Implications of Classification of Os Trigonum: A Study Based on Computed Tomography Three-Dimensional Imaging

Os trigonum: a discussion of its role in posterior ankle impingement syndrome and a meta-analysis of its prevalence

PURPOSE

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.

CONCLUSION

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.

The Stieda process of the talus: the anatomical knowledge and clinical significance of an overlooked protrusion

Background

The Stieda process (SP) is an extended lateral tubercle of the posterior process of the talus. Although there are different classifications for SP in the literature, it is essential to know the differential diagnosis of SP from fractures and accessory ossicles. This review aims to classify the SP and to guide the formation, prevalence, etiopathology, symptoms, differential diagnosis, and treatment.

Main body of the abstract

The authors conducted a literature review that lasted up to September 2022 and used the databases PubMed, Web of Science, and Google Scholar to explore the SP of the talus in all of its aspects. Out of 3802 publications, only 34 could be included, and most of them were studies on posterior ankle impingement syndrome (PAIS). The occurrence, prevalence, etiopathology, clinical significance, symptoms, differential diagnosis, and treatment methods of SP were investigated based on the literature. SP is formed by the fusion of a secondary ossification center at the posterolateral side of the talus with an incidence of 12–36.5%. It is frequently observed in males. It causes reduced plantar flexion, impairment in the inversion of the foot, pain, and swelling in the posterior ankle joint, PAIS, and SP fractures after trauma.

Short conclusion

SP can be diagnosed by lateral ankle radiography or MRI in patients complaining of PAIS. The initial treatment of the SP should include reducing inflammation, swelling, pain, and limiting activities. If neither modality affects the patient, surgical treatment will be performed, and SP will be resected until the impingement disappears.

Posterior Ankle Impingement Syndrome Clinical Features Are Not Associated With Imaging Findings in Elite Ballet Dancers and Athletes

OBJECTIVE

To assess the association between clinical features and magnetic resonance imaging (MRI) findings in posterior ankle impingement syndrome (PAIS) and to compare the prevalence of imaging findings between participants with and without a clinical diagnosis of PAIS.

DESIGN

Case-control study.

SETTING

Elite ballet and sport.

PARTICIPANTS

Eighty-two male (54%) and female participants comprising ballet dancers (n = 43), cricket fast bowlers (n = 24), and football (soccer) players (n = 15).

INDEPENDENT VARIABLES

Clinical: posterior ankle pain on body chart, passive plantarflexion pain provocation test. Patient-reported outcome measures: Oslo Sports Trauma Research Center Overuse Injury Questionnaire, Foot and Ankle Ability Measure Sports subscale.

MAIN OUTCOME MEASURES

Imaging findings including posterior ankle bone marrow edema, os trigonum (± bone marrow edema, and increased signal at synchondrosis), Stieda process (± bone marrow edema), talocrural and subtalar joint effusion-synovitis size, flexor hallucis longus tendinopathy, and tenosynovitis identified as present or absent on 3.0-Tesla MRI.

RESULTS

Imaging findings were not associated with posterior ankle pain or a positive ankle plantarflexion pain provocation test. Imaging findings were not associated with patient-reported outcome measures. Imaging findings did not differ between PAIS-positive and PAIS-negative groups. Os trigonum and Stieda process were prevalent despite clinical status.

CONCLUSIONS

The lack of association between imaging findings and clinical features questions the role of imaging in PAIS. Clinicians should rely primarily on clinical assessment in the diagnosis and management of patients with PAIS.

The Prevalence of Accessory Ossicles, Sesamoid Bones, and Biphalangism of the Foot and Ankle: A Radiographic Study

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.

Conclusion:

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.

Clinical Relevance:

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.

Magnetic resonance imaging findings associated with posterior ankle impingement syndrome are prevalent in elite ballet dancers and athletes

OBJECTIVE

To report the prevalence of MRI features commonly associated with posterior ankle impingement syndrome in elite ballet dancers and athletes and to compare findings between groups.

MATERIALS AND METHODS

Thirty-eight professional ballet dancers (47.4% women) were age- and sex-matched to 38 elite soccer or cricket fast bowler athletes. All participants were training, playing, and performing at full workload and underwent 3.0-T standardised magnetic resonance imaging of one ankle. De-identified images were assessed by one senior musculoskeletal radiologist for findings associated with posterior ankle impingement syndrome (os trigonum, Stieda process, posterior talocrural and subtalar joint effusion-synovitis, flexor hallucis longus tendon pathology and tenosynovitis, and posterior ankle bone marrow oedema). Imaging scoring reliability testing was performed.

