Easy to gain but hard to lose: the evolution of the knee sesamoid bones in Primates-a systematic review and phylogenetic meta-analysis.

Sesamoids are variably present skeletal elements found in tendons and ligaments near joints. Variability in sesamoid size, location and presence/absence is hypothesized to enable skeletal innovation, yet sesamoids are often ignored. Three knee sesamoids-the cyamella, medial fabella and lateral fabella-are present in primates, but we know little about how they evolved, if they are skeletal innovations, or why they are largely missing from Hominoidea. Our phylogenetic comparative analyses suggest that sesamoid presence/absence is highly phylogenetically structured and contains phylogenetic signal. Models suggest that it is easy to gain but difficult/impossible to lose knee sesamoids and that the fabellae may have similar developmental/evolutionary pathways that are distinct from the cyamella. Sesamoid presence/absence is uncorrelated to the mode of locomotion, suggesting that sesamoid biomechanical function may require information beyond sesamoid presence, such as size and location. Ancestral state reconstructions were largely uninformative but highlighted how reconstructions using parsimony can differ from those that are phylogenetically informed. Interestingly, there may be two ways to evolve fabellae, with humans evolving fabellae differently from most other primates. We hypothesize that the 're-emergence' of the lateral fabella in humans may be correlated with the evolution of a unique developmental pathway, potentially correlated with the evolution of straight-legged, bipedal locomotion.

Prevalence of the Fabella and Determination of the Fabella Index / Prevalencia de la Fabela y Determinación del Índice Fabelar

SUMMARY: The fabella is a bony anatomical variable, which in humans is located posterior to the lateral condyle of the femur, in the tendinous portion of the lateral head of the gastrocnemius muscle. Its prevalence rate has been reported in different populations, ranging from 3% to 86%. This study aimed to create an index that classifies the fabella according to its dimensions, determine the prevalence of the fabella in the Colombian population, and identify possible differences according to the fabella index (FI), sex, age, laterality, and degree of fabellar degeneration. A retrospective study used 93 lateral knee radiographs belonging to Colombian individuals. A fabella index was established to classify fabellae into longifabellar, medifabellar, and equifabellar, and radiological classification was used to identify the degree of fabellar degeneration (DFD). The prevalence of fabella was 36.30 %, and this variant was associated with the individual's sex, with male subjects having 2.66 times the probability of presenting fabella. A higher prevalence of medifabellar fabellae (57.60 %) was observed, followed by longifabellar (24.20 %) and equifabellar (18.20 %). There was a positive and moderate correlation between the DFD and age. We consider that larger fabellae can cause entrapment of the common fibular nerve, compression of the popliteal artery, and tear of the medial meniscus, so the FI becomes relevant in clinical practice, providing information on the type of fabella and its associated pathological manifestations. This study introduces a novel fabella index and investigates the frequency of fabella in the Colombian population. The findings of this study will serve as a reference for future research and contribute to the field of knee orthopedics and surgery in this population.

La fabela es una variable anatómica ósea, que en humanos se localiza posterior al cóndilo lateral del fémur, en la porción tendinosa de la cabeza lateral del músculo gastrocnemio. Su tasa de prevalencia se ha reportado en diferentes poblaciones, cuyos valores oscilan entre 3 % y 86 %. El objetivo de este estudio fue crear un índice que clasifique la fabela según sus dimensiones, determinar la prevalencia de la fabela en población colombiana, así como identificar posibles diferencias en función del índice fabelar, sexo, edad, lateralidad y grado de degeneración de la fabela. Se desarrolló un estudio retrospectivo en el que se dio uso a 93 radiografías laterales de rodilla, pertenecientes a individuos colombianos. Se estableció un índice fabelar que clasificó las fabelas en longifabelares, medifabelares y equifabelares, además utilizamos la clasificación radiológica para identificar los grados de degeneración fabelar (GDF). La prevalencia de la fabela fue del 36,30 %, se encontró asociación de esta variante al sexo del individuo, siendo los hombres quienes tuvieron 2,66 veces más probabilidades de presentar la fabela. Se observó mayor prevalencia de fabelas tipo medifabelar 57,60 %, seguido de tipo longifabelar 24,20 % y equifabelar 18,20 %. Hubo correlación positiva y moderada entre la edad y el grado de degeneración fabelar. Consideramos que las fabelas con mayores dimensiones podrían causar atrapamiento del nervio fibular común, compresión de la arteria poplítea y desgarro del menisco medial, por lo que el índice fabelar adquiere relevancia en la práctica clínica, al dar información del tipo de fabela y sus manifestaciones patológicas asociadas. El presente estudió es el primero en proponer un índice fabelar y la frecuencia de la fabela en población colombiana, por lo que servirá de referencia para futuras investigaciones, además de brindar un aporte al área traumatológica y quirúrgica de la rodilla en esta población.

