Evaluation of the ankle syndesmosis: A plastination slices study

Fibular notch morphometry and its clinical importance on dry bones

The aim of the present study was to determine the morphometric characteristics of the fibular notch (FN). This study was carried out with 76 dry adult tibial bone specimens (right 38, left 38) with unknown age and sex collected from the Department of Anatomy, Cukurova University, Adana. The mean width of the FN was 23.04 ± 2.02 mm; the mean depth of the FN 3.63 ± 0.83 mm; the mean height of the FN was 41.76 ± 4.01 mm. The mean anterior facet length and posterior facet length was found to be 10.44 ± 1.94 mm and 13.93 ±1.63 mm, respectively. The mean value of the angle between the anterior and posterior facets was found to be 140.56° ± 11.72. The mean value of the angle between the anterior surface of the tibia and the intertubercular line was 75.5° ± 5.47. No statistically significant differences were detected between the right and left sides for all measurements. It is considered that knowing the morphometric and anatomical characteristics of the fibular notch in detail will help radiologists evaluate the talocrural region. It is also considered that these data will guide surgeons and help determine the appropriate size for ankle reconstruction operations.

The morphometry of distal tibia and posterior malleolus and its clinical implications in total ankle prosthesis

PURPOSE

The aim of this study is to reveal the morphometry of the distal tibia and posterior malleolus and to generate morphometric reference data for the tibial component of total ankle prosthesis.

METHODS

This study was performed on 121 human dry tibiae (47 right, 74 left). The morphometric measurements of distal tibial structures, tibial length and the distance between the medial and posterior malleolus were measured in this study. Measurements on 44 tibiae were repeated three times and averaged for minimizing intra-observer error.

RESULTS

The tibial length was found 34.19 ± 2.31 cm. Mean values of width of fibular notch at tibial plafond and 10 mm proximal to the tibial plafond were 25.71 ± 2.44 mm and 17.81 ± 2.46 mm, respectively. Mean depth of fibular notch at tibial plafond and 10 mm proximal to the tibial plafond were 3.60 ± 1.04 mm and 3.37 ± 1.24 mm, respectively. Mean height of fibular notch was found 48.21 ± 10.51 mm. Mean width and height of medial malleolus were 25.08 ± 2.13 mm and 14.73 ± 1.85 mm, respectively. Mean width and length of tibial plafond were 27.71 ± 2.74 mm and 26.96 ± 2.62 mm, respectively. Mean values of width and height of posterior malleolus were measured 21.41 ± 3.26 mm and 6.74 ± 1.56 mm, respectively. Mean distance between medial and posterior malleolus was found 37.17 ± 3.53 mm. Mean width and depth of malleolar groove were 10.26 ± 1.84 mm and 1.73 ± 0.75 mm, respectively. The mean intra-class correlation values were found between the 0.959 and 0.999.

CONCLUSIONS

Knowing the distal tibial morphometry is crucial for designing convenient ankle replacement implants for Turkish population. To our knowledge, this study is the first in the literature that identifies posterior malleolar morphometry on dry tibiae. We believe that this study will make a significant contribution to the literature about distal tibial morphometry and especially the posterior malleolus and the data of our study can be used for designing total ankle prosthesis in Turkish population.

Normal Distal Tibiofibular Syndesmosis Assessment Using Postmortem Computed Tomography (PMCT)

BACKGROUND

Distal tibiofibular syndesmotic injuries, often misdiagnosed, can lead to substantial morbidity. This study utilized postmortem computed tomography (PMCT) to define normal syndesmotic relationships in 131 subjects.

METHODS

Three parameters were measured: fibular rotation (FR), sagittal translation (ST), and incisura depth (ID).

RESULTS

Interobserver reliability was excellent for FR and ID but moderate for ST. Anatomical variability was wide, with FR ranging from -0.4° to 16.6°, ST from 0.33 mm to 3.49 mm, and ID from 1.89 mm to 6.05 mm. Side-to-side variability within subjects was minimal. Gender-specific differences were observed in ST, possibly due to size variations, highlighting the need for gender-specific diagnostic criteria.

