Galen of Pergamum was the first to use the term sesamoid, which comes from the Latin sesamum, to describe the little, spherical bones located near the joints. The bones were given the name because they resembled the flat, oval-shaped seeds of "Sesamum Indicum," an ancient East Indian plant that the Greeks used for purification [1, 2]. Sesamoid bones are tiny, ovoid or circular bones that reside in the joint capsule or beneath tendons in the hands and feet [3]. Sesamoid bones are typically found in the hands and feet. They can also be found in the knee (patella) and wrist (pisiform bone). The placement and number of sesamoid bones in the hand vary greatly, despite the fact that some sesamoids, such as the pisiform bone and patella, are found in all individuals. The occurrence of sesamoid bones at various metacarpophalangeal (MCP) and interphalangeal (IP) joints varies greatly, although practically all adults have one at the first metacarpophalangeal (MCP) joint [1, 4]. It is still unclear what role the hand’s sesamoid bones serve in the body [5]. Sesamoids are thought to serve a variety of functions, the most notable of which are to reduce tendon friction, protect the tendon, lower pressure, and hold the flexor pollicis longus in place [5, 6].

In order to correctly diagnose hand diseases, it is crucial to understand where the sesamoid is located. Particularly in comminuted articular fractures, the sesamoid bone can be easily misinterpreted as an avulsion fracture fragment. In addition, after a fracture-dislocation, sesamoid bones themselves may fracture or become imprisoned inside the joint [7, 8]. Clinical characteristics mentioned included inflammation, arthritic changes, and painful clicking [9, 10, 11]. Along with the sesamoid bone, trigger thumb was seen, simulating stenosing tendinopathy [12, 13].

Sesamoid bones are known to occur more or less frequently in some populations than others, depending on their geographic origin [14, 15]. According to a study, Caucasians have a 100% sesamoid bone incidence rate for the thumb and a 35% to 70% incidence rate for MP joints in the index and little fingers, respectively [16]. In Saudi Arabia population, Sesamoid bones observed in MCP I (100%), MCP V (53%), MCP II (46%), MCP III (2%), MCP IV (2%) and IP I (53%) [17]. Only 2.3% and 1.5% of hands showed sesamoids at the MCP joints of the middle and ring fingers respectively in Arab population [15]. Documentation of occurrences of sesamoids in the \(3^{rd}\) and \(4^{th}\) MCP is very rare [5].

Previous research on the form and prevalence of hand sesamoid bones employed plain radiographs, postmortem investigations, ultrasonography (USG) and digital tomosynthesis (DTS) [17]. It is easy to count many subjects using a plain radiograph, but correct counting may be challenging because to the superimposition of complex tiny bones, such as nearby metacarpal and phalangeal bones. User-dependent and not the best method for evaluating bone structures, ultrasound. Digital tomosynthesis is not always available and does not yield images of the similar quality as computed tomography (CT). Despite having a small number of participants, cadaveric investigations have certain advantages for morphological examination.

The sesamoid bones can cause pain and discomfort if they are injured or become inflamed. Understanding the presence and distribution of sesamoid bones in the hand is critical for accurately diagnosing and treating hand-related disorders. The purpose of this study was to use radiographs to analyse the distribution and pattern of sesamoid bones of the hand in the Saudi Arabian population.

This retrospective study was conducted in Medical Center, Majmaah University in Saudi Arabia for 3 months, from May 2023 to July 2023 in the department of orthopedics and radiology.

Majmaah University’s ethics committee approved the study with IRB number HA-01-R-088 dated 30.4.2023. Participants provided informed consent, and all acquired data was kept confidential and utilised solely for the purpose of this study. The sample size was estimated using the EPI info programme. Based on a 95% confidence interval, 5% margin of error, and the entire population. The sample size was estimated using the EPI info programme. Based on a 95% confidence interval, 5% margin of error, and the entire population. The predicted sample size was 200. Therefore 200 patients were taken as sample size for the study and Two radiology examination were analyzed for same patients.

A) Inclusion Criteria

The patients from Saudi Arabia who had sesamoid bone in hand and required hand radiographs for any reason, such as for the diagnosis of a hand-related condition or for pre-employment screening and above than 10 years of age were included in this study.

B) Exclusion Criteria

Patients less than 10 years and images not had all MCP joint and IP joints were excluded in this study. Any adult male or female who had acute Trauma, congenital anomalies (e.g. Coalition), joint disease (e.g. Osteoarthritis).

All the radiographs were assessed by an experienced radiologist and orthopedic surgeon. The radiologist and orthopedic surgeon assessed the presence and distribution of sesamoid bones in the hand, including at the MCP and IP joints. All the demographic data of patients, imaging studies, collaborate with radiologists to analyze imaging X-rays of individuals with hand injuries or conditions. Sesamoid bone and distributions of the patients were recorded systematically that provided the detailed information on the location and number of sesamoid bones was present in their hands.

