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

Abstract

Background The os trigonum is an accessory bone that is not fully fused with the talus during secondary ossification, and is one of the risk factors of posterior malleolus impact syndrome. The purpose of this study was to classify the os trigonum and to guide the diagnosis and treatment of related clinical diseases. Material/Methods Ankle computed tomography (CT) scans of 586 Chinese patients between October 2014 and October 2018 were reviewed. CT images of 1011 ankle joints were reconstructed to evaluate the classification of the os trigonum and the measurement of anatomical parameters. Results The incidences of os trigonum in 3 groups were determined as type I (1.9%), type II (10.5%), and type III (14.7%). The macro-axis of type II (0.89±0.31) cm was significantly larger than with type I (0.65±0.24 cm) and type III (0.74±0.23 cm) (p<0.05).The minor axis of similar of type I (0.41±0.23 cm) was significantly shorter than that of type II (0.58±0.32 cm) and type III (0.55±0.16 cm) (p<0.05).The distance from os trigonum to calcaneal tubercle was significantly different than that of type I (1.33±0.52 cm), type II (1.67±0.55 cm), and type III (1.84±0.45 cm) (p<0.05). Conclusions This study showed that os trigonum has a high incidence. Type I was the least common, the volume of type II was larger, and type III was more common. The anatomical parameters of each type may improve treatment of related diseases and the further development of ankle arthroscopic surgery.

A Comprehensive Study of the Anatomical Variations of the Posterolateral Tubercle of Talus

“…However, the frequency of occurrence of the os trigonum alone was widely investigated in normal feet and it varies from 2 to 50 % (Burman & Lapidus, 1931;Mann & Owsley), and a population-specific incidence was also reported for os trigonum (Mann & Owsley; Zwiers et al). On the other hand, the frequency of the enlarged posterolateral talar tubercle (Stieda's process) is rarely reported with incidences of 35.7 % and 14.7 % in the Netherlands and Chinese population, respectively (Zwiers et al;Fu et al, 2019). The aim of this study was to provide a comprehensive understanding of the anatomical variations of the posterolateral tubercle of talus and to establish their prevalence on CT imaging.…”

A comprehensive study of the anatomical variations of the posterolateral tubercle of talus&nbsp;

“…The different morphological variants of os trigonum described in this study were also previously identi ed in a CT based study of a Chinese population (Fu et al, 2019). Three basic types of os trigonum based on the mode of connection were identi ed; Type 1 was a single bone that was not connected to talus, type 2 was connected to the posterior talar process by a hyaline cartilage, and type 3 was the Stieda's process.…”

“…In the study of Zwier et al, Stieda's process was found in about one-third of the patients without os trigonum (Zwiers et al, 2018). In another CT based study of a Chinese population, Stieda's process was identi ed in 14.7% of patients (Fu et al, 2019).…”

“…However, the frequency of occurrence of the os trigonum alone was widely investigated in normal feet and it varies from 2 to 50% (MS Burman & PW Lapidus, 1931;Mann & Owsley, 1990), and a population-speci c incidence was also reported for os trigonum (Mann & Owsley, 1990;Zwiers et al, 2018). On the other hand, the frequency of the enlarged posterolateral talar tubercle (Stieda's process) is rarely reported with incidences of 35.7% and 14.7% in the Netherlands and Chinese population, respectively (Fu et al, 2019;Zwiers et al, 2018). The aim of this study was to provide a comprehensive understanding of the anatomical variations of the posterolateral tubercle of talus and to establish their prevalence on CT imaging.…”

The Anatomical Variations of the Posterolateral Tubercle of Talus in Patients with Posterior Ankle Impingement Syndrome

“…In a recent CT based study, Stieda's process was found in about one-third of the patients without os trigonum (6). In another CT based study of a Chinese population, Stieda's process was identi ed in 14.7% of patients (7).…”