrees for a true mortise projection with anatomic fibula length, changed by approximately 1 degree per millimeter of fibula length change. On average, 14.7 degrees of caudal rotation obscured 2 mm of fibular shortening by virtue of producing the same TCA as a true mortise view with anatomic fibula length, designated a false positive view. Axial rotation had a comparatively small effect. Observers 1 and 2 were, respectively, 91% and 88% less likely to accurately judge the image alignment of the false positive images compared to true mortise images. Moreover, intraobserver agreement was poor to moderate (mean 0.47, range 0.13-0.59) and interobserver agreement was uniformly poor (mean 0.08, range 0.01-0.20).

CONCLUSION

In our study using digitally reconstructed radiographs from CT scans of 30 limbs, we found that sagittal plane rotation impacts the radiographic appearance of fibula length as measured by the TCA. Limb axial rotation had a comparatively small effect. Further study of human perception of Shenton line and dime sign is needed before the effect of rotation on these parameters can be fully understood.

LEVEL OF EVIDENCE

Level IV, case series.

Total Ankle Replacement in Cavovarus Deformity: How Far Can We Go?

Because of the good functional results and satisfactory implant survival achieved with modern models, total ankle replacement (TAR) has become a legitimate alternative to ankle fusion. However, alignment and balance are mandatory for implant survival. Satisfactory results can be achieved in patients with significant preoperative deformity if alignment and balance were obtained. If not, a staged procedure involving deformity correction and secondary TAR is possible. The authors describe the principal aspects of this concept and illustrate their current approach to TAR in cavovarus deformity.

Anterior Incisura Fibularis Corner Landmarks Can Safely Validate the Optimal Distal Tibiofibular Reduction in Malleolar Fractures-Prospective CT Study

BACKGROUND

Distal tibiofibular injuries are common in patients with malleolar fractures. Malreduction is frequently reported in the literature and is mainly caused by insufficient intraoperative radiological evaluation. In this direction, we performed a prospective observational study to validate the efficacy of the anatomical landmarks of the anterior incisura corner.

METHODS

Patients with malleolar fractures and syndesmotic instability were reduced according to specific anatomic landmarks and had a postoperative bilateral ankle CT. The quality of the reduction was compared to the healthy ankles.

RESULTS

None of the controlled parameters differed significantly between the operated and healthy ankles. Minor deviations were correlated to the normal incisura morphology rather than the reduction technique.

CONCLUSIONS

The anterior incisura anatomical landmarks can be an efficient way of reducing the distal tibiofibular joint without the need for intraoperative radiological evaluation.

Factors and Radiographic Findings Influencing Patient-Reported Outcomes Following Maisonneuve Fractures

BACKGROUND

This research adds to the literature by providing prognostic information for physicians and patients regarding the outcomes of operative management of Maisonneuve fractures (MFs). To date, this is the only cohort study of patient-reported outcomes measurement information systems (PROMIS) scores following surgical fixation of MF. Patient outcomes were compared focusing on the mean population with an inter-analysis using basic demographic information, radiographic findings, and patient comorbidities and their respective impact on PROMIS scores.

METHODS

A total of 24 patients between 2012 and 2020 met the inclusion criteria and completed PROMIS surveys at a minimum of 18 months postoperatively. Patient charts were reviewed through the electronic medical record (EMR) for demographic information and comorbidities as well as operative variables. PROMIS scores for physical function (PF), pain interference (PI), and depression were obtained via follow-up visits and phone calls. The impact of categorical variables on complications was compared using Chi-Squared tests. Variables were analyzed with a type 3 SS test to stratify independent risk factors' effect on PROMIS scores and to account for confounding variables.

RESULTS

PROMIS PF averaged 44.84 and was significantly affected by BMI>30 (p=.033), hypertension (HTN) (p=.026), patients with clinical anxiety or depression (p=.047), and subsequent screw removal (p=.041). PROMIS PI averaged a score of 54.57 and was significantly affected by BMI>30 (p=.0046), coronary artery disease (CAD) (p=.0123), patients with clinical anxiety or depression (p=.0206), and subsequent screw removal (p=.0039). PROMIS depression scores averaged 46.03 and were significantly affected by the presence of CAD (p=.049) and subsequent screw removal (p=.023).

CONCLUSION

Patient-reported outcomes following MF surgery demonstrated PROMIS scores within +/- 1 standard deviation of the population-based control, and thus many patients can reasonably expect to return to a level of function comparable to the general population. Nonetheless, the significant effects of patient comorbidities and surgical variables ought to be evaluated and utilized as prognostic indicators when managing patient expectations prior to operative treatment of an MF injury.

High-Ankle Sprain and Syndesmotic Instability: How Far Have We Come with Diagnosis and Treatment?

Probably one of the most controversial subjects in the orthopedic field is the distal tibiofibular articulation. Even though its most primary knowledge can be a matter of enormous debate, it is in the diagnosis and treatment most of the disagreements reign. Distinguishing between injury and instability remains challenging as well as an optimal clinical decision regarding surgical intervention. The last years presented technology and that was able to bring body to an already well-developed scientifical rationale. In this review article, we aim to demonstrate the current data behind syndesmotic instability in the ligament scenario, whereas using few fracture concepts.

Comparison of the diagnostic value of measurements of transverse syndesmotic interval and 'lambda sign' in distinguishing latent syndesmotic diastasis in chronic lateral ankle instability: a cross-sectional study of 188 cases

INTRODUCTION

Chronic lateral ankle instability (CLAI) could accompany with latent syndesmotic diastasis (LSD), which is difficult to distinguish before surgery. Tibiofibular interval width and extravasation of joint fluid ('lambda sign') on MRI are widely used in the diagnosis of syndesmotic injury, but the reliability of these methods in distinguishing the associated LSD in CLAI was rarely studied. Our objective was to compare the diagnostic value of the measurement of the transverse tibiofibular interval and 'lambda sign' on MRI in distinguishing LSD in CLAI and to investigate the radiological predictor that best matched the intraoperatively measured syndesmotic width.

METHODS

138 CLAI patients undergoing arthroscopy in our institute from March 2017 to June 2020 were enrolled (CLAI group). Anterior space width (ASW) and posterior space width (PSW) at 10 mm layer above tibial articular and fluid height above tibial articular surface (FH) were measured on preoperative MRI. The same parameters were measured on MRI of 50 healthy volunteers as control group. At arthroscopy, syndesmotic width was measured and the patients were divided into arthroscopic widening (AW) and arthroscopic normal (AN) subgroup taking 2 mm as critical value. The CLAI group was compared with the control group to explore the interval changes related to CLAI. The AW and AN subgroups were compared to explore the potential diagnostic indicators and reference values for the LSD.

RESULTS

All parameters showed significant difference between CLAI group and control group (p < 0.05), but only PSW (p = 0.004) showed significant difference between AW and AN subgroups other than FH (p = 0.461). Only PSW was involved in formula of multiple-factor analysis (p = 0.005; OR, 1.819; 95%CI, 1.196-2.767). ROC analysis showed critical value of PSW was 3.8 mm (sensitivity, 66%; specificity, 66%; accuracy, 66.7%), while accuracy of lambda sign was 41.3%.

CONCLUSIONS

Transverse tibiofibular interval measurements were more reliable than the 'lambda sign' in distinguishing associated LSD in CLAI patients. The PSW ≥ 3.8 mm could be a predictor of syndesmotic diastasis.

