Accessory ossicles and sesamoid bones of the ankle and foot: imaging findings, clinical significance and differential diagnosis

Accessory ossicles and sesamoid bones are frequent findings in routine radiographs of the ankle and foot. They are commonly considered fortuitous and unrelated to the patient's complaint; however, they may eventually cause painful syndromes or degenerative changes in response to overuse and trauma. They may also suffer or simulate fractures. Our aim was to review, illustrate and discuss the imaging findings of some of the more frequent accessory ossicles and sesamoid bones of the ankle and foot region, with particular emphasis on those that may be of clinical significance or simulate fractures.     

Os peroneum friction syndrome complicated by sesamoid fatigue fracture: a new radiological diagnosis?

Injuries to the peroneal tendons are relatively common worldwide but tendon rupture without significant trauma is uncommon. Ankle mechanics can be seriously affected by disruption of one or both of the peroneal tendons although complete rupture can also remain asymptomatic. Accessory ossicles are sesamoid bones and are common findings in routine radiology of the foot and ankle. Although in the vast majority these "os" are normal variants of anatomy, they can lead to painful syndromes and suffer fractures and even undergo degenerative changes in response to overuse and trauma. Although similar syndromes have been discussed in the surgical literature, there is a lack of literature describing the use of modern imaging in the accurate diagnosis and its subsequent assistance towards appropriate management of os peroneum friction syndrome complicated by sesamoid fatigue syndrome. This article presents the plain film, sonographic and magnetic resonance imaging findings in a case of os peroneum friction syndrome complicated by a sesamoid fatigue fracture as well as reviewing the pertinent literature.     

Painful accessory bones of the foot

Sesamoid bones and secondary centers of ossification account for the accessory bones of the foot, and there is a wide range of frequency with which these different ossicles appear. They are usually incidental asymptomatic findings on imaging studies, and their clinical importance lies in not mistaking them for fractures. Occasionally these ossicles can become painful due to fracture, degenerative changes, avascular necrosis, and irritation or impingement of adjacent soft tissue.     

Overuse of concomitant foot radiographic series in patients sustaining minor ankle injuries

Radiographic series of the foot are often obtained in conjunction with ankle X-rays when the clinical presentation is limited to trauma to the ankle. The Ottawa Ankle and Foot Rules were established in 1992 and serve as reliable guidelines to determine when an ankle or foot series is warranted in patients who have sustained minor ankle and/or foot injury. We retrospectively reviewed radiographic studies of all patients over a period of 18 months who simultaneously had ankle and foot plain radiographs performed for acute complaints limited to the ankle alone. Of the 243 patients who met our inclusion criteria, 55 patients had fractures, 46 in or near the ankle joint, and nine which were located at the base of the fifth metatarsal bone. No fractures or dislocations were noted elsewhere in the foot. All of the fifth metatarsal fractures were evident on adequately performed ankle series. Our findings suggest that films of the foot are not necessary when trauma is limited to the ankle and when an appropriately performed ankle series has been completed.     

Os cuboideum secundarium: A rare accessory ossicle with the potential to mimic a mass on magnetic resonance imaging

Accessory ossicles are common incidental findings on radiographs of the ankle and foot. While typically asymptomatic and of no clinical significance, they are sometimes associated with local pain or even mistaken for pathological conditions such as fractures. Given the potential for misinterpretation, it is important to understand their typical locations and appearances. This case highlights an exceptionally rare accessory ossicle called the os cuboideum secundarium, located adjacent to the cuboid and calcaneus. Interestingly, this case demonstrates the potential for this rare ossicle to mimic a mass on magnetic resonance imaging (MRI). Furthermore, despite the significant improvements in the understanding of musculoskeletal pathology afforded by advancements in cross-sectional imaging techniques, this case is a reminder of certain pitfalls that remain. Lastly, it highlights the importance of radiographs as an initial diagnostic study in evaluating foot pain.     

Ankle and foot injuries: analysis of MDCT findings

OBJECTIVE: The purpose of our study was to assess MDCT findings and the advantages of MDCT compared with radiography in patients referred to a level 1 trauma center for diagnostic evaluation of acute ankle and foot trauma. MATERIALS AND METHODS: During a period of 37 months, 388 patients underwent MDCT of the ankle and foot due to an acute trauma. Imaging studies (MDCT and radiography) were retrospectively reevaluated with respect to fracture location, fracture type, and mechanism of injury, and findings from the primary radiographs of the ankle and foot were compared with MDCT findings. RESULTS: Of the 388 patients, 344 (89%) had one or more fractures in the ankle or foot. A total of 517 fractures were found in all anatomic regions: ankle, calcaneus, talus, midfoot, and forefoot. The three most common occult fractures in the ankle not detected on primary radiography were isolated fractures of the posterior and medial malleolus and Tillaux fractures. The calcaneus was the most commonly fractured bone, and the sensitivity of radiography in the detection of calcaneal fractures was 87%. The sensitivity of radiography in the detection of talar fractures was 78%, whereas it was only 25-33% in the detection of midfoot fractures. A Lisfranc fracture-dislocation was not detected on primary radiography in five (24%) of 21 cases. The three main injury mechanisms were falling from a height (164 patients [48%]), a simple fall (68 patients [20%]), and a traffic accident (47 patients [14%]). CONCLUSION: In patients with injuries from high-energy polytrauma and in those with complex ankle and foot fractures, the sensitivity of radiography is only moderate to poor; in these cases, MDCT is recommended as the primary imaging technique.     

