Magnetic resonance imaging characterization of individual ankle syndesmosis structures in asymptomatic and surgically treated cohorts

Ultrasound Assessment of Ankle Syndesmotic Injuries in a Pediatric Population

OBJECTIVE

To determine sensitivity and specificity for anterior-inferior tibiofibular ligament (AiTFL) integrity and tibiofibular clear-space (TFCS) cut-off points for dynamic evaluation using ultrasound (US) in a pediatric population.

DESIGN

Prospective cohort study.

SETTING

Tertiary care university-affiliated pediatric hospital patients between the ages of 12 and 18 sustaining acute ankle trauma with syndesmotic injury.

INTERVENTIONS

Participants were assigned to the syndesmotic injury protocol that included a standardized MRI and US.

MAIN OUTCOME MEASURES

Anterior-inferior tibiofibular ligament integrity for static assessment and TFCS measurements for dynamic assessment on US. For dynamic assessment, the distance between the distal tibia and fibula was first measured in neutral position and then in external rotation for each ankle. The US results on AiTFL integrity were compared with MRI, considered as our gold standard. Optimal cut-off points of TFCS values were determined with receiver operating characteristics curve analysis.

RESULTS

Twenty-six participants were included. Mean age was 14.8 years (SD = 1.3 years). Sensitivity and specificity for AiTFL integrity were 79% and 100%, respectively (4 false negatives on partial tears). For dynamic assessment, the cut-off points for the differences in tibiofibular distance between the 2 ankles in 1) neutral position (TFCS N I-U ) and 2) external rotation (TFCS ER I-U ) were 0.2 mm (sensitivity = 83% and specificity = 80%) and 0.1 mm (sensitivity = 83% and specificity = 80%), respectively.

CONCLUSIONS

Static US could be used in a triage context as a diagnostic tool for AiTFL integrity in a pediatric population as it shows good sensitivity and excellent specificity.

Normal Values for Distal Tibiofibular Syndesmotic Space With and Without Subject-Driven External Rotation Stress

BACKGROUND

The diagnosis and treatment of distal tibiofibular syndesmosis (DTFS) injury can be challenging, especially in cases of subtle instability that may be masked on 2-dimensional conventional radiographs. Weightbearing computed tomography (WBCT) has recently emerged as a useful diagnostic tool allowing direct assessment of distal tibiofibular area widening. The purpose of the current study was to examine and report normal threshold values for DTFS area measurements in a cohort of healthy volunteers, assessing the ankles in natural weightbearing position and under subject-driven external rotation stress.

METHODS

In this prospective study, we enrolled 25 healthy volunteers without a history of DTFS injury or high ankle sprain, previous foot and ankle surgery, or current ankle pain. Subjects with any prior ankle injuries were excluded. Study participants underwent bilateral standing nonstress and external rotation stress WBCT scans. The DTFS area (mm2) was semiautomatically quantified on axial-plane WBCT images 1 cm proximal to the apex of the talar dome using validated software. Syndesmosis area values were compared between "unstressed" and "stressed" ankles, as well as left and right ankles. Statistical analysis was performed using independent t tests/Wilcoxon analysis with statistical significance defined as P <.05.

RESULTS

The study cohort consisted of 50 ankles in 25 patients (12 males, 48%) with a mean age of 28.7 ± 9.3 years. In the unstressed ankle, the mean pooled DTFS area was determined to be 103.8 + 20.8 mm2. The mean syndesmosis area of unstressed left ankles (104.2 + 19.5 mm2) was similar to unstressed right ankles (109.2 + 17.2 mm2) in the cohort (P = .117). With external rotation stress, the DTFS area of left ankles (mean difference -0.304 mm2, CI -12.1 to 11.5; P = .082), right ankles (mean difference -5.5 mm2, CI 16.7-5.7; P = .132), and all ankles (mean difference -2.9 mm2, CI -10.8 to 5.1; P = .324) remained similar.

CONCLUSION

This study presents normal values and range for DTFS area calculation. In uninjured ankles with expected intact ligaments, subject-driven external rotation stress did not result in significant widening of the DTFS space as imaged on with WBCT.

LEVEL OF EVIDENCE

Level II, cross-sectional study.

Technical note: Intraoperative ultrasound measurement for evaluating the stability of the inferior tibiofibular joint in patients with ankle fractures

OBJECTIVES

Injury to the tibiofibular syndesmosis is a common complication of ankle fractures. Currently, it is challenging to determine the stability of the tibiofibular joint caused by ankle fractures during surgery. This study aims to establish a standardized method for dynamically evaluating the stability of the inferior tibiofibular joint under intraoperative ultrasound and assess its utility in surgery, thereby assisting in determining the necessity for fixation of the inferior tibiofibular joint after fracture reduction and fixation.

METHODS

The stability of the inferior tibiofibular joint was assessed using an intraoperative ultrasonic external rotation stress test, with a torque set at 7.2 N·m. The measured parameters included the width of the inferior tibiofibular space in neutral (N) and external rotation (E) positions, stretch ratio (E/N), and injured/healthy side stretch ratio (I/H). Patients with Weber B or C type ankle fractures were selected as participants.

RESULTS

For the case with Weber C fracture, the N measurement was 4.22 mm after fracture fixation, while E measured 5.77 mm and E/N ratio was 1.37, which were larger than those on the healthy side (N: 4.17, E: 4.50, E/N:1.08), with an I/H ratio of 1.27. Intraoperative X-ray revealed instability of the inferior tibiofibular joint. After inserting a tibiofibular screw, the N measurement was 4.20 mm, while the E measurement recorded 4.32 mm, resulting in an E/N ratio of 1.03 and an I/H ratio of 0.95, indicating improved joint stability. For the Weber B fracture case, the N measurement was 3.55 mm after fracture fixation, while E measured 3.98 mm and the E/N ratio was 1.12, slightly lower than those on the healthy side (N: 3.94, E: 4.47, E/N: 1.13), with an I/H ratio of 0.99. The intraoperative X-ray revealed stability of the inferior tibiofibular joint. Therefore, no further fixation was performed on it.

