Talocalcaneal Ligament Research Articles

Sonographic visibility of the sinus tarsi with a 12 MHz transducer.

To assess the value of ultrasonography in studies of the ligaments within the sinus tarsi (ST) in healthy subjects. We examined 20 healthy volunteers using a 12-MHz transducer with THI and compound imaging. With the foot in inversion, the following structures were examined with coronal and transverse scans: (1) the root of the inferior extensor retinaculum (RIER); (2) the interosseous talocalcaneal ligament (ITCL); (3) the cervical ligament (CL); (4) the bifurcate ligament (BL); (5) the synovial recesses, which were examined for possible distention (distended synovial recesses, DSR). The sonographic features, orientation, and thickness of each ligament were assessed. The easiest structure to identify (visualized in 20/20 subjects) was the RIER, which formed a semiarch. The two deeper layers were hypoechoic, the superficial layer hyperechoic. The ITCL was situated posteriorly and deep with an oblique course. It appeared hypoechoic with a mean thickness of 4.06mm±0.7. It was visualized in 18/20 (90%) subjects. The CL (isoechoic/hyperechoic) was located more anteriorly at an intermediate depth. The orientation was almost vertical. It was visualized in 17/20 (85%) subjects, with a mean thickness of 2.28mm±0.34. The BL appeared hypoechoic. It was visualized in 19/20 (95%) subjects with transverse (anterior end of the ST) and longitudinal scans. The calcaneonavicular and calcaneocuboid components displayed mean (SD) thicknesses of 2.09mm±0.37 and 2.7mm±0.32, respectively. The ITCL and RIER were visualized in the same scan as a semiarch. DSR was observed in 4/20 (20%) subjects. The present study shows that, in patients with suspected ST pathology, the anatomic structures that make up this recess can be adequately examined with ultrasonography performed with ordinary 12-MHz transducers.

Anatomic Alignment and Integrity of the Sustentaculum Tali in Intra-Articular Calcaneal Fractures: Is the Sustentaculum Tali Truly Constant?

In an intra-articular calcaneal fracture, the sustentaculum tali is generally thought to remain tightly bound to the talus by the interosseous talocalcaneal ligaments, spring ligament, and deltoid ligament, providing a "constant" fragment that remains anatomically aligned. The extensile lateral approach is commonly used for reduction based on this assumption, but because it provides only limited access to the medial aspect of the calcaneus, indirect fracture reduction is required to restore an anatomic relationship of these fragments to the sustentacular fragment. The purpose of this study was to determine the prevalence and displacement of sustentacular fractures in patients with an intra-articular calcaneal fracture, and thus determine whether the sustentacular fragment can be accurately considered as constant and can be consistently relied on to maintain anatomic alignment. All patients with an intra-articular calcaneal fracture who presented to two level-I trauma centers from 2006 to 2012 were included in the study if computed tomography scanning was performed. The presence or absence of a sustentacular fracture was documented, along with the displacement and the comminution of any such fracture and the subluxation or dislocation of the sustentaculum tali. Sustentacular fractures were present in ninety-four (44.3%) of the 212 patients who met the inclusion criteria. Seventy-two (76.6%) of the sustentacular fractures were nondisplaced, eleven (11.7%) were displaced, and ten (10.6%) were comminuted. The articulation between the sustentaculum tali and the talus was anatomically aligned in 166 (78.3%) of the calcaneal fractures, subluxated in forty-three (20.3%), and dislocated in two (0.9%). This study provides a detailed description of the frequency of sustentacular fractures, the displacement of such fractures, and articular subluxation or dislocation associated with intra-articular calcaneal fractures. Fixation by means of a lateral approach may be compromised when the sustentaculum tali is fractured or subluxated. A medial approach or combined medial and lateral approaches may be considered in such circumstances. Special attention should be paid to the integrity and alignment of the sustentacular fragment prior to surgical fixation. Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