Injuries to dancers. Prevalence, treatment and prevention

Studies from the USA and UK indicate that the back, neck and shoulder and the lower limb (particularly the hip, knee, ankle and foot) are the most frequent sites of injury among dancers. Most injuries are soft tissue injuries. Most dancers experience injuries at some time and about half have chronic injuries. Shoulder injuries appear to be caused by frequent or unaccustomed lifting, and are treated by rest and oral anti-inflammatory medication. Back injuries include sprains, prolapsed or herniated intervertebral discs, and spondylolytic stress fractures. Several risk factors, especially training error, have been identified for overuse injuries. Hip injuries include degenerative changes and osteoarthritis, stress fractures, bursitis and damage to the sciatic nerve. The most common foot injury is an anterior lateral ligament sprain, which may lead to permanent instability in the ankle. More soundly based research into the prevalence, diagnosis and treatment of injuries is needed.     

趾短伸肌性跟骨撕脱骨折

趾短伸肌性跟骨撕脱骨折实际并非罕见，但由于骨折片较薄、较小，易被血肿遮盖而误诊为“扭伤”、“籽骨”或其他骨折，影响及时治疗，应引起重视。本文结合收治的5例，对其损伤机理，诊断和治疗作了分析讨论。     

Troublesome stress fractures of the foot and ankle

Athletes engaged in repetitive activity with recent increases in training or competition are at risk for stress fractures of the foot and ankle. Physical and radiographic findings are often unremarkable and diagnosis may be difficult. Although many of these injuries may be managed symptomatically, certain types of stress fractures are at higher risk for delayed union, nonunion, or refracture without aggressive immobilization or surgical fixation.     

Detecting and Treating Common Foot and Ankle

Midfoot and forefoot fractures commonly seen in a primary care practice include navicular and metatarsal stress fracture, tarsometatarsal fracture-dislocation, and acute fracture of the metatarsals, sesamoid, great toe, or lesser toes. A careful history to determine the mechanism of injury and a methodical physical exam to detect sites of tenderness are essential. X-rays are usually required, but stress fractures may warrant bone scans. Compared with ankle and hindfoot fractures, sports-related midfoot and forefoot fractures are more often treated conservatively with casting or wooden shoes. Tarsometatarsal disruption and Jones fractures are more likely to require surgery.     

多层螺旋CT多平面重建与容积再现评价足部骨折

目的探讨多层螺旋CT多平面重建（MPR）及三维容积重建（3DVR）在足部及踝关节创伤性骨折中的诊断价值。方法对35例临床考虑足踝创伤性骨折患者行16层螺旋CT（3～5mm）薄层扫描与多平面重建。结果CT扫描显示本组35例骨折部位包括跟骨25例，跖骨4例，内踝2例，外踝1例，骰骨1例，舟骨2例，距骨1例，胫骨下端2例。多平面重建能准确显示关节受累范围及骨折内部骨碎块大小及移位程度，三维重建在显示骨折的空间关系上具有优势。结论多层螺旋CT重建技术在足部及踝关节骨折的诊断中具有非常高的应用价值，其与轴位CT图像相结合，能为临床医生制定手术方案提供全面、准确的依据。     

Imaging patterns of lower extremity injuries in victims of intimate partner violence (IPV)

Purpose

To describe the pattern and distribution of lower extremity injuries in victims of intimate partner violence (IPV).

Materials and methods

A retrospective radiological review of 688 patients reporting IPV to our institution’s violence intervention and prevention program between January 2013 and June 2018 identified 88 patients with 154 lower extremity injuries. All lower extremity injuries visible on radiological studies were analyzed. Concomitant, recurrent, and associated injuries were also collected, in addition to the demographic data.

Results

The injuries consisted of 103 fractures, 46 soft tissue injuries, and 5 dislocations. The foot was the most common site of injury representing 39% (60/154) of total injuries, 48% (49/103) of fractures, 17% (8/46) of soft tissue injuries, and 3 dislocations. The ankle was the second most common site of injury representing 30% (47/154) of total injuries, 20% (21/103) of fractures, and 57% (26/46) of soft tissue injuries. Recurrent injuries of the lower extremity were seen in 30% (26/88) of victims who had 74 recurrent injuries. The most common sites of recurrent injury were the foot and ankle, representing 72% (53/74) of recurrent injuries.