CONCLUSIONS

Although establishing universal reference values is challenging, using contralateral ankles for comparison can enhance diagnostic accuracy in syndesmotic injuries. This study, the first of its kind, offers valuable insights into normal distal tibiofibular syndesmotic relationships based on PMCT data. Future validation studies in patients with syndesmotic injuries can further improve diagnostic accuracy.

Distal tibiofibular syndesmosis: A meta-analysis of cadaveric studies

Though injuries to the distal tibiofibular (DTF) syndesmosis are commonly encountered in orthopedic and trauma settings, its anatomical structures have been poorly researched. The commonly overlooked DTF ligament injuries are known to cause chronic ankle pain, instability and post-traumatic osteoarthritis. Quantitative and morphological evidence synthesis has not been yet conducted. A meta-analysis was conducted to collect data from morphological studies to document more accurate details on the prevalence, size, and insertion sites of its components. The Checklist for Anatomical Reviews and Meta-Analyses (CARMA) was followed. Ten studies met the inclusion criteria with a total of 265 investigated ankles. The analysis demonstrated that the anterior and posterior tibiofibular ligaments along with the interosseous ligament were present in 100% of joints. The inferior transverse tibiofibular and the distal fascicle of the anterior tibiofibular ligament were the least prevalent with frequencies of 96% and 86.5%, respectively. The inferior transverse ligament was recorded as the longest ligament. The widest ligament was found to be the interosseous tibiofibular ligament at its fibular attachment. The thickest of the ligamentous components was the posterior tibiofibular ligament. While more cadaveric research is warranted, these results would help directing future biomechanical investigations and planning new research to further aid in diagnostic and therapeutic approaches to the injuries of the distal tibiofibular syndesmosis.

The Syndesmosis, Part II: Surgical Treatment Strategies

Syndesmotic injuries in the setting of ankle fracture are critically important to diagnosis and treat to restore an anatomic tibiotalar relationship. Physical examination and clinical suspicion remain critically important for diagnosis. Ultrasound examination and weight-bearing computed tomography scans are evolving to help diagnosis more subtle injuries. Although flexible syndesmotic fixation may decrease malreduction rates, the benefits over rigid fixation is the subject of ongoing study. Anatomic reduction remains critical regardless of fixation choice. Routine removal of rigid syndesmotic hardware does not seem to offer substantial clinical improvement in pain or range of motion; however, broken hardware may cause irritation.

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.

Influence of syndesmotic injuries and posterior malleolar ankle fractures on fibula position in the ankle joint: a cadaveric study

PURPOSE

The aim of this study was to identify to what extent a dissection of the syndesmosis and an avulsed posterior edge of the tibia can change the tibiofibular diastasis and fibular rotation.

METHODS

Three-dimensional scans with a mobile C-arm of 22 cadaver legs were taken of the intact fibula, after dissection of the anterior part of the syndesmosis and the interosseous membrane, osteotomy of the posterior malleolus, and osteosynthesis. The tibiofibular diastasis as well as the angle of fibular rotation was identified in the four steps and the means compared to each other using a t test for paired samples.

RESULTS

The distinction between the intact fibula vs. the osteotomy of the posterior tibia was 0.082 ± 0.332 mm for the tibiofibular distance in the incisura tibiofibularis (p 0.261) and 0.046 ± 0.486 degrees for the angle of the fibular rotation (p 0.665).

CONCLUSION

Neither the dissection of the syndesmosis nor the osteotomy of the posterior malleolus significantly influenced the position of the fibula in the incisura tibiofibularis in the cadaveric model. However, in the nonweight-bearing situation, a lesion of the syndesmotic complex might not be evident in intraoperative three-dimensional imaging.