The effects of a semi‐rigid ankle brace on a simulated isolated subtalar joint instability

Subtalar joint instability is hypothesized to occur after injuries to the calcaneofibular ligament (CFL) in isolation or in combination with the cervical and the talocalcaneal interosseous ligaments. A common treatment for hindfoot instability is the application of an ankle brace. However, the ability of an ankle brace to promote subtalar joint stability is not well established. We assessed the kinematics of the subtalar joint, ankle, and hindfoot in the presence of isolated subtalar instability, investigated the effect of bracing in a CFL deficient foot and with a total rupture of the intrinsic ligaments, and evaluated how maximum inversion range of motion is affected by the position of the ankle in the sagittal plane. Kinematics from nine cadaveric feet were collected with the foot placed in neutral, dorsiflexion, and plantar flexion. Motion was applied with and without a brace on an intact foot and after sequentially sectioning the CFL and the intrinsic ligaments. Isolated CFL sectioning increased ankle joint inversion, while sectioning the CFL and intrinsic ligaments affected subtalar joint stability. The brace limited inversion at the subtalar and ankle joints. Additionally, examining the foot in dorsiflexion reduced ankle and subtalar joint motion.

Ligament Structures in the Tarsal Sinus and Canal

The concrete anatomy and functional characteristics of the subtalar ligaments have been a matter of debate that some believe has hampered the progress of clinical ligament reconstruction. In 32 fresh-frozen cadaver feet, the course of the inferior extensor retinaculum (IER) and other subtalar ligaments was carefully measured and photographed both from the portal of the tarsal sinus and from a posterior view. The IER inserted inside the tarsal sinus and canal by means of 3 roots: a lateral, an intermediate, and a medial one. These roots, along with the tarsal canal, divided the subtalar space into 3 parts. In front of the IER and inside the tarsal sinus, the thick cervical ligament (CL) lay at a 45-degree angle to the calcaneus. Behind the IER and inside the posterior capsule, in most cases (25 of 32 specimens), the posterior capsular ligament (PCaL) lay directly in front of the posterior talocalcaneal facet. Inside the tarsal canal, the fan-shaped medial root of the IER spread from outside upper lateral to lower medial, and the interosseous talocalcaneal ligament (ITCL) ran from upper medial to lower lateral; fibers of these 2 ligaments blended tightly together to form a V-shaped ligament complex. Just anterior to this complex in some cases (20 of 32 specimens), a short narrow upright ligament, the tarsal canal ligament (TCL), was located behind the middle talocalcaneal joint. The results of this study show that the CL is the primary ligament in the tarsal sinus and that the ITCL is a thin single band rather than a strong bilaminar ligament located inside the tarsal canal. Instead, the medial root of the IER is the primary ligamentous structure in the tarsal canal. The anatomical description provided here may provide a more accurate theoretical foundation for clinical subtalar stability restoration.

Safety and Efficiency of a 2-Portal Lateral Approach to Arthroscopic Subtalar Arthrodesis: A Cadaveric Study

To investigate the safety and efficiency of a 2-portal lateral (anterior and middle) approach to arthroscopic subtalar arthrodesis. A cadaveric study was performed on 30 feet of 15 fresh cadaveric bodies (15 right and 15 left; 21 female specimens and 9 male specimens). The mean age at death was 78 ± 6.7 years. The procedure was performed with the specimen in the supine position through 2 lateral (anterior and middle) sinus tarsi portals by use of a 4.0-mm arthroscope. A 3.5-mm synovial shaver was used for debridement, and a 4.5-mm shielded bur was used to resect posterior subtalar facets. The feet were then dissected. The primary outcomes were the percentage of resected joint surface and the distances between portals and both sural and superficial peroneal nerves. The secondary outcomes were injury of sinus tarsi ligaments and lateral arterial network, calcaneofibular ligament, peroneal tendons, flexor hallucis longus tendon, and posterior tibial neurovascular bundle. The mean percentages of resected talar and calcaneal posterior subtalar facets were 94% ± 7.2% and 91% ± 6.8%, respectively. The minimum distance of either subtalar portal to the nerves was 4 mm. No nerve injury was observed. In 28 of 30 cases, the lateral sinus tarsi arterial network was found intact. In all cases the inferior retinaculum extensor was transfixed by the portals. In all cases both cervical and interosseous talocalcaneal ligaments were found intact. In 3 cases a shaving lesion was observed on the peroneus brevis tendon. According to this cadaveric study, more than 90% freshening of the posterior subtalar articular facets can be achieved through a 2-portal lateral (anterior and middle) approach. This technique is reproducible and safe with regard to the surrounding nerves. The 2 lateral portals may offer a safe and effective alternative approach for arthroscopic arthrodesis of the posterior subtalar joint.