C) Statistical Analysis

The statistical analysis was performed using SPSS version 26 (Armonk, NY: IBM Corp., USA). Descriptive and inferential statistics were used. The statistical significance was assessed using a p-value of 0.05 at 95% confidence interval. Descriptive statistics show numerical and percentage representations of all categorical variables, while mean and standard deviation summaries are supplied for all continuous variables. The independent factors were compared to the dependent variable using the Chi-square test. A p-value of <0.05 indicated statistical significance.

Total 200 patients who had sesamoid bone in hand were included in this study all of them were between 10 years to 84 years. Age distribution of all 200 patients shown in line chart of the patients. 41 (20.5%) patients were from age group of 30-39 years followed by 50-59 years 36 (18%), 60-69 years 35 (17.5%). Among all patients 77 (38.5%) were male and 123 (61.5%) were female with average (mean ± SD) age of 43.03 ± 16.84 and 47.17 ± 16.64 respectively. Average age of all patients was 45.57 ± 16.84 (Table 1 ). No statistical significance was seen between age and gender among the included patients (p-value 0.29) shown in Table 1.

Total 200 patients were had sesamoid bone examined in their first radiological examination of MCP. The X ray images of the hands were shown in Table / Figure (1-3). Among them 72 (36%) patients had \(1^{st}\), \(2^{nd}\) and \(5^{th}\) MCP followed by \(1^{st}\) MCP 58 (29%), \(1^{st}\) and \(5^{th}\) MCP 45 (22.5%), \(1^{st}\) and \(2^{nd}\) MCP 43 (21.5%) with average age of 47.71±17.09, 41.76±18.08, 48.16±15.76 and 42±14.77 respectively reported sesamoid bone at MCP joint (Table 2). The least sesamoid bone was reported \(1^{st}\), \(2^{nd}\) and \(3^{rd}\) MCP 1 (0.5%) and \(1^{st}\), \(2^{nd}\), \(4^{th}\) and \(5^{th}\) MCP 1 (0.5%). In female sesamoid bone were investigated in \(1^{st}\), \(2^{nd}\) and \(5^{th}\) MPC 54 (27%) followed by \(1^{st}\) MCP 27 (13.5%), \(1^{st}\) and \(5^{th}\) MCP 24 (12%), \(1^{st}\) and \(2^{nd}\) MCP 12 (6%) with average age of 47.96±17.02, 45.15±18.08, 48.17±16.41 and 43.67±16.20 respectively. In males most prevalent sesamoid \(1^{st}\) MCP 31 (55.5%) followed by \(1^{st}\) and \(5^{th}\) MCP 21 (10.5%), \(1^{st}\), \(2^{nd}\) and \(5^{th}\) MCP 18 (9%), \(1^{st}\) and \(2^{nd}\) MCP 5 (2.5%) and \(1^{st}\), \(2^{nd}\), \(3^{rd}\) and \(5^{th}\) MCP 2 (1%) with mean age of 38.81±17.55, 48.14±14.98, 46.94±17.30, 38.0±9.44 and 32 years respectively (Table 2).

Second radiological examination in same patients, 64 (32%) patients had \(1^{st}\), \(2^{nd}\) and \(5^{th}\) MPC followed by \(1^{st}\) MCP 47 (23.5%), \(1^{st}\) and \(5^{th}\) MCP 43 (21.5%), \(1^{st}\) and \(2^{nd}\) MCP 17 (8.5%) with average age of 48.38±17.13, 41.09±16.72, 49.02±16.59 and 38.24±14.59 respectively reported sesamoid bone at MCP joint (Table 3). The least sesamoid bone was reported bilateral \(1^{st}\) MCP 6 (3.0%) and bilateral \(1^{st}\) and \(2^{nd}\) MCP 2 (1%) with mean age of 44±18.51 and 46.5±3.5. Second radiological examination in female sesamoid bone at MCP were investigated in \(1^{st}\), \(2^{nd}\) and \(5^{th}\) MPC 48 (24%) followed by \(1^{st}\) and \(5^{th}\) MCP 23 (11.5%), \(1^{st}\) MCP 22 (11%), \(1^{st}\) and \(2^{nd}\) MCP 10 (5%) with average age of 48.88±17.1, 49±15.38, 46.77±16.65 and 37.6±16.75 respectively (Table 3). In males most prevalent sesamoid bone was at \(1^{st}\) MCP 25 (12.5%) followed by \(1^{st}\) and \(5^{th}\) MCP 20 (10.0%), \(1^{st}\), \(2^{nd}\) and \(5^{th}\) MCP 16 (8.0%), \(1^{st}\) and \(2^{nd}\) MCP 7 (3.5%), bilateral \(1^{st}\) MCP 3 (1.5%), bilateral \(1^{st}\) and \(5^{th}\) MCP 3 (1.5%), \(1^{st}\), \(2^{nd}\), \(3^{rd}\) and \(5^{th}\) MCP 2 (1%) and bilateral \(1^{st}\), \(2^{nd}\) and \(5^{th}\) MCP 1 (0.5%) with mean age of 36.08±15.11, 49.05±17.89, 46.88±17.14, 39.14±10.73, 56.33±10.4, 35.67±7.4, 32±0 and 66±0 years respectively (Table 4). Sesamoid bone at Bilateral \(1^{st}\) and \(2^{nd}\) MCP was not reported in male but reported in female. The statistical significance p value 0.62 were analyzed (Table 3). The correlation between first radiological examination and second radiological examination of sesamoid bone at MCP were analyzed statistically significant (chi square 623.73, p value <0.001) shown in Table 4.

