Talar avascular necrosis (AVN) is a devastating condition that frequently follows type III and IV talar neck fractures. As 60% of the talus is covered by hyaline cartilage, its vascular supply is limited and prone to trauma, which may eventually lead to AVN development. Early detection of AVN (Hawkins sign, MRI) is crucial, as it may prevent the development of the irreversible stages III and IV of AVN. Alertness is advised regarding non-obvious conditions that may cause this complication (sub chondroplasty, systemic lupus erythematosus, diabetes mellitus). Although, in stages I-II, AVN may be treated with non-surgical procedures (ESWT therapy, non-weight bearing) or joint-sparing techniques (core drilling, bone marrow aspirate injections), stages III-IV require more advanced procedures, such as joint-sacrificing procedures (hindfoot arthrodesis/ankle arthrodesis), or replacement surgery, including total talar replacement (TTR) or combined total ankle replacement (TAR). The advancement of 3D-printing technology and increased access to implant manufacturing are contributing to a rise in the production rates of third-generation total talar prostheses. As a result, there is a growing frequency of alloplasty procedures and combined total ankle replacement (TAR) surgeries. By performing TTR as opposed to deses, the operator avoids (i) delayed union, (ii) a shortening of the limb, (iii) a lack of mobility, and (iv) the stiffening of adjacent joints, which are the main disadvantages of joint-sacrificing procedures. Simultaneously, TTR and combined TAR offer (i) a brief period of weight-bearing restriction, (ii) quick pain relief, and (iii) preservation of the length of the limb. Here, we summarize the most up-to-date knowledge regarding AVN diagnosis and treatment, with a special focus on the role of TTR.

Disuse osteopenia (DO) is a disorder due to reduced weight-bearing often following immobilization injuries. It is most commonly observed in the ankles and knees and is believed to be due primarily to increased bone reabsorption associated with disuse. Both traditional radiography and magnetic resonance (MR) imaging are useful in identifying abnormalities associated with DO. Specifically, linear subchondral osteopenia has been given the term "Hawkins sign" when seen in the talus, but this finding may also be seen elsewhere. When present, it not only is an indication of DO but also indicates the presence of sufficient vascular flow, and the unlikely development of avascular necrosis. We report a case of Hawkins sign of the knee demonstrated on radiography and MR and demonstrate the clinical importance of recognizing this sign, outside its usual setting, in assessing the prognosis of a healing fracture.

The talus, a highly specialized bone with a unique anatomic design, is crucial for normal ambulation. Although uncommon, talar fractures can be potentially devastating to the patient. Although all talar fractures require appropriate diagnosis and treatment, some require surgical skill for appropriate correction. This article reviews the literature on talar fractures and their treatments.

Imaging signs form an important part of the language of radiology, but are not represented in established lexicons. We sought to incorporate imaging signs into RSNA's RadLex® ontology of radiology terms. Names of imaging signs and their definitions were culled from books, journal articles, dictionaries, and biomedical web sites. Imaging signs were added into RadLex as subclasses of the term "imaging sign," which was defined in RadLex as a subclass of "imaging observation." A total of 743 unique imaging signs were added to RadLex with their 392 synonyms to yield a total of 1,135 new terms. All included definitions and related RadLex terms, including imaging modality, anatomy, and disorder, when appropriate. The information will allow RadLex users to identify imaging signs by modality (e.g., ultrasound signs) and to find all signs related to specific pathophysiology. The addition of imaging signs to RadLex augments its use to index the radiology literature, create and interpret clinical radiology reports, and retrieve relevant cases and images.

Avascular necrosis of the talus is a well-documented complication following fractures, although less is known about this complication following reconstructive foot and ankle surgery. Knowledge of the blood supply of the talus is necessary for surgical dissection of the talus, especially when the approach traverses the sinus tarsi. In this article, we describe a rare case of avascular necrosis of the talus after talonavicular arthrodesis, using a medial surgical approach.

Recently, it has been shown that avascular necrosis of the talus can occur in only a portion of the talar body. There is little information regarding the geographic location of the avascular segment and the clinical significance of an incomplete avascular process.

Seven patients with partial avascular necrosis after Hawkins type II or III fracture dislocations were evaluated with magnetic resonance scans. The precise anatomic location of the avascular segment was determined and assigned to a specific quadrant of the talar body. The operative exposure, incidence of collapse, and time to operative intervention was recorded.

The avascular segment of the talar body was located predominantly in the anterior lateral and superior portion in six of the seven patients. Collapse occurred in three of the patients in the area of avascular process. There were no observable trends with regard to operative exposure, Hawkins classification, incidence of collapse, or time to operative intervention to the location of the avascular segment.

Partial avascular necrosis can occur after fracture dislocation of the talus. The predominant location of the avascular segment was the anterior lateral and superior portion of the talar body. This observation corresponds to regional damage to the blood supply of the talus and may help clarify the pathogenesis of partial avascular process.

Fractures of the talus represent serious injuries of the foot skeleton. The most significant complications include osteonecrosis and posttraumatic malalignment with subsequent arthritis. The aim of our study was to compare treatment and outcome of fractures of the talus between children and adolescents.

From 1990 to 2005, 24 patients (18 male, 6 female) presented with 25 fractures of the talus. The medical records were reviewed retrospectively. Follow-up was performed by radiographical grading, and the functional outcome was measured using the Foot-Function-Index.

Nine patients were 12 years of age or younger, and 15 patients presenting 16 talar fractures were older than 12 years. Although most fractures of the talus in children younger than 12 years were classified as Marti-Weber type I and II fractures, more than two thirds of the fractures in patients older than 12 years were Marti-Weber type III and IV fractures. Two thirds of the patients younger than 12 years were treated nonoperatively, whereas nonoperative treatment was possible in only three talar fractures in adolescents. No necrosis at follow-up (mean period, 3.2 years; range, 7 months to 8.4 years after end of treatment) was detected in children (<12a), whereas five patients older than 12 years developed persisting necrosis.

Even though there is no apparent difference in the cause of the trauma leading to fractures of the talus, adolescents present with more severe fractures of the talus compared with children younger than 12 years. In addition, we did not observe persistent osteonecrosis in patients younger than 12 years old, and the outcome is favorable in most cases irrespective of the mode of treatment.