Accessory Ossicles Research Articles

Endoscopic Accessory Navicular Synchondrosis Fusion

The accessory navicular bone is one of the most common accessory ossicles of the foot. Fewer than 1% of accessory navicular bones are symptomatic, and most of these are type II accessory navicular bones. A separation of the synchondrosis is considered one of the main causes of pain. After an injury to the synchondrosis has resulted in a chondro-osseous disruption, the combined forces of tension and shear from the posterior tibial tendon and the foot aggravate the injury and prevent it from healing. Fusion of the synchondrosis is a logical surgical treatment option if the pain is recalcitrant to conservative measures. The purpose of this technical note is to report an endoscopic approach to achieve fusion. It has the advantages of better cosmesis, less scar pain, less risk of nonunion, and potential to examine the tibialis posterior tendon and the talonavicular joint.

Cerebro-costo-mandibular syndrome: Clinical, radiological, and genetic findings.

Cerebro-Costo-Mandibular syndrome (CCMS) is a rare autosomal dominant condition comprising branchial arch-derivative malformations with striking rib-gaps. Affected patients often have respiratory difficulties, associated with upper airway obstruction, reduced thoracic capacity, and scoliosis. We describe a series of 12 sporadic and 4 familial patients including 13 infants/children and 3 adults. Severe micrognathia and reduced numbers of ribs with gaps are consistent findings. Cleft palate, feeding difficulties, respiratory distress, tracheostomy requirement, and scoliosis are common. Additional malformations such as horseshoe kidney, hypospadias, and septal heart defect may occur. Microcephaly and significant developmental delay are present in a small minority of patients. Key radiological findings are of a narrow thorax, multiple posterior rib gaps and abnormal costo-transverse articulation. A novel finding in 2 patients is bilateral accessory ossicles arising from the hyoid bone. Recently, specific mutations in SNRPB, which encodes components of the major spliceosome, have been found to cause CCMS. These mutations cluster in an alternatively spliced regulatory exon and result in altered SNRPB expression. DNA was available from 14 patients and SNRPB mutations were identified in 12 (4 previously reported). Eleven had recurrent mutations previously described in patients with CCMS and one had a novel mutation in the alternative exon. These results confirm the specificity of SNRPB mutations in CCMS and provide further evidence for the role of spliceosomal proteins in craniofacial and thoracic development.

The Rare Lesser Metatarsal Bipartite Sesamoid – A Case Report and Literature Review

INTRODUCTION AND OBJECTIVES: There are several various accessory ossicles and sesamoid bones that can be seen throughout the foot and ankle, with reported incidence of 21.2% and 9.6%, respectively. Accessory ossicles and sesamoid bones usually remain asymptomatic until an inciting event (trauma, overuse) occurs and can then cause pain or degenerative changes. They can also be found in routine imaging. One of these confusing findings are lesser metatarsal sesamoids, which are a rare occurrence. Here radiographically we demonstrate the first such case of a fifth metatarsal bipartite sesamoid. METHODS: A 31-year old female presented to the senior authors office for evaluation of the right foot after a motor vehicle accident (MVA). She was told she sustained a foot fracture at an outside emergency department. Her case was reviewed for presentation. RESULTS: Physical exam did not elicit any pain to the forefoot as all symptoms were in the patients ankle. The initial radiograph was reviewed which revealed a bipartite sesamoid of the fifth metatarsal. No pedal fractures to the foot or ankle were appreciatd. MRI was ordered and confirmed this diagnosis with no active pathology to the forefoot. CONCLUSIONS: number one at 7.6% and foot and ankle at 51.4%, respectively. One study found that initial emergency room diagnosis and final foot and ankle outpatient clinic diagnosis did not match in 21.4% of patients evaluated. Lesser metatarsal sesamoids are more common in the 2nd and 5th metatarsal and overall range between 0.2–15%. However, no literature to the authors knowledge exists demonstrating a bipartite lesser sesamoid, and more specifically to 5th metatarsal.

Painful Os Peroneum Syndrome: Underdiagnosed Condition in the Lateral Midfoot Pain.

Os peroneum is an accessory ossicle located within the peroneus longus tendon. The painful os peroneum syndrome (POPS) results from a wide spectrum of conditions, including fractures, diastases, and other causes. POPS can result in tenosynovitis or discontinuity of the peroneus longus tendon with a clinical presentation of pain in the lateral aspect of the midfoot. Authors report a typical case of POPS, illustrating this entity through different imaging methods (radiographs, ultrasound, and magnetic resonance imaging). We emphasize the prevalence of this ossicle and discuss painful complications.