E12 technique: Conventional epoxy resin sheet plastination

Epoxy plastination techniques were developed to obtain thin transparent body slices with high anatomical detail. This is facilitated because the plastinated tissue is transparent and the topography of the anatomical structures well preserved. For this reason, thin epoxy slices are currently used for research purposes in both macroscopic and microscopic studies. The protocol for the conventional epoxy technique (E12) follows the main steps of plastination-specimen preparation, dehydration, impregnation and curing/casting. Preparation begins with selection of the specimen, followed by freezing and slicing. Either fresh or fixed (embalmed) tissue is suitable for epoxy plastination, while slice thickness is kept between 1.5 and 3 mm. Impregnation mixture is made of epoxy E12 resin plus E1 hardener (100 ppw; 28 ppw). This mixture is reactive and temperature sensitive, and for this reason, total impregnation time under vacuum at room laboratory temperature should not last for more than 20-24 hr. Casting of impregnated slices is done in either flat chambers or by the so-called sandwich method in either fresh mixture or the one used for impregnation. Curing is completed at 40°C to allow a complete polymerization of the epoxy-mixture. After curing, slices can be photographed, scanned or used for anatomical study under screen negatoscope, magnification glass or fluorescent microscope. Based on epoxy sheet plastination, many anatomical papers have recent observations of and/or clarification of anatomical concepts in different areas of medical expertice.

Learning anatomy of the foot and ankle using sagittal plastinates: A prospective randomized educational trial

BACKGROUND

Foot and ankle anatomy is highly complex and presents a considerable educational challenge for the medical student or junior doctor. The successful interpretation of cross-sectional radiological images requires a detailed knowledge of anatomy and spatial relationships. Plastic-impregnated cadaveric prosection slices, known as 'sagittal plastinated slices', or 'SPS', are becoming popular as an adjunct to traditional anatomical teaching methods.

OBJECTIVES

To compare the impact of SPS versus conventional anatomy teaching resources (dry bones and whole cadaveric feet) on learners' ability to correctly identify structures of the foot and ankle on sagittal MRI images.

METHODS

Randomized educational study using sequential exploratory mixed-methods.

RESULTS

The intervention group anatomy test scores were a mean of 1.2 higher after the educational intervention, compared to 0.7 for the control group (scores out of 14), but this was not statistically significant (p=0.41). Learners reported that the SPS intervention was most useful to augment and refine their knowledge after a teaching session using conventional resources.

CONCLUSION

The qualitative results showed that SPS provide a valuable adjunct to traditional teaching methods in both anatomy and radiology of the foot and ankle, which should be used after teaching with traditional methods.

Three-Dimensional Computed Tomographic Characterization of Normal Anatomic Morphology and Variations of the Distal Tibiofibular Syndesmosis

Malreduction of distal tibiofibular syndesmosis (DTFS) leads to poor functional outcomes after ankle fracture surgery. Difficulty achieving anatomic alignment of the syndesmosis is due to variable morphology of the fibular incisura of the tibia and a paucity of literature regarding its morphologic characteristics. We surveyed 775 consecutive ankle computed tomography (CT) scans performed from June 2008 to December 2011, and 203 (26.2%) were included for evaluation. Two observers performed quantitative measurements and qualitative evaluated fibular incisura morphology. Tang ratios for fibular rotation, anterior and posterior tibiofibular distances, fibular incisura depth, and subjective morphologies on CT were assessed using conventional multiplanar reconstruction (MPR) and maximum intensity projections (MIPs). On conventional CT, the mean Tang ratio was 0.97 ± 0.06; the mean anterior tibiofibular distance was 2.17 ± 0.87 mm; the mean posterior tibiofibular distance was 3.52 ± 0.94 mm; and the mean depth of fibular incisura was 3.29 ± 1.19 mm. Five morphologic variations of the fibular incisura were identified: crescentic, trapezoid, flat, chevron, and widow's peak. The most common fibular incisura morphology was crescentic (61.3%), followed by trapezoid shape (25.1%); the least common morphology was flat (3.1%). Interobserver variability with intraclass correlation coefficient (ICC) was slightly higher for all quantitative measures on MPR (ICC = 0.72 to .81) versus MIP (ICC = 0.64 to 0.75). ICC for incisura shape and depth assessments was poor on both modalities (0.13 to 0.38). This comprehensive CT study reports on quantitative and qualitative descriptive measures to evaluate fibular incisura morphologies and fibular orientation. It also defines the frequency of DTFS measures and the interobserver performance on 2 CT evaluation methods.