Salvage of Chronic Syndesmosis Instability: A Retrospective Review With Mid-Term Follow-Up

Malreduced syndesmotic injuries lead to poor outcomes. No consensus exists regarding preferred surgical treatment. This study aims to assess clinical and radiographic outcomes in patients undergoing distal tibiofibular arthrodesis or stabilization. Retrospective review identified patients undergoing distal tibiofibular arthrodesis or stabilization between 2003 and 2019. Surgical factors, revision surgeries, and American Orthopedic Foot and Ankle Score ankle-hindfoot scores were collected. Radiographs were independently evaluated by 4 surgeons. Seventy patients were included. Mean American Orthopedic Foot and Ankle Score scores (n = 33) improved from 48 ± 16 preoperatively to 85 ± 14 (p < .001) at a median follow-up of 31.1 months. Mean Kellgren scores (n = 47) increased from 2.1 ± 1 to 2.5 ± 1 (p < .001) and the mean medial clear space decreased from 3.2 mm ± 0.8 mm to 2.8 mm ± 0.8 mm (p <.001) with no differences between the arthrodesis and stabilization groups. Zero patients progressed to arthroplasty or fusion. Patients demonstrated significant functional improvement after distal tibiofibular arthrodesis and stabilization. Progression of arthritis, while statistically significant, was not clinically significant.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

LEVEL OF EVIDENCE

Level III.

Radiological outcomes of bimalleolar fractures: Are timing of surgery and type of reconstruction important?

OBJECTIVE

The goal of open reduction and internal fixation (ORIF) of bimalleolar ankle fractures is to reconstitute ankle anatomy. The most commonly used radiological parameters to assess adequacy of reduction are talocrural angle (TCA), medial clear space (MCS), tibiofibular overlap (TFO) and tibiofibular clear space (TFCS). There is little research about the radiological outcomes of surgery in bimalleolar fractures. We aimed at assessing the adequacy of ORIF and the factors involved in anatomical restoration (specifically time to surgery), postoperatively and at follow-up.

METHODS

TCA, MCS, TFO and TFCS were measured in preoperative and postoperative radiographs of 107 bimalleolar ankle fractures and in 83 follow-up radiographs, accounting for a total of 297 radiographs and 1182 measurements. Preoperative radiographs were categorized according to Danis-Weber classification. For all included cases, basic demographic data, dates of radiographs and surgery, and type of fixation used were acquired. Variables associated with postoperative and follow-up total anatomical reconstitution (i.e., when the four assessed radiological parameters were normalized), normalization of each radiological parameter, and improvement in the number of normalized radiological parameters were identified through univariable Cox regression analysis.

RESULTS

In our sample, 23.8% of the ankle fractures in postoperative radiographs and 28% in follow-up radiographs achieved a complete anatomical restoration. Type C fractures (hazard ratio [HR]=0.1, 95% confidence interval [CI]=0.02-0.7, P=0.021) were associated with lower chances of total anatomical reconstitution. The use of reconstruction plates (HR=0.1, 95% CI=0.03-0.7, P=0.014) and one third tubular plates (HR=0.2, 95% CI=0.03-0.8, P=0.026) decreased the chances of improving the number of normalized radiological parameters. Waiting days until surgery impaired total anatomical reconstitution (HR=0.8, 95% CI=0.6-0.9, P=0.012) and also reduced the chances of improving the number of normalized radiological parameters (HR=0.9, 95% CI=0.9-1.0, P=0.045).

CONCLUSION

The radiological results for the treatment of bimalleolar fractures are time sensitive, and surgery should thus be performed as soon as possible, using adequate fixation materials, in order to achieve a better restoration of ankle anatomy.

LEVEL OF EVIDENCE

IV, retrospective study.

Intraoperative Assessment of Reduction of the Ankle Syndesmosis

PURPOSE OF REVIEW

Postoperative malreduction of the ankle syndesmosis is common, poorly defined, and its assessment is controversial. In the absence of a gold standard method to evaluate the ankle syndesmosis, a variety of techniques have been described. As the knowledgebase expands, data illustrating caveats for such techniques has become available. The purpose of this review is to highlight literature-sourced technical pearls and their related caveats for the intraoperative assessment of the ankle syndesmosis.

RECENT FINDINGS

Although numerical criteria are commonly used to assess syndesmotic reduction, anatomical variation in the healthy population frequently exceeds proposed cutoffs. Patient-specific uninjured anatomy can be defined by comparing to the uninjured contralateral ankle; however, side-to-side variation is present for many anatomical relationships. Advanced imaging (e.g., lateral radiographs, 3-dimensional radiography) can influence intraoperative surgeon decision-making and improve syndesmosis reduction, but minute improvements in syndesmosis reduction may not outweigh increased operating time and costs. Intraoperative imaging is an adjunct, not a replacement for direct visualization or palpation when reducing the syndesmosis. Arthroscopy may benefit younger patients with high physical demands by improving identification of intra-articular pathology absent on MRI. Although anatomical reduction is important to restore pre-injury biomechanics, it is unclear whether differences in reduction quality influence patient-reported outcomes. In the absence of a gold standard, awareness of the options for intraoperative assessment of the syndesmosis and their respective accuracy and limitations reported herein could enhance surgeons' ability to intraoperatively reduce the syndesmosis with the tools currently available.

The Relationship Between the Distal Tibial Fibular Syndesmosis and the Varus Deformity in Patients With Varus Ankle Osteoarthritis

Background:

The impact of varus ankle osteoarthritis (OA) on the distal tibial fibular syndesmosis is poorly described. This study aimed to investigate the possible relationship between the condition of the distal tibial fibular syndesmosis and the degree of the varus deformity using weightbearing simulated computed tomography (CT), in patients with varus ankle OA.

Methods:

This retrospective comparative study included 155 varus ankles, divided into 4 Takakura-Tanaka groups (stage 2, 3a, 3b, and 4). A control group comprised 35 ankles without prior ankle disorders. The angles between the tibial shaft and the articular surface of the tibial plafond on the anteroposterior view (TAS), and articular surfaces of the tibial plafond and talar dome (TTW) were measured from weightbearing ankle radiographs. The varus angle of the ankle (VA) was defined as 90 – TAS + TTW. On the CT axial view, 1 cm proximal to the tibial plafond, the area of the syndesmosis (“CT-area”) and the distance between the fibula and the tibia (CT-FCS) were measured.

Results:

The CT area in stages 2, 3a, 3b, 4, and control group were 99, 79, 77, 103, and 97 mm², respectively. The CT-FCS were 3.5, 3.1, 2.9, 4.3, and 3.9 mm, respectively. In all 155 OA ankles, CT area and CT-FCS were negatively correlated with the VA (correlation coefficient r = –0.38, P < .01; and r = 0.38, P < .01, respectively). Both CT area and CT-FCS were significantly smaller in stages 3a and 3b than in the control group (P < .01).

Conclusion:

There may be a relationship between the narrowing of the syndesmosis and the varus deformity in patients with varus ankle OA, especially in stages 3a and 3b.

Clinical Relevance:

Clinicians should be aware of the impact of varus ankle arthritis on the distal tibial fibular syndesmosis when operatively treating varus ankle OA. For some patients, the isolated treatment for the tibiotalar joint may be insufficient, and treatment for the syndesmosis as well as tibiotalar joint may be needed.

Level of Evidence:

Level III, retrospective case control study.