CONCLUSION

Standardized intraoperative ultrasound stress test allows for real-time, dynamic assessment of the stability of the inferior tibiofibular joint after ankle fracture reduction and fixation, which can help guide the fixation of the inferior tibiofibular joint, thereby reducing the risk of postoperative traumatic arthritis.

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.

Shoe-Integrated Sensor System for Diagnosis of the Concomitant Syndesmotic Injury in Chronic Lateral Ankle Instability: A Prospective Double-Blind Diagnostic Test

Chronic lateral ankle instability (CLAI) is commonly secondary to prior lateral ankle ligament injury, and the concomitant latent syndesmosis injury would prolong recovery time and increase the risk of substantial traumatic arthritis. However, differentiating syndesmotic injury from isolated lateral ankle ligament injury in CLAI cases is difficult by conventional physical and radiological examinations. To improve the accuracy of syndesmotic injury diagnosis, a shoe-integrated sensor system (SISS) is proposed. This system measures plantar pressure during walking to detect the presence of syndesmotic injury. The study included 27 participants who had ankle sprains and underwent an examination. Plantar pressure in eight regions of interest was measured for both limbs, and syndesmotic injuries were examined using arthroscopy. The width of the syndesmosis was measured to evaluate its severity. The characteristics of plantar pressure were compared between patients with normal and injured syndesmosis. The results indicated that peak plantar pressure ratios with logistic regression predicted value > 0.51 accurately distinguished concomitant syndesmotic injury during walking, with high sensitivity (80%) and specificity (75%). The post-test probability of having a syndesmotic injury was positively 80% and negatively 25%. These findings demonstrate the effectiveness of cost-effective wearable sensors in objectively diagnosing concomitant syndesmotic injuries in cases of CLAI.

Anterior Inferior Tibiofibular Ligament Suture Tape Augmentation for Isolated Syndesmotic Injuries

BACKGROUND

The best operative construct and technique for treatment of isolated syndesmotic injuries is highly debated. The purpose of this study was to determine whether the addition of anterior inferior tibiofibular ligament (AITFL) suture repair or suture tape (ST) augmentation provides any biomechanical advantage to the operative repair of an isolated syndesmotic injury.

METHODS

Twelve lower leg specimens underwent biomechanical testing in 6 states: (1) intact, (2) AITFL suture repair, (3) AITFL suture repair + transsyndesmotic suture button (SB), (4) AITFL suture repair + ST augmentation + SB, (5) AITFL suture repair + ST augmentation, and (6) complete syndesmotic injury. The ankle joint was subjected to 6 cycles of 5 Nm internal and external rotation torque under a constant axial load. The spatial relationship between the tibia, fibula, and talus was continuously recorded with a 5-camera motion capture system.

RESULTS

AITFL suture repair and AITFL suture repair + ST augmentation showed no statistically significant change in fibula kinematics compared to the intact state. Compared to native, AITFL suture repair + SB showed increased fibular external rotation (+2.32 degrees, P < .001), and decreased tibiofibular gap (overtightening) (-0.72 mm, P = .007). AITFL suture repair + ST augmentation + SB also showed increased fibular external rotation (+1.46 degrees, P = .013). Sagittal plane motion of the fibula was not significantly different between any states. None of the repairs restored intact state talus rotation; however, the repairs that used ST augmentation reduced the talus external rotation laxity compared to the complete syndesmotic injury.

CONCLUSION

AITFL suture repair and AITFL ST augmentation best restored the rotational kinematics and stability of the fibula and ankle joint in an isolated syndesmotic injury model.

CLINICAL RELEVANCE

AITFL suture repair with or without ST augmentation may be a good operative addition or alternative to SB fixation for isolated syndesmotic disruptions.

Which test is the best? An updated literature review of imaging modalities for acute ankle diastasis injuries

Ankle diastasis injuries, or ankle syndesmotic injuries, are common among athletes who usually experience a traumatic injury to the ankle. Long‐term complications are avoidable when these injuries are diagnosed promptly and accurately treated. Whilst ankle arthroscopy remains the gold standard diagnostic modality for ankle diastasis injuries, imaging modalities are still widely utilised due to the treatment having greater accessibility, being less invasive and the most cost effective. There are various imaging modalities used to diagnose diastasis injuries, varying in levels of specificity and sensitivity. These observation methods include; X‐ray, computed tomography (CT), magnetic resonance imaging (MRI) and ankle arthroscopy. This article uncovers common criteria and parameters to diagnose diastasis injuries through the implementation of different imaging modalities. The conclusions addressed within this article are deduced from a total of 338 articles being screened with only 43 articles being selected for the purposes of this examination. Across most articles, it was concluded that that plain X‐ray should be used in the first instance due to its wide availability, quick processing time, and low cost. CT is the next recommended investigation due to its increased sensitivity and specificity, ability to show the positional relationship of the distal tibiofibular syndesmosis, and reliability in detecting minor diastasis injuries. MRI is recommended when ankle diastasis injuries are suspected, but not diagnosed on previous imaging modalities. It has the highest sensitivity and specificity compared to X‐ray and CT.

Volume measurements on weightbearing computed tomography can detect subtle syndesmotic instability