The morphology of cyamella and its prevalence in Turkish society.

OBJECTIVE: The aim of this study is to determine the prevalence and morphometry of cyamella, one of the sesamoid bones around the knee joint. PATIENTS AND METHODS: In this retrospective study, a total of 9,500 plain/digital radiographs of 6,500 patients over the age of 18 who applied to Elazig Fethi Sekin City Hospital between January 2021 and January 2022 were examined. RESULTS: Examinations revealed cyamella in a total of 76 (0.8%) knees in the direct X-ray images of 49 (0.75%) patients. Eighteen (36.74%) of the patients with the presence of cyamella were males, and 31 (63.26%) were females. The mean age of the patients with cyamella was 50.9±12.9. Twenty-seven (55.1%) of the 49 cyamella were bilateral; seven (14.3%) were in the right knee, and 15 (30.6%) were in the left knee. The comparison of cyamella sizes between genders revealed a statistically significant difference in the transverse measurements only (p=0.015) in the right knee, while a statistically significant difference was found in all 3 parameters (p=0.032 for thickness; p=0.04 for transverse; p=0.026 for length) in the left knee. CONCLUSIONS: We believe that sufficient knowledge regarding the prevalence and distribution of cyamella in patients presenting with the complaint of knee pain and its differentiation from fabella, another sesamoid bone in the same region, as well as other anatomical structures, will aid an early and accurate diagnosis.

The morphology of fabella and its prevalence in Turkish society.

OBJECTIVE: Fabella is a sesamoid whose prevalence is unstable and can be found as bone or cartilage, which changes over time. This study aims to reveal the prevalence, distribution, gender differences, and morphometric characteristics of cartilage and bony fabella in the Turkish population. PATIENTS AND METHODS: The study included 2.035 individuals over 18 years of age. MR images of 121 individuals, whose MR images of both knees could be obtained by anteroposterior and lateral radiographs of the participants, were evaluated retrospectively. RESULTS: The prevalence of fabella was 39.6% in females, 38.4% in males, and 38.8% in total. The prevalence of cartilage fabella was 9.1%, whereas bone fabella incidence was 29.7% regardless of gender. The fabella's mean thickness, width, length, and distance to the epicondylus lateralis femoris were 3.84 mm, 6.04 mm, 6.23, and 31.26 mm, respectively. CONCLUSIONS: The data of this study showing the occurrence and morphometric characteristics of bony and cartilaginous fabella allow early and accurate diagnosis of various pathological conditions caused by fabella.

Ultrasound evaluation of the first finger's sesamoid bones: diagnostic value of sesamoid and subsesamoid indices.