Sub-Acute Syndesmotic Injury: A Review and Proposed Treatment Algorithm

Sub-acute syndesmotic injuries are classified as from six weeks to six months from the initial injury date and can be considered a distinct group of patients; however, they are often mistreated and progress to chronic injuries with significant sequelae. The authors performed a comprehensive literature search on the MEDLINE database. The search yielded 165 studies up to January 2021, after the application of inclusion/exclusion criteria. This yielded 10 studies with a total of 156 relevant patients for review. We found that a delay in diagnosis is common and has a negative impact on outcomes. If a sub-acute syndesmotic injury is suspected and plain radiographs are inconclusive, magnetic resonance imaging is indicated if there is still an index of suspicion. Surgical intervention should aim to restore normal length and rotational alignment of the fibula whilst also addressing the need to debride tissues within the joint and syndesmosis. Syndesmosis must then be adequately reduced and stabilised with syndesmotic screw fixation, and augmentation with tendon/ligament reconstruction should be considered. All studies showed an average improvement in functional outcome measures post-operatively. The only study to compare sub-acute and chronic patients' functional outcomes post-operatively showed significant improvement in the sub-acute cohort; highlighting the importance of early intervention. We suggest a treatment algorithm that may help with the diagnosis and management of these injuries. We believe this will help all healthcare professionals to standardise care. Further research is required to assess sub-acute injury outcomes with tendon/ligamentous augmented reconstruction, as no level 1 or 2 studies currently exist.

APKASS Consensus Statement on Chronic Syndesmosis Injury, Part 1: Clinical Manifestation, Radiologic Examination, Diagnosis Criteria, Classification, and Nonoperative Treatment

Background

Clinical manifestation, radiologic examination, diagnostic criteria, classification, and nonoperative treatment strategies regarding chronic syndesmosis injury remain unclear.

Purpose

An international group of experts representing the fields of sports injuries in the foot and ankle area were invited to collaboratively advance toward consensus opinions based on the best available evidence regarding chronic syndesmosis injuries. All were members of the Asia-Pacific Knee, Arthroscopy and Sports Medicine Society (APKASS).

Study Design

Consensus statement.

Methods

From November to December 2020, a total of 111 international experts on sports medicine or ankle surgery participated in a 2-stage Delphi process that included an anonymous online survey and an online meeting. A total of 13 items with 38 statements were drafted by 13 core authors. Of these, 4 items with 15 clinical questions and statements were related to the clinical manifestation, radiologic examination, diagnostic criteria, classification, and nonoperative treatment strategies for chronic syndesmosis injury and are presented here. Each statement was individually presented and discussed, followed by a general vote. The strength of consensus was characterized as follows: consensus, 51% to 74%; strong consensus, 75% to 99%; unanimous, 100%.

Results

Of the 15 questions and statements, 5 reached unanimous support and 10 achieved strong consensus.

Conclusion

This APKASS consensus statement, developed by international experts in the field, will assist surgeons and physical therapists with diagnosis, classification, and nonoperative treatment strategies for chronic syndesmosis injury.

Acute syndesmotic injuries in ankle fractures: From diagnosis to treatment and current concepts

A stable and precise articulation of the distal tibiofibular syndesmosis maintains the tibiofibular relationship, and it is essential for normal motion of the ankle joint. The disruption of this joint is frequently accompanied by rotational ankle fracture, such as pronation-external rotation, and rarely occurs without ankle fracture. The diagnosis is not simple, and ideal management of the various presentations of syndesmotic injury remains controversial to this day. Anatomical restoration and stabilization of the disrupted tibiofibular syndesmosis is essential to improve functional outcomes. In such an injury, including inadequately treated, misdiagnosed and correctly diagnosed cases, a chronic pattern characterized by persistent ankle pain, function disability and early osteoarthritis can result. This paper reviews anatomical and biomechanical characteristics of this syndesmosis, the mechanism of its acute injury associated to fractures, radiological and arthroscopic diagnosis and surgical treatment.

Fixation of Posterior Malleolar Fractures with Posterior Plating Through a Posterolateral Approach

BACKGROUND

We aimed to evaluate radiologic and clinical outcomes of ankle fractures involving posterior fragments that were fixed with a posterior plate by the posterolateral approach.

METHODS

Sixty-five patients who were followed for at least 12 months and were older than 18 years were included. The posterior malleolus fractures were classified according to the Haraguchi classification system with computed tomography (CT). The posterior malleolus fragments were fixed with a plate through a posterolateral approach. Intra-articular step-off, reduction of the posterior malleolar fragment, and fibular position in the incisura were evaluated by early postoperative CT. American Orthopaedic Foot and Ankle Society (AOFAS) score and visual analog scale pain score were used for clinical assessment.

RESULTS

The posterior malleolus fractures were classified as Haraguchi type 1 in 45 patients (69.2%), Haraguchi type 2 in 12 patients (18.5%), and Haraguchi type 3 in eight patients (12.3%). No patients showed signs of instability or loss of reduction on direct radiographs during follow-up. Postoperative CT showed no loss of reduction in the posterior malleolus and tibiofibular alignment. On evaluation, there was no intra-articular step-off (<1) in any of the patients. The mean AOFAS score was calculated to be 91.6. The mean visual analog scale score was 1.2.

CONCLUSIONS

We conclude that direct posterior fixation with the posterolateral approach can be a good option for ankle fractures involving posterior malleolar fragments.

Traumatic injuries of the distal tibiofibular syndesmosis

The distal tibiofibular syndesmosis (DTFS) is frequently injured during ankle trauma. The sequelae can be significant, including chronic instability, early osteoarthritis and residual pain. The aim of this study is to summarize the current state knowledge about these injuries by answering four questions. They frequently occur in the context of an ankle sprain (20-40% of cases) or during various types of ankle fractures (20-100% of cases). They cannot be ruled out based solely on fracture type and must be investigated when a fibular or posterior malleolar fracture is present. Clinical examination and imaging are essential but do not provide a definitive diagnosis. Ultrasonography, CT scan and MRI have high sensitivity, but their static nature does not allow a treatment strategy to be defined. Dynamic radiographs must be taken, either with load or during a procedure. If instability is detected, stabilization is the general rule. In fracture cases, reduction is achieved by restoring the length and rotation of the distal fibular fragment, preferably during an open procedure. In sprain cases, reduction is not a problem unless there is ligament interposition. Tibiofibular fixation is done 1.5 to 3cm from the talocrural joint, while ensuring the reduction is perfect. The main complication-non-healing of the syndesmosis-is attributed to poor initial reduction. This or functional discomfort during weight bearing will require removal of the fixation hardware. In most cases, this allows functional recovery and correction of the inadequate reduction. Persistence of instability will require ligament reconstruction or fusion of the syndesmosis. Chronic instability can lead to ankle osteoarthritis. LEVEL OF EVIDENCE: V, expert opinion.

Weightbearing Cone-Beam Computed Tomography of Acute Ankle Syndesmosis Injuries

Syndesmotic injuries are common, but only a subset of these injuries are unstable. A noninvasive tool for identifying instability would aid in the selection of patients for surgery. Weightbearing computed tomography (CT) data have been reported for healthy patients, but there are limited data on unstable syndesmoses. We evaluated the syndesmotic area of arthroscopically proven unstable ankles after acute injury. This is a prospective comparative study of consecutive patients recruited to a weightbearing CT database. Thirty-nine patients were included for analysis with arthroscopically proven unstable syndesmoses and an uninjured contralateral ankle. The syndesmosis area was measured for both ankles, in non-weightbearing and weightbearing positions, and compared. Syndesmosis area of the unstable ankle was significantly greater than the uninjured ankle of the same patient, by a mean of 22.9 ± 10.5 mm². This was a significantly greater difference than that observed with non-weightbearing CT (9.8 ± 10.2 mm², p < .001). Dynamic change in area, from non-weightbearing to weightbearing, of the unstable ankle (13.7% [16.6 ± 9.9 mm²]) was significantly greater than that of the uninjured ankle (3.1% [3.4 ± 6.7 mm²], p < .001). The intraobserver and interobserver correlations were good with intraclass correlation coefficients of 0.983 and 0.970, respectively. Weightbearing CT demonstrated significantly greater diastasis in unstable ankles than did conventional non-weightbearing CT. Syndesmosis area measurement was reliable and reproducible. Dynamic change in area and weightbearing comparison with the contralateral uninjured ankle are 2 parameters that may prove useful in the future for predicting syndesmotic instability.