RESULTS

Posterior talocrural effusion-synovitis (90.8%) and subtalar joint effusion-synovitis (93.4%) were common in both groups, as well as the presence of either an os trigonum or Stieda process (61.8%). Athletes had a higher prevalence of either os trigonum or Stieda process than dancers (74%, 50% respectively, P = 0.03). Male athletes had a higher prevalence of either os trigonum or Stieda process than male dancers (90%, 50% respectively, P = 0.01), or female athletes (56%, P = 0.02). Posterior subtalar joint effusion-synovitis size was larger in dancers than athletes (P = 0.02). Male and female dancers had similar imaging findings. There was at least moderate interobserver and intraobserver agreement for most MRI findings.

CONCLUSION

Imaging features associated with posterior impingement were prevalent in all groups. The high prevalence of os trigonum or Stieda process in male athletes suggests that this is a typical finding in this population.

Geometrical characteristics of the symptomatic and non-symptomatic ossa trigona

BACKGROUND

Posterior ankle impingement is strongly associated with the presence of an os trigonum, however, most patients with an os trigonum will never develop symptoms. It is hypothesized that the os trigonum is larger in the symptomatic ankle than in the non-symptomatic ankle, the distance between os trigonum and tibia is smaller and there are more degenerative changes in ankles with symptoms of posterior impingement. In this study the geometrical characteristics of the ipsilateral and contralateral os trigonum are compared in patients with a bilateral os trigonum and unilateral posterior impingement symptoms.

METHODS

Patients with a bilateral os trigonum and unilateral posterior impingement complaints were included. Comparison between the symptomatic and asymptomatic ankles was done within each patient. From the CT-scan of each ankle, the tibia, fibula, calcaneus, talus and os trigonum were segmented and a geometric model was created. Based on these bone models, the volume of the os trigonum and talus, the size of the os trigonum, the distance between os trigonum and surrounding bones (talus, calcaneus, fibula and tibia) were calculated. In addition, the CT images were assessed for the type of os trigonum, the presence of cysts, irregular synchondrosis, calcifications and whether the os trigonum consisted of more than one fragment.

RESULTS

A total of 22 patients were included in this study. In seventeen of the 22 patients, the symptomatic os trigonum was larger in comparison with the non-symptomatic side in terms of length (median Δ 2.4 mm, 8.9 versus 10.6 mm) and relative volume (median Δ 0.09%, 0.30 versus 0.45% of talar volume). Distances between the ossa trigona and surrounding bones were not statistically significantly different between both sides. Calcifications were more frequently found around the os trigonum in the symptomatic side (10 versus 3/22).

CONCLUSIONS

The findings in this study support the hypothesis that symptomatic ossa trigona are larger in comparison with asymptomatic ossa trigona. Calcifications around the os trigonum were found more frequently in symptomatic than in non-symptomatic ossa trigona.

LEVEL OF EVIDENCE

III.

Sonographic visibility of the main posterior ankle ligaments and para-ligamentous structures in 15 healthy subjects

The present article describes the ultrasound (US) appearance of ligaments and paraligamentous structures which are not included in standard US imaging of the ankle: the posterior inferior tibiofibular ligament (PITFL), the transverse tibiofibular ligament (TTFL), the posterior talofibular ligament (PTFL), the posterior intermalleolar ligament (PIL), the synovial recess (SR) of the posterior joint and the os trigonum (OT). Two skilled operators examined 15 ankles in 15 healthy volunteers. Correlation between thickness of the main ligaments and body mass index (BMI) was also analyzed. Compound and tissue harmonic imaging (THI) were carried out using 12-, 6-15- and 9-MHz linear probes. Exploration of the posterior ankle ligament complex is accurately described including correct ankle position, echogenicity, shape, direction and thickness. Both operators identified and measured the main ligaments (PITFL, TTFL and PTFL) in all volunteers (Intraclass Correlation Coefficient ranged from 0.8 to 1); both operators also detected SR and OT in 2/15 ankles and posterior intermalleolar ligament (PIL) in 5/15 ankles. Pearson's test showed a significant correlation (< 0.05) between TTFL thickness and BMI. Also, a dynamic study was carried out showing tension of the PTFL during dorsiflexion in 7/15 subjects. Our results highlight the potential role of accurate US imaging in detecting posterior ankle ligament involvement in acute and chronic traumas. To our knowledge, there are no previous articles in the literature dealing with this topic providing an accurate description of the US procedure, and in particular, no study has been carried out to identify OT.