PURPOSE: Our analysis focuses explicitly on applying two sonographic and morphological indexes (sesamoid index and subsesamoid index) to better evaluate post-traumatic consequences to the sesamoids of the first finger. METHODS: In 2 years, we enrolled 75 patients, divided into two groups: 60 without any history of trauma and 15 reporting hyperextension trauma of the first finger. We performed clinical and instrumental examinations (sonography and X-ray) on patients with one or more symptoms compatible with sesamoiditis, while an MRI scan was performed only on patients with an acute onset and severe symptomatology. We measured both the short and long-axis diameter (in mm) for each sesamoid as well as the relation between the two parameters (sesamoid index, SI and subsesamoid index, SubI). RESULTS: All 15 patients showed sonographic alterations of the SI above the reference range, while the alterations of SubI varied according to the acuteness and gravity of trauma. In all cases, the X-ray did not show any relevant alterations. MRI scans in patients with acute symptoms confirmed the sonographic findings. CONCLUSION: Sonography enabled diagnosis of micro-injuries which were invisible to X-Ray and allowed to detect possible damages to the sesamoid complex, providing a qualitative and quantitative evaluations of the post-traumatic alteration of the metacarpophalangeal joint of the 1st finger and is therefore valid, combined with clinical examination and hand X-ray, in the evaluation of sesamoiditis without the need to perform further examinations.

Prevalence, coincidence and distribution patterns of sesamoid bones of the hand / Patrones de prevalencia, coincidencia y distribución de los huesos sesamoideos de la mano

SUMMARY: The aim of this study is to identify the prevalence and distribution patterns of sesamoid bones at the metacarpophalangeal (MCP) and interphalangeal (IP) joints and to determine if there is an association between the distribution patterns and age, gender, and hand side. Patients who had a direct radiograph of the hand obtained between 2019-2020 were retrospectively evaluated. All radiographs were evaluated in terms of the prevalence, coincidence, and distribution patterns of sesamoid bones. Presence of an association between distribution patterns and age, sex and side was also assessed. A total of 1501 hand radiographs were included into the study. There were 12 different patterns of sesamoid bone distribution. The most common distribution pattern was the presence of sesamoid bone at the first MCP joint only (25.8 %). There was a positive correlation between the second and third MCP, second and fifth MCP, second and first IP, third and fourth MCP and fifth MCP and first IP joints. The pattern with a sesamoid bone at the first MCP joint only was more prevalent among males, whereas the pattern involving coincidence of sesamoid bones at the first, second, fifth MCP and first IP joints was more prevalent among females (p<0.001, p=0.031). A positive correlation was observed between age and the number of MCP joints with sesamoid bones (p<0.001). The number of MCP joints with sesamoid bones was found to be higher in females (p<0.001). This study is important in that it provided anatomical data that can be guiding for clinicians in terms of diagnosis and management of hand disorders.

RESUMEN: El objetivo de este estudio fue identificar la prevalencia y los patrones de distribución de los huesos sesamoideos en las articulaciones metacarpofalángicas (MCF) e interfalángicas (IF) y determinar si existe una asociación entre los patrones de distribución y la edad, el sexo y el lado de la mano; fueron evaluadas retrospectivamente radiografías de la mano obtenidas en 2019- 2020. Todas las radiografías se evaluaron en términos de prevalencia, coincidencia y patrones de distribución de los huesos sesamoideos. También se evaluó la presencia de una asociación entre los patrones de distribución y la edad, el sexo y el lado. Se incluyeron en el estudio un total de 1501 radiografías de mano. Se observaron 12 patrones diferentes de distribución de los huesos sesamoideos. El patrón de distribución más común fue la presencia de hueso sesamoideo solo en la primera articulación MCF (25,8 %). Hubo una correlación positiva entre la segunda y la tercera MCF, la segunda y la quinta MCP, la segunda y la primera IF, la tercera y cuarta MCF y la quinta MCF y las primeras articulaciones IF. El patrón con un hueso sesamoideo en la primera articulación MCF fue más prevalente entre los hombres, mientras que el patrón de coincidencia de los huesos sesamoideos en la primera, segunda, quinta articulación MCF y la primera articulación IF fue más prevalente entre las mujeres (p <0.001, p = 0,031). Se observó una correlación positiva entre la edad y el número de articulaciones MCF con huesos sesamoideos (p <0,001). El número de articulaciones MCF con huesos sesamoideos era mayor en las mujeres (p <0,001). Este estudio es importante debido a que proporcionó datos anatómicos que pueden ser una guía para los médicos en el diagnóstico y tratamiento de los trastornos de la mano.