Os Vesalianum - A Confounding Diagnosis

A 42-year-old, diabetic patient presented with history of pain in right little toe and swelling of right foot following trivial trauma the day before. X-ray right foot revealed what was thought to be base of the fifth metatarsal fracture. There was no tenderness, hence it was thought that it might be an accessory ossicle. To confirm the diagnosis, an X-ray of left foot was done, which also showed a small smooth edged bone lying adjacent to base of the fifth metatarsal, which was similar to that found in right foot and hence, our diagnosis of os vesalianum was confirmed. It is important to differentiate and keep this diagnosis in mind whenever managing cases without a clear clinical presentation.

Bilateral carpal second row duplication – a case report

Introduction The number of carpal bones may be increased due to anatomical variants or true congenital anomalies. Numerical increment arises from additional bones or from split bones. Over twenty different accessory carpal ossicles have been described. However, no case of bilateral total second carpal row duplication has ever been reported, associated or not with other general conditions. Case report A 75-years-old woman first presented with pain in the left wrist, located at the base of the fifth metacarpal. The pain was mechanical, slowly progressive over a few months, of low intensity, with no traumatism or inflammation. The wrist mobility was subnormal, no hyper-laxity was noted. In her medical history, she reported a diagnosis of both Marfan and Ehlers-Danlos syndromes in childhood, with no clear medical evidence, no further investigation or follow-up since 1953. A standard X ray first revealed an abnormal number of carpal bones, respecting the global shape of the wrist anatomy. The CT-scan showed a total second row duplication - in each wrist, the trapezium and the trapezoid are each divided in four regular fragments with symmetry in both frontal and sagittal plans. The capitate and the hamatum are each divided in three regular fragments, with a sagittal alignment. No anatomical anomalies were noted regarding the first row. The total count of carpal bones in each wrist was 18. The CT-scan also showed bilateral chondrocalcinosis, with scapho-lunate dislocation on the left side, compatible with a SCAC wrist. The base of the left fifth metacarpal, the only initial clinical complaint of the patient, was articulated with all three hamatum fragments and presented degenerative arthritic changes. Further questioning revealed several ancient articular pains. Old X rays showed an early-onset, severe osteoarthritis of knees and hips with irregular epiphysis. Further imaging investigation showed irregular epiphysis of the elbows, with chronicle left radial head luxation, and bilateral tarsal duplication - each foot has six cuneiform bones, with an axial symmetry, as in the carpus. These clinical and radiological features are compatible with the diagnosis of Multiple Epiphyseal Dysplasia. Conclusion The wrists anomalies we observed in this patient, especially the CT-scan findings, present all the characteristics of bipartite bones, caused by a lack of fusion of the initial ossification centers, or, in this case, quadripartite or tripartite bones. Some syndromes are known to provide carpal malformations, but none were reported causing second row carpal duplication.

Anatomy, feeding ecology, and ontogeny of a transitional baleen whale: a new genus and species of Eomysticetidae (Mammalia: Cetacea) from the Oligocene of New Zealand.

The Eocene history of cetacean evolution is now represented by the expansive fossil record of archaeocetes elucidating major morphofunctional shifts relating to the land to sea transition, but the change from archaeocetes to modern cetaceans is poorly established. New fossil material of the recently recognized family Eomysticetidae from the upper Oligocene Otekaike Limestone includes a new genus and species, Waharoa ruwhenua, represented by skulls and partial skeletons of an adult, juvenile, and a smaller juvenile. Ontogenetic status is confirmed by osteohistology of ribs. Waharoa ruwhenua is characterized by an elongate and narrow rostrum which retains vestigial alveoli and alveolar grooves. Palatal foramina and sulci are present only on the posterior half of the palate. The nasals are elongate, and the bony nares are positioned far anteriorly. Enormous temporal fossae are present adjacent to an elongate and narrow intertemporal region with a sharp sagittal crest. The earbones are characterized by retaining inner and outer posterior pedicles, lacking fused posterior processes, and retaining a separate accessory ossicle. Phylogenetic analysis supports inclusion of Waharoa ruwhenua within a monophyletic Eomysticetidae as the earliest diverging clade of toothless mysticetes. This eomysticetid clade also included Eomysticetus whitmorei, Micromysticetus rothauseni, Tohoraata raekohao, Tokarahia kauaeroa, Tokarahia lophocephalus, and Yamatocetus canaliculatus. Detailed study of ontogenetic change demonstrates postnatal elaboration of the sagittal and nuchal crests, elongation of the intertemporal region, inflation of the zygomatic processes, and an extreme proportional increase in rostral length. Tympanic bullae are nearly full sized during early postnatal ontogeny indicating precocial development of auditory structures, but do increase slightly in size. Positive allometry of the rostrum suggests an ontogenetic change in feeding ecology, from neonatal suckling to a more specialized adult feeding behaviour. Possible absence of baleen anteriorly, a delicate temporomandibular joint with probable synovial capsule, non-laterally deflected coronoid process, and anteroposteriorly expanded palate suggests skim feeding as likely mode of adult feeding for zooplankton. Isotopic data in concert with preservation of young juveniles suggests the continental shelf of Zealandia was an important calving ground for latitudinally migrating Oligocene baleen whales.