An Unusual Variety of Simultaneous Fracture Dislocation Pattern: Medial Swivel Dislocation of Talonavicular Joint with Displaced Fractures of the Fourth and Fifth Metatarsals

In published studies, a very rare, special type of Chopart dislocation termed a swivel dislocation has been reported. This injury is characterized by dislocation of the talonavicular joint, but the calcaneocuboid joint remains intact. The foot creates a typical rotational movement without inversion or eversion. The axis of rotation is the interosseous talocalcaneal ligament, which remains intact. We report the case of an 18-year-old male who had experienced a medial swivel dislocation of the talonavicular joint associated with displaced fractures of the fourth and fifth metatarsals. The occurrence, features, and method of treatment of this rare injury are presented.

Ligaments of the tarsal sinus: improved detection, characterisation and significance in the paediatric ankle with 3-D proton density MR imaging

No study in the paediatric literature--and only a single study in all of the literature--has evaluated the visualization frequency of the sinus tarsi ligaments on MRI. That 20-year-old study demonstrated only limited visualisation. The objective of this study is to re-evaluate the visualisation frequency of the sinus tarsi ligaments and to characterise their morphology on isotropic three-dimensional proton density imaging (3-D-PD). The authors hypothesise that by using 3-D-PD, these ligaments will be able to be demonstrated in nearly all paediatric patients. Patients were scanned on either 1.5- or 3-Tesla scanners using 3-D-PD. Of 174 patients reviewed, 50 were identified who met inclusion and exclusion criteria. The interosseous talocalcaneal ligament (ITC), the cervical ligament (CL) and the roots of the inferior extensor retinaculum (IER) were successfully visualised and characterised in three planes in 50 out of 50 children. The mean ligament thickness was 4.22 mm for the ITC, 2.74 mm for the CL and 1.04 mm for the IER roots. With modern parameters, the tarsal sinus ligaments can be visualised in 100% of patients, a percentage substantially higher than previously reported.

Paper 100: Middle Term and Long Term Results of Interosseous Talocalcaneal Ligament Reconstruction with Arthroscopy

Paper 100: Middle Term and Long Term Results of Interosseous Talocalcaneal Ligament Reconstruction with Arthroscopy

