Anterior Subtalar Joint Research Articles

Statistical shape modeling of mean shape and principal variability of the human talar bone in the Chinese population.

The talar bone plays a crucial role in ankle biomechanics and stability. Understanding the shape variability of the talar bone within specific populations is essential for various clinical applications. In this study, we aimed to investigate the mean shape and principal variability of the human talar bone in the Chinese population using statistical shape modeling (SSM). CT scans of 214 tali were included to create SSM models. Principal component analysis was used to describe shape variation among the male, female, and overall groups. The largest amount of variation among three groups ranges from 17.2%-18.8% of each variation. The first seven principal components (modes) captured 62.4%-67.5% of the cumulative variance. No dominant shape of the talus was found. Male tali generally have a larger size than the female tali, with the exception of the articular surface of the anterior subtalar joint. SSM is an effective method of finding mean shape and principal variability. Considerable variabilities were noticed among these three groups and all principal modes of variation. No dominant talar model was found to represent the majority of tali, regardless the gender. Such information is crucial to improve the current understanding of talar pathologies and their treatment strategies.

Regional variation of ankle and hindfoot cartilage T2 mapping values at 3 T: A feasibility study

ObjectiveTo develop a method for T2 mapping of the entire tibiotalar/hindfoot articular surfaces and to examine regional T2 variation in asymptomatic volunteers, establishing necessary methods for future T2 mapping work in patients with ankle/hindfoot injury. Materials and methodsTwenty-six asymptomatic volunteers (11 female/13 male, aged 23–64 years in final analysis) underwent sagittal T2 mapping. Tibiotalar and hindfoot cartilage surfaces were segmented by two raters. The tibiotalar joint cartilage was divided into subregions to assess T2 variation across the joint. The articular surface and subregion mean T2 values were compared using Tukey post hoc pairwise comparisons to test for statistical significance. Results and conclusionMean ankle/hindfoot cartilage T2 ranged from 37 ± 3 to 47 ± 7 ms. Tibial plafond mean T2 was significantly different from the middle and posterior subtalar cartilage T2 (both articular surface comparisons resulted in P < .05). Talar dome mean T2 was significantly different from the posterior calcaneal-side and talar-side subtalar cartilage, and middle calcaneal-side subtalar cartilage (P < .05 for all comparisons). Tibial plafond middle versus lateral, anterior versus middle, middle versus posterior, and anterior versus posterior subregion T2 values were significantly different (P < .05 for all comparisons). Talar dome medial versus middle, middle versus lateral, anterior versus middle, and middle versus posterior subregion T2 values were significantly different (P < .05 for all comparisons). Ankle/hindfoot joint cartilage T2 mapping and segmentation was found to be feasible for all cartilage surfaces except the anterior subtalar joint facet. Mean T2 differed significantly between ankle/hindfoot joint and subregion cartilage in asymptomatic volunteers.

Arthroscopic Management of Osteochondral Lesion of Plantar Medial Talar Head

Osteochondral lesions of the talar head can be classified into 4 types: type 1 is located at the anterior part of the talar head, type 2 is at the plantar side of the talar head, type 3 is at the plantar lateral side of the talar head, and type 4 is at the plantar medial aspect of the talar head. The purpose of this Technical Note is to describe the details of arthroscopic management of an osteochondral lesion of the plantar medial talar head. It includes arthroscopic synovectomy of the medial recess of the anterior subtalar joint, debridement, and microfracture of the osteochondral lesion.

Sonographic and Anatomic Description of the Subtalar Joint

Our study provides a detailed anatomic and sonographic description of the subtalar joint, a single joint that, anatomically, is divided into the anterior subtalar joint (ASTJ) and the posterior subtalar joint (PSTJ). Cadaver specimens of the ankle and foot were examined in detail by ultrasound (US), and the subtalar joints of all the specimens were injected with colored latex of a contrasting color under US guidance. Compatible with other studies, examination of the sections revealed lack of communication between the ASTJ and the PSTJ and communication between the PSTJ and the posterior recess of the tibiotalar joint. A recommended list of standardized ultrasound scans was developed using a Delphi consensus process, which allows sonographers to evaluate both the ASTJ and PSTJ from the medial, lateral and posterior aspects. The recommended ultrasound scans were found to be applicable based on a test of agreement between images acquired in cadaver specimens and images acquired in four centers using healthy patients.