The value of SPECT/CT in carpal boss.

To assess the value of SPECT/CT in patients with carpal boss (CB). In 24 wrists with CB (18 right-sided, 6 left-sided) in 21 patients, planar images and SPECT/CT images were obtained. Three patients had bilateral CB. The grade of uptake (0 absent, 1 low, 2 moderate, 3 high) on planar imaging and SPECT/CT was assessed and compared with CT findings, clinical symptoms and follow-up findings. CB affected carpometacarpal joint II in 4 wrists, carpometacarpal joint III in 17 wrists and both carpometacarpal joints II and III in 3 wrists. Of the 24 CB, 12 (50 %) were active (i.e. increased radionuclide uptake) on planar images and 18 (75 %) on SPECT/CT images. Of the 17 symptomatic CB, 10 (59 %) were active on planar images and 14 (82 %) were active (mean grade 1.9, range 1 - 3) on SPECT/CT images. Of the 7 asymptomatic CB, 2 were active on planar images and 4 were active (mean grade 1.25, range 1 - 2) on SPECT/CT images. CT alone showed CB in all patients and an accessory ossicle (os styloideum) in 8 wrists. MR imaging was available in 7 patients and positive for CB in 5 (sensitivity 71 %). Plain radiographs were available in 17 patients and positive in 10 (59 %). Therapeutic infiltration of the CB was performed in 9 patients, and resection of the CB in 7 patients. SPECT/CT provides important morphological and metabolic information for the clinical assessment of CB, but because SPECT/CT tends to overestimate the clinical importance of CB, we recommend that planar images should still be obtained.

Secondary ossification centers in the development of the medial malleolus.

Accessory ossicles of the medial malleolus have been reported, however, these have not been linked to a pattern of development and are considered anomalies. Here, we describe a pattern of ossification of the medial malleolus in children including a secondary ossification center. Twenty anteroposterior (AP) and mortise x-rays of each sex and age from 4 to 12 were randomly selected from skeletally immature patients identified at our institution. X-rays were excluded if there was a cast or splint, fracture, hardware, or obvious tibial deformity. Each x-ray was evaluated and categorized to a 4-part stage of development. These stages were then applied to randomly selected AP hip to ankle films from the same age groups. Four distinct stages of medial malleolus ossification were identified on ankle x-rays. Stage 1 consists of the widening of the epiphysis that did not reach the medial border of the metaphysis. In stage 2, the epiphysis had widened medially to the level of the metaphysis, however, had not extended distally to the level of the dome of the talus. In stage 3, the proximal portion of the medial malleolus has ossified distal to the dome of the talus with ossification centers at this level identified. Stage 4 consisted of a completely fused ossification center extending distally to a mature medial malleolus. The stages were reconfirmed on AP standing hip to ankle to have a similar distribution, secondary ossification centers were more common in females aged 6 to -9 and males aged 8 to 11 years. The medial malleolus develops in predictable stages which may involve a secondary ossification center in the final stages of development. These findings were initially described on AP and mortise views, then confirmed on AP hip to ankle radiographs were evaluated to exclude potentially confounding ankle pain. These secondary ossification centers were seen at similar ages on both ankle and hip to ankle x-rays. Level III.

Accessory ossicles and sesamoid bones: recognition and treatment.