While weightbearing computed tomography (WBCT) allows three-dimensional (3D) visualization of the distal syndesmosis, image interpretation has largely relied on one-dimensional (1D) distance and, more recently, two-dimensional (2D) area measurements. This study aimed to (1) determine the sensitivity and specificity of 2D area and 3D volume WBCT measurements towards detecting subtle syndesmotic instability, (2) evaluate whether the patterns of changes in the 3D shape of the syndesmosis can be attributed to the type of ligament injury. A total of 24 patients with unilateral subtle syndesmotic instability and 24 individuals with uninjured ankles (controls) with bilateral ankle WBCT were assessed retrospectively. First, 2D areas at 0, 1, 3, 5, and 10 cm, and 3D volumes at 1, 3, 5, and 10 cm above the tibial plafond were measured bilaterally. Secondly, the 3D model of the distal tibiofibular space was created based on WBCT in a subset of 8 out of 24 patients in whom the type of ligament injury was recognized via magnetic resonance imaging. The 3D model of the injured side was superimposed on the uninjured contralateral side to visualize the pattern of changes in different planes. Volume measurement up to 5 cm above the tibial plafond showed the lowest p-value (<0.001 vs. other methods), higher sensitivity (95.8%, 95% confidence interval [CI]: 87.8-100), and specificity (83.3%, 95% CI: 68.4-98.2) for detection of syndesmotic instability. No specific pattern of changes in the 3D shape could be attributed to a type of ligament rupture. We suggest 3D volume measurements, best measured up to 5 cm proximal to the plafond, as a promising means of diagnosing syndesmotic instability, particularly for subtle cases that are hard to detect. Clinical significance: The ability to compare the ankle joints bilaterally in a 3D manner under physiologic weight provided by weightbearing CT has led to a more accurate diagnostic method. Using volumetric measurement up to 5 cm above the tibial plafond showed higher sensitivity and specificity for recognizing an unstable syndesmosis, especially in subtle cases. However, our preliminary investigations showed that the pattern of 3D alterations in the distal tibiofibular joint space based on WBCT images does not indicate the type of syndesmotic ligamentous injury. Our results can also help image viewing programs to improve their measurement tools to facilitate 3D measurement for the syndesmosis as well as other conditions that may benefit from 3D evaluation of the clinical images.

Utility of WBCT to Diagnose Syndesmotic Instability in Patients With Weber B Lateral Malleolar Fractures

BACKGROUND

Diagnosing syndesmotic instability accompanying Weber B ankle fractures can be challenging. This study aimed to evaluate the ability of weight-bearing computed tomography (WBCT) to diagnose syndesmotic instability using one-dimensional, two-dimensional, and three-dimensional measurements among patients with unilateral Weber B lateral malleolar fractures with symmetric medial clear space (MCS) on initial radiographs and yet demonstrated operatively confirmed syndesmotic instability.

METHODS

The treatment group included 23 patients with unilateral surgically confirmed syndesmotic instability accompanying Weber B ankle fractures who underwent preoperative bilateral foot and ankle WBCT. The control group included 18 unilateral Weber B ankle fracture patients without syndesmotic instability who underwent bilateral WBCT. Measurements on WBCT images included the following: (1) syndesmotic area, (2) anterior, middle, and posterior distal tibiofibular distance, (3) fibular rotation, (4) distance from fibular tip to plafond, (5) fibular fracture displacement, and (6) MCS distance. In addition, the following volumetric measurements were calculated: (1) syndesmotic joint volume from the tibial plafond extending to 3 and 5 cm proximally, (2) MCS volume, and (3) lateral clear space volume. Area under the receiver operating characteristic curve analysis and Delong test were used, and optimal cutoff values to distinguish between stable and unstable syndesmosis were determined using Youden J statistic.

RESULTS

Among patients with unilateral syndesmotic instability and Weber B ankle fractures, all WBCT measurements were significantly greater than uninjured side, except MCS distance, syndesmotic area, and anterior and posterior tibiofibular distances (P values <0.001 to 0.004). Moreover, syndesmosis volume spanning from the tibial plafond to 5 cm proximally had the largest area under the curve of 0.96 (sensitivity = 90%; specificity = 95%), followed by syndesmosis volume up to 3 cm proximally (area under the curve = 0.91; sensitivity = 90%; specificity = 90%). Except for MCS volume and distal fibular tip to tibial plafond distance, the control group showed no side-to-side difference in any parameter.

CONCLUSION

Syndesmotic joint volume measurements seem to be best suited to diagnose syndesmotic instability among patients with Weber B ankle fractures, compared with other two-dimensional and three-dimensional WBCT measurements.

LEVEL OF EVIDENCE

Level III, comparative diagnostic study.

Diagnosis and Treatment of Syndesmotic Unstable Injuries: Where We Are Now and Where We Are Headed

Up to 10% of ankle sprains are considered "high ankle" sprains with associated syndesmotic injury. Initial diagnosis of syndesmotic injury is based on physical examination, but further evaluation of the distal tibiofibular joint in the sagittal, coronal, and rotational planes is necessary to determine instability. Imaging modalities including weight-bearing CT and ultrasonography allow a physiologic and dynamic assessment of the syndesmosis. These modalities in turn provide the clinician useful information in two and three dimensions to identify and consequently treat syndesmotic instability, especially when subtle. Because there is notable variability in the shape of the incisura between individuals, contralateral comparison with the uninjured ankle as an optimal internal control is advised. Once syndesmotic instability is identified, surgical treatment is recommended. Several fixation methods have been described, but the foremost aspect is to achieve an anatomic reduction. Identifying any associated injuries and characteristics of the syndesmotic instability will lead to the appropriate treatment that restores the anatomy and stability of the distal tibiofibular joint.

Pediatric versus adult magnetic resonance imaging patterns in acute high ankle sprains

BACKGROUND

There is a paucity of literature describing MRI patterns of high ankle sprains in pediatric patients. Radiologists should understand MRI patterns of these injuries in both adults and children.

OBJECTIVE

To describe normal MRI appearance of pediatric syndesmotic ligaments and compare MRI patterns of high ankle sprains in children versus adults.

MATERIALS AND METHODS

We reviewed consecutive ankle MRIs performed over 3 years and divided them into three cohorts: a normal pediatric (≤16 years) cohort, and pediatric and adult cohorts with acute/subacute ankle syndesmosis injuries. Our retrospective review assessed interobserver agreement (Cohen kappa coefficient) and normal pediatric syndesmotic anatomy. We compared patterns of high ankle sprains (Fisher exact test) including ligament tears, periosteal stripping, avulsions and fractures.

RESULTS

Of the 582 ankle MRIs, we included 25 in the normal pediatric cohort, 20 in the pediatric injury cohort and 23 in the adult injury cohort. The anterior and posterior tibiofibular ligaments all attached to cortex or cartilaginous precursor, while the interosseous ligament/membrane complex attached to the fibrous periosteum in 22/25 (88%) normal pediatric cases. Tibial periosteal stripping at the interosseous ligament/membrane complex attachment occurred in 7/20 (35%) pediatric and 1/23 (4%) adult injury cases (P=0.02). No other statistically significant differences were found. Interobserver agreement ranged from kappa=0.46 to kappa=0.82 (ligament tears), 0.38 to 0.45 (avulsions) and 0.69 to 0.77 (periosteal stripping).