Fluid distribution in ankle and midfoot joints: MR findings in asymptomatic volunteers.

The purpose of this study is to assess the amount of fluid in the joints of the ankle and midfoot on MR imaging in asymptomatic volunteers. Twenty-one healthy asymptomatic volunteers (42 ankles) were evaluated with MRI imaging. There were 13 men and 8 women. The mean age was 24.7years (19-42years). MR imaging was performed on a 3T MR system using proton density weighted images with fat saturation (TR 2969, TE 30ms, NA 2, slice thickness 2.5mm). Images were obtained in three orthogonal planes. The images were interpreted by two radiologistsin two sessions. The maximum size of the joint effusion was measured in one plane. Descriptive statistics and variation between interpretation sessions were calculated. Fluid in the anterior tibiotalar joint had a mean size of 2.0mm (0.0-5.5mm), in the posterior tibiotalar joint 3.1mm (0.0-6.3mm), in the talonavicular joint 0.7mm (0.0-2.9mm), and in the anterolateral recess 2.0mm (0.0-4.3mm). Fluid in the posterior aspect of the posterior subtalar joint had a mean size of 2.6mm (0.0-9.4mm), in the anterior aspect of the posterior subtalar joint 1.9mm (0.0-6.6mm), at the middle subtalar joint 0.1mm (0.0-1.7mm), and at the anterior subtalar joint 1.6mm (0.0-6.0mm). Fluid in the tibiofibular joint had a mean height of 8.1mm (0.0-16.4mm). In asymptomatic volunteers, moderate to large amounts of fluid were common in all joint recessesof ankle and midfoot, and most pronounced in the anterior and posterior tibiotalar joint, anterolateral recess, and posterior subtalar joint. This should not be mistaken for evidence of a pathological condition.

Arthroscopic Release of Lateral Half of the Talocalcaneonavicular Joint

Arthrofibrosis of the talocalcaneonavicular joint can follow trauma or surgery of the joint. Arthroscopic release of the lateral half of the talocalcaneonavicular joint is indicated if the painful restriction of hindfoot inversion together with tenderness of the lateral side of the joint that is not controlled with conservative treatment. This procedure is contraindicated in other causes of painful stiffness including post-traumatic arthritis, osteonecrosis, and malunion. This technique includes arthroscopic release of the lateral side of the anterior subtalar joint and the talonavicular joint. This is a technically demanding technique and should be reserved for the experienced foot and ankle arthroscopists.

Arthroscopic Capsular Release of the Talocalcaneonavicular Joint

Arthrofibrosis of the talocalcaneonavicular joint can follow talar neck fracture especially if anterior approaches have been used for fracture fixation. Capsular release of the talocalcaneonavicular joint is indicated if the painful hindfoot stiffness cannot be controlled with conservative treatment. Open capsular release of the talocalcaneonavicular joint demands extensive soft tissue dissection and hinders early postoperative mobilization exercise of the joint. The purpose of this technical note is to describe a minimally invasive approach of arthroscopic capsular release of the talocalcaneonavicular joint that is composed of arthroscopic release of the talonavicular joint and the anterior subtalar joint. This allows immediate postoperative mobilization of the joint.

Ultrasound of talocalcaneal coalition: retrospective study of 11 patients

To present the ultrasound appearance of talocalcaneal coalitions (TCC). We present a retrospective review of 11 patients (8 women and 3 men, age range 17-58years, mean age 35.3years) in which ultrasound, the first imaging study carried out, detected a TCC that was not known or suspected clinically. Patients were subsequently examined by standard radiographs, computed tomography (CT) or magnetic resonance imaging (MRI). In 9 patients with fibrous coalition ultrasound showed a reduced joint space of the medial aspect of the anterior talocalcaneal joint associated with an irregular, pointed appearance of its outline. In 2 patients with osseous coalitions ultrasound revealed a smooth continuity of the hyperechoic bone surface between the medial talus and the substentaculum tali. The diagnosis was confirmed in 4 patients with CT and in 3 with MRI. In the remaining 4 patients standard radiographs were consistent with TCC. Owing to its tomographic capabilities ultrasound can detect TCC. We suggest that study of the anterior subtalar joint should be a part of every ankle ultrasound examination as it can show a clinically unsuspected TCC. Confirmation of the coalition by CT or MRI is required in the preoperative assessment to better assess the type and extent of the congenital anomaly as well as the adjacent joints.