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.

Is Incisura Fibularis a Reliable Landmark for Assessing Syndesmotic Stability? A Systematic Review of Morphometric Studies

Incisura fibularis (IF) is an important landmark in assessing syndesmotic stability radiologically postinjury. The purpose of this review was to explore the anatomy and morphometrics of this widely used anatomical landmark and to further the understanding of the same. A systematic review was conducted online using PubMed and Google Scholar, per PRISMA guidelines. Predefined eligibility criteria were applied, and the data thus compiled were analyzed. Wide variability in morphometrics and, thus, anatomy of IF were observed in the present review, which was influenced by gender. There was no side-to-side variability seen in this study. The study stresses the need to consider the anatomical and gender-based variability while assessing syndesmotic stability and further supports the recommendation of side-to-side comparison.

LEVELS OF EVIDENCE

Anatomical, Level V.

Evaluation of Reduction Accuracy of Suture-Button and Screw Fixation Techniques for Syndesmotic Injuries

BACKGROUND

Among the most important predictors of functional results of treatment of syndesmotic injuries is the accurate restoration of the syndesmotic space. The purpose of this study was to investigate the reduction performance of screw fixation and suture-button techniques using images obtained from computed tomography (CT) scans.

METHODS

Patients at or below 65 years who were treated with screw or suture-button fixation for syndesmotic injuries accompanying ankle fractures between January 2012 and March 2015 were retrospectively reviewed in our regional trauma unit. A total of 52 patients were included in the present study. Fixation was performed with syndesmotic screws in 26 patients and suture-button fixation in 26 patients. The patients were divided into 2 groups according to the fixation methods. Postoperative CT scans were used for radiologic evaluation. Four parameters (anteroposterior reduction, rotational reduction, the cross-sectional syndesmotic area, and the distal tibiofibular volumes) were taken into consideration for the radiologic assessment. Functional evaluation of patients was done using the American Orthopaedic Foot & Ankle Society (AOFAS) ankle-hindfoot scale at the final follow-up. The mean follow-up period was 16.7 ± 11.0 months, and the mean age was 44.1 ± 13.2.

RESULTS

There was a statistically significant decrease in the degree of fibular rotation (P = .03) and an increase in the upper syndesmotic area (P = .006) compared with the contralateral limb in the screw fixation group. In the suture-button fixation group, there was a statistically significant increase in the lower syndesmotic area (P = .02) and distal tibiofibular volumes (P = .04) compared with the contralateral limbs. The mean AOFAS scores were 88.4 ± 9.2 and 86.1 ± 14.0 in the suture-button fixation and screw fixation group, respectively. There was no statistically significant difference in the functional ankle joint scores between the groups.

CONCLUSION

Although the functional outcomes were similar, the restoration of the fibular rotation in the treatment of syndesmotic injuries by screw fixation was troublesome and the volume of the distal tibiofibular space increased with the suture-button fixation technique.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Incisura Morphology as a Risk Factor for Syndesmotic Malreduction

BACKGROUND

The goal of this study was to objectively assess if rotational or translational syndesmotic malreduction is associated with certain syndesmotic morphologies. Prior studies based on subjective assessment of syndesmotic morphology and reduction have not shown any difference between groups.

METHODS

Thirty-five prospectively recruited patients with operatively treated syndesmotic injuries were recruited at an Urban Level I Trauma Center. Patients underwent postoperative bilateral computed tomographic (CT) scans of the ankle to assess incisura depth and syndesmotic reduction. The uninjured extremity was used as a control. Side-to-side differences of syndesmotic reduction were measured at several anatomic points and compared to the incisura depth.