CONCLUSION

The normal interosseous ligament/membrane complex typically attaches to fibrous periosteum rather than bony cortex. Tibial periosteal stripping, usually without tibial fracture, is significantly more common among pediatric high ankle sprains. MRI patterns of high ankle sprains are otherwise not significantly different between children and adults.

APKASS Consensus Statement on Chronic Syndesmosis Injury, Part 2: Indications for Surgical Treatment, Arthroscopic or Open Debridement, and Reconstruction Techniques of Suture Button and Screw Fixation

Background:

The indications for surgical treatment of chronic syndesmosis injury are challenging for many orthopaedic clinicians, as there is no international consensus on the optimal management of these injuries.

Purpose:

An international group of experts representing the field of sports injuries in the foot and ankle area was invited to collaboratively advance toward consensus opinions based on the best available evidence regarding chronic syndesmosis injury. 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, 9 items with 17 clinical questions and statements were related to indications for surgical treatment, arthroscopic versus open debridement, and suture button versus screw fixation reconstruction techniques 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%; and unanimous, 100%.

Results:

Of the 17 questions and statements, 4 achieved unanimous support, 11 reached strong consensus, and 2 reached consensus.

Conclusion:

This APKASS consensus statement, developed by international experts in the field, will assist surgeons and physical therapists with surgical indications and techniques for chronic syndesmosis injury.

Diagnostic accuracy of clinical tests assessing ligamentous injury of the ankle syndesmosis: A systematic review with meta-analysis

OBJECTIVE

To summarise and evaluate research on the diagnostic accuracy of clinical tests for ligamentous injury of the ankle syndesmosis.

METHODS

CINAHL, Embase, and MEDLINE were searched from inception to February 12, 2021. Studies comparing clinical examination to arthroscopy, magnetic resonance imaging, or ultrasound were considered eligible. Meta-analysis was based on random effect modelling and limited to studies fulfilling all QUADAS-2 criteria. Sensitivity (SN), specificity (SP) and likelihood ratios determined diagnostic accuracy, all with 95% confidence intervals (CI).

RESULTS

Six studies were included (512 participants; 13 clinical tests; 29% median prevalence). No individual test was associated with both high sensitivity and high specificity. Tests with the highest sensitivity were: palpation [SN 92% (95%CI 79-98)] and dorsiflexion lunge [SN 75% (95% CI 64-84%); n = 2 studies]. Tests with the highest specificity were: squeeze test [SP 85% (95% CI 81-89%); n = 4 studies] and external rotation [SP 78% (95% CI 73-82%); n = 4 studies].

CONCLUSIONS

Clinical examination should involve initial clustering of tests with high sensitivity (palpation; dorsiflexion lunge), followed by a test with high specificity (squeeze). However, as these tests cannot definitively stratify syndesmotic injuries into stable vs unstable, decisions on optimal management (conservative vs surgery) require additional imaging or arthroscopy.

Utility of Volumetric Measurement via Weight-Bearing Computed Tomography Scan to Diagnose Syndesmotic Instability

BACKGROUND

Weight-bearing computed tomography (WBCT) allows evaluation of the distal syndesmosis under physiologic load. We hypothesized that WBCT volumetric measurement of the distal syndesmosis would be increased on the injured as compared to the contralateral uninjured side and that these 3-dimensional (3D) calculations would be a more sensitive determinant than 2-dimensional (2D) methodology among patients with syndesmotic instability.

METHODS

Twelve patients with unilateral syndesmotic instability requiring operative fixation who underwent preoperative bilateral foot and ankle WBCT were included in the study group. The control group consisted of 24 patients without ankle injury who underwent similar imaging. On WBCT scan, 2D measurements of the syndesmosis joint were first measured 1 cm above the joint line in the axial plane via syndesmotic area and distances between the anterior, middle, and posterior quadrants. Thereafter, comparative 3D volumetric measurements of the syndesmotic joint were also calculated: (1) from the tibial plafond extending until 3 cm proximally, (2) 5 cm proximally, and (3) 10 cm proximally.

RESULTS

In patients with unilateral syndesmotic instability, all 3 weight-bearing volumetric measurements were significantly larger on the injured side as compared to the contralateral, uninjured side (P < .001). In the control group, there was no difference between syndesmotic volumes at any level. Of these 3 anatomic reference points, the 3D measurement spanning from the tibial plafond to a level 5 cm proximally had the highest relative volumetric ratio between the injured and uninjured side, suggesting it is the most sensitive in distinguishing between stable and unstable syndesmotic injury (P < .001). Notably, this 3D volumetric measurement was also more sensitive than 2D measurements (P = .001).

CONCLUSION

3D volumetric measurement of the syndesmosis joint appears to be the most effective way to diagnose syndesmotic instability, compared with more traditional 2D syndesmosis measurement.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

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.

The arthroscopic syndesmotic assessment tool can differentiate between stable and unstable ankle syndesmoses

PURPOSE

Patients with stable isolated injuries of the ankle syndesmosis can be treated conservatively, while unstable injuries require surgical stabilisation. Although evaluating syndesmotic injuries using ankle arthroscopy is becoming more popular, differentiating between stable and unstable syndesmoses remains a topic of on-going debate in the current literature. The purpose of this study was to quantify the degree of displacement of the ankle syndesmosis using arthroscopic measurements. The hypothesis was that ankle arthroscopy by measuring multiplanar fibular motion can determine syndesmotic instability.

METHODS

Arthroscopic assessment of the ankle syndesmosis was performed on 22 fresh above knee cadaveric specimens, first with all syndesmotic and ankle ligaments intact and subsequently with sequential sectioning of the anterior inferior tibiofibular ligament, the interosseous ligament, the posterior inferior tibiofibular ligament, and deltoid ligaments. In all scenarios, four loading conditions were considered under 100N of direct force: (1) unstressed, (2) a lateral hook test, (3) anterior to posterior (AP) translation test, and (4) posterior to anterior (PA) translation test. Anterior and posterior coronal plane tibiofibular translation, as well as AP and PA sagittal plane translation, were arthroscopically measured.