Hindfoot Joint Pressure in Supination Sprains

Background: Hindfoot trauma including ankle and subtalar sprains may be followed by osteochondral lesions and persisting pain originating from posttraumatic arthritis. Hypothesis: “Acute severe” supination sprains and “mild supination sprains with increasing ligamentous incompetence” of the hindfoot lead to medial ankle and subtalar stress concentrations that may contribute to osteochondral lesions (OCLs) and subsequent arthritis. Study Design: Controlled laboratory study. Methods: “Acute severe” sprains and “mild sprains with increasing ligamentous incompetence” (consecutive anterior talofibular ligament [ATFL], calcaneofibular ligament [CFL], and lateral talocalcaneal ligament [LTCL] transections) were simulated in human lower leg specimens (7 different specimens for each condition). The effect on the migration of the center of force (COF) and on the tibiotalar and subtalar pressures at 700-N (acute severe) and 150-N (mild sprain with increasing ligamentous incompetence) axial static and dynamic loads, respectively, was recorded using pressure sensors. Results: In the “acute severe” sprain, the peak pressure increase reached the level of significance in the ankle (P = .042) and in the subtalar medial facet (P = .046). The ankle COF migrated significantly toward the medial (P = .001) and posterior (P = .023) directions. In the “mild sprain with increasing ligamentous incompetence” condition, the ankle (P = .018) and subtalar (medial facet, P = .022) peak pressure increased significantly with intact ligaments and with all ligaments cut. The ankle COF migrated significantly toward the medial direction when the ATFL and CFL or when all 3 ligaments were severed. The anteroposterior ankle COF migration was anterior when all ligaments were intact or when only the ATFL was severed but posterior when the CFL or when the CFL and the LTCL were severed in addition. Conclusion: Next to chronic inhomogeneous load distribution in the unstable hindfoot and shear stress during sprains, intra-articular pressure elevation (impact) in the ankle and subtalar joint during hindfoot supination sprains with intact ligaments or incompetent ligaments likely contributes to OCLs of the medial talar dome and the medial subtalar facet. Clinical Relevance: Intra-articular hindfoot pressure elevation (impact) in “acute severe” and in “mild hindfoot supination sprains with increasing ligamentous incompetence” is substantial for the development of OCLs at the medial midtalar dome and the medial facet of the subtalar joint.

Association of Hindfoot Ligament Tears and Osteochondral Lesions

This study aimed to identify the prevalence of ligament and joint surface anatomy variants, ligament tears, and osteochondral lesions (OCLs) in the hindfoot. These data were used to identify associations between anatomic variants or ligament tears and OCLs. Seventy-two cadaver hindfoot specimens were examined. Hindfoot ligament presence, number of ligament fascicles, variable ligament attachment sites, ligament tears, presence of joint facets, variable joint surface shape, and the location and grade of OCLs were identified in each specimen. The data were analyzed for significant associations between variables. Fourteen of the 30 studied ligaments were always present and 14 had variable number of fascicles. The lateral talocalcaneal and dorsolateral calcaneocuboid ligaments had varying positional attachments. Osteochondral lesions were present in 86% of specimens with the majority in the talocrural joint. Of the 235 lesions identified, 31 were grade 3 or above. Ligament tears occurred in 2% of all ligaments observed. Tears in the lateral talocalcaneal, medial calcaneocuboid, and dorsolateral calcaneocuboid ligaments were associated with an increased number of hindfoot OCLs. We demonstrated the prevalence of morphologic ligament and joint surface variants, ligament tears, and osteochondral lesions in the hindfoot. Tears in ligaments stabilizing the calcaneocuboid joint were implicated in an increase in hindfoot joint damage. We believe anatomic studies can be used to clarify the association between traumatic injuries and their sequelae.

Influence of kinematic analysis methods on detecting ankle and subtalar joint instability

Patients with subtalar joint instability may be misdiagnosed with ankle instability, which may lead to chronic instability at the subtalar joint. Therefore, it is important to understand the difference in kinematics after ligament sectioning and differentiate the changes in kinematics between ankle and subtalar instability. Three methods may be used to determine the joint kinematics; the Euler angles, the Joint Coordinate System (JCS) and the helical axis (HA). The purpose of this study was to investigate the influence of using either method to detect subtalar and ankle joints instability. 3D kinematics at the ankle and subtalar joint were analyzed on 8 cadaveric specimens while the foot was intact and after sequentially sectioning the anterior talofibular ligament (ATFL), the calcaneofibular ligament (CFL), the cervical ligament and the interosseous talocalcaneal ligament (ITCL). Comparison in kinematics calculated from sensor and anatomical landmarks was conducted as well as the influence of Euler angles and JCS rotation sequence (between ISB recommendation and previous research) on the subtalar joint. All data showed a significant increase in inversion when the ITCL was sectioned. There were differences in the data calculated using sensors coordinate systems vs. anatomic coordinate systems. Anatomic coordinate systems were recommended for these calculations. The Euler angle and JCS gave similar results. Differences in Euler angles and JCS sequence lead to the same conclusion in detecting instability at the ankle and subtalar joint. As expected, the HA detected instability in plantarflexion at the ankle joint and in inversion at the subtalar joint.