Accessory ossicles and sesamoid bones are normal variants of bone development. In foot and ankle X-rays these bones can appear similar to, or can obscure, fractures, which makes the X-rays difficult to interpret. This article illustrates and describes some of the more common ossicles and sesamoid bones, and provides a brief description of the management of the patients with foot or ankle pain whose X-rays are inconclusive.

Chronic Ankle Pain After An Initial ‘Twisting’ Injury To The Ankle

A 42-year-old woman was admitted to our outpatient clinic with chronic left ankle pain that began after having a twisting ankle injury fifteen days prior. Immediately after the injury, she was admitted to the nearest emergency department and foot radiographs were taken. Lateral and oblique foot radiographs revealed no abnormal findings, and the patient was diagnosed as simple ankle sprain and was treated with anti-inflammatory medications, elastic bandage, rest, and ice. Although the soft tissue swelling subsided gradually, the patient suffered from chronic ankle pain and persistent antalgic gait. On physical examination, there was tenderness over the foot distal and inferior to the anterior talofibular ligament (ATFL). The range of ankle movements was slightly painful and inversion of the ankle produced considerable pain. Neurovascular examination was normal. The initial foot radiographs were available and re-evaluated (Figure 1). Figure 1 (a) Lateral and (b) oblique foot radiographs of the patient. DIAGNOSIS: Fracture of Anterior Superior Process of Calcaneus: A Commonly Missed Fracture A careful examination of the initial lateral foot radiograph raised the suspicion of fracture of the anterior superior process of calcaneus (ASPC) (Figure 2a). Further imaging with computerized tomography (CT) and multiplanar reconstruction confirmed our preliminary diagnosis (Figure 2b, c). Below-knee plaster cast was applied and continued for four weeks, after which a gradual return to full activities was allowed. At the final follow-up six months after the initial injury, the patient was free of pain and was able to return to his previous level of activity. Figure 2 (a) Lateral foot radiograph validated a suspected fracture line at the anterior superior process of calcaneous (black drawing). (b) Sagittal and (c) axial CT demonstrated the fracture (white arrows). Fracture of ASPC is a rare fracture that constitutes 3% of all calcaneal fractures.1, 2 The mechanism of the injury is often an inversion injury with the foot in plantar flexion, similar to simple ankle sprain.1, 2, 3 Because of its infrequency, the similarity between typical history and clinical presentation of an ankle sprain and difficulties in direct radiographic evaluationof the fractures of the ASPC is usually misdiagnosed as ankle sprain at initial emergency visits. On the other hand, early identification and prompt treatment of these moderately seeming fractures may prevent chronic ankle problems as observed in our patient. Therefore, emergency physicians should be aware of this fracture. In order to prevent misdiagnosis, a high level of suspicion and investigation is necessary. Furthermore, the physical examination the tenderest point on palpation should be correctly identified. In the fracture of the ASPC, the tender point is 3–4 cm distal to the lateral malleolar tip over the bifurcate ligament.2, 3 Whereas in ankle sprain of the ATFL is usually tender. [4] In addition to a careful physical examination, a careful examination of the foot radiographs is important. Anteroposterior and lateral foot radiographs should be obtained as the first line imaging work-up. However, complex anatomic structure of the foot and superimposition on direct radiography makes the evaluation difficult causing these fractures may easily be missed. In case of suspicion, computed tomography (CT) is the most useful imaging method to detect and define the extent of the fracture.[4] Sagittal reconstruction best demonstrates the fracture.[3] The os calcaneus secundarius is an uncommon accessory ossicle of the midfoot which is present in the 5% of the normal population.3, 4, 5 However, in the context of foot trauma, this normal anatomic variant may be misdiagnosed as a fracture of the ASPC. Thus, os calcaneus secundarius should be considered in the differential diagnosis of acute fractures of the ASPC. The most important radiographic clue to differentiate an os calcaneus secundarius from an acute fracture is the oval configuration and well-corticated margins.3, 4 Conservative treatment in the form of plaster cast immobilization that last 4 weeks is sufficient for the treatment.1, 4

Morphological variations of the anterior thoracic skeleton and their forensic significance: Radiographic findings in a Spanish autopsy sample