Prevalence of metacarpophalangeal sesamoid bones of the hand in Turkish population.

OBJECTIVES: This study aims to investigate the prevalence and location of the metacarpophalangeal (MCP) sesamoid bones using computed tomography (CT) images. PATIENTS AND METHODS: A total of 767 hands of 735 patients (503 males, 232 females; mean age: 36.9±17.0 years; range, 18 to 105 years) obtained from picture archiving and communication system were retrospectively analyzed between January 2016 and December 2019. The sesamoid bones of MCP joints I, II, III, IV, and V were recorded. Data including age, sex, side, number, pathologies, and location of the sesamoid bones were recorded. RESULTS: The prevalence of sesamoid bones was found to be 100%, 37.61%, 1.17%, 0.5%, and 80% in MCP I, II, III, IV, and V, respectively. There was no significant correlation between the sex of the patient and presence of sesamoid bone at MCP II or MCP V (p>0.970 and p=0.176, respectively). The presence of sesamoid bone at MCP II was statistically significantly correlated with the presence of sesamoid bone at MCP V (p<0.001). There was no statistically significant difference in the side and sesamoid prevalence in the remaining 703 patients (p>0.05). CONCLUSION: The prevalence of MCP V sesamoid bone is higher than previous studies from our country. The CT of hand can be used to determine sesamoid fractures and degenerative conditions of sesamoids.

Prevalence and distribution of sesamoid bones of the hand in Omani subjects: a radiological study.

Sesamoid bones show considerable variations in their occurrence among various ethnicities. This study aims to evaluate the prevalence and distribution patterns of the sesamoid bones of the hands among Omani patients who were referred for radiological investigations. The influence of gender and different age groups on the occurrence of sesamoid bones of the hand was determined using the Chi-square test. Spearman's rank correlation was used to determine the coexistence of sesamoid bones at the metacarpophalangeal joints. A total of 541 hand radiographs were reviewed. A high prevalence of sesamoid bones at the fifth metacarpophalangeal joint and the interphalangeal joint of the thumb was noted with a frequency of 64% and 49.7%, respectively. There were ten different patterns of sesamoid bones detected, the most common of which was the presence of sesamoid bones at the first and fifth metacarpophalangeal joints found in 32.9% of the radiographs. A statistically significant gender difference was observed at the interphalangeal joint of the thumb (p = 0.025) and fifth metacarpophalangeal joint (p = 0.027) with a female dominance. A significant association between the age and prevalence of sesamoid bones was noted at the fifth metacarpophalangeal joint (p = 0.03). The prevalence of the sesamoid bones of the hand in Omani subjects seems to differ from other Middle Eastern populations, particularly at the fifth metacarpophalangeal joint and the interphalangeal joint of the thumb. In the meantime, the baseline data of our study can be helpful while treating the patients complaining of hand discomfort or pain.

Sesamoid bones of the hand: A multicenter study.