Comparison of cross-sectional anatomy and computed tomography of the tarsus in horses

To compare computed tomography (CT) images of equine tarsi with cross-sectional anatomic slices and evaluate the potential of CT for imaging pathological tarsal changes in horses. 6 anatomically normal equine cadaveric hind limbs and 4 tarsi with pathological changes. Precontrast CT was performed on 3 equine tarsi; sagittal and dorsal reconstructions were made. In all limbs, postcontrast CT was performed after intra-articular contrast medium injection of the tarsocrural, centrodistal, and tarsometatarsal joints. Images were matched with corresponding anatomic slices. Four tarsi with pathological changes underwent CT examination. The tibia, talus, calcaneus, and central, fused first and second, third, and fourth tarsal bones were clearly visualized as well as the long digital extensor, superficial digital flexor, lateral digital flexor (with tarsal flexor retinaculum), gastrocnemius, peroneus tertius, and tibialis cranialis tendons and the long plantar ligament. The lateral digital extensor, medial digital flexor, split peroneus tertius, and tibialis cranialis tendons and collateral ligaments could be located but not always clearly identified. Some small tarsal ligaments were identifiable, including plantar, medial, interosseus, and lateral talocalcaneal ligaments; interosseus talocentral, centrodistal, and tarsometatarsal ligaments; proximal and distal plantar ligaments; and talometatarsal ligament. Parts of the articular cartilage could be assessed on postcontrast images. Lesions were detected in the 4 tarsi with pathological changes. CT of the tarsus is recommended when radiography and ultrasonography are inconclusive and during preoperative planning for treatment of complex fractures. Images from this study can serve as a CT reference, and CT of pathological changes was useful.

Hindfoot Endoscopic Findings of Posterior Ankle Impingement Syndrome in Ballet Dancers (SS-56)

Introduction Posterior ankle pain is a common but serious problem in ballet dancers. Certain kinds of pathological conditions have been reported, such as os trigonum (OT) syndrome, fracture of the Stieda process, flexor hallucis longus (FHL) tendinosis and/or tenosynovitis, soft tissue impingement, and so on. They are considered as a pathological unit of posterior ankle impingement syndrome (PAIS). The purpose of this study is to elucidate the pathologies of PAIS and to clarify how to approach and treat these conditions. Methods Between September 2007 and August 2010, 35 feet of 32 patients, including only one foot of a male patient, underwent hindfoot endoscopic surgery due to PAIS. Average age was 19.6 years (range, 12-40) at the time of surgery. The pathological conditions were retrospectively analyzed mainly with operative findings, also referring with X-ray, MRI, and histological findings. Surgical technique presented by van Dijk was applied to all feet. Results Synchondrosis injury (SCI) was detected in 14 feet, synovitis associated with one or more movable os trigonum (mOT) in 12, a fracture (or microfracture) in os trigonum or posterior process of the talus in four, DJD beneath the OT in two. Injury to the FHL tendon matrix was observed in 23 feet, distal insertion of FHL muscle fibers in 12, and anomalous muscle (FDAL) in two. Intermalleolar ligament (IML), which is also called a tibial slip, a part of transverse tibiofibular ligament, or a pseudomeniscoid were found in 21 feet (60%), ranging from 1 to 5 mm in width. Among them, five were adherent to the FHL tendon sheath, and three had behavior linked with the FHL motion, which seemed to undergo posterior ankle impingement. Osteochondral lesion of the medial talar trochlea were observed in two feet, nodular fibrosis in posterior talocalcaneal ligament and marked synovitis in ankle and posterior subtalar joint in one, respectively. A great majority of feet were affected with two or more pathologic conditions, except four feet. 22 feet (62.9%) had combined bony impingement (SCI, mOT, fracture) with FHL tendon injury. Conclusion Bony impingement was the major pathological process, related in more than 90 percent of the patients; special attention, however, should be paid to some other conditions that concomitantly existed. The hindfoot arthroscopic approach has great diagnostic potentials to posterior aspect of ankle and posterior subtalar joint. And also enables to treat bony impingement, IML lesions, and tenolysis of the FHL and/or FDAL tendon. But when repair of the severely injured FHL tendonor extirpation of ganglions on the tendon sheath is necessary, the other approach should be considered.