Injury mechanism affects the stability of suture-button syndesmosis fixation

BACKGROUND

Ankle syndesmosis injury is a common condition, and the injury mechanism can be sorted into pure syndesmosis injury, Weber-B, and Weber-C type fractures. This study aims to evaluate the treatment outcomes and stability of suture-button fixation for syndesmosis injury with different injury mechanisms. We hypothesized that injury mechanisms would alter the stability of suture-button fixation.

METHODS

We retrospectively reviewed 63 patients with ankle syndesmosis injury who underwent surgery with TightRope (Arthrex, Naples, FL, USA) from April 2014 to February 2019. The stability of suture-button fixation with TightRope was evaluated by comparing the preoperative, postoperative, and final follow-up measurements of tibiofibular clear space (TFCS), tibiofibular overlap (TFO), and medial clear space (MCS). A subgroup analysis for each demographic group and injury type including pure syndesmosis injury, Weber-B, and Weber-C type fractures were performed.

RESULTS

Syndesmosis was effectively reduced using TightRope. After the index surgery, the tibiofibular clear space was reduced from 7.73 to 4.04 mm, the tibiofibular overlap was increased from 3.05 to 6.44 mm, and the medial clear space was reduced from 8.12 to 3.54 mm. However, syndesmosis widening was noted at the final follow-up, especially in Weber-C type fractures (TFCS 3.82 to 4.45 mm, p < 0.01 and TFO 6.86 to 6.29 mm, p = 0.04). Though widened, the final follow-up values of tibiofibular clear space and tibiofibular overlap were in the acceptable range. Postoperatively and at the final follow-up, medial clear space was found to be significantly larger in the Weber-C group than in the pure syndesmosis and Weber-B groups (p < 0.05).

CONCLUSIONS

Suture-button fixation can offer anatomic reduction and dynamic fixation in syndesmosis injuries. However, when using this modality for Weber-C type fractures, more attention should be focused on the accuracy of reduction, especially of medial clear space, and rediastasis should be carefully monitored.

TRIAL REGISTRATION

This trial was retrospectively approved by TMU-JIRB. Registration number N202004122, and the date of approval was May 06, 2020.

LEVEL OF EVIDENCE

III.

Chronic Syndesmotic Injuries: Arthrodesis versus Reconstruction

"Chronic syndesmotic injury covers a broad range of symptoms and pathologies. Anterolateral ankle impingement without instability is treated by arthroscopic debridement. Subacute, unstable, syndesmotic injuries are treated by arthroscopic or open debridement followed by secondary stabilization using suture button device or permanent screw placement. Chronic syndesmotic instability is treated by a near-anatomic ligamentoplasty supplemented by screw fixation. In case of poor bone stock, failed ligament reconstruction, or comorbidities, tibiofibular fusion with bone grafting is preferred. Malleolar malunions and particularly anterior or posterior syndesmotic avulsions must be corrected in order to achieve a stable and congruent ankle mortise."

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.

The Valid Diagnostic Parameters in Bilateral CT Scan to Predict Unstable Syndesmotic Injury with Ankle Fracture

The purpose of this study is to evaluate the reasonable parameters to predict unstable syndesmotic injuries in ankle fractures. Seventy consecutive patients who underwent preoperative bilateral computed tomography (CT) scans were enrolled. Group A consisted of 20 patients intraoperatively diagnosed with syndesmotic injuries according to an intraoperative stress test and group B consisted of 50 patients who had nosyndesmotic injuries. The tibiofibular overlap (TFO) and tibiofibular clear space (TFCS) were measured using preoperative ankle radiographs. Measuring the anterior fibular distance (AFD), posterior fibular distance (PFD), anterior translation distance (AT), fibular diastasis (FD), anterior-posterior translation (APT), fibular length (FL), and surface area of syndesmosis (SAS) 1.0 and 1.5 which 1.0 cm and 1.5 cm above the tibial plafond was done via preoperative CT scan. The ratio of measurements (Injured/Intact) of the TFO, PFD, APD, and SAS 1.0 showed statistically significant differences. The researchers identified the SAS 1.0 as the most reasonable parameter to predict transfixation using receiver-operating characteristic (ROC) curve analysis. The SAS 1.0 is most valid parameter to predict syndesmotic injuries in this study and these results show that performing a bilateral CT scan on an ankle fracture may provide substantial information in measuring valid parameters.

The evaluation of radiological measurements used in diagnosis and treatment of syndesmosis injury: A regional study in Turkey

OBJECTIVES

This study aims to improve the diagnostic reliability of syndesmosis injuries through evaluation of radiological measurements in the Turkish population and to provide mean reference values to prevent malreduction and overcompression during the treatment.

PATIENTS AND METHODS

This retrospective study was performed between January 2018 and May 2018. The bilateral anteroposterior (AP) and lateral radiographs of 100 patients (60 males, 40 females; mean age 42.9 years; range, 23 to 72 years) who presented at our polyclinic were analyzed. Tibiofibular overlap (TFO), tibiofibular clear space (TFCS) and medial clear space (MCS) measurements were performed on the AP radiographs. The lateral radiographs were evaluated in respect of the anterior tibiofibular interval (ATFI), posterior tibiofibular interval (PTFI), and anterior tibiofibular ratio (ATFR) for syndesmosis reduction assessment. The lower and upper limits, mean and median values of the measurements were recorded.

RESULTS

The measurements on the AP radiographs were determined to be as TFO: 7.9±2.4 mm (4-13), TFCS: 3.8±0.9 mm (2.2-6), MCS: 3.3±0.4 mm (2.7-4.5), and superior clear space: 3.3±0.3 mm (2.7-3.8). According to the measurements on the AP radiographs, the TFCS did not show any difference in terms of the variables of age, gender and side (p=0.070, p=0.219 and p=1.0, respectively). These measurements on the AP radiographs showed a high statistical consistency in terms of side (p=0.72, p=1.0, p=0.900 and p=0.920, respectively). The measurements on the lateral radiographs were as ATFI: 12.8±2.4 mm (8-18), PTFI: 6.1±2.9 mm (3-15) and ATFR: 0.4±0.1 (0.28-0.5). According to the measurements on the lateral radiographs, the ATFR did not show any difference in terms of the variables of age, gender and side (p=0.750, p=0.570 and p=0.848, respectively). The lateral measurements indicated statistical consistency in terms of side (p=0.400, p=0.260 and p=0.848, respectively).

CONCLUSION

On the AP radiographs, TFCS was found to be reliable and the intraoperative evaluation of its high consistency with the opposite extremity is appropriate to avoid overcompression. The evaluation of ATFR on lateral radiographs was found to be reliable and evaluation is recommended to avoid intraoperative malreduction.

Acute and Chronic Syndesmotic Instability: Role of Surgical Stabilization

Acute and chronic syndesmotic injuries significantly impact athletic function and activities of daily living. Patient history, examination, and judicious use of imaging modalities aid diagnosis. Surgical management should be used when frank diastasis, instability, and/or chronic pain and disability ensue. Screw and suture-button fixation remain the mainstay of treatment of acute injuries, but novel syndesmotic reconstruction techniques hold promise for treatment of acute and chronic injuries, especially for athletes. This article focuses on anatomy, mechanisms of injury, diagnosis, and surgical reduction and stabilization of acute and chronic syndesmotic instability. Fixation methods with a focus on considerations for athletes are discussed.