OBJECTIVES: This study aims to document a detailed investigation on the sesamoid bones (SBs) of Turkish subjects from different parts of Turkey in a multi-center study, in both hands, according to gender, frequency and divisions of the bones' coexistence and bilaterality by radiography. PATIENTS AND METHODS: This retrospective and three-centered study was performed between June 2010 and April 2012. Sesamoid bones were examined by anteroposterior and oblique X-rays of 1,444 hands of 772 subjects (367 males, 405 females; mean age 42.7 years; range, 18 to 87 years). All X-rays were evaluated by at least two independent observers. In controversial circumstances, at least three observers together gave the final decision by consensus. RESULTS: Metacarpophalengeal (MCP) joint of the thumb (MCP 1) had sesamoid in all subjects (100%) and it was seen bilaterally. The prevalence of the SB was 42.8% in the second MCP joint (MCP 2) in 772 subjects and 36.6% in 1,444 hands, 1.6% in the third MCP joint (MCP 3) for the subjects and 1.1% for the hands, 0.1% in the fourth MCP joint (MCP 4) for the subjects and 0.1% for the hands, and 72.5% in the fifth MCP joint (MCP 5) for the subjects and 62.5% for the hands. The prevalence of SB in the first interphalangeal joint (IP 1) was 21.8% and SB was detected in 18.6% of the hands. Sesamoid bones of the MCP 2, MCP 5, and IP 1 was recorded more frequently in females. Sesamoid bone of the same joints (MCP 2, MCP 5 and IP 1) was detected more frequently bilaterally than unilateral right side and more frequently unilaterally on right side than unilateral left side. CONCLUSION: The distribution of SBs varies according to hand regions, gender, and side. Having knowledge of the locations and the rate of bilaterality of SBs may assist clinicians in both clinical and radiological diagnoses.

Human biological variation in sesamoid bone prevalence: the curious case of the fabella.

The fabella is a sesamoid bone located in the gastrocnemius behind the lateral femoral condyle. In humans, fabellae are 3.5 times more common today than they were 100 years ago, with prevalence rates varying between and within populations. In particular, fabellae have been assumed to be more common in Asians than non-Asians, equally common in men and women, potentially more common in older individuals, and bilateral cases (one per knee) appear to be more common than unilateral ones. The roles of genetic and environmental factors in this phenotypic variation have been hypothesized, but not rigorously investigated. Given its clinical and evolutionary significance (i.e. being associated with several knee ailments, causing medical issues on its own, interfering with medical devices, and being less common in humans than in other mammals), it is important comprehensively to understand prevalence rate variation, and the roles of genetics and environmental factors in that variation. To address these questions, we performed a meta-analysis on data from studies published from 1875 to 2018 to investigate possible variation in sexual dimorphic (n = 22 studies, 7911 knees), ontogenetic (n = 10 studies, 4391 knees), and global (n = 65 studies, 21 626 knees) fabella prevalence rates. In addition, we investigated what proportion of cases are bilateral (n = 37 studies, 900 individuals), and among unilateral cases (n = 20 studies, 204 individuals), if fabellae are more common in the left or right knee. Our results show that, today, fabellae are 2.47-2.60% more common in men than women, and prevalence rates increase ontogenetically in old age (i.e. 70 years old), implying that fabellae can ossify early (i.e. 12 years old) or late in life. Approximately 72.94% of cases are bilateral, and among unilateral ones, fabellae are equally common in right and left knees. There is marked regional variation in fabella prevalence rates, with rates being highest in Asia, followed by Oceania, South America, Europe, Middle East, and North America, and lowest in Africa. Worldwide, an average of 36.80% of knees has ossified fabellae detectable by dissection. These results imply that, while the ability to form a fabella may be genetically controlled, the mechanisms that trigger fabella ossification may be environmentally controlled. What these environmental factors are, can only be speculated.

The Os Peroneum incidence - A cadaveric study.

BACKGROUND: The Os Peroneum (OP) is a small sesamoid bone, which can be found in the Peroneus Longus Tendon (PLT) sheath, near the calcaneocuboid joint. Size and shape variability is quite common as well as a multipartite OP that can be found in some cases. Trying to explore and understand this variability, this study was carried out in order to provide us with answers about the presence and shape of OP in our specimens. METHODS: Twenty cadaveric lower extremities were obtained according to the body donation program of our institution. Dissections were performed to expose the OP (when present) starting proximally at the origin of the PLT and Peroneal Brevis Tendon (PBT) finalizing at the insertion of the PLT in the first metatarsal. RESULTS: In twenty feet, nine distinct OP were found, whilst six feet had a thickening of the tendon. On the remaining five foot, we did not identify an OP. CONCLUSIONS: In this study, 45% of the feet analyzed had an OP. The authors believe the variability of OP prevalence reported in the literature can be associated with differences in its definition.