Arthroscopic surgery for treatment of sinus tarsi syndrome

Objective To investigate the result of arthroscopic surgery in the treatment of sinus tarsi syndrome. Methods The study involved 15 patients (6 males and 9 females) with sinus tarsi syndrome admitted to First Hospital of Nanjing from July 2006 to May 2008. The age of the patients ranged from 23 to 63 years ( average 46.3 years). All the patients had one side involvement, including 10 patients with left side involvement and five with right side involvement. All the operations were performed under the tourniquet control and the patients were placed at the lateral decubitus position. The lateral, anterolateral and posterolateral portals were applied intraoperatively and the medial portal was applied when necessary. Visual analogue scale (VAS) and American orthopedic foot and ankle scale (AOFAS) ankle-hindfoot scale were used for follow-up evaluation. Results More than two lesions were found under arthroscope in all patients. The lesions included scar tissue hypertrophy and inflammation in the sinus tarsal canal, soft tissue impingement in the subtalar joint, synovitis, partial tears of subtalar capsule, interosseous talocalcaneal ligament or cervical ligament, cartilage injury and subtalar degeneration. All patients were followed up for 19-35 months (mean 26. 1 months). At the final follow-up, the VAS score was improved from preoperative 7.6 points ( range 6-9 points) to postoperative 2.5 points (range 1-4 points) (P＜0.01 ), and the AOFAS score improved from preoperative 41. 9 points (range 20-67 points) to postoperative 83. 1 points ( range 70-100 points) ( P ＜ 0. 01 ). The excellence rate of the AOFAS score reached 73% at the final follow-up. Conclusion For patients with sinus tarsi syndrome after a failed conservative treatment, arthroscopic surgery should be performed as soon as possible and the clinical result is satisfactory. Key words: Subtalar joint; Ankle injuries; Arthroscopy

Portal safety and efficacy of anterior subtalar arthroscopy: a cadaveric study

Anterior subtalar arthroscopy was performed in 14 feet of 7 cadaveric bodies using the primary visualization and working portals. The cartilage of the anterior/middle calcaneal facet that can be reached was marked. The feet were dissected and the distances between the portals and surrounding cutaneous nerves were measured. Any damage to the ligaments of the sinus tarsi was noted. The percentage area of the articular cartilage that was marked was measured. In all specimens, the primary visualization portal tract passed through the lateral root of the inferior extensor retinaculum. The primary working portal tract passed through the lateral root in nine specimens (64%). Cervical ligament was intact in all specimens. In three specimens (21%), the primary visualization portal tract passed through the posterior edge of the intermediate root of the inferior extensor retinaculum. The interosseous talocalcaneal ligament was intact in all specimens. The primary visualization portal tract passed through the medial root of the inferior extensor retinaculum in eight specimens (57%). The primary working portal tract passed through the medial root of the inferior extensor retinaculum in one specimen. The average working area on the calcaneal facet was 95% +/- 4% of the total articular surface. There was no case of nerve injury in all specimens. In conclusion, anterior subtalar arthroscopy is a minimally invasive approach to deal with pathologies of this joint without the need of extensive resection of the ligamentous structures of the sinus tarsi.

