From the Guidelines
A sesamoid bone is a small, rounded bone embedded within a tendon or joint capsule, functioning like a pulley to increase mechanical advantage and protect tendons from wear and tear. The most well-known example is the patella (kneecap), but sesamoid bones also commonly occur in the hands and feet, particularly under the first metatarsal bone in the foot 1. These bones develop in response to mechanical stress and can vary in number between individuals. Problems with sesamoid bones include sesamoiditis (inflammation), fractures, and dislocation, which typically cause localized pain and difficulty with movement.
Some key points to consider about sesamoid bones include:
- They can be affected by various conditions, such as fractures, acute and chronic stress-related changes, and sesamoiditis, which can be diagnosed using imaging modalities like MRI 1 and CT scans 1.
- Sesamoid bones play a crucial role in reducing friction and distributing pressure, thereby improving muscle efficiency.
- Activities involving repetitive pressure on the affected area, such as ballet dancing or running, can put particular stress on the sesamoid bones in the feet, leading to increased risk of problems like sesamoiditis and fractures.
- Imaging modalities like bone scintigraphy with single-photon emission computed tomography (SPECT)/CT can be useful in assessing pathologic conditions affecting the first metatarsal sesamoids, including sesamoiditis, inflammatory or deposition arthropathies, osteoarthritis, and osteonecrosis 1.
In terms of diagnosis and management, it is essential to use the most appropriate imaging modality, such as MRI or CT scans, to accurately diagnose and manage conditions affecting the sesamoid bones. This can help improve outcomes and reduce morbidity, mortality, and impact on quality of life.
From the Research
Definition of Sesamoid Bone
- A sesamoid bone is a type of bone that is embedded within a tendon or a muscle, and is typically found in areas where a tendon or muscle passes over a joint 2, 3.
- The patella, also known as the kneecap, is the largest sesamoid bone in the body and plays a crucial role in the knee joint, improving output force and velocity of the knee extensors 2, 3.
Characteristics of Sesamoid Bones
- Sesamoid bones have a unique microanatomy, with a spongiosa surrounded by a compact cortex 3.
- The trabeculae in sesamoid bones are oriented in a specific way to withstand stresses and maintain the bone's position against the surrounding joint 3.
- Sesamoid bones can vary in size, shape, and structure among different species and individuals, reflecting adaptations to different functional constraints 3.