RESULTS

As additional ligaments of the syndesmosis were transected, all arthroscopic multiplanar translation measurements increased (p values ranging from p < 0.001 to p = 0.007). The following equation of multiplanar fibular motion relative to the tibia measured in millimeters: 0.76*AP sagittal translation + 0.82*PA sagittal translation + 1.17*anterior third coronal plane translation-0.20*posterior third coronal plane translation, referred to as the Arthroscopic Syndesmotic Assessment tool, was generated from our data. According to our results, an Arthroscopic Syndesmotic Assessment value equal or greater than 3.1 mm indicated an unstable syndesmosis.

CONCLUSIONS

This tool provides a more reliable opportunity in determining the presence of syndesmotic instability and can help providers decide whether syndesmosis injuries should be treated conservatively or operatively stabilized. The long-term usefulness of the tool will rest on whether an unstable syndesmosis correlates with acute or chronic clinical symptoms.

Dynamic Fixation versus Static Fixation in Treatment Effectiveness and Safety for Distal Tibiofibular Syndesmosis Injuries: A Systematic Review and Meta-Analysis

To compare the effectiveness and safety of dynamic fixation (DF) and static fixation (SF) in distal tibiofibular syndesmosis injuries (DTSI) by a system review and meta-analysis. PubMed, Cochrane, and EMBASE were systematically searched by computer to select clinical randomized controlled trials (RCT) and cohort trials comparing DF and SF in treating patients with DTSI. RCT and cohort trials comparing DF and SF for patients with DTSI were included. Inclusion criteria: (i) prospective or retrospective study of patients with DTSI; (ii) patients were diagnosed as having DTSI by imageology and only received DF treatment or SF treatment; (iii) the study compared DF and SF in DTSI; and (iv) one or more of the following outcomes were reported: ankle joint functional score, surgical complications, malreduction of syndesmosis, and second operations. Exclusion criteria: (i) non-human studies; (ii) DTSI patients accompanied with other complications or other joints injuries; and (iii) full text unavailable. RevMan V5.3 software was used to perform the statistical analysis. Outcomes analyzed by Revman software showed that there were no statistically significant differences between DF and SF in the American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot score (MD, 1.90; 95% CI, -0.23 to 4.03; P = 0.08; I² = 0%), Olerud-Molander (OM) score (MD, 1.92; 95% CI, -7.96 to 11.81; P = 0.70; I² = 55%), incidence of syndesmotic malreduction (RR, 0.19; 95% CI, 0.03 to 1.09; P = 0.06; I² = 0%), and overall postoperative complication rate (RR, 0.30; 95% CI, 0.09 to 0.99; P = 0.05, I² = 75%) and the rate of second procedure was significantly lower with DF (RR, 0.17; 95% CI, 0.07 to 0.43; P = 0.0002, I² = 54%). Compared to SF, DF has an advantage, with a low rate of second procedures to treat DTSI.

Range of Normal and Abnormal Syndesmotic Measurements Using Weightbearing CT

BACKGROUND

Early recognition of syndesmotic instability is critical for optimizing clinical outcome. Injuries causing a more subtle instability, however, can be difficult to diagnose. The purpose of this study was to evaluate both distal tibiofibular articulations using weightbearing computed tomography (CT) in patients with known syndesmotic instability, thereafter comparing findings between the injured and uninjured sides. We also aimed to define the range of normal measurement variation among patients without syndesmotic injury.

METHODS

Patients with unilateral syndesmotic instability requiring operative fixation (n = 12) underwent preoperative bilateral ankle weightbearing CT. A separate cohort of patients without ankle injury who also underwent bilateral ankle weightbearing CT were included as comparative controls (n = 24). For each weightbearing CT, a series of 7 axial plane tibiofibular joint measurements, including 1 angular measurement, were utilized to evaluate parameters of the syndesmotic anatomy at a level 1 cm above the tibial plafond. Values were recorded by 2 independent observers to assess for interobserver reliability.

RESULTS

Among those with unilateral syndesmotic instability, values differed between the injured and uninjured sides in 4 of the 7 measurements performed including the syndesmotic area: direct anterior, middle, and posterior differences, and sagittal translation (P < .001, < .001, < .001, and < .001, respectively). In the control population without ankle injury, no differences were identified between any of the bilateral measurements (P value range, .172-.961).

CONCLUSION

This study highlights the ability of weightbearing CT to effectively differentiate syndesmotic diastasis among patients with surgically confirmed syndesmotic instability from those without syndesmotic instability. It underscores the substantial utility and importance of using the contralateral, uninjured side as a valid internal control whenever the need for confirming potential syndesmotic instability arises. Prospective studies are necessary to fully understand the accuracy of weightbearing CT in diagnosing occult syndesmotic instability among patients for whom the diagnosis remains in question.

LEVEL OF EVIDENCE

Level III, comparative diagnostic study.

MRI for high ankle sprains with an unstable syndesmosis: posterior malleolus bone oedema is common and time to scan matters

PURPOSE

Early clinical examination combined with MRI allows accurate diagnosis of syndesmosis instability after a high ankle sprain. However, patients often present late. The aims of the current study were to describe MRI characteristics associated with syndesmosis instability and to test the hypothesis that MRI patterns would differ according to time from injury.

METHODS

Over a 5-year period, 164 consecutive patients who had arthroscopically proven syndesmosis instability requiring fixation were retrospectively studied. Patients with distal fibula fractures were not included. Injuries were classified as acute in 108 patients (< 6 weeks), intermediate in 32 (6-12 weeks) and chronic in 24 patients (> 12 weeks).

RESULTS

Posterior malleolus bone oedema was noted in 65 (60.2%), and posterior malleolus fracture in 17 (15.7%) of acute patients, respectively, which did not significantly differ over time. According to MRI, reported rates of posterior syndesmosis disruption significantly differed over time, observed in 101 (93.5%), 28 (87.5%) and 13 (54.2%) of acute, intermediate and chronic patients, respectively (p < 0.001). Apparent rates of PITFL injury significantly reduced with time (p < 0.001).

