Prevalence and classification of accessory navicular bone: a medical record review

Abstract

BACKGROUND: The accessory navicular bone (ANB) is one of the most common accessory bones in the foot. Certain pathologies, such as posterior tibial tendon insufficiency are associated with ANB, and should be differentiated from midfoot and hindfoot fractures such as navicular tuberosity avulsion fractures. There are few studies addressing the prevalence and types of ANB in Saudi Arabia. OBJECTIVES: Determine the prevalence and morphological variations of ANB and its relation with age and sex in patients visiting foot and ankle clinics. DESIGN: Medical record review SETTING: Orthopedic foot and ankle clinic at a university hospital. PATIENTS AND METHODS: The presence of ANB was retrospectively analyzed in radiographs from patients who presented to the orthopedic foot and ankle at our university hospital from February 2010 to December 2020. The patients were stratified according to sex, age, and diagnosis. For each ANB, recorded information included site, size, classification, subtypes, and symptomatology. Purposive sampling was used to select the patients for the study (non-probability sampling). MAIN OUTCOME MEASURES: Prevalence of ANB in patients attending a foot and ankle clinic. SAMPLE SIZE: 117 patients and 194 feet. RESULTS: ANB was analyzed in 1006 radiographs from 503 patients. ANB was detected in 117 (23.3%) patients and 194 (19.3%) feet Prevalence was significantly higher in females (67.5%) than in males (32.5%) (Z=5.359, P <.001). The ages ranged from 19 to 86 years, with a mean age of 48.26 (14.5) years. The most common site was bilateral (77 patients, 65.8 %). Type I was the most common type, with a prevalence of 42.1%. There were no significant differences in types in relation to sex, but all types and subtypes differed significantly from each other. CONCLUSION: ANB was common among patients presenting to the foot and ankle clinic, with an overall prevalence of 23.3%. It should be considered among the differential diagnosis in chronic foot pain, and should be differentiated from midfoot and hindfoot fractures. Further studies with a larger, randomized sample are needed, for more accuracy and to confirm the reported results. LIMITATIONS: Retrospective chart review, non-probability sampling, and use of plain radiographs. CONFLICT OF INTEREST: None.