Radiological examination of accessories and sesamoid bones in knee and foot

Accessory and sesamoid bones may mimic fractures, causing misdiagnosis, contributing to or exacerbating the underlying pathology by causing symptoms. There were limited studies in the literature reporting the prevalance of variations in accessory and sesamoid formations around the knee joint and around the foot and ankle. Therefore, in our study, the presence of sesamoid and accessory bones in the knee and foot-ankle region, we aimed to retrospectively examine and compare the prevalance with radiographs according to age, gender and anatomical localizations. In the study, a total of 2300 knees belonging to 1150 people (330 males and 820 females) aged 18 years and older who had bilateral anteroposterior and lateral knee radiographs, and 339 individuals over the age of 18 who had unilateral or bilateral anteroposterior, lateral and oblique foot and ankle radiographs (345 foot radiographs of 176 men, 163 women) were included. Radiographs were evaluated retrospectively. A significant difference of p<0,05 was accepted for the data obtained. Presence of accessory and sesamoid bone; were compared according to gender, age and anatomical localization. The prevalence of fabella and bipartite patella in the knee region was investigated. The overall prevalence of fabella (unilateral or bilateral) was 29,91%. Fabella was unilateral 6% and bilateral 23,91%. There was no significant gender difference between age groups. In our study, the differences in unilateral, bilateral and total prevalance of fabella between men and women were not statistically significant. There was no significant gender difference in age groups. The prevalence of fabella was similar across age groups (no statistically significant difference, p= 0,0704). The overall prevalence of bipartite patella was 0,17%. The prevalence of bipartite patella in men was 0,60%. Bipartite patella was present in only 2 men. Bipartite patella was not found in women. There was no significant difference in the prevalence of bipartite patella between the genders (2 men/0 women; p=0,0829). The prevalence of foot accessory bone was 42,9%. The prevalance of accessory bones in cases with accessory bones are as follows: navicular bone 49,13%, os trigonum 16,76%, os supratalar 8,67%, os intermetatarseum 8,09%, os calcaneus secundarius 8,09%, os supranaviculare % 3,47, os subfibulare 2,89%, os vesalianum 1,73%, os subtibiale 1,16%. In 23,47% of the foot radiographs had only sesamoid bone; 19,42% had only accessory bone. Accessory and sesamoid bone were seen together in 23,76% of radiographs. Os peroneum 25,80%; hallux interphalangeal sesamoid 19,42%; sesamoid bone in the 2nd metatarsophalangeal (MTP) 3,19%; sesamoid bone in the 4th MTP 1.45% and sesamoid bone in the 5th MTP 13,91% was seen. Among the feet with accessory bone, there was a significant difference between men and women only in the accessory navicular bone (p=0,0001). Among age groups, the prevalance of accessory bone by gender was statistically significant only in the 26-35 age group (p=0,0001). There was a significant correlation between the prevalence of sesamoid bone and gender in os peroneum (p=0,0361) and hallux interphalangeal (p=0,0420). When we examine the relationship between the incidence of all MTP joint sesamoids, peroneum and hallux interphalangeal sesamoid bones; there was a statistically significant difference between the os peroneum and sesamoids in all MTP joints (p=0,0001). The difference between 1. MTP sesamoid and hallux interphalangeal sesamoid and other MTP joint sesamoids was statistically significant (p=0,0001). There was a statistically significant difference between the hallux interphalangeal sesamoid and the 2nd MTP, 3rd MTP and 4th MTP sesamoid (p=0,0001). There was a statistically significant difference between the 2nd MTP and 3rd MTP (p=0,0009) and 5th MTP (p=0,0001) sesamoid bone. There was a statistically significant difference between 3. MTP and 5. MTP sesamoid bone (p=0,0001), and there was a statistically significant difference between 4. MTP and 5. MTP sesamoid bone (p=0,0001). The difference between the incidence of sesamoid according to gender was statistically significant in cases aged between 26-35 years (p=0,0334) and those with hallux interphalangeal sesamoid. The difference between the incidence of sesamoid according to gender was statistically significant in the 36-45 age group with hallux interphalangeal sesamoid (p=0,0070) and 5. MTP (P=0,0298). There was no statistical difference in terms of gender in other age groups. There was a statistically significant difference in terms of gender only in cases with sesamoid in the 1st MTP (p=0,0463). In cases with more than one sesamoid, there was a statistically significant difference in terms of gender in cases with 1st MTP - hallux interphalangeal (p=0,0466), and in cases with 1st MTP-Os peroneum (p=0,0246). In our study, we examined the prevalence, symmetry pattern, age and gender differences of fabella and bipartite patella in the knee region, and age and gender differences in the prevalence of the foot-ankle region. Our study has the largest sample on the Turkish population in the current literature in terms of fabella and bipartite patella. The prevalence of accessory and sesamoid bones in the knee and foot-ankle region in our study is similar to previous studies in the Turkish population. The location and clinical importance of the accessory and sesamoid bones in the knee and foot should be well known in order to reduce misdiagnoses arising from accessory and sesamoid bones in patients who apply to health institutions with knee or foot complaints. Keywords: Accessory bone, sesamoid bone, radiography, knee, foot.