CONCLUSIONS

MRI detected a posterior syndesmosis injury in 93.5% of patients acutely but became less reliable with time. The clinical relevance of this study is that posterior malleolus bone oedema may be the only marker of a complete syndesmosis injury and can help clinically identify those injuries which require arthroscopic assessment for instability. If suspicious of a high ankle sprain, we advocate early MRI assessment to help determine stable versus unstable injuries as MRI becomes less reliable after 12 weeks.

LEVEL OF EVIDENCE

III.

Diagnostic Accuracy of Radiologic Methods for Ankle Syndesmosis Injury: A Systematic Review and Meta-Analysis

: Misdiagnosis and inadequate treatment of syndesmosis could result in significant long-term morbidity including pain, instability, and degenerative changes of the ankle joint. The objective of this systematic review and meta-analysis was to determine whether radiologic tests accurately and reliably diagnose ankle syndesmosis injury. Medline, Embase, and Cochrane were searched. The database search resulted in 258 full text articles that we assessed for eligibility, we used eight studies that met all the inclusion criteria. In subgroup meta-analysis, the sensitivity analysis showed significant differences only in the MRI (Magnetic Resonance Imaging), and specificity was not statistically significant. In diagnostic meta-analysis, the pooled sensitivity and specificity were 0.528 and 0.984 for X-rays, 0.669 and 0.87&nbsp;for CT (Computed Tomography), and 0.929 and 0.865 for MRI, all respectively. For sensitivity, MRI showed significantly sensitivity as higher than the other methods, and we detected no significance for specificity. Syndesmosis injuries differed significantly in the accuracy of radiological methods according to the presence of accompanied ankle fractures. In patients with fractures, simple radiography has good specificity, and CT and MRI have high sensitivity and specificity irrespective of fracture; in particular, MRI has similar accuracy to gold standard arthroscopic findings.

Compatibility of Lauge-Hansen Classification Between Plain Radiographs and Magnetic Resonance Imaging in Ankle Fractures

We evaluated the accuracy of the predictive injury sequences of the Lauge-Hansen (L-H) classification using magnetic resonance imaging (MRI) in patients with ankle fractures and determined the possible causes of mismatch. Sixty-five patients with ankle fractures who had a complete series of anteroposterior, lateral, and oblique radiographs and ankle MRI studies available were included. The fracture pattern was assigned by 2 senior orthopedic surgeons according to the L-H classification system. The syndesmotic ligaments, lateral collateral ligaments, and medial deltoid complex ligaments were evaluated on the preoperative MRI scans. Comparisons were performed between the predicted ankle ligamentous injury based on the radiographic L-H classification and preoperative MRI analysis. Of the 65 feet in 65 patients, 50 feet (76.9%) were classified as having a supination-external rotation (SER) fracture, 6 feet (9.2%) as having a pronation-external rotation fracture, 4 feet (6.2%) as having a supination adduction fracture, and 2 feet (3.1%) as having a pronation abduction fracture. The overall compatibility of the radiologic classification with the MRI classification was 66.1%. In the evaluation of 50 feet with the MRI SER designation, maximum compatibility was found for stage 4 (77.3%). The main cause for the discrepancy in the SER designation was missing the presence of deltoid ligament disruption on the plain radiographs, especially in the stage 2 and 3 SER fracture pattern. In the evaluation of deltoid complex injuries, all injuries were localized to the anterior part of the medial deltoid complex. The validity of the L-H classification system was low. A new classification system is needed to address the medial malleolus fracture or deltoid complex injuries without posterior injury. Also, stress radiographs could be added to standard radiographs for the classification to address deltoid complex injuries.

Preoperative MRI is helpful but not sufficient to detect associated lesions in patients with chronic ankle instability

PURPOSE

The aim of this study was to determine the reliability and validity of preoperative magnetic resonance imaging (MRI) scans for the detection of additional pathologies in patients with chronic ankle instability (CAI) compared to arthroscopic findings.

METHODS

Preoperative MRI images of 30 patients were evaluated regarding articular and periarticular comorbidities and compared to intraoperative findings. The reliability of MRI was determined by calculating specificity, sensitivity, as well as positive and negative predictive values. The accuracy of the classification of cartilage lesions by Outerbridge and Berndt and Harty rating scales was determined by calculating the area under the receiver operating curve (AUC).

RESULTS

In total, 72 additional pathologies were found arthroscopically compared to 73 lesions gathered from MRI images. Sensitivity ranged from 89% for peroneal tendinopathy to 28% for additional ligamentous lesions. Specificity ranged from 100% for anterolateral impingement, loose bodies and peroneal tendinopathy to 38% for additional ligamentous lesions. For cartilage lesions, sensitivity was at 91% and specificity was at 55% for the Outerbridge grading scale. For the Berndt and Harty classification system, sensitivity was at 91% and specificity was at 28%. Correlation of additional pathologies ranged from weak (r s = 0.48; p = 0.02) to moderate results (r s = 0.67; p < 0.001).

CONCLUSION

CAI is associated with a high incidence of additional pathologies. In some cases, MRI delivers insufficient results, which may lead to misinterpretation of present comorbidities. MRI is a helpful tool for preoperative evaluation, but arthroscopy remains gold standard in the diagnosis of associated lesions in patients with CAI.

LEVEL OF EVIDENCE

III.

Five-Year Outcomes After Treatment for Acute Instability of the Tibiofibular Syndesmosis Using a Suture-Button Fixation System

Background:

Suture-button repair is a widely accepted surgical treatment for acute and isolated ankle syndesmosis injuries. To our knowledge, midterm results have not previously been reported.

Purpose:

To evaluate the clinical, qualitative, and quantitative radiological midterm outcomes of suture-button repair after acute isolated ankle syndesmosis injuries.

Study Design:

Retrospective case series; Level of evidence, 4.