The anterior thoracic skeleton may exhibit a number of morphological variations or anomalies, including accessory ossicles, atypical fusion or nonfusion of bony segments, and accessory foramina. Awareness of these minor skeletal variants is important in forensic medicine given that they may be mistakenly identified as pathological or traumatic lesions. The identification of subtle morphological anomalies may also aid in the process of individualization by serving as points of similarity if their occurrence was recorded antemortem. This study assessed the prevalence of anatomical variants of the sternum and ribs in a modern population from Spain, since the frequency of these skeletal anomalies differs between population groups. The occurrence of sternal clefts and foramina, bifurcated ribs, fusion of the manubriosternal and sternoxiphoidal junctions, and type of xiphoid process end was evaluated on posterior-anterior digital radiographs. None of the morphological variations were associated with sex or age, with the exception of two traits related to the xiphoid process. The xiphoid process was absent more often in younger individuals, particularly specimens below the age of 30 years, whereas, complete fusion of the sternoxiphoidal junction was more often observed in individuals above 50 years of age. However, these morphological variants are highly variable in the study sample and thus they have limited utility in forensic age estimation in the Spanish population. Nonetheless, the presence of various morphological anomalies such as sternal foramina, bifid ribs, and triple-ended xiphoid processes may provide information useful for establishing a personal identification.

Progress in the clinical imaging research of bone diseases on ankle and foot sesamoid bones and accessory ossicles.

Sesamoid bones and accessory ossicles are research focuses of foot and ankle surgery. Pains of the foot and ankle are related to sesamoid bones and accessory ossicles. The specific anatomical and functional relationship of sesamoid bones and accessory ossicles can cause such bone diseases as the dislocation of sesamoid bones and accessory bones, infection, inflammation and necrosis of sesamoid bones, cartilage softening, tenosynovitis of sesamoid bones and the sesamoid bone syndrome. However, these bone diseases are often misdiagnosed or mistreated. In patients with trauma history, relevant diseases of sesamoid bones and accessory ossicles as above mentioned are highly probable to be misdiagnosed as avulsion fractures. In such cases, radiographic findings may provide a basis for clinical diagnosis.

Carpal boss: a sonographic view.

Radiol Bras. 2014 Mar/Abr;47(2):VII Mass on the dorsal aspect of the wrist, either with or without associated pain, is a frequent complaint in orthopedic surgeon daily practice. In such cases, synovial or ganglion cyst is the most common diagnosis, but this is not the only diagnosis for that condition, so it is very important to know the differential diagnoses. Dorsal wrist mass may originate from soft tissues and in such cases the differential diagnoses include ganglion cyst, soft tissue calcifications, tendon sheath giant cell tumor, lipoma and neuroma, amongst other possible small tumors. However, the mass may result from bone changes including small tumors such as osteochondromas, osteomas, degenerative changes with marginal osteophytes and presence of an accessory ossicle such as the os styloideum. Carpal boss is a bone protuberance located adjacent to the base of the second or third metacarpal bone, adjacent to the capitate or to the trapezoid, resulting from degenerative alterations with osteophytes at the base of the second or third metacarpal bone, from the presence of an accessory ossicle (os styloideum), or both. Generally, the symptomatic presentation of this condition, with pain, for example, is observed in individuals at the fourth decade of life, but it may also affect children and adolescents. Although the determination of a bony prominence on the dorsal wrist is subjective and there is no absolute criterion to establish the diagnosis, a study involving cadavers dissection have found bony prominence in 39 out 202 dissected wrists, most frequently between the second metacarpal and the trapezoid bones. Clinical diagnosis may be difficult and imaging methods can give a significant contribution in these cases. Plain radiography is quite useful, but it is important to note that the accessory ossicle is not always clearly seen at conventional or routine wrist radiography, and further imaging in specific planes are required. Due to their sectional nature, computed tomography and magnetic resonance imaging can greatly facilitate the identification of the accessory bone or the degenerative disease. Because of its great soft tissue contrast capability, magnetic resonance imaging can detect alterations in signal with a pattern of edema which may result from biomechanical alterations caused by repeated trauma in association with the presence of symptoms. A brief literature review on PubMed has not identified any study associating the diagnosis of carpal boss with ultrasonography, although this imaging method is frequently utilized to investigate the

Imaging of Tarsal Navicular Disorders

The tarsal navicular is a bone within the midfoot that plays a critical role in maintaining the arch of the foot. This bone is clinically relevant because it may be affected by a wide array of pathologies. Our approach includes a detailed description of the imaging characteristics and disorders affecting the tarsal navicular. Organization includes (a) normal imaging, (b) accessory ossicles, (c) coalition, (d) fractures, (e) Kohler's disease, (f) osteonecrosis, (g) osteochondral lesions, (h) arthropathies, and (i) tumors. The purpose of this article is to discuss normal variants and pathological processes that can affect the tarsal navicular, with emphasis on the often-overlooked imaging findings.

