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Orthopedics

Anatomy, Sesamoid Bones

A sesamoid bone is a small bone commonly found embedded within a muscle or tendon near joint surfaces, existing as focal areas of ossification and functioning as a pulley to alleviate stress on that particular muscle or tendon. Unlike standard bones, which connect via joints, sesamoid bones connect to muscles via tendons. The word sesamoid derives from the Arabic word 'sesamum' translating to sesame, given that many sesamoid bones are small. Sesamoid bones are most commonly located in the foot,

v1 · Reviewed Nov 7, 2026 by Automated Clinical Reviewer (Strict Verbatim v1)
  • Injuries to the patella greatly reduce its leverage and extensor capabilities; these injuries commonly result from trauma and increased tension.
  • A lack of sesamoid bone formation often indicates a delay in puberty and can be useful for monitoring its progression.
  • A sesamoid bone is a small bone commonly found embedded within a muscle or tendon near joint surfaces, existing as focal areas of ossification and functioning as a pulley to alleviate stress on that particular muscle or tendon.
  • Sesamoid bones relieve tension within muscles and tendons, allowing for increased weight-bearing and tolerance by redistributing forces throughout a muscle or tendon, thereby protecting them from significant strain and injury.
  • While most sesamoid bones are small, they play a critical role in our body by providing leverage, reducing friction, and enabling our unique biomechanics and distinct range of motion.
  • The body contains many sesamoid bones, often providing added strength to t­­he muscles and supporting tendon stability.
  • In the wrist, the presence of the pisiform bone within the flexor carpi ulnaris tendon has led to debate over whether it is a sesamoid bone or a vestigial bone.
  • In the lower extremities, the patella is found in the knee and is the largest sesamoid bone.
  • Other lower limb sesamoids that can be seen as normal variants in humans include the fabella (often near the lateral head of the gastrocnemius), cyamella (within the popliteus tendon), os peroneum (located within the peroneus longus tendon), and the hallux sesamoid pair (one on the medial and the lateral side of the first metatarsal bone of the foot).
  • Another sesamoid bone within the ear is the lenticular process of the incus, often known as the fourth ossicle of the middle ear.
  • Sesamoid excision has been studied in athletes with a sesamoid bone injury to determine whether their ability was affected.
  • A successful union of a hallux sesamoid fracture is challenging, and a sesamoidectomy was considered to improve outcomes.
  • Often, avascular necrosis of the sesamoid can be managed medically, but ultimately, a sesamoid excision provides complete pain relief and greater patient satisfaction.
  • Whereas a sesamoid bone often posed no significant discomfort or pain, any fracture or injury to a sesamoid bone greatly benefited from excision instead of a union repair.
  • The study showed that about 80% of athletes who underwent a sesamoidectomy could return to sports in 5 months.
  • The study showed that sesamoidectomy provided better pain relief and allowed a return to normal activities within 12 weeks.
  • These bones have a limited blood supply and are susceptible to avascular necrosis, which can lead to complications.
  • The proximity of nerves to sesamoid bones can create clinical complications.
  • Any fracture to the pisiform bone is associated with ulnar nerve compression and complications.
  • Similarly, a case of os peroneum fracture has been shown to cause sural nerve entrapment.
  • The presence of the fibula near the gastrocnemius can lead to common fibular nerve palsy, requiring a possible fibullectomy if symptoms persist despite conservative management.
  • Without the patella, knee joint instability, reduced range of motion, and difficulty straightening the leg would be common problems.
  • review
    Anatomy, Sesamoid Bones. StatPearls [Internet] — Anthony Y. Yeung, Tafline C. Arbor, Dr. Rohin Garg — StatPearls Publishing, 2023

Decision support only. Verify against local protocols and current labeling. Source: www.ncbi.nlm.nih.gov