Mechanical Stability of the Subtalar Joint After Lateral Ligament Sectioning and Ankle Brace Application

Background The roles of each ligament supporting the subtalar joint have not been clarified despite several biomechanical studies. The effects of ankle braces on subtalar instability have not been shown. Hypothesis The ankle brace has a partial effect on restricting excessive motion of the subtalar joint. Study Design Controlled laboratory study. Methods Ten normal fresh-frozen cadaveric specimens were used. The angular motions of the talus were measured via a magnetic tracking system. The specimens were tested while inversion and eversion forces, as well as internal and external rotation torques, were applied. The calcaneofibular ligament, cervical ligament, and interosseous talocalcaneal ligament were sectioned sequentially, and the roles of each ligament, as well as the stabilizing effects of the ankle brace, were examined. Results Complete sectioning of the ligaments increased the angle between the talus and calcaneus in the frontal plane to 51.7° ± 11.8° compared with 35.7° ± 6.0° in the intact state when inversion force was applied. There was a statistically significant difference in the angles between complete sectioning of the ligaments and after application of the brace (34.1° ± 7.3°) when inversion force was applied. On the other hand, significant differences in subtalar rotation were not found between complete sectioning of the ligaments and application of the brace when internal and external rotational torques were applied. Conclusion The ankle brace limited inversion of the subtalar joint, but it did not restrict motion after application of internal or external rotational torques. Clinical Relevance In cases of severe ankle sprains involving the calcaneofibular ligament, cervical ligament, and interosseous talocalcaneal ligament injuries, application of an ankle brace might be less effective in limiting internal-external rotational instabilities than in cases of inversion instabilities in the subtalar joint. An improvement in the design of the brace is needed to restore better rotational stability in the subtalar joint.

Ligaments of the Posterior and Lateral Talar Processes: MRI and MR Arthrography of the Ankle and Posterior Subtalar Joint with Anatomic and Histologic Correlation

MRI and combined ankle and posterior subtalar MR arthrography in cadavers were used to evaluate the ligaments of the posterior and lateral talar processes. Subsequent anatomic and histologic correlation was performed. Ten cadaveric ankles were used. Routine radiography and MRI were initially performed. Ankle and posterior subtalar MR arthrography, followed by anatomic and histologic analysis, was then performed to allow better assessment of the ligaments of the lateral and posterior talar process. In all subjects, MR arthrography provided superior delineation of the articular and periarticular structures, as well as the ligaments. The lateral talocalcaneal and medial talocalcaneal ligaments were best seen in the axial and coronal planes, respectively. The axial plane was best for visualizing the fibulotalocalcaneal ligament, and the sagittal plane was best for evaluating the posterior talocalcaneal ligament. The anterior and posterior talofibular ligaments and the posterior tibiotalar ligament (superficial and deep portions) were best seen in the axial plane. Histologic analysis was correlated to anatomic sectioning and showed the attachment sites of these ligaments. Combined ankle and posterior subtalar MR arthrography enhances visualization of the ligaments attaching to the posterior and lateral talar processes, including the posterior, lateral, and medial talocalcaneal and fibulotalocalcaneal ligaments.

