OBJECTIVE: the os trigonum is a supernumerary bone that may lead to posterior ankle impingement syndrome. The present study aims to assess the prevalence of this bone.
METHODS: A meta-analysis regarding the presence of the os trigonum was performed. For this, the MEDLINE and SciElo databases were searched using \"os trigonum\" as the keyword. Only original articles, theses, books, dissertations, and monographs were included. Papers with a sample size of < 50 individuals were excluded. The data extracted from the articles were: the total sample size, the prevalence of the trigonum, the method of analysis, the region of the sample, and data regarding sex and side (left or right). Statistical analysis was performed using MedCalc Statistical Software version 14.8.1 (MedCalc Software bvba, Ostend, Belgium). The heterogeneity between the studies was assessed using the I² estimation and the Cochran Q test. For all analyses, a random effect was used and a value of p < 0.05 was considered significant.
RESULTS: 249 papers were found, while 18 were included in the meta-analysis. A total of 17,626 ankles were included. The pooled prevalence of the os trigonum was 10.3% (95% CI 7-14.1%) in the present study. There was no significant difference regarding sex or side, while studies conducted in imaging exams showed a higher prevalence in comparison to cadaveric studies.
CONCLUSIONS: Our results suggest that the os trigonum is relatively common. Knowledge of the prevalence of the os trigonum may help surgeons and clinicians diagnose posterior ankle impingement syndrome.

UNASSIGNED: Accessory ossicles are well-corticated bony structures found close to bones or a joint. They may be unilateral or bilateral. The os tibiale externum is also known as accessory navicular bone, os naviculare secundarium, accessory (tarsal) scaphoid, or prehallux. It is found within the tibialis posterior tendon near its insertion on the navicular bone. The os peroneum is a small sesamoid bone located within the peroneus longus tendon, adjacent to the cuboid. We present a case series of five patients with accessory ossicles of the foot to demonstrate pitfalls in the diagnosis of foot and ankle pain.
UNASSIGNED: The case series includes four patients with os tibiale externum and one patient with os peroneum. Only one patient had symptoms related to os tibiale externum. The accessory ossicle in the rest of the cases was discovered incidentally after trauma to the ankle or foot. The symptomatic os tibiale externum was managed conservatively with analgesics and shoe inserts for medial arch support.
UNASSIGNED: Accessory ossicles are considered developmental anomalies and they originate from ossification centers that have failed to fuse with the main bone. Clinical suspicion and awareness about the existence of the commonly occurring accessory ossicles of the foot and ankle are necessary. They can be a confounding factor in the diagnosis of foot and ankle pain. Failure to notice their presence might result in a misdiagnosis and unnecessary immobilization or surgery for the patients.

BACKGROUND: Sesamoids and accessory bones are generally small-sized and oval-shaped structures whose function and pathology are not fully elucidated. Despite their small size, sesamoid bones can directly or indirectly cause diagnostic problems. Sesamoid bones are less common in the elbow region and may need to be differentiated from a lot of diagnoses such as fractures, osteochondritis dissecans, calcific tendinitis, and synovial chondromatosis.
METHODS: A 55-year-old female patient presented with right elbow pain. An oval mass was seen near the medial epicondyle on the radiograph. A dynamic ultrasound examination was performed to reveal the relationship between the bone mass and the surrounding tissues, especially the ulnar nerve. Due to the well-circumscribed mass, a diagnosis of os subepicodlare mediale, a rare sesamoid bone, was made in light of current literature.
CONCLUSIONS: When a bone mass is seen in patients presenting with elbow pain, it will be useful to know and consider the sesamoid bones. In addition, ultrasonography should be performed in addition to radiography for a localized sesamoid bone in the medial region and adjacent to the ulnar nerve. Thus, the relationship of the sesamoid bone with existing and potential complaints can be revealed and correct diagnosis-treatment approaches can be applied.

There are many osseous variants that occur around the elbow joint such as supracondylar process, supratrochlear foramen, accessory ossicles, and others. Scientific databases were searched for variants around the elbow joint. Elbow radiographs from our center demonstrating some of these findings were included in the study. The aim of the present review was to provide comprehensive information on the terminology, prevalence, history, etiology, and clinical importance of these variants. These anatomical variants are important for radiologists while interpreting radiographs, computed tomography, and magnetic resonance imaging for trauma and orthopedic surgeons during osteosynthesis at the distal humerus, proximal ulna, and radius.

BACKGROUND: Accessory ossicles, sesamoid bones, and biphalangism of toes are the most common developmental variations of the foot. These bones may be associated with painful syndromes; however, their clinical importance is not well understood because the reported prevalence varies widely. Therefore, we aimed to investigate these variants in Turkish subjects.
METHODS: A total of 1651 foot radiographs were retrospectively assessed. Radiographs of feet were examined regarding the prevalence, sex, and bilaterality of accessory ossicles, sesamoid bones, and biphalangism in Turkish subjects.
RESULTS: Accessory ossicles (26.1%) and sesamoid bones (8%) were detected. The most common accessory ossicles were os trigonum (9.8%), accessory navicular bone (7.9%), and os peroneum (5.8%). Also, we detected os supratalare (0.48%), os calcanei secundarium (0.42%) os subfibulare (0.42%), os supranaviculare (0.36%), os vesalianum (0.30%), os subtibiale (0.24%), os intermetatarseum (0.12%), and os subcalcis (0.12%). We observed bipartite hallux sesamoid in 1.8% and interphalangeal sesamoid bone of the hallux in 0.7% of radiographs. Incidences of metatarsophalangeal sesamoid bones were found as 0.6%, 0.06%, 0.6%, and 5.8% in the second, third, fourth, and fifth digit, respectively. We observed biphalangeal toe in 0.5%, 1.7%, 3.5%, and 37.6% in the second, third, fourth, and fifth toe, respectively.
CONCLUSIONS: This study is the first detailed report on the incidence of the most common variants of the foot and ankle in a wide-ranging patients\' series in Turkish subjects. Our study\'s findings will contribute to reducing misdiagnosis.
CONCLUSIONS: The results of this study may provide anatomical data that could help clinicians in the diagnosis and management of disorders that present with pain and discomfort in the feet. Knowledge of these variants is important to prevent misinterpreting them as fractures.