Three-Dimensional CT Findings of Os Calcaneus Secundarius Mimicking a Fracture.

Os calcaneus secundarius is one of several accessory ossicles of the foot that have been identified as normal variants of skeletal development. It may cause ankle pain and may mimic an avulsion fracture of the anterior calcaneal process. A twenty-year-old male was admitted to our institution with right ankle pain following an inversion injury. An axial CT image of the patient's right ankle revealed a shape with smooth and sharp margins, identified as a well-corticated bone fragment in the subtalar region. A diagnosis of an accessory ossicle, os calcaneus secundarius, was made based on radiographic findings. As a result of this case, it is recommended that potential locations of the accessory bones should be well understood in order to prevent misdiagnosis and inappropriate surgical procedures. Os calcaneus secundarius must be considered when an apparent bone fragment or a suspicious fracture line at the anterior region of os calcaneus is demonstrated.

The cyamella, a lost sesamoid: Normal variant or posterolateral corner anomaly?

Cyamella, an accessory sesamoid ossicle of the popliteus in the region of the proximal myotendinous junction, is an extremely unusual finding, with a paucity of current published literature describing its MR appearance. In this case study, we describe MRI findings in a 44-year-old female presenting with pain after a stretching workout. Bone edema in the cyamella, edema in the myotendinous portion of the popliteus, and pericapsular edema at the posterolateral corner were identified. While commonly seen in certain mammalian species, cyamella is rare in humans. The upright walking posture of humans requires posterolateral corner structures to play a greater role in structural support and weight-bearing. We hypothesize that the cyamella, while intrinsic to certain mammalian species, may interfere with these biomechanical functions in upright walking posture, thereby predisposing to isolated injury of the posterolateral corner in humans.

Ossicle in anterior cruciate ligament: a rare occurrence.

The occurrence of an intra-articular ossicle is not rare in the knee, with reports suggesting the existence of meniscal osscile. There are also reports describing the attachment of the posterolateral bundle of the anterior cruciate ligament (ACL) to an accessory ossicle. However, despite an extensive search of the English literature we did not find much written about an intrasubstance ossicle in the ACL. We present the case of a 13-year-old male with an intrasubstance ossicle in the anteromedial bundle of the ACL of his right knee.

Magnetic resonance imaging in adolescent symptomatic navicular tuberosity

The accessory navicular bone is one of the most common accessory ossicles, which sometimes become symptomatic. Abnormalities in magnetic resonance (MR) image, e. g. edema-like bone marrow pattern, have been reported for symptomatic accessory navicular. However, it has not been completely understood the edema-like bone marrow pattern correlates to the symptom of navicular tuberosity. We investigated the edema-like bone marrow pattern in correlation with alleviation of the symptom and the presence of accessory navicular bone. Ten adolescents with pain localized to the navicular tuberosity were recruited and seven cases were further examined with consecutive MR images. Edema-like bone marrow pattern was found in all symptomatic navicular but not in asymptomatic navicular. Intensity of the pattern diminished with alleviation of the symptom. Moreover, this correlation was recognized even in the patients who had no accessory navicular bones. MR images could be used not only for diagnosis but for monitor of healing in adolescent symptomatic navicular. There may be different pathologic mechanism for adolescent symptomatic navicular tuberosity, such as an osteitis, in adolescents.

Sesamoiditis of the cyamella: imaging features of this rare presentation

We report a unique case of sesamoiditis in an extremely rare accessory genicular ossicle. Common to lower primates, the cyamella or popliteus tendon sesamoid bone is usually absent in humans. A 19-year-old male sustained a twisting injury to the right knee and presented with mechanical symptoms of knee pseudo-locking. A plain radiograph of the knee illustrated the presence of a cyamella. Magnetic resonance imaging demonstrated marked bone marrow oedema of this sesamoid structure and in the adjacent popliteus tendon. To our knowledge, documented sesamoiditis of this osseous structure on radiological imaging has not been published in English literature and this case highlights the imaging features of this uncommon entity.