Sesamoid bones are frequently seen in the hand, especially in the thumb and little finger. The study looked extensively at the distribution of sesamoid bones in the hand. Using radiographs, we sought to determine the distribution and pattern of sesamoid bones of the hand in the Saudi population. The sesamoid bone was analyzed in the initial radiological evaluation of 200 patients with MCP. Average ages were 47.71±17.09, 41.76±18.08, 48.16±15.76, and 42±14.77 for patients with \(1^{st}\), \(2^{nd}\), and \(5^{th}\) MPC, \(1^{st}\) MCP, \(1^{st}\) and \(5^{th}\) MCP, and \(1^{st}\) and \(2^{nd}\) MCP sesamoid bones, respectively. Sesamoid bone incidence was lowest for MCP levels \(1^{st}\), \(2^{nd}\), \(4^{th}\) and \(5^{th}\) MCP 1 (0.5%).

Many studies were undertaken to determine the distribution and prevalence of sesamoid bone in the hand. Al khabori H et al reported a significant incidence of sesamoid bones at the fifth metacarpophalangeal joint (64%), as well as the interphalangeal joint of the thumb (49.7%) [18]. Sesamoid bones were more prevalent in elderly adults at the fifth metacarpophalangeal joint (p = 0.03). Sesamoid bones appear to be more prevalent in the fifth metacarpophalangeal joint and the interphalangeal joint of the thumb in Omani patients than in other Middle Eastern populations [18]. Similar findings were reported in this investigation, with sesamoid bones most commonly found at the fifth metacarpophalangeal joint. This finding is similar with Ozkan Kose’s studies in Turkey, where he identified identical levels of sesamoid bone in the first and second metacarpophalangeal joints [19].

Sesamoid bones in the hand have also been investigated to determine their distribution. The total number of sesamoid bones discovered in a Chinese population study was 1,641. The prevalence of sesamoid bones was 100% at the first metacarpophalangeal joint (MCPJ), 59.0% at the second MCPJ, 2.93% at the third MCPJ, 0 at the fourth MCPJ, 47.6% at the fifth MCPJ, and 28.0% at the first IPJ. Radiographs of both hands indicated the same number of sesamoid bones [20].

A second study from China found that the prevalence of sesamoid bones was 60.8% for the MCP joint in the index finger and 59.1% for the MCP joint in the little finger. Only 15.9% of hands possessed sesamoid bones in their thumb IP joints. Aside from the thumb MCP joints, two sesamoid bones were rarely found in other hand joints [4].

In this investigation, the sesamoid bones were evaluated using two radiological examinations, an accurate approach for assessing bone positions and three-dimensional pictures for quality studies. In this study we reported correlation between first radiological examination and second radiological examination of sesamoid bone at MCP were analyzed statistically significant (chi square 623.73, p value <0.001). But in previous studies they reported no statistically significant correlation between two investigations [21].

Radiologists and orthopedic surgeons may be affected clinically by the existence and placement of sesamoid bones. Sesamoids can be misdiagnosed on radiographs as fractures or other diseases, resulting in needless procedures. Furthermore, sesamoids may have a role in a number of diseases, including osteoarthritis, tendinopathy, and ligament injuries.

The study concluded that this is the first radiological examination were study having two imaging evaluation in same patients. The most prevalent sesamoid bone was reported at \(1^{st}\), \(2^{nd}\) and \(5^{th}\) MCP followed by \(1^{st}\) MCP. This study also reported 7 and 9 different patterns of the sesamoid bone distribution in different two radiological evaluations. Hand sesamoid bones are not common in trauma patients and are often misdiagnosed when they occur in another location on the hand. Therefore, the findings of this study are significant because they provide orthopedic surgeon with anatomical data that may assist in the diagnosis and treatment of patients.

The authors declare no conflict of interests. All authors read and approved final version of the paper.

All authors contributed equally in this paper.

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