A fracture of the small bones beneath the big toe joint, known as the sesamoids, is a specific and painful foot injury. These tiny bones bear significant weight with every step, so an injury severely impacts mobility. A fracture often causes sharp, deep pain at the ball of the foot. Understanding the role of these bones and the consequences of the injury is the first step toward proper recovery.
Understanding the Sesamoid Bones
The sesamoids are two small, pea-shaped bones located on the underside of the forefoot, directly beneath the head of the first metatarsal bone. These bones are unique because they are embedded within a tendon, rather than being connected to other bones by a joint. This arrangement allows the sesamoids to act as a pulley system, increasing the leverage for the tendons that move the big toe.
The sesamoids are a weight-bearing surface, absorbing the force placed on the ball of the foot during walking, running, and jumping. They help the big toe move normally and provide the mechanical advantage needed for the “push-off” phase of the gait cycle. Since they are constantly subjected to high forces, they are vulnerable to injury, including acute fractures from trauma or chronic stress fractures from overuse.
The Immediate Answer: Walking After Injury
While it is physically possible to bear weight on a foot with a broken sesamoid, it is inadvisable and causes intense pain. The fractured bone is situated directly in the path of maximum force when the foot pushes off the ground, causing a deep, sharp ache with each step. Continuing to walk places tremendous stress on the compromised bone fragments and the surrounding tendons and joint capsule.
Continued pressure can lead to further displacement of the fracture fragments, complicating the healing process. Repeated impact can also impair the blood supply to the sesamoid, creating a risk of avascular necrosis, or the death of bone tissue. Medical professionals recommend immediate rest and non-weight bearing until a proper diagnosis is made. This initial step protects the fracture site from additional trauma and allows for effective healing.
Identifying Signs of a Sesamoid Fracture
A sesamoid fracture is often distinguished from sesamoiditis by the nature of the pain’s onset. An acute fracture causes immediate, sharp pain following a specific trauma, such as a fall or hard landing on the ball of the foot. The pain is highly localized to the area directly beneath the big toe joint.
Bruising and noticeable swelling around the ball of the foot are often present, especially with an acute fracture. A key symptom is difficulty or pain when trying to bend or straighten the big toe. The pain from a fracture is more intense and sudden than the gradual, dull ache characteristic of sesamoiditis, which is inflammation.
Necessary Steps for Diagnosis and Treatment
A medical professional begins diagnosis with a physical examination, checking for localized tenderness and evaluating the range of motion in the big toe. Imaging studies are necessary to confirm a fracture and rule out other conditions. Standard X-rays are the first step, though they can be inconclusive due to the small size of the bones or if the individual has a naturally divided (bipartite) sesamoid bone.
If the diagnosis remains unclear, a bone scan or MRI may be used to identify subtle stress fractures or issues with blood flow. Treatment for a sesamoid fracture is usually non-surgical, beginning with immobilization to take pressure off the injured site. This often involves wearing a stiff-soled shoe, a walking boot, or a short leg-fracture brace for several weeks.
Non-weight bearing may be required for six to twelve weeks to allow the bone fragments to heal. If conservative management fails to relieve pain or if the fracture fragments are severely displaced, surgery may be considered as a last resort. This procedure, known as a sesamoidectomy, involves the partial or complete removal of the fractured bone. Surgeons are cautious with this approach because removing a sesamoid can affect the biomechanics and strength of the big toe joint.