Conclusion

Recurrent injuries of the foot and ankle, synchronous craniofacial injuries, and upper extremity injuries in young women (<35 years) should prompt radiologists to consider IPV.

     

Three-dimensional computed tomography of the foot: optimizing the image

The complex anatomy of the foot can be imaged using high resolution computed tomography. High resolution serial nonoverlapping CT scans of foot anatomy have a high degree of soft tissue contrast, and excellent geometrical accuracy (no magnification error). Three-dimensional surface reconstruction from CT scans of the foot were performed using specially developed computer software. These surface reconstructions display the osseous and soft tissue anatomy of the foot in a form similar to anatomic preparations. The removal of overlying skin, disarticulation of the ankle, tarsals and metatarsals was accomplished using computer methods. Major factors necessary to optimize three-dimensional images are presented and illustrated. The technique has been applied in living subjects with arthritis, carpal coalitions, osteochondritis dissecans, and fractures. These images have been useful in communicating the findings on high resolution CT scans to referring clinicians, correlating CT findings in areas of complex anatomy, and eliminating overlying or obscuring structures by mathematically disarticulating the foot and individual tarsal bones.     

Stress fractures in athletes

During the 14-year period of 1971-1985, 368 stress fractures in 324 athletes were treated. The series contained 268 fractures in males and 100 fractures in females; 32 fractures occurred in children (less than 16 years), 117 in adolescents (16-19 years), and 219 in adults. Forty-six fractures were incurred by athletes at an international level, 274 by athletes at a national or district level and 48 by recreational athletes. Of the total cases, 72% occurred to runners and a further 12% to athletes in other sports after running exercises. The distribution of the stress fractures by site was: tibia 182, metatarsal bones 73, fibula 44, big toe sesamoid bones 15, femoral shaft 14, femoral neck 9, tarsal navicular 9, pelvis 7, olecranon 5 and other bones 10. Of the total fractures, 342 were treated conservatively and 26 fractures required surgical treatment. The operative indication was dislocation in 5 cases and delayed union/nonunion in 21 cases. The sites most often affected by delayed union were: anterior midtibia, sesamoid bones of the big toe, base of the fifth metatarsal, olecranon, and tarsal navicular. The athletes at an international level experienced the greatest risk of multiple separate fractures, protracted healing, or fractures requiring surgery.     

Computed tomography (CT) of fractures of the ankle and foot: correlating fracture patterns with the presence of tenosynovial fat: Tenosynovial fat in ankle and foot fractures

PurposeTo correlate ankle and foot fracture patterns with the presence of tenosynovial fat on computed tomography (CT).Materials and MethodsIn this retrospective, cross-sectional, observation study, two blinded musculoskeletal radiologists independently reviewed 89 CT scans of patients with ankle or foot fractures and recorded the presence of fat about Henry’s knot, tibialis posterior tendon, and peroneus longus tendon.ResultsThe agreement between the two readers ranged from excellent to substantial. Sixteen to 23 percent of fractures were associated with tenosynovial fat.ConclusionsThe finding of tenosynovial fat following ankle or foot trauma warrants a closer search for a fracture.     

Imaging of the symptomatic type II accessory navicular bone

Accessory ossicles of the foot are commonly mistaken for fractures. The accessory navicular is one of the most common accessory ossicles of the foot. There is a higher incidence in women and the finding might be bilateral in 50-90%. This entity is usually asymptomatic, although populations with medial foot pain have a higher prevalence. Three types of accessory navicular bone have been described. The type II accessory navicular is the most commonly symptomatic variant with localized chronic or acute on chronic medial foot pain and tenderness with associated inflammation of overlying soft tissues. Plain radiographic identification of the accessory navicular is insufficient to attribute symptomatology. Ultrasound allows for comparison with the asymptomatic side and localization of pain. Bone scintigraphy has a high sensitivity but positive findings lack specificity. Magnetic resonance imaging is of high diagnostic value for demonstrating both bone marrow and soft tissue oedema.     

足副舟骨扭伤的影像学特征

目的总结51例足副舟骨DR摄影的影像学特征。方法 51例患者均有足副舟骨扭伤史。均摄患足X线足正位和外斜位片,其中21例加照对侧足外斜位以鉴别骨折。结果 51例足副舟骨影像学表现较多样,主要分3型:Ⅰ型为圆形或卵圆形籽骨27例(52.9%),与舟骨完全分离;Ⅱ型与足舟骨通过纤维软骨或软骨相连21例(41.2%);Ⅲ型也称舟骨角型3例(5.9%)。Ⅰ型和Ⅲ型足副舟骨影像学表现清晰,而Ⅱ型影像学表现复杂,不易确诊。结论足副舟骨的影像学表现较复杂多样,尤其Ⅱ型足副舟骨的X线表现易误诊为骨折,需加照健侧副舟骨以鉴别骨折,必要时行CT、MRI或核素扫描以确诊。足正位和外侧斜位可以清晰显示舟骨结节和副舟骨之间的关系,可以作为足副舟骨影像学检查的首选方法。