RESULTS

There was a significant correlation between more shallow syndesmoses and increased anterior translation of the fibula in the incisura (r = -0.63, P ≤ .001). Six of 8 patients with "shallow" (≤2.5 mm) incisura were anteriorly malreduced greater than or equal to 1.5 mm compared to the contralateral ankle. The anterior malreduction rate in those with a shallow incisura was significantly greater than in the "non-shallow" patients (P < .001). There were 9 patients with incisurae greater than or equal to 4.5 mm deep. Five of the "deep" patients had posterior malreductions greater than or equal to 1.5 mm. The posterior malreduction rate in the "deep" group was significantly greater than the "non-deep" patients (P = .02). There was a significant correlation between increasing syndesmotic depth and increased malrotation (r = .46, P = .01).

CONCLUSION

Syndesmotic morphology was found to be associated with specific malreduction patterns. Shallow syndesmoses were correlated with anterior fibular malreduction, and were less likely to be malrotated. Conversely, deep syndesmoses predisposed to posterior sagittal plane and rotational malalignment. Preoperative CT scans that assess the syndesmosis morphology may allow surgeons to alter reduction strategies to avoid syndesmotic malreduction.

LEVEL OF EVIDENCE

Level III, retrospective cohort study.

Posterior translation of the fibula may indicate malreduction: CT study of normal variation in uninjured ankles

OBJECTIVES

The aim of our study was to assess the intersubject and intrasubject variations of distal tibiofibular syndesmosis on computed tomography (CT) scans and to define standardized measures to verify syndesmosis reduction.

DESIGN

A retrospective study of 107 CT scans of ankles with normal tibiofibular syndesmosis.

SETTING

Main trauma center, university teaching hospital.

PATIENTS

The CT scans of 64 patients were reviewed by 2 musculoskeletal radiologists.

MAIN OUTCOME MEASUREMENTS

Bilateral variation was estimated. The intra- and interobserver reliabilities were calculated using standardized measurement points. CT measurements included the length of the tibial incisura (LI), A width and P width of the incisura (PW), depth of the incisura, narrowest part of the incisura, and sagittal translation of the fibula.

RESULTS

In 97% of normal cases, the fibula is situated either centrally or anteriorly in the tibial incisura. There were significant differences in PW and LI between genders, and the difference between the PW and A width was significantly larger in males (2.7 mm, SD 2.1) than in females (1.9 mm, SD 1.6, P = 0.023, t test). Significant asymmetry was not detected between ankles in single subjects. All CT measurements demonstrated good inter- and intraobserver reliabilities.

CONCLUSIONS

If P translation of the fibula is present, malreduction should be considered. Sagittal translation measurements are not affected by the size of the joint or the gender of the patient, in contrast to traditionally used cross-sectional measurement methods.

Intraoperative three-dimensional imaging in the treatment of acute unstable syndesmotic injuries

BACKGROUND

Acute unstable syndesmotic ankle injuries are treated primarily by reduction and stabilization with a syndesmotic screw. Examination with fluoroscopy or standard radiographs may not provide reliable information about the quality of the reduction. There is evidence that intraoperative three-dimensional imaging can demonstrate a large proportion of malreductions. The aim of this study was to determine whether intraoperative three-dimensional imaging improves the detection of inadequate positioning of the distal aspect of the fibula in the tibiofibular incisura after syndesmotic screw insertion compared with the findings on standard intraoperative fluoroscopy.

METHODS

Of 2286 ankle fractures treated operatively from August 2001 to February 2011, 251 consecutive cases (11%) were identified in a retrospective chart review. All had an unstable syndesmosis and underwent syndesmosis stabilization on the basis of an intraoperative hook test. After fluoroscopy, an intraoperative three-dimensional scan was performed. The result of this scan was documented by the surgeon and analyzed retrospectively with regard to the incidence and nature of the need for intraoperative revisions.