Fracture anatomy of the calcaneus with axial loading. Cadaver experiments

Summary The fracture anatomy of the calcaneus was investigated in 30 lower leg specimens. They were submitted to axial loads with metal weights on a vertical sledge. The fractured specimens were studied radiographically and by anatomic dissection. Intra-articular fractures of the calcaneus occurred in 25 specimens. Fracture lines could be divided into a relatively constant primary fracture in 22 specimens, which ran from the posterior subtalar joint surface to the tuber calcanei, and highly variable secondary fractures in 24 specimens. In order to facilitate classification of the fracture specimens, the calcaneus was divided into four segments: the sustentacular segment, the posterior subtalar joint segment, the segment of the anterior process, and the tuberosity segment. In addition, the following joints were identified: the posterior subtalar joint, the anterior subtalar joint, and the calcaneo-cuboid joint. Each specimen was classified by the number of segments (x) and the number of joints (y) affected, and accordingly labelled as x-segment, y-joint fracture. The addition of both numbers was used to grade the severity of the fracture. The minimum fracture grade was three; in five specimens the maximum of seven was reached. The mean fracture grade was 5.1, composed of 3.4 segments and 1.7 joints. This classification could easily be applied to all 25 experimental fracture specimens, as well as to 33 clinical cases.

Ankle joint biomechanics

According to Fick, the three-dimensional patterns of foot motion are best characterized as jawlike movement. Anatomically and biomechanically, this process represents conjoined, synchronous motion within the three mobile segments of the ankle-foot unit: the upper ankle joint, the posterior lower ankle joint and the anterior lower ankle joint. Foot kinematics can be described more completely if the anterior subtalar joint is defined not only as the talocalcaneal navicular joint, but as including the calcaneocuboid joint, thus representing the transverse joint of the tarsus, i.e., the Chopart joint. The axes of these three joints can be defined precisely. In some parts they represent a screwlike motion, clockwise or counter-clockwise, around the central ligamentous structures (fibulotibial ligament, talocalcaneal interosseous ligament, bifurcate ligament). The individual anatomy and structure of these ligaments provide variations in the degree and direction of foot motion. A precise knowledge of foot kinematics is important in surgical ligament and joint reconstruction as well as in selective foot arthrodeses. Das dreidimensionale Bewegungsspiel des Fußes ist am enfachsten durch die sog. Maulschellenbewegung des Fußes nach Fick [5] beschrieben. Gedanklich, biomechanisch und funktionell anatomisch ist dieser Vorgang untrennbar in einer konzertierten, synchronen Bewegung in den 3 gekoppelten Bewegungssegmenten des Sprunggelenkes, dem oberen, hinteren und vorderen unteren Sprunggelenk. Die Kinematik wird verständlicher, wenn das vordere untere Sprunggelenk nicht als Articulatio talo-calcaneo-navicularis definiert ist, sondern das Kalkaneo-Kuboid-Gelenk miteinschließt, was der Articulatio transversa tarsi bzw. dem Chopart-Gelenk entspricht. Die Bewegungsachsen dieser 3 Gelenkabschnitte sind definierbar, sie entsprechen teilweise Achsen einer Schraube mit gleich- oder gegensinniger Drehbewegung, welke regelmäßig durch die zentralen Bandstrukturen verlaufen (Ligg. fib./tib., Lig. talo-calcaneare-interosseum, Lig. bifurcatum). Je nach Anatomie und Struktur dieser Bänder sind die individuellen Bewegungsachsenabweichungen und Freiheitsgrade der Bewegung gegeben. Hinsichtlich rekonstruktiver Bandchirurgie, Gelenkwiederherstellung und/oder arthrodetischer Maßnahmen im Fußbereich erscheint die Kenntnis und Beachtung dieser Bewegungsachsen bedeutsam.