Objective  Accessory ossicles of the wrist are generally asymptomatic and detected incidentally as radiological findings. These bones are rarely symptomatic but can produce pain in cases of impingement or direct trauma. More frequently, these bones are misinterpreted as avulsion fractures in trauma patients, which may lead to unnecessary immobilization and overtreatment. The aim of this study is to determine the incidence of accessory ossicles of the wrist and also determine if the incidence is related to age, gender, or ongoing wrist pain. Materials and Methods  A total of 1146 wrist radiographs were included in the study. All radiographs were analyzed for the presence of 20 different accessory ossicles of the wrist. Patients were also divided into two groups, as with and without accessory ossicle. Two groups were compared in terms of age, gender, and side. Results  About 113 accessory ossicles were detected in 111 (9.7%) radiographs. The most common accessory ossicles were os triangulare and os ulnostyloideum, and the least common accessory ossicles were os gruberi and os praetrapezium. Patients who had accessory ossicle had a significantly higher age than those who did not have accessory ossicle. There was no significant difference between the patients with and without accessory ossicle in terms of gender and side. Conclusions  The results of this study showed that the most common accessory ossicles in the wrist were os triangulare and os ulnostyloideum, and the incidence of accessory bones increased with age. Clinical Relevance  Since accessory ossicles of the wrist can be confused with fractures in trauma patients and are frequently ignored in patients presenting with pain, it is very important to know the incidence and distribution of these ossicles. Therefore, this study is important, in that it provides potentially guiding anatomical data for clinicians in terms of diagnosis and management.

Accessory bones in the region of the elbow are rare variants with high clinical significance as they may be confused with avulsion fractures. We investigated their prevalence and performed a statistical analysis to support their congenital origin. Their localization was mapped to show their exact site of occurrence. We evaluated anteroposterior and lateral X-ray images of 2413 elbows in a Central European population from which a group of accessory bony structures was selected. Their character was evaluated, and accessory bones were identified. We used logistic regression to evaluate the potential relationship between the occurrence of accessory bones, the age of patients, and the occurrence of calcar olecrani. The prevalence of accessory bones of the elbow in the sample was 0.77%. Our results did not show a statistically significant relationship with the occurrence of calcar olecrani or with the age of patients. The most common type was os subepicondylare mediale (type V) in 0.46%, which was located distal to the medial epicondyle of the humerus, followed by os subepicondylare laterale (type III; 0.21%), situated laterally to the lateral epicondyle of the humerus. In comparison with previous reports, os sesamoideum mediale (type IV) was located more distally. Our data suggest that congenital accessory bones are a rare entity. Knowledge of their exact localization should be considered during diagnosis of avulsion fractures and other unclear diagnoses including accessory bony structures in the elbow region.

This study describes five bilateral anatomical variations in the feet of a 97-year-old male cadaver. Following routine dissection, all variants were measured and documented. Three accessory tendons and two accessory ossicles were identified. Bilateral accessory tendons were present from the tibialis anterior (type II), peroneus tertius (type III), and peroneus brevis muscles. Accessory tendon length was 36-104 mm and width was 1-3 mm each inserting more distally then the main tendon. Accessory ossicles were identified as an accessory navicular and os peroneum, respectively. Individually, each variation has varying prevalence rates in the literature, but to date, no known studies have been published describing the combined presence of all five bilateral variations. The acknowledgement of multi-variant cases such as this one may be helpful in the clinical setting, particularly for patients with pathology or for those undergoing foot and ankle surgery.

Accessory anatomical structures in the ankle and foot usually represent incidental imaging findings; however, they may also eventually represent a source of pathology, such as painful syndromes, degenerative changes, be the subject of overuse and trauma, or appear as masses and cause compression syndromes or impingement. This review aims to describe and illustrate the imaging findings related to the presence of accessory ossicles and muscles in the midfoot and forefoot through different techniques, with special attention on those variants that associate factors of clinical relevance or that would trigger challenges in the differential diagnosis.

Accessory anatomical structures in the ankle and foot usually represent incidental imaging findings; however, they may also eventually represent a source of pathology, such as painful syndromes, degenerative changes, be the subject of overuse and trauma or appear as masses and cause compression syndromes or impingement.This review aims to describe and illustrate the imaging findings related to the presence of accessory ossicles and muscles in the ankle and hindfoot through different techniques, with special attention to those variants that associate factors of clinical relevance or that trigger challenges in the differential diagnosis.