RESULTS

The intraoperative three-dimensional scan altered the surgical outcome in eighty-two ankles (32.7%). In most ankles (seventy-seven; 30.7%), the reduction was improved, with the most common improvement being the alignment of the fibula in the tibiofibular incisura in sixty-four patients (25.5%) followed by correction of the fracture reduction in thirteen patients (5.2%). The other five alterations involved implant corrections. The most common malpositions requiring correction after insertion of a positioning screw, with or without additional fixation, were anterior displacement and internal rotation of the distal aspect of the fibula.

CONCLUSIONS

Following open reduction and internal fixation of an ankle fracture, the correct position of the syndesmosis cannot be evaluated reliably with use of conventional radiographs or intraoperative fluoroscopy. In view of the high proportion of positive findings in this study, we believe that any treatment of a syndesmotic injury should include intraoperative three-dimensional imaging or at least a postoperative computed tomography scan.

Normal tibiofibular relationships at the syndesmosis on axial CT imaging

OBJECTIVES

Computed tomography (CT) is reported to be superior to plain radiography for imaging the syndesmosis, but CT criteria differentiating normal from abnormal tibiofibular relationships do not exist. The purpose of this study was to define normal tibiofibular relationships at the syndesmosis on axial CT imaging and to report the reliability of these measurements.

METHODS

Thirty healthy volunteers underwent CT evaluation of bilateral ankles. Axial CT measurements consisted of tibiofibular clear space, tibiofibular overlap, anterior tibiofibular interval, and fibular rotation (θ(fib)). To assess reliability, 3 investigators independently made each CT measurement on 2 separate occasions.

RESULTS

Sixty ankles were included for analysis. CT measurements demonstrated excellent intrarater and interrater reliability. There was significant anatomic variability between individuals. Specifically, statistically significant gender differences were discovered in CT measurements of tibiofibular overlap and anterior tibiofibular interval. Variance between ankles of each subject was calculated. In an uninjured population, tibiofibular intervals do not vary by more than 2.3 mm, and the rotation of the fibula does not vary by more than 6.5° between ankles of the same person.

CONCLUSIONS

Measurements of tibiofibular relationships made on axial CT images are reliable. Because of significant anatomic variation between individuals, using a patient's contralateral ankle for comparison provides a precise definition of normal tibiofibular relationships. These criteria allow for the detection of subtle variations in the tibiofibular relationships indicating instability and provide a tool for postoperatively assessing the reduction of the injured syndesmosis.

Anatomy of the distal tibiofibular syndesmosis in adults: a pictorial essay with a multimodality approach

A syndesmosis is defined as a fibrous joint in which two adjacent bones are linked by a strong membrane or ligaments.This definition also applies for the distal tibiofibular syndesmosis, which is a syndesmotic joint formed by two bones and four ligaments. The distal tibia and fibula form the osseous part of the syndesmosis and are linked by the distal anterior tibiofibular ligament, the distal posterior tibiofibular ligament, the transverse ligament and the interosseous ligament. Although the syndesmosis is a joint, in the literature the term syndesmotic injury is used to describe injury of the syndesmotic ligaments. In an estimated 1–11% of all ankle sprains, injury of the distal tibiofibular syndesmosis occurs. Forty percent of patients still have complaints of ankle instability 6 months after an ankle sprain. This could be due to widening of the ankle mortise as a result of increased length of the syndesmotic ligaments after acute ankle sprain. As widening of the ankle mortise by 1 mm decreases the contact area of the tibiotalar joint by 42%, this could lead to instability and hence early osteoarthritis of the tibiotalar joint. In fractures of the ankle, syndesmotic injury occurs in about 50% of type Weber B and in all of type Weber C fractures. However,in discussing syndesmotic injury, it seems the exact proximal and distal boundaries of the distal tibiofibular syndesmosis are not well defined. There is no clear statement in the Ashhurst and Bromer etiological, the Lauge-Hansen genetic or the Danis-Weber topographical fracture classification about the exact extent of the syndesmosis. This joint is also not clearly defined in anatomical textbooks, such as Lanz and Wachsmuth. Kelikian and Kelikian postulate that the distal tibiofibular joint begins at the level of origin of the tibiofibular ligaments from the tibia and ends where these ligaments insert into the fibular malleolus. As the syndesmosis of the ankle plays an important role in the stability of the talocrural joint, understanding of the exact anatomy of both the osseous and ligamentous structures is essential in interpreting plain radiographs, CT and MR images, in ankle arthroscopy and in therapeutic management. With this pictorial essay we try to fill the hiatus in anatomic knowledge and provide a detailed anatomic description of the syndesmotic bones with the incisura fibularis, the syndesmotic recess, synovial fold and tibiofibular contact zone and the four syndesmotic ligaments. Each section describes a separate syndesmotic structure, followed by its clinical relevance and discussion of remaining questions.