Methods:

Clinical outcomes were measured using the Foot and Ankle Disability Index (FADI) and the American Orthopaedic Foot and Ankle Society (AOFAS) score. Three-tesla magnetic resonance imaging (MRI) was performed bilaterally at the ankle. Besides morphological sequences for evaluation of the syndesmosis and degenerative changes of the ankle using the Ankle Osteoarthritis Scoring System (AOSS), the MR protocol included a coronal 2-dimensional multislice multiecho sequence for quantitative cartilage T2-weighted mapping. Spearman correlations and paired t tests were used for statistical analysis.

Results:

This retrospective study included 19 consecutive patients (mean age, 29.7 ± 11.5 years) with acute isolated syndesmosis injuries treated with a suture-button system between January 2006 and June 2014, with a mean follow-up of 5.1 ± 2.6 years. Postoperatively, the median FADI score was 136 (range, 78-136), and the median AOFAS score was 100 (range, 87-100). Seventeen (89.5%) patients reported to have reached their preinjury level of sports activities. MRIs of 16 patients were obtained and all showed intact anterior and posterior syndesmotic ligaments; however, in most patients, the previously injured syndesmotic ligament was thickened compared with the uninjured ankle. Average width of the anterior (P = .81) and posterior (P = .60) syndesmosis was not significantly different between the ipsilateral (3.2 ± 1.2 and 4.4 ± 0.9 mm) and contralateral ankles (3.0 ± 0.6 and 4.2 ± 0.7 mm). The median AOSS score was 1.5 (range, 0-11) for the ipsilateral ankle and 0 (range, 0-6) for the contralateral ankle. T2 values of articular cartilage did not significantly differ between the involved and the uninjured ankle (P = .68). Five patients needed hardware removal due to persistent skin irritation, and 1 patient suffered from reinstability of the ankle resulting in revision surgery 2 years after the index surgery.

Conclusion:

Suture-button fixation is an excellent treatment for acute and isolated syndesmosis injuries, resulting in stable ankles without early or advanced osteoarthritic changes at midterm follow-up.

3D Model Analysis of Ankle Flexion on Anatomic Reduction of a Syndesmotic Injury

BACKGROUND

The effect of ankle positioning during suture-button fixation for syndesmosis repair on range of motion (ROM) and anatomic reduction has yet to be investigated. The purpose of this cadaveric study was to compare the effects of 3 different ankle positions during suture-button repair on volumetric reduction of the syndesmosis, fibular displacement, and ROM of the ankle using 3-dimensional computed tomography (CT) analysis. The null hypothesis was that ankle position during fixation would not affect syndesmotic volume restoration, fibular displacement, or ROM.

METHODS

Twelve matched pair (n = 24) human cadaveric specimens were used for this study. Prior to syndesmotic sectioning, ROM assessment and CT scans were performed. Following sectioning of the syndesmosis, specimens were repaired in plantarflexion, dorsiflexion, or neutral, and simulated postrepair ROM evaluations and CT scans were repeated. Least squares mean differences between repair groups and the preinjury state were compared by analysis of variance and Tukey's method.

RESULTS

There were no significant differences between repair groups for volumetric reduction ( P = .917), fibular displacement (anterior-posterior, P = .805; medial-lateral, P = .949), or dorsiflexion capacity ( P = .249). Among all specimens, compared with the preinjury state, there was a significant mean ± SD volume reduction of 337 ± 400 mm³ and medial displacement of 1.9 ± 1.5 mm.

CONCLUSION

This study failed to reject the null hypothesis and demonstrated that ankle flexion at the time of syndesmotic fixation with a suture-button construct had no significant in vitro effect on volume changes, fibular displacement, or dorsiflexion capacity. However, in comparison to the preinjured state, suture-button repair resulted in significant overcompression with respect to syndesmosis volume and medial displacement of the fibula.

CLINICAL RELEVANCE

Ankle position at the time of syndesmotic fixation did not affect overall ankle ROM when using a suture-button construct; however, overcompression was observed in all positions. The clinical impact of syndesmotic overcompression remains largely unknown.

A 3-D CT Analysis of Screw and Suture-Button Fixation of the Syndesmosis

BACKGROUND

Historically, syndesmosis injuries have been repaired with screw fixation; however, some suggest that suture-button constructs may provide a more accurate anatomic and physiologic reduction. The purpose of this study was to compare changes in the volume of the syndesmotic space following screw or suture-button fixation using a preinjury and postoperative 3-D computed tomography (CT) model. The null hypothesis was that no difference would be observed among repair techniques.

METHODS

Twelve pairs of cadaveric specimens were dissected to identify the syndesmotic ligaments. Specimens were imaged with CT prior to the creation of a complete syndesmosis injury and were subsequently repaired using 1 of 3 randomly assigned techniques: (a) one 3.5-mm cortical screw, (b) 1 suture-button, and (c) 2 suture-buttons. Specimens were imaged postoperatively with CT. 3-D models of all scans and tibiofibular joint space volumes were calculated to assess restoration of the native syndesmosis. Analysis of variance and Tukey's method were used to compare least squares mean differences from the intact syndesmosis among repair techniques.

RESULTS

For each of the 3 fixation methods, the total postoperative syndesmosis volume was significantly decreased relative to the intact state. The total mean decreases in volume compared with the intact state for the 1-suture-button construct, 2-suture-button construct, and syndesmotic screw were -561 mm³ (95% CI, -878 to -244), -964 mm³ (95% CI, -1281 to -647) and -377 mm³ (95% CI, -694 to -60), respectively.

CONCLUSION

All repairs notably reduced the volume of the syndesmosis beyond the intact state. Fixation with 1 suture-button was not significantly different from screw or 2-suture-button fixation; however, fixation with 2 suture-buttons resulted in significantly decreased volume compared with screw fixation.

CLINICAL RELEVANCE

The results of this study suggest that the 1-suture-button repair technique and the screw fixation repair technique were comparable for reduction of syndesmosis injuries, although both may overcompress the syndesmosis.

Arthroscopic Quantification of Syndesmotic Instability in a Cadaveric Model

PURPOSE

To investigate whether arthroscopy or stress radiography can identify instability resulting from single-ligament injury of the ankle syndesmosis and to determine whether either modality is capable of differentiating between various levels of ligament injury.