How many bones? Every bone in my body.

Textbooks frequently report that there are 206 human bones, or 200 bones and 6 auditory ossicles. The human bone counts in history and within adulthood were reviewed. Tallies of 197 to 307 bones have been reported over the past several centuries. The relatively low modern reckoning of 206 was due to exclusion of teeth and sesamoid ossicles, and to reassessments of the hyoid, sacrum, coccyx, and sternum as unitary bones. An audit of bone counts during adulthood failed to confirm a rational justification for the total of 206. The number is higher in young adults and lower in the elderly. Difficulties in establishing a definitive bone count include individual differences and the inconsistency of viewing the adult cranium as a collection of 21 bones. Clin. Anat. 33:187-191, 2020. © 2019 Wiley Periodicals, Inc.

Presencia y biometría del os peroneum en individuos chilenos: estudio radiológico / Presence and biometry of os peroneum in Chilean individuals: radiological study

RESUMEN: El esqueleto está formado por 206 huesos constantes (200 huesos axiales y apendiculares más los 6 osículos del oído). Sin embargo, aparte de éstos existen otros huesos que pueden ser inconstantes, los que se denominan accesorios y sesamoideos. Basado en lo anterior, el objetivo fue identificar el os peroneum, que es uno de los huesos sesamoideos que podría estar presente en el pie humano, relacionando su presencia con el sexo, grupos etarios y dominancia, registrando también mediciones de cada hueso encontrado. Se realizó un estudio de tipo descriptivo, en donde se utilizaron radiografías de 200 pacientes, de ambos sexos, chilenos, de la IX región de La Araucanía, 50 de sexo masculino y 150 de sexo femenino, con edades entre 15 y 90 años. De los 200 pacientes estudiados, se encontraron 28 (14 %) con presencia de Os peroneum, 23 del sexo femenino y 5 de sexo masculino. En 16 (57,1 %) individuos se determinó que los huesos eran bilaterales. Los registros biométricos del hueso en estudio se muestran en tablas. Los datos obtenidos complementarán el conocimiento morfológico y médico acerca de este hueso en la población chilena, ya que el dolor en la zona lateral del pie puede ser causado por un espectro de etiologías, y con los datos obtenidos, caracterizar a nuestra población, aportando otra posible causa al dolor lateral de pie.

SUMMARY: The skeleton is made up of 206 constant bones (200 bones and the 6 ossicles of the ear). However, apart from these there are other bones that can be inconstant, which are called accessories and sesamoids. Based on the above, the objective was to identify to the Os peroneum, which is one of the sesamoid bones that could be present in the human foot, relating its presence with sex, age groups and dominance, also recording measurements of each bone found. A descriptive study was carried out, in which radiographs of 200 patients of both sexes were used, Chilean, from the IX region of La Araucanía, 50 male and 150 female, aged between 15 and 90 years. Of the 200 patients studied, 28 (14 %) were found with the presence of peroneal bone, 23 of the female sex and 5 of the male sex. In 16 (57.1 %) individuals it was determined that the bones were bilateral. The biometric records of the bone under study are shown in tables. The data obtained will complement the morphological and medical knowledge about this bone in the Chilean population, since the pain in the lateral zone of the foot can be caused by a spectrum of etiologies, and with the data obtained, characterize our population, providing another possible cause to lateral standing pain.

Accessory ossicles of the foot-an imaging conundrum.

Various anatomical variations can be found in the foot and ankle, including sesamoid bones and accessory ossicles. These are usually incidental findings and remain asymptomatic; however, they may cause complications resulting in painful syndromes or degenerative changes secondary to overuse or trauma. They can also lead to fractures or simulate fractures. These complications are challenging to diagnose on radiographs. Advanced imaging with US, CT, MRI, or Tc-99m bone scan is useful for definitive diagnosis. This study aims to illustrate how imaging modalities can be used to diagnose complications of common sesamoids and accessory ossicles of the ankle and foot (hallux sesamoids, os trigonum, accessory navicular, os supranaviculare, os peroneum, os intermetatarseum, and os calcaneus secundarius) and demonstrate the imaging differences between fractures and their mimics.