Tri-ligamentous reconstruction of the distal tibiofibular syndesmosis: a minimally invasive approach

The distal tibiofibular syndesmosis provides stability to the ankle mortise, and it is composed of the anterior inferior tibiofibular, posterior inferior tibiofibular, interosseous, and inferior transverse tibiofibular ligaments and the interosseous membrane. Subacute or chronic syndesmosis injuries can present after missed diagnosis in the acute period or after failed or inadequate nonoperative management. It can result in chronic ankle pain and progressive degeneration of the ankle. Reconstructive options for chronic syndesmosis disruption include arthroscopic debridement and screw fixation, arthrodesis of the syndesmosis, advancement of the anterior tibiofibular ligament, reconstruction of the interosseous and anterior inferior tibiofibular ligament, or tri-ligamentous reconstruction of the syndesmosis. We describe a minimally invasive technique of nearly anatomical reconstruction of the 3 syndesmotic ligaments. The syndesmosis is debrided and reduced under arthroscopic guidance and anatomical reduction of the syndesmosis can be achieved. Although we describe this technique for surgeons to consider, we recognize that a thorough clinical review of the method, complete with objective and subjective clinical outcome measurements, is warranted before widespread use of the technique.

In search of clinical truths: equine and comparative studies of anatomy

The importance of correlating anatomical studies with diagnostic and therapeutic approaches in practice has long been recognised. Such studies in the horse have, until recently, lagged behind this discipline in human medicine and surgery. Clinical techniques by which this correlation is achieved include radiography, ultrasound, computed tomography and magnetic resonance imaging. This review presents published literature on the subject and, in addition, describes the part played by plastination, a recently developed technique for the preservation of biological specimens. In this, tissue fluids and part of the lipids are replaced by certain polymers yielding specimens that can be handled without gloves, do not smell or decay, and even retain microscopic properties of the original sample. The technique has proved to be a useful tool to correct previously presented anatomical descriptions and is one now favoured by human surgeons. Studies of the horse employing this technique include those of the temporomandibular joint and tarsus. The aim of the review is to stimulate further correlations of anatomical structure and equine medical and surgical procedures, thereby advancing knowledge and understanding in practice and teaching.

The posteromedial neurovascular bundle of the ankle: an anatomic study using plastinated cross sections

PURPOSE

The aim of this study was to evaluate the topography of the posteromedial neurovascular bundle of the ankle. The anatomic relation of the posteromedial neurovascular bundle at different levels of the ankle was studied as an aid in planning minimally invasive surgery. A thorough knowledge of the local anatomy is a prerequisite before attempting release of the tibial nerve or when using the posteromedial portal for ankle arthroscopy.

METHODS

A slice anatomy study was performed on 12 intact right male cadaveric lower limbs. The distal third of each limb was cut and the foot positioned in the neutral position. The measurements were performed at the level of the tibiotalar joint, at the tip of the medial malleolus, and at the sustentaculum tali.

RESULTS

The tibial nerve is predicted to be 11.8 +/- 2.4 mm and the posterior tibial artery 16.7 +/- 3.8 mm anterior from the calcaneal tendon at the level of the tibiotalar joint. At the tip of the malleolus medialis, the tibial nerve is 14.3 +/- 2.5 mm and the posterior tibial artery 22.1 +/- 4.1 mm anterior to the Achilles tendon. The medial plantar nerve is situated at the sustentaculum tali level 8.4 +/- 3.4 mm and the lateral plantar nerve 16.1 +/- 3.1 mm posterior to the sustentaculum.