METHODS

Syndesmotic/deltoid ligament sectioning was performed in 10 cadaver legs. Arthroscopic evaluation and fluoroscopic stress testing were completed after each sectioning. In group 1 (n = 5), sectioning began with anteroinferior tibiofibular ligament (AITFL), then interosseous membrane (IOM), posteroinferior tibiofibular ligament (PITFL), and deltoid. In group 2 (n = 5), this order was reversed. Measurements were made by determining the largest-sized probe that would fit in the anterior and posterior syndesmosis. Radiographic parameters included tibiofibular overlap/clear space and medial clear space.

RESULTS

No radiographic measurement proved useful in distinguishing between intact and transected AITFL. Anterior probe (AP) size reached significance when distinguishing between intact and AITFL-transected specimens (P < .0001). AP detected significant differences comparing single with 2-, 3-, and 4-ligament (AITFL, IOM, PITFL, deltoid) disruptions (P = .05, <.0001, and <.0001, respectively). Significant differences were observed between 2- and 3/4-ligament (P = .02) transections. Posterior probe (PP) size detected significant differences between intact and single-, double-, triple-, and complete ligament transections (P values .0006, <.0001, <.0001, <.001, respectively). PP detected significant differences between single- and double-, triple-, and complete ligament transection models (P = .0075, .0010, and .0010, respectively). PP distinguished between 2- and 3/4-ligament (P = .03) transections.

CONCLUSIONS

Stress radiography did not distinguish between intact and single-ligament disruption, and was unreliable in distinguishing between sequential transection models. Arthroscopy significantly predicted isolated disruption of the AITFL or deltoid ligaments. Also, probing was able to differentiate between most patterns of ligament injury, including sequential transections.

CLINICAL RELEVANCE

These data can aid surgeons during arthroscopy of the ankle when attempting to correlate intraoperative syndesmotic evaluation findings with the extent of ligament injury.

Biomechanical Analysis of the Individual Ligament Contributions to Syndesmotic Stability

BACKGROUND

Biomechanical data and contributions to ankle joint stability have been previously reported for the individual distal tibiofibular ligaments. These results have not yet been validated based on recent anatomic descriptions or using current biomechanical testing devices.

METHODS

Eight matched-pair, lower leg specimens were tested using a dynamic, biaxial testing machine. The proximal tibiofibular joint and the medial and lateral ankle ligaments were left intact. After fixation, specimens were preconditioned and then biomechanically tested following sequential cutting of the tibiofibular ligaments to assess the individual ligamentous contributions to syndesmotic stability. Matched paired specimens were randomly divided into 1 of 2 cutting sequences: (1) anterior-to-posterior: intact, anterior inferior tibiofibular ligament (AITFL), interosseous tibiofibular ligament (ITFL), deep posterior inferior tibiofibular ligament (PITFL), superficial PITFL, and complete interosseous membrane; (2) posterior-to-anterior: intact, superficial PITFL, deep PITFL, ITFL, AITFL, and complete interosseous membrane. While under a 750-N axial compressive load, the foot was rotated to 15 degrees of external rotation and 10 degrees of internal rotation for each sectioned state. Torque (Nm), rotational position (degrees), and 3-dimensional data were recorded continuously throughout testing.

RESULTS

Testing of the intact ankle syndesmosis under simulated physiologic conditions revealed 4.3 degrees of fibular rotation in the axial plane and 3.3 mm of fibular translation in the sagittal plane. Significant increases in fibular sagittal translation and axial rotation were observed after syndesmotic injury, particularly after sectioning of the AITFL and superficial PITFL. Sequential sectioning of the syndesmotic ligaments resulted in significant reductions in resistance to both internal and external rotation. Isolated injuries to the AITFL resulted in the most substantial reduction of resistance to external rotation (average of 24%). However, resistance to internal rotation was not significantly diminished until the majority of the syndesmotic structures had been sectioned.

CONCLUSION

The ligaments of the syndesmosis provide significant contributions to rotary stability of the distal tibiofibular joint within the physiologic range of motion.

CLINICAL RELEVANCE

This study defined normal motion of the syndesmosis and the biomechanical consequences of injury. The degree of instability was increased with each additional injured structure; however, isolated injuries to the AITFL alone may lead to significant external rotary instability.

Isolated syndesmotic injuries in acute ankle sprains: diagnostic significance of clinical examination and MRI

PURPOSE

Acute ankle sprains are frequently accompanied by syndesmotic injuries. These injuries are often overlooked in clinical examinations. The aim of this study was (1) to evaluate the incidence of syndesmotic injuries in acute ankle sprains using MRI, (2) to determine the accuracy of common clinical diagnostic tests, (3) to analyse their inter-rater reliability, and (4) to evaluate the role of clinical symptoms in the diagnosis of syndesmotic injuries.

METHODS

A total of 100 patients with acute ankle sprain injury without associated fractures in plane radiographs were enrolled. The clinical assessment was performed by two independent examiners. Local findings, ankle ligament palpation, squeeze test, external rotation test, Drawer test, Cotton test, and the crossed-leg test (two examiners) were compared with MRI results (read by two blinded radiologists) as a reference standard.

RESULTS

Ninety-six participants (57% male) met the inclusion criteria. MRI detected a ruptured anterior inferior tibiofibular ligament (AITFL) in 14 patients (15%); 9 partial tears and 5 complete tears were evident. Evidence of pain at rest was found to predict syndesmotic injuries most accurately (p = 0.039). The palpation test over the proximal fibula produced the highest inter-rater correlation (κ = 0.65), but the lowest sensitivity for syndesmotic injuries of 8%. All other clinical tests demonstrated moderate to fair inter-rater reliabilities (κ = 0.37-0.52). Low sensitivity values were found with all clinical tests (13.9-55.6%).

CONCLUSION

In this study, clinical examination was insufficient to detect syndesmotic injuries in acute ankle sprains. MRI scanning revealed a syndesmotic lesion in 15% of patients. MRI scanning should be recommended in patients with ongoing pain at rest following ankle sprains.

LEVEL OF EVIDENCE

I.