Functional Outcomes of Unstable Ankle Fractures in Adolescents

BACKGROUND

The purpose of this study was to describe the functional outcomes and complications of unstable supination external rotation (SER) and pronation external rotation (PER) ankle fractures in adolescents. A secondary outcome was to compare functional outcomes of SER stage IV injuries that were treated definitively with closed reduction and cast application to a similar group of minimally displaced fractures treated with open reduction and internal fixation (ORIF).

METHODS

A retrospective review of adolescents aged 10 to 18 years with unstable ankle fractures treated at a single institution between 2009 and 2017 was conducted. All patients had functional outcomes data from the Foot and Ankle Ability Measure obtained at a minimum of 1-year follow-up.

RESULTS

In total, 67 adolescents (41 SER, 26 PER) were included (mean follow-up: 52.3±24.8 mo). A total of 56 were treated with ORIF and 11 were closed reduced and casted. No patients treated nonsurgically had a loss of reduction and none required subsequent surgical intervention. Preoperative radiographic predictors of syndesmotic injury (>6 mm of tibiofibular clear space or <2 mm of tibiofibular overlap) were not sensitive and only moderately specific predictors of intraoperative syndesmotic injury. There was no difference in functional outcome between the 11 SER stage IV fractures treated nonoperatively and a group of minimally displaced SER injuries treated with ORIF. Patients with open or partially open physes had better functional outcomes. Patients with syndesmotic injuries, medial malleolus fractures, or fracture-dislocations were not associated with lower functional outcome scores in our adolescent cohort.

CONCLUSIONS

Unstable SER and PER injuries in adolescents have favorable functional outcomes at intermediate-term follow-up, though a minority continue to have impaired ankle function. Minimally displaced SER stage IV injuries with near anatomic alignment after closed reduction can be successfully treated with continued closed management, and have no difference in functional outcomes compared with similar injuries treated with ORIF.

LEVEL OF EVIDENCE

Level III.

Accuracy of cone-beam computed tomography for syndesmosis injury diagnosis compared to conventional computed tomography

BACKGROUND

Syndesmosis injury can lead to ankle mortise instability and early osteoarthritis. Several multiple detector computed tomography (MDCT) methods for measurement have been developed. Weight-bearing cone beam CT (WB CBCT) is an emerging technique that offers the possibility of upright-position scanning and lower doses. This study sought to assess the diagnostic accuracy of WB CBCT in syndesmose injury compared to MDCT, with instability confirmed via manual testing upon arthroscopic examination.

METHODS

Three musculoskeletal radiologists with different levels of expertise prospectively analyzed 11 MDCT and eight WB CBCT scans of the same trauma-afflicted ankles with clinical suspicion of syndesmosis lesion over a period of 5 months. They evaluated 10 methods of measurement in both sides. Syndesmosis was considered pathological on arthroscopic examination in four patients. Correlation between readers was evaluated with intra-class correlation testing (p < 0.05 was considered significant). Capacity of discrimination was assessed by area under the curve (AUC) for all methods.

RESULTS

Inter-observer agreement was near excellent for both WB CBCT and MDCT for the anterior tibio-fibular (TF) distance (ICC = 0.781 and 0.831, respectively), posterior TF distance (ICC = 0.841 and 0.826), minimal TF distance (ICC = 0.899 and 0.875), and TF surface (ICC = 0.93 and 0.84). AUC were better for MDCT than WB CBCT in assessing syndesmosis instability for: anterior TF distance (ROC = 0.869 vs. 0.555, p = 0.01), minimal TF distance (ROC = 0.883 vs. 0.608, p = 0.02) and antero-posterior fibular translation (ROC = 0.894 vs. 0.467, p = 0.006).

CONCLUSIONS

MDCT demonstrated better ability to distinguish pathological syndesmosis than WB CBCT, with the antero-posterior fibular translation the best discriminating measurement. The physiological widening of the contralateral syndesmosis occurring with the WB CBCT upright position may explain these results.

Syndesmotic Screw Removal in a Clinic Setting Is Safe and Cost-effective

Background. There is no consensus in the literature regarding the necessity of syndesmotic screw removal, but the majority of surgeons prefer screw removal in the operating room. Purpose. The aim of this study is to analyze the safety and cost-effectiveness of syndesmotic screw removal in the clinic. Methods. A retrospective chart review was performed on all acute, traumatic ankle fractures that required syndesmotic stabilization over 5 years at a level 1 trauma center. Radiographs were evaluated for maintenance of syndesmotic reduction. Orthopaedic clinic visits and operating room costs were calculated. Results. Of 269 patients, syndesmotic screws were successfully removed in the clinic in 170 patients and retained in 99 patients. Two superficial infections (1.2%) developed following screw removal. The superficial infection rate was 3.3% (2 of 60) in patients who did not receive antibiotics compared with 0% (0 of 110) in patients who received antibiotics (P = .12). No patient lost syndesmotic reduction after screw removal. Cost savings of $13 829 per patient were achieved by syndesmotic screw removal in the clinic. Conclusion. Our study demonstrates that syndesmotic screw removal in the clinic is safe, does not result in tibiofibular diastasis, is cost-effective, and results in substantial financial savings. Level of Evidence: Level IV.

Validation of radiological reduction criteria with intraoperative cone beam CT in unstable syndesmotic injuries

Purpose

Acute unstable syndesmotic lesions are regularly treated with closed or open reduction and fixation with either a positioning screw or tight rope. Conventional fluoroscopy is limited to identify a malreduction of the ankle mortise. The aim of the study was to validate the reduction criteria of intraoperative cone beam CT in unstable syndesmotic injuries by analyzing the clinical outcome.

Methods

Acute unstable syndesmotic injuries were treated with a positioning screw fixation, and the reduction in the ankle mortise was evaluated with intraoperative cone beam CT. The patients were grouped postoperatively according to the radiological reduction criteria in the intraoperative 3D images. The reduction criteria were unknown to the surgeons. Malreduction was assumed if one or more reduction criteria were not fulfilled.

Results

Seventy-three of the 127 patients could be included in the study (follow-up rate 57.5%). For 41 patients (56.2%), a radiological optimal reduction was achieved (Group 1), and in 32 patients (43.8%) a radiological adverse reduction was found (Group 2). Group 1 scored significantly higher in the Olerud/Molander score (92.44 ± 10.73 vs. 65.47 ± 28.77) (p = 0.003), revealed a significantly higher range of motion (ROM) (53.44 vs. 24.17°) (p = 0.001) and a significantly reduced Kellgren/Lawrence osteoarthritis score (1.24 vs. 1.79) (p = 0.029). The linear regression analysis revealed a correlation for the two groups with the values scored in the Olerud/Molander score (p < 0.01).

Conclusion

The reduction criteria in intraoperative cone beam CT applied to unstable syndesmotic injuries could be validated. Patients with an anatomic reduced acute unstable syndesmotic injury according to the criteria have a significantly better clinical outcome.

MRI of the distal tibiofibular joint

The distal tibiofibular joint is a fibrous joint that plays a crucial role in the stability of the ankle joint. It is stabilized by three main ligaments: the anterior inferior tibiofibular ligament, the posterior inferior tibiofibular ligament, and the interosseous tibiofibular ligament, which are well delineated on magnetic resonance imaging. Pathology of the distal tibiofibular joint is mostly related to trauma and the longer-term complications of trauma, such as soft tissue impingement, heterotopic ossification, and synostosis. This review article outlines the MRI anatomy and pathology of this joint.