Os Conundrum: Identifying Symptomatic Sesamoids and Accessory Ossicles of the Foot.

OBJECTIVE. Sesamoids and accessory ossicles are frequently encountered normal osseous structures in the foot that may be an uncommon cause of pain. Familiarity with their imaging findings allows the radiologist to provide reassurance in normal cases and increase confidence when making the relatively uncommon diagnosis of a pathologic sesamoid or symptomatic ossicle. CONCLUSION. Image-guided injections targeted to the symptomatic ossicle can confirm the suspected diagnosis and predict therapeutic outcomes before surgical intervention.

Establishing a common instantaneous center of rotation for the metatarso-phalangeal and metatarso-sesamoid joints: a theoretical geometric model based on specific morphometrics.

BACKGROUND: Previous research has identified separate sagittal plane instantaneous centers of rotation for the metatarso-phalangeal and metatarso-sesamoid joints, but surprisingly, it does not appear that any have integrated the distinctive morphological characteristics of all three joints and their respective axes into a model that collectively unifies their functional motions. Since all joint motion is defined by its centers of rotation, establishing this in a complicated multi-dimensional structure such as the metatarso-phalangeal-sesamoid joint complex is fundamental to understanding its functionality and subsequent structural failures such as hallux abducto valgus and hallux rigidus. METHODS: Based on a hypothesis that it is possible to develop an instantaneous center of rotation common to all four osseous structures, specific morphometrics were selected from a sequential series of 0.5-mm sagittal plane C-T sections in one representative cadaver specimen randomly selected from a cohort of nine, seven which were obtained from the Body Donation Program, Department of Anatomy, University of California, San Diego School of Medicine, and two which were in the possession of one author (MD). All mature skeletal specimens appeared grossly normal, shared similar morphological features, and displayed no evidence of prior trauma, deformity, or surgery. Specific C-T sections isolated the sagittal plane characteristics of the inter-sesamoidal ridge and each sesamoid groove, and criteria for establishing theoretical sesamoid contact points were established. From these data, a geometric model was developed which, to be accurate, had to closely mimic all physical and spatial characteristics specific to each bone, account for individual variations and pathological states, and be consistent with previously established metatarso-phalangeal joint functional motion. RESULTS: Sequential sagittal plane C-T sections dissected the metatarsal head from medial to lateral and, at approximately midway through the metatarsal head, the circular nature of the inter-sesamoidal ridge (crista) was isolated; other C-T sections defined, respectively, the elliptical characteristics of the tibial (medial) and fibular (lateral) sesamoid grooves in each specimen. A general plane model representing the most basic form of the joint was developed, and its center of rotation was established with a series of tangential and normal lines. Simplified tibial sesamoid and fibular plane models were developed next which, when combined, permitted the development of a spherical model with three separate contact points. Based on the morphometrics of each sesamoid groove and a more distally positioned tibial sesamoid, the model was modified to accurately define the center of rotation and one distinctive sagittal plane geometric and functional characteristic of each groove. CONCLUSION: Consistent with our hypothesis, this theoretical geometric model illustrates how it is possible to define an instantaneous center of rotation common to all three joints while simultaneously accounting for morphometric and spatial variability. This should provide additional insight into metatarso-phalangeal-sesamoid joint complex functionality and the physical characteristics that contribute to its failure.

Gross osteology and radiology of the pelvic limb of the adult small East African goat.

