Book contents
- Frontmatter
- Contents
- List of contributors
- Preface
- Acknowledgments
- Section 1 Brain, head, and neck
- Section 2 Spine
- Section 3 Thorax
- Section 4 Cardiovascular
- Section 5 Abdomen
- Section 6 Pelvis
- Section 7 Musculoskeletal
- Case 78 Pseudofracture from motion artifact
- Case 79 Mach effect
- Case 80 Foreign bodies not visible on radiographs
- Case 81 Accessory ossicles
- Case 82 Fat pad interpretation
- Case 83 Posterior shoulder dislocation
- Case 84 Easily missed fractures in thoracic trauma
- Case 85 Sesamoids and bipartite patella
- Case 86 Subtle knee fractures
- Case 87 Lateral condylar notch sign
- Case 88 Easily missed fractures of the foot and ankle
- Section 8 Pediatrics
- Index
- References
Case 85 - Sesamoids and bipartite patella
from Section 7 - Musculoskeletal
Published online by Cambridge University Press: 05 March 2013
- Frontmatter
- Contents
- List of contributors
- Preface
- Acknowledgments
- Section 1 Brain, head, and neck
- Section 2 Spine
- Section 3 Thorax
- Section 4 Cardiovascular
- Section 5 Abdomen
- Section 6 Pelvis
- Section 7 Musculoskeletal
- Case 78 Pseudofracture from motion artifact
- Case 79 Mach effect
- Case 80 Foreign bodies not visible on radiographs
- Case 81 Accessory ossicles
- Case 82 Fat pad interpretation
- Case 83 Posterior shoulder dislocation
- Case 84 Easily missed fractures in thoracic trauma
- Case 85 Sesamoids and bipartite patella
- Case 86 Subtle knee fractures
- Case 87 Lateral condylar notch sign
- Case 88 Easily missed fractures of the foot and ankle
- Section 8 Pediatrics
- Index
- References
Summary
Imaging description
There are several sesamoid bones that we expect to see in most, if not all, patients, as well as other variants that may also be detected. The largest and best known sesamoid bone is the patella, which is part of the extensor mechanism of the knee (Figures 85.1–85.4).
In the foot, there are typically two first hallux sesamoid bones within the two heads of the flexor hallucis brevis tendon, forming part of the first metatarsophalangeal joint capsule along the plantar surface of the first metatarsal head (Figures 85.5–85.9) [1]. The tibial sesamoid is medial and the fibular sesamoid lies laterally. Additionally, the os peroneum may be seen along the lateral aspect of the midfoot within the distal peroneus longus tendon (Figures 85.10–85.12).
Each hand typically has five sesamoid bones: two at the first metacarpophalangeal (MCP) joint, one each at the second and fifth MCP joints, and one at the first interphalangeal joint (Figures 85.13 and 85.14).
Importance
Sesamoids are accessory ossific structures that are contained within a tendon or joint capsule and reduce friction during flexion and extension as they slide over adjacent structures. In distinction to accessory ossicles, sesamoids form from their own ossification center. Like accessory ossicles, the importance of sesamoids is recognizing their normal and variant appearances that maybe mimic or hide acute pathology.
- Type
- Chapter
- Information
- Pearls and Pitfalls in Emergency RadiologyVariants and Other Difficult Diagnoses, pp. 303 - 308Publisher: Cambridge University PressPrint publication year: 2013