足関節外側靭帯断裂における足関節造影の検討

We investigated the diagnostic value of arthrography in ankle sprains. In the 57 patients operated upon, arthrographic findings were compared with surgical findings. Extracapsular contrast medium leakage in an arthrogram performed within 3 days from the injury, showed a reliabily of 100% in predicting ligamentous rupture. Peroneal sheath and subtalar joint communication were of value in the diagnosis of calcaneofibular ligament rupture. Sinus tarsi leakage and anterior subtalar Joint communication, which were not previously reported, were thought to correlate to subtalar sprains.

The subtalar joint: embryology and morphology.

Several different aspects of the subtalar joint are studied. Embryology indicates that it is a recently acquired structure. The anterior subtalar joint does not have a uniform morphology, and it has been subdivided into three anatomical descriptions (ovoid, bean, and two part). To correct the confusion found in other papers, we intend to clearly describe the anatomy of the ligaments. The form and function of the retinacula, cervical ligament, and ligament of the canal are studied. The microscopic anatomy of ligaments is studied, dealing specifically with their innervation and the structure of their fibers.

Computed tomography of the hindfoot.

This investigation used computed tomography (CT) to study the normal anatomy of the hindfoot and to demonstrate abnormalities in patients with rheumatoid arthritis, pes planovalgus , old trauma, and soft-tissue masses. The hindfeet of 10 normal volunteers and 17 patients were scanned in the coronal and axial transverse planes. The articular surfaces of the tibia, talus, and calcaneus were assessed, as were the relationships of each bone to the others. Normal subjects had markedly symmetrical hindfeet . The "heel valgus angle" (relating the calcaneus to the tibia) was 5.2 +/- 1.6 degrees (mean +/- standard error of the mean). The "sustentacular angle" (indicating the angle of elevation of the sustentaculum tali at the midsubtalar joint) was 18.3 +/- 1.3 degrees. The "medial offset" of the talar head with respect to the calcaneus (measured at the anterior subtalar joint) averaged 5.2 +/- 1.8 mm. Patients with rheumatoid arthritis had erosions involving both sides of the subtalar joint, leading to talocalcaneal alignment abnormalities. In patients with pes planovalgus the heel valgus angle was greater and the elevation of sustentaculum tali lower in the foot that was most severely affected. Bony talocalcaneal fusions, fractures, and the erosions of pigmented villonodular synovitis were detected on CT. The pattern of postoperative bone healing after attempted subtalar fusion could be demonstrated. We conclude that CT is a useful tool for pre- and postoperative evaluation of the hindfoot.

Radiographic Anatomy of the Hindfoot

Lead markers were placed on various osseous structures of the talus and calcaneus in fresh amputation specimens to analyze the radiographic anatomy of the hindfoot. Analysis of the talocalcaneal articulations revealed that only the central one-third of the posterior subtalar joint can be visualized on the lateral projection, whereas the axial view profiles only the anterior one-third of the joint. The anterior two-thirds of the middle subtalar joint is profiled on the lateral projection, whereas no portion of the middle articulation can be visualized on the axial view. The anterior subtalar joint can not be identified on either lateral or axial radiographs. In addition, nine extra-articular osseous landmarks on the talus and calcaneus were investigated. The identification of these structures is helpful in the diagnosis of pathologic disorders affecting the adult hindfoot.

The radiology of the subtalar joint with special reference to talo-calcaneal coalition

Congenital talo-calcaneal coalition is one of the conditions responsible for spastic flat foot. The common site is across the middle talo-calcaneal joint, and although routine radiographic views of the foot do not show the coalition, important secondary signs may be present. The findings in 17 cases are reviewed, the following secondary signs being recognised: 1. A talar beak. 2. Narrowing of the posterior talo-calcaneal joint space. 3. Rounding of the lateral process of the talus. 4. Failure of visualisation of the middle subtalar joint in the lateral view, and 5. Asymmetry of the anterior subtalar joints in the lateral oblique vies. The differential diagnosis of these signs is discussed and the normal anatomy of the subtalar joints is illustrated. Some diagnostic pitfalls are described.