Syndesmotic Ligaments of the Ankle: Anatomy, Multimodality Imaging, and Patterns of Injury

Injuries to the syndesmotic ligaments of the ankle or "high ankle sprains" are common in acute ankle trauma but can be difficult to diagnose both clinically and on imaging. Missed injuries to the syndesmosis can lead to chronic ankle instability, which can cause persistent pain and lead to early osteoarthritis. This review will illustrate the anatomy of the syndesmotic ligamentous complex, describe radiographic, CT, and MR imaging of the syndesmosis, demonstrate typical mechanisms of injuries and associated fracture patterns, and provide an overview of important management considerations.

Reducing the Syndesmosis Under Direct Vision: Where Should I Look?

OBJECTIVES

To compare the quality of syndesmotic reduction obtained using the incisura versus the ankle articular surface as the visual cue. Secondarily, we evaluated the difference in the anterior to posterior depth of the fibula to the tibia at the joint level and the fibula to the incisura 1 cm above the joint.

METHODS

Seven surgeons reduced disrupted syndesmoses of 10 cadaveric ankles using either the anterolateral articular surface of the distal tibia to the anteromedial fibular articular surface or the location of the fibula within the incisura as a visual reference. Malreductions in translation were measured in millimeter from the anatomical position of the fibula. The anterior to posterior distances of the tibia and fibula were also measured at both levels to determine the differences in their depths.

RESULTS

The translational reduction was within 2 mm in 93% (0.7 ± 0.7 mm) of reductions using the articular surface as a reference compared with 80% (1.2 ± 1.0 mm) using the incisura as a reference (P = 0.0001). All surgeons' reductions were better using the joint articular surface as the visual reference. The difference in the fibular and the tibial depth was smaller at the level of the articular surface versus the incisura (2.1 mm vs. 5.9 mm; P = 0.0002).

CONCLUSIONS

The articular surface is a significantly more accurate visual landmark for translational reduction of the syndesmosis. This is potentially explained by the larger differences in the fibula and tibial depth at the incisura versus the articular surface.

Weight-Bearing Radiographic Analysis of the Tibiofibular Syndesmosis

Background: Diagnosis of distal tibiofibular syndesmotic injuries includes assessment of radiographs; however, there exist no agreed on standard diagnostic criteria. Previous studies lack consistency with radiographic evaluation methods. The dynamic nature of the ankle joint supports analyzing anatomical parameters using weight-bearing films to assess for tibiofibular syndesmotic integrity. Methods: Weight-bearing tibiofibular syndesmosis radiographs of 39 male and 40 female patients were retrospectively analyzed by 3 investigators, at different levels of orthopaedic training. Measurements 1 cm above the tibial plafond for the anterior tibiofibular overlap (TFO) and tibiofibular clear space (TCS) were recorded and standardized by the fibular width (FW) at 2 time points. Data were compared to check for agreement between the sets of measurements for each rater and agreement between investigators, and to ascertain underlying gender differences. Results: There was good intraobserver correlation (intraclass correlation coefficient [ICC] > 0.90) among investigators for each parameter. A significant difference in the TFO was noted between genders (P < .05). We establish the following radiographic (anteroposterior view) parameters for an intact syndesmosis: male patients, TCS <4.57 mm or TCS/FW <29% and TFO >9.29 mm or TFO/FW > 57%; female patients, TCS <4.28 mm or TCS/FW <30% and TFO >7.41 mm or TFO/FW >51%. Conclusions: Our study provides a more objective approach by utilizing weight-bearing radiographs and performing all measurements 1 cm above the tibial plafond. Levels of Evidence: Level IV.

Tibiofibular relationships of the normal syndesmosis differ by age on axial computed tomography-Anterior fibular translation with age

INTRODUCTION

This study aimed to assess the tibiofibular relationships of normal syndesmosis on axial computed tomography (CT) images and evaluate the measurement differences by gender, age, and body sides.

PATIENTS AND METHODS

The cases of 120 volunteers who underwent bilateral ankle CT were retrospectively reviewed. Volunteers were divided into three groups of 40 (20 men and 20 women) as follows: 20-40, 40-60, and 60-80 years old. Radiographic evaluation included the anterior tibiofibular clear space (ATFCS), posterior tibiofibular clear space (PTFCS), anterior tibiofibular interval (ATFI), length of incisura (LI), depth of incisura (DI), and fibular width (FW). Each measured parameter was compared based on gender, age, and body sides. To calibrate anatomical variations among the volunteers, ATFCS, PTFCA, and ATFI were expressed as ratios of FW.

RESULTS

PTFCS and ATFI were significantly larger in the men (p = 0.001, 0.001). LI and FW were significantly smaller in the women (p <0.001, <0.001). Calibrated ATFCS, PTFCS, and ATFI did not differ between the genders. ATFCS, PTFCS, and ATFI were significantly different among the age groups (p = 0.001, 0.001, and <0.001, respectively). These calibrated parameters showed significant differences according to age (p = 0.009, 0.006, and <0.001, respectively). There were no significant differences between sides. All CT measurements, except DI, showed high intra- and inter-observer reliabilities.

CONCLUSIONS

Axial CT images of the normal syndesmosis showed significant differences according to gender and age, but not between sides. In light of the anatomical variation, narrowing of the syndesmotic joint due to anterior translation of the fibula following aging may represent the most significant finding.

LEVEL OF EVIDENCE

Level IV, case series.

A standardised computed tomography measurement method for distal fibular rotation

PURPOSE

The aim of the study is to identify an ideal location to measure fibular rotation in the ankle joint using axial computed tomography (CT) scans. Another objective was to detect the average fibular rotation in the uninjured ankle joint in a large cohort.

METHODS

Standardised axial CT with coronal/sagittal reconstructions was performed in healthy ankle joints. Three investigators performed the measurements. In the axial view, each investigator appointed the ideal location to measure the angle of fibular rotation with the use of reference lines either 4, 6, 8 or 10 mm distal from the talar joint line. Inter- and intraobserver reliability, as well as the intraclass correlation coefficient, were determined.

RESULTS

CT scans of one hundred individuals-78 males and 22 females-were analysed. The most common locations for measuring the fibular rotation were in 31% of cases 4 mm and in 51% of cases 6 mm distal the talar joint line. The external rotation of the fibula averaged 8.42° ± 4.86° (range 0°-26°). The intraclass coefficient correlations (ICC) for interrater and intrarater reliability were 0.75.

CONCLUSIONS

The results of the study demonstrate a reproducible location to measure the fibular rotation in the ankle joint. The most convenient location to measure fibular rotation with a high reliability was 6 mm distal to the talar joint line.

Assessing Quality of Syndesmotic Reduction in Surgically Treated Acute Syndesmotic Injuries: A Systematic Review

There is no universal method with cutoff values for the assessment of distal tibiofibular joint reduction in acute syndesmotic injuries. It is important to detect malreductions because they may lead to impaired functional outcome and may demand reoperations. The aim of this study was to systematically review the literature to evaluate the appropriateness of different image techniques in determining syndesmotic malalignment. A literature search was conducted in Medline, Embase, and the Cochrane Library to search for articles assessing syndesmotic reduction. Excluded were articles where no criteria and/or measurements for syndesmotic reduction were provided, only normative values were provided and reviews. In total, 2157 articles were found, of which 1421 studies were screened for title and abstract after exclusion of duplicates. One hundred ten studies were eligible for full-text analysis. Of these, 61 were excluded. Three studies where added after screening the included references. Fifty-two studies were included, of which 32 were original publications and 20 were publications referring to the original publications. From the original publications, 14 used plains radiographs, 19 computed tomographic (CT) scans, and 5 used 3-dimensional CT scans (some authors used >1 modality in their study). For each modality, a large number of parameters and different cutoff values were reported. CT scanning is superior to plain radiography in the assessment of the quality of joint reduction. Parameters used the most were fibular position in the incisura and fibular rotation. The criteria for adequate reduction should at least include the position of the fibula in the incisura and rotation of the fibula, while ensuring adequate fibular length, all equaling or at least approaching the values of the uninjured contralateral side.