The ligaments and articular surfaces of the talocalcaneal joint: a cadaveric study

IntroductionThe articulation between the talus and the calcaneus, the subtalar joint, is important in chronic ankle instability. The relationship between the ligaments and the articular surfaces of this joint has not been thoroughly discussed in the literature. This study aims to describe and quantify the relationship between the morphology and attachments of the interosseous talocalcaneal ligament (ITCL) and the total surface area and configuration of the joint facets on the calcaneus.Methods20 subtalar joints from embalmed cadavers will be dissected and distracted. Measurements of the ITCL and the joint facets on the calcaneus will be reported.ResultsPreliminary results suggest a positive correlation between thickness of ITCL and total surface area of the talar facets on the calcaneus.DiscussionSubtalar joint instability may contribute to recurrent ankle sprains. Knowledge of the ligaments and articular surfaces of the joint is critical for effective diagnosis and treatment. Reconstruction of the ITCL could be crucial in the treatment of chronic ankle instability. Precise information about the morphology, attachments and relationship of the ITCL to the joint facets is necessary to maximize the positive results of reconstructive surgery. This work was supported by the Anatomy & Cell Biology Department at the University of Western Ontario and the Ontario Graduate Scholarship program.Grant Funding SourceOGS

Subtalar dislocation: rare and often forgotten

A 17-year-old boy presented to the emergency department (ED) with pain and ankle deformity following an inversion injury during a basketball game. Radiographs of the right ankle (Fig. 1) showed loss of talonavicular alignment (white arrow) and widening of the talocalcaneal joint (black arrows). Furthermore, the midfoot was medially displaced in relation to the ankle (curved arrow). The findings are consistent with medial subtalar dislocation. Following failed manipulation and reduction (M&R) in the ED, successful closed M&R was achieved under general anaesthesia. Fig. 1 Radiographs of the right ankle showed loss of talonavicular alignment (white arrow) and widening of the talocalcaneal joint (black arrows). The midfoot was medially displaced in relation to the ankle (curved arrow) Medial subtalar dislocation is a rare dislocation and is not commonly seen as a sports injury as it requires transfer of a large amount of kinetic energy [1]. The weaker talocalcaneal and talonavicular ligaments often bear the brunt of the energy and are more commonly disrupted, compared to the relatively stronger calcaneonavicular ligament. Due to the high energy nature, up to 40% of dislocations are associated with open injury or have significant internal soft tissue injury related to ligament disruption. Clinically, it is important to recognize the midfoot deformity, and the foot is typically supinated and held in plantar flexion. This uncommon midfoot deformity is often not appreciated and standard ankle radiographs are performed. Nevertheless, prompt M&R prior to imaging should be attempted in all ankle injuries with significant deformity, as there is a high risk of neurovascular compromise [2]. Careful assessment and documentation of the overlying skin condition and distal neurovascular status are essential both in the acute and post-M&R period as skin necrosis as well as neurovascular injury can occur as a result of the initial injury or the M&R. Ankle radiographs, if performed, appear deceptively normal as the ankle joint remains intact. Careful scrutiny of the talonavicular and talocalcaneal joints is crucial for correct diagnosis. Long-term sequelae include talar avascular necrosis [3] and osteochondral fracture [4], as well as chronic instability and pain. Urgent reduction is important, and closed reduction under general anaesthesia is usually successful, often facilitated by keeping the knee in flexion to relax the gastrocnemius muscle. However, the capsule of the talonavicular joint and the extensor digitorum brevis tendon often block reduction and open reduction will then be necessary.

Anatomy of the subtalar joint and imaging of talo-calcaneal coalition

Talo-calcaneal coalitions may be intra-articular or extra-articular in position and may be classified as fibrous, cartilaginous or osseous in morphology. Fibrous coalitions, particularly extra-articular talo-calcaneal coalitions, may have cross-sectional imaging findings that resemble normal anatomic variants, particularly the medial talo-calcaneal ligament and to a lesser extent the presence of an accessory articular facet between the posterior margin of the sustentaculum and postero-medial process of the talus. Typically, in the adult fibrous coalition, there will be some osseous deformity at the entheses, allowing differentiation from a medial talo-calcaneal ligament. The anatomy of the subtalar joint and its ligamentous supports, normal anatomic variations and their corresponding imaging appearance are reviewed in the first part of this article. In the second part, the various forms of talo-calcaneal coalition and their imaging appearance are reviewed.