The aim of this study was to provide the detailed normal gross osteology and radiographic anatomy of the pelvic limb in adult small East African goats as a reference for clinical use, biomedical research and teaching. Radiography of the pelvic limb was performed in five adult small East African goats. Bone specimens of four skeletally mature small East African goats were used for gross osteological study. The ilial wing was wide. The ischiatic tuberosity was prominent and well developed. The acetabulum was rounded. The minor trochanter was located caudomedially, and the femoral trochlea was deep and narrow. The lateral and medial condyles of the femur were approximately of the same size. The tibial tuberosity was prominent, and the cochlea grooves were deep with a pronounced intermediate ridge. The trochlea of the talus was deep. The patella presented a prominent tuberosity on the cranial surface. The metatarsal sesamoid bone was seen in all animals. The observed gross osteology and radiographic anatomy of the pelvic limb of small East African goats was consistent with the presence of strong extensor muscles of the hip, stifle and tarsus for propulsion during terrestrial walking and trotting.

Anatomía imagenológica de los huesos accesorios y sesamoideos inconstantes del miembro inferior: ensayo iconográfico / Imaging anatomy of the accessory and inconstant sesamoid bones of the lower limb: an iconographic essay

Se realiza un estudio sobre la anatomía e imagenología de los huesos sesamoideos inconstantes y de los huesos accesorios del miembro inferior. Para ello, se presenta una selección de estudios imagenológicos de pacientes que presentan este tipo de huesos, recolectados durante los últimos tres años.

Prevalence of the fabella and its association with pain in the posterolateral corner of the knee: A cross-sectional study in a Romanian population.

The functions and clinical consequences of the fabella, a sesamoid bone found in the posterolateral aspect of the knee joint, are still a reason of intense debate in the scientific literature. Its incidence was reported to range between 20% and 87% and its presence was usually associated with the persistent pain in the posterolateral region of the knee. The aim of our study was to measure the prevalence, anatomic and clinical features of the fabella within a cross-sectional study, conducted in a Romanian orthopaedic center. Between 2015 and 2017, a consecutive series of 562 patients with knee injuries or persistent knee pain has been examined by radiographs and Magnetic Resonance Imaging and a set of anatomical and clinical parameters have been recorded. Collected data was evaluated with RadiANT DICOM Viewer and statistically analyzed with GraphPad Prism 7. The level of significance was set at P <.05. The incidence of the fabella in our study group was 16.93%, lower than previously reported for Caucasian populations. We found statistically significant differences regarding the possible association of the fabella with pain in the posterolateral corner of the knee (P = .04) and the 2 dimensions of the bone according to gender (P = .03 respectively P = .01), but the prevalence was not influenced by gender (P = .6). The anatomic characteristics could be important in differentiating this sesamoid bone from calcifications or loose bodies located in the knee joint region. Due to the high association with the posterolateral knee pain, the fabella should be recorded during knee examination as a differential diagnosis, before any surgical procedure.

Morphological, radiographic and computed tomographic evaluation of the metatarsophalangeal joint of the one-humped camel.

The camel digits have a complex structure with tendons, joints and ligaments. The objective of the study was to determine the anatomical features of the metatarsophalangeal joint and its puncture site in dromedary camel using anatomical dissection, radiography, computed tomography (CT) bone and soft tissue window scans and 3D reconstruction render volume of CT. The study used six adult camels of both sexes (three males and three females), aged 9-15 years (Mean ± SD equal 11.80 ± 2.59 years). The camel fetlock possesses two metatarsophalangeal joints, left and right ones. The study described in detail the bony structures, ligaments and joint capsule of the metatarsophalangeal joint. The straight sesamoidean ligament was recorded in the studied one-humped camel joints. The joint capsule exhibited two recesses: dorsal and plantar recess. This is the first study to report the dorsal recess as triangular in outline with one proximal recess and two distal recesses, and the plantar recess as having two proximal recesses and one distal recess. The soft tissues examined around the fetlock were the proper extensor tendon, superficial, deep digital flexor tendon, digital scutum, collateral ligaments and sesamoidean ligaments. The plantar and dorsal pouches were the sites of joint injection. The present findings regarding joint injection indicate the plantar approach through plantar recess to fetlock to be preferable than the dorsal one as we used the proximal sesamoid bones and suspensory ligament as landmarks to inject easily.