Comparison of Clamp Reduction and Manual Reduction of Syndesmosis in Rotational Ankle Fractures: A Prospective Randomized Trial

An optimal outcome of surgical treatment for a syndesmotic injury depends on accurate reduction and adequate fixation. It has been suggested that the use of a reduction clamp for reduction of the syndesmosis results in better reduction and a lower rate of redisplacement than manual reduction. However, these concepts have never been scientifically evaluated. We compared these 2 methods in a prospective randomized trial. A total of 85 acute ankle rotational fractures combined with syndesmotic injury were randomized to syndesmosis reduction with either a reduction clamp or manual manipulation. Reduction of the syndesmosis was assessed radiographically by measuring the tibiofibular clear space, tibiofibular overlap, and the medial clear space immediately postoperatively and at the final follow-up examination. Ankle joint range of motion, visual analog scale score, Olerud-Molander ankle scoring system, and complications were obtained at the last follow-up visit to assess the clinical outcomes. Of the 3 radiographic measurements, the tibiofibular clear space and tibiofibular overlap differed significantly between the 2 groups (p < .05). The clinical outcomes did not differ significantly between the 2 groups (p > .05). Although differences were found in the radiographic measurements, most syndesmoses in both groups were within the normal range at the final follow-up visit, and the 2 methods of syndesmosis reduction provided similar clinical outcomes. Accordingly, the results of the present study suggest that both of these methods are effective and reliable for reduction of the syndesmosis in rotational ankle fractures.

Morphology of the Incisura Fibularis at the Distal Tibiofibular Syndesmosis in the Japanese Population

The morphology of the distal tibiofibular syndesmosis can determine the pathology and mechanism of syndesmotic injury. The present study assessed measurements obtained from computed tomography (CT) images of the normal distal tibiofibular syndesmosis in Japanese subjects. CT scans of 120 right feet with a normal distal tibiofibular syndesmosis obtained from January 2009 to December 2016 were retrospectively assessed at the level 10 mm proximal to the tibial plafond. The incisura fibularis was considered concave when its depth was ≥4 mm and shallow when its depth was <4 mm. The depth of the incisura fibularis, anterior tibiofibular distance (TFD), posterior TFD, and longitudinal/transverse length of the distal fibula were measured. The incisura fibularis was concave in 64.2% of the feet and shallow in 35.8%. The mean anterior TFD was 2.2 ± 0.8 mm (2.4 ± 0.8 mm in males; 2.1 ± 0.8 mm in females; 2.1 ± 0.8 mm for concave; 2.2 ± 0.9 mm for shallow). The mean posterior TFD was 5.9 ± 1.6 mm (6.7 ± 2.1 in males; 5.7 ± 1.3 mm in females; 5.5 ± 1.3 mm for concave; 6.5 ± 1.9 mm for shallow). The mean longitudinal/transverse length of the distal fibula at the level of the syndesmosis was 1.2 mm (1.3 mm in males; 1.2 mm in females; 1.1 mm for concave; 1.3 mm for shallow). The mean posterior TFD was significantly greater than the mean anterior TFD and was also significantly greater in males than in females. Significant differences were found in the body mass index, posterior TFD, and longitudinal/transverse length of the distal fibula according to whether the incisura fibularis was concave or shallow. The present study has provided measurements of the normal tibiofibular syndesmosis in the Japanese population. These data suggest that the morphology of the syndesmosis varies, especially with respect to whether the incisura fibularis is concave or shallow.

Radiographic evaluation of the normal ankle joint in children and adolescent

BACKGROUND

The purpose of this study was to determine the reliability of numerous radiographic measurements of the skeletally immature ankle joint, timing of ossification of medial malleolus and appearance of tibial incisura and differences in the values of radiographic measurements based on age and sex.

METHODS

This study included 590 subjects (0-15 years), who underwent ankle AP, lateral and mortise radiographs. Presence of the medial malleolus and incisura fibularis were recorded. Tibiofibular overlap, tibiofibular clear space, medial clear space, talar tilt, talocrural angle, relative fibular width and fibular position were measured.

RESULTS

All radiographic measurements showed good to excellent intraobserver and interobserver reliability (ICCs, 0.603 to 0.949). The timing of ossification of medial malleolus and appearance of tibial incisura between boys and girls were not different. Tibiofibular clear space on mortise views, and medial clear space on AP and mortise view significantly decreased by age. Tibiofibular overlap on AP and mortise views, relative fibular width on AP view significantly increased by age. Talocrural angle, tibiofibular overlap on AP view, tibiofibular clear space on AP and mortise views, medial clear space on AP and mortise views and fibular position were significantly larger in boys than in girls. The difference in tibiofibular overlap, tibiofibular clear space and medial clear space on AP view of both sides was <50% in 97.1%, 93.1%, and 97.2% of patients, respectively. The difference in tibiofibular overlap, tibiofibular clear space and medial clear space on mortise view of both sides was <50% in 98.0%, 96.5%, and 100% of patients, respectively.

CONCLUSIONS

For skeletally immature patients, the criteria for absolute radiographic values used in adults to assess distal tibiofibular syndesmosis or deltoid ligament injury cannot be applied, but comparison of both sides of ankle joint could help physicians to predict the need for additional evaluations.

Syndesmotic stability: Is there a radiological normal?-A systematic review

BACKGROUND

Syndesmotic injury and instability poses a diagnostic challenge with unreliable clinical tests and inconsistent radiologic measures. Thus, used widely in clinical practice, there is huge debate pertaining to the reliability and validity of the radiologic parameters used for syndesmotic instability.

OBJECTIVE

Hence the purpose of the review was to explore the normal radiologic measures and morphometrics of distal tibiofibular syndesmosis and its relationships, which can aid in diagnosing syndesmotic instability.

METHOD

Computerised literature searches was performed for articles published in English using Pubmed, from inception through June 2016. All published articles reporting the normal anatomic and morphometric measures of distal tibiofibular syndesmosis with the use of any radiological modality individually or in combination, either in cadaveric or in live subjects were included. Studies done on or reporting of measures in healthy ankles or radiologically normal ankles were only included.

RESULTS

In this review wide anatomic and morphologic variability was observed amidst the landmarks used commonly for assessing syndesmotic instability and hence the normal measures. Further age and gender based variations were seen across the most commonly used radiologic measures for syndesmotic instability diagnosis, demanding the modification of existing radiologic criteria.

Imaging in syndesmotic injury: a systematic literature review

OBJECTIVES

To give a systematic overview of current diagnostic imaging options for assessment of the distal tibio-fibular syndesmosis.

MATERIALS AND METHODS

A systematic literature search across the following sources was performed: PubMed, ScienceDirect, Google Scholar, and SpringerLink. Forty-two articles were included and subdivided into three groups: group one consists of studies using conventional radiographs (22 articles), group two includes studies using computed tomography (CT) scans (15 articles), and group three comprises studies using magnet resonance imaging (MRI, 9 articles).The following data were extracted: imaging modality, measurement method, number of participants and ankles included, average age of participants, sensitivity, specificity, and accuracy of the measurement technique. The Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) tool was used to assess the methodological quality.