CONCLUSIONS

On the basis of our anatomic data, a posteromedial portal made at the level of the tip of the medial malleolus seems to be safe, effective, and reproducible. Therefore a portal at this level would be advantageous for an endoscopic tarsal tunnel release or when using the posteromedial portal for ankle arthroscopy. Anatomic characteristics should be kept in mind when ankle surgery is performed, thereby reducing the risk of injury to the medial neurovascular bundle and offering easy access inside the posterior compartment of the ankle.

CLINICAL RELEVANCE

This cadaveric study suggests that, by placing the posteromedial ankle portal at the tip of the medial malleolus, the risk of neurovascular injuries could be reduced.

Isolated anterior syndesmosis diastasis without fracture

Pure syndesmosis disruption at ankle without fracture of the fibula was rare. We reported a young man who had persistent left ankle pain and swelling 4 weeks after road traffic accident. X-rays did not reveal any fracture along whole fibula. Computed tomography showed anteriorly displaced fibula at syndesmosis level. Arthroscopic reduction and syndesmosis screw fixation followed by ligament reconstruction was done. Finally, he enjoyed pain-free range of motion of his ankle.

Three-dimensional reconstruction of the ankle by means of ultrathin slice plastination

Computerized reconstruction of anatomical structures is becoming very useful for developing anatomical teaching modules and animations. Although databases exist consisting of serial sections derived from frozen cadaver material, plastination represents an alternate method for developing anatomical data useful for computerized reconstruction. Plastination is used as an excellent tool for studying different anatomical and clinical questions. The sheet plastination technique is unique because it offers the possibility to produce transparent slices series, which can easily be processed morphometrically. The purpose of this study was to describe a method for developing a computerized model of the human ankle using plastinated slices. This method could be applied to reconstruct any desired region of the human body.A human ankle was obtained, plastinated, sectioned, and subjected to 3D computerized reconstruction using WinSURF modeling system (SURFdriver Software). Qualitative observations revealed that the morphological features of the model were consistent with those displayed by typical cadaveric specimens. Morphometric analysis indicated that the model did not significantly differ from a sample of cadaveric specimens. These data support the use of plastinates for generating tissues sections useful for 3D computerized modeling.

Anatomical evaluation and clinical importance of the tibiofibular syndesmosis ligaments

The aim of this study was to describe the detailed anatomical arrangement of ligaments of the tibiofibular syndesmosis and to highlight the clinical aspects of fracture dislocations. This study was performed on 42 legs of adult human embalmed cadavers. Tibiofibular syndesmosis ligaments attachments and their mutual relationships were described and their dimensions were measured. The anterior tibiofibular ligament is usually composed of three parts. This ligament runs obliquely at laterodistaly direction making 35 degrees angle with horizontal plane and posteriorly 65 degrees angle with sagittal plane. The posterior tibiofibular ligament runs almost horizontally 20 degrees angle with horizontal plane. The mean thicknesses of tibial and fibular attachments are 6.38+/-1.91 mm and 9.67+/-1.74 mm, respectively. The inferior transverse ligament originates from just below the posterior tibiofibular ligament, which has variations on the shape and dimensions due to its attachment points. The average length is 36.60+/-9.51 mm. The network between the fibular notch and the distal fibula has been filled with the interosseous tibiofibular ligament whose fibers follow the laterodistal and anterior direction from the tibia to the fibula. It lies proximally 30-40 mm from the mortise. At the inferior view of the tibiofibular syndesmosis a pyramidal shaped cartilaginous facet was observed which was attached to the fibula. The length of this cartilage was variable. Some of synovial plicas from the ankle joints synovial membrane were observed at this view. We conclude that the results of this study may be useful to both orthopedic surgeons and radiologists for anatomic evaluation of the tibiofibular syndesmosis area.