RESULTS

The three most common techniques used for assessment of the syndesmosis in conventional radiographs are the tibio-fibular clear space (TFCS), the tibio-fibular overlap (TFO), and the medial clear space (MCS). Regarding CT scans, the tibio-fibular width (axial images) was most commonly used. Most of the MRI studies used direct assessment of syndesmotic integrity. Overall, the included studies show low probability of bias and are applicable in daily practice.

CONCLUSIONS

Conventional radiographs cannot predict syndesmotic injuries reliably. CT scans outperform plain radiographs in detecting syndesmotic mal-reduction. Additionally, the syndesmotic interval can be assessed in greater detail by CT. MRI measurements achieve a sensitivity and specificity of nearly 100%; however, correlating MRI findings with patients' complaints is difficult, and utility with subtle syndesmotic instability needs further investigation. Overall, the methodological quality of these studies was satisfactory.

Comparing Different Surgical Techniques for Addressing the Posterior Malleolus in Supination External Rotation Ankle Fractures and the Need for Syndesmotic Screw Fixation

Trimalleolar ankle fractures are unstable injuries with possible syndesmotic disruption. Recent data have described inherent morbidity associated with screw fixation of the syndesmosis, including the potential for malreduction, hardware irritation, and post-traumatic arthritis. The posterior malleolus is an important soft tissue attachment for the posterior inferior syndesmosis ligament. We hypothesized that fixation of a sizable posterior malleolar (PM) fracture in supination external rotation type IV (SER IV) ankle fractures would act to stabilize the syndesmosis and minimize or eliminate the need for trans-syndesmotic fixation. A retrospective review of trimalleolar ankle fractures surgically treated from October 2006 to April of 2011 was performed. A total of 143 trimalleolar ankle fractures were identified, and 97 were classified as SER IV. Of the 97 patients, 74 (76.3%) had a sizable PM fragment. Syndesmotic fixation was required in 7 of 34 (20%) and 27 of 40 (68%), respectively, when the PM was fixed versus not fixed (p = .0002). When the PM was indirectly reduced using an anterior to posterior screw, 7 of 15 patients (46.7%) required syndesmotic fixation compared with none of 19 patients when the PM fragment was fixated with direct posterior lateral plate fixation (p = .0012). Fixation of the PM fracture in SER IV ankle fractures can restore syndesmotic stability and, thus, lower the rate of syndesmotic fixation. We found that fixation of a sizable PM fragment in SER IV or equivalent injuries through posterolateral plating can eliminate the need for syndesmotic screw fixation.

An anthropometric study of distal tibiofibular syndesmosis (DTS) in a Chinese population

Background

To improve the diagnostic accuracy of distal tibiofibular syndesmoses (DTS), this study quantified the range in variations of the normal DTS in a Chinese population, based on CT scan images.

Methods

The study population comprised 92 patients with unilateral ankle injury. CT scans included the non-injured contralateral DTS. The position of the fibula relative to the fibular notch (incisure) of the tibia was quantified by inclusion or separation indices, based on whether the fibula was within or outside the fibular incisure, respectively. The patients were apportioned accordingly to either a DTS contained- or separate-type group (average ages 45 and 42.1 years, respectively; 19 men/26 women and 24 men/23 women). Further variations in the position of the fibula relative to the tibia were quantified with length, anterior, and posterior indices.

Results

The baseline characteristics of the contained- and separate-type groups were statistically comparable. The length, anterior, extra-anterior, posterior, and extra-posterior indices were successfully calculated. The anterior index of the contained group was significantly greater than that of the separated group, while the posterior index was significantly less.

Conclusions

This study provides measurements of the normal tibiofibular syndesmosis in a Chinese population. In individuals whose fibula lay within the fibular incisure of the tibia, the fibula was likely to be more anterior than that of individuals whose fibula lay outside the incisure. Offered as a reference, these data should improve diagnosis of injury of the DTS.

Syndesmotic Injury Assessment With Lateral Imaging During Stress Testing in a Cadaveric Model

BACKGROUND

External rotation, lateral, and sagittal stress tests are commonly used to diagnose syndesmotic injuries, but their efficacy remains unclear. The purpose of this study was to characterize applied stresses with fibular motion throughout the syndesmotic injury spectrum. We hypothesized that sagittal fibular motion would have greater fidelity in detecting changes in syndesmotic status compared to mortise imaging.

METHODS

Syndesmotic instability was characterized using motion analysis during external rotation, lateral, and sagittal stress tests on cadaveric specimens (n = 9). A progressive syndesmotic injury was created by sectioning the tibiofibular and deltoid ligaments. Applied loads and fibular motion were synchronously measured using a force transducer and motion capture, respectively, while mortise and lateral radiographs were acquired to quantify clinical measurements. Fibular motion in response to these 3 stress tests was compared between the intact, complete lateral syndesmotic injury and lateral injury plus a completely sectioned deltoid condition.

RESULTS

Stress tests performed under lateral imaging detected syndesmotic injuries with greater sensitivity than the clinical-standard mortise view. Lateral imaging was twice as sensitive to applied loads as mortise view imaging. Specifically, half as much linear force generated 2 mm of detectable syndesmotic motion. In addition, fibular motion increased linearly in response to sagittal stresses (Pearson's r [ρ] = 0.91 ± 0.1) but not lateral stresses (ρ = 0.29 ± 0.66).

CONCLUSION

Stress tests using lateral imaging detected syndesmotic injuries with greater sensitivity than a typical mortise view. In addition to greater diagnostic sensitivity, reduced loads were required to detect injuries.

CLINICAL RELEVANCE

Syndesmotic injuries may be better diagnosed using stress tests that are assessed using lateral imaging than standard mortise view imaging.

Radiographic Change of the Distal Tibiofibular Joint Following Removal of Transfixing Screw Fixation

BACKGROUND

Syndesmosis disruptions in the ankle joint are typically treated with anatomic reduction followed by transfixing screw and/or suture button fixation. The purpose of our study was to analyze the effects of the removal of transfixing screws on syndesmosis integrity using plain radiographs and computed tomography (CT) scans.

METHODS

Twenty-nine cases (29 patients) who had been treated with transfixing screw fixation for syndesmosis disruptions were studied prospectively. Plain radiographs and CT scans were obtained 1 day before and 3 months after the removal of transfixing screws. The tibiofibular clear space (TCS) and tibiofibular overlap (TFO) were measured on plain radiographs, and the anterior and posterior measurement ratio (A/P ratio) of the syndesmosis was measured on axial CT scans to radiographically analyze the effect of the removal of screws on syndesmosis integrity.

RESULTS

On plain radiographs, syndesmosis diastasis was not observed before or after the removal of transfixing screws. No statistically significant difference was found in the TCS and the TFO between measurements at prescrew removal and at postscrew removal ( P = .761 and .628, respectively). However, the syndesmosis was found malreduced on CT scans in 7 cases (24.1%) before screw removal. All 7 cases showed anterior malreduction of the syndesmosis, 5 (71.4%) of which spontaneously reduced after screw removal. The A/P ratio of the 7 cases decreased from a mean of 1.37 (range, 1.26-1.61) at prescrew removal to a mean of 1.12 (range, 0.96-1.25) at postscrew removal ( P = .016).

CONCLUSION

Syndesmosis malreduction not observed on plain radiographs after performing transfixing screw fixation was identified with CT scans. Of the cases with a malreduced syndesmosis, 71.4% showed spontaneous reduction after screw removal. Therefore, we believe the removal of transfixing screws is recommended after confirming malreduction on CT scans, although plain radiographs demonstrate anatomic reduction.

LEVEL OF EVIDENCE

Level II, prospective prognostic study.