foot and ankle blog

August 18, 2009

Fibular sesamoidectomy – pros and cons

Sesamoid fracture

Sesamoid fracture

I just got out of surgery after performing a fibular sesamoidectomy.  In this particular case, the sesamoid had been fractured some 15 years ago and had progressively become necrotic secondary to avascular necrosis (AVN).  In this patient’s case, he is an active runner and hasn’t been able to run in the past two years due to sesamoid pain.  I thought it might be timely to address the pros and cons of a procedure known as a fibular sesamoidectomy.

The fibular sesamoid is one of two sesamoid bones found on the bottom or plantar aspect of the great toe joint (first metatarsal phalangeal joint).  A good way to describe the two sesamoid bones is to compare them to the knee cap (patella).  Each of the sesamoids are used to facilitate the transfer of force (pulling force called traction) generated by a muscle and tendon.  And this transfer of force is around a corner.  In the case of the knee, the quadriceps muscle and patellar tendon use the patella to change direction at the level of the knee.  The same holds true for the sesamoids.  The extensor hallucis brevis (EHB) tendon originates on the bottom of the heel.  The distal tendons (2) of the EHB inset into the base of the proximal phalanx of the great toe.  As the great toe bends, the sesamoids are used to facilitate the transfer of load beneath the great toe joint.

The two most common injuries of the sesamoids are fractures and AVN.  The literature varies in regards to the success of conservative care for sesamoid fractures.  The literature is consistent in the success rate of treating sesamoid AVN noting that the success rate is poor.

The outcome of sesamoid fractures varies due to a number of contributing factors.  Those factors include the patient’s general health and ability to heal, activities to which the patient wishes to return to, the extent of the fracture and the patient’s age.  Many sesamoid fractures will go on to form a fibrous union that is not truly bone, but is structurally sufficient to support load applied to the fracture site.  And in a small percentage of patient, the fracture results in degenerative change of the dorsal articular surface of the sesamoid.  This degenerative change in the cartilage is called chondromalacia and result in pain with weight bearing.

Excision of the fibular sesamoid is typically a reliable procedure reserved for folks who fail to respond to conservative post fracture.  Once healed, the balance of the three tendons that pull on the plantar aspect of the great toe is weakened subsequent to the excision of the fibular sesamoid.  But in the great majority of cases, the balance is sufficient to maintain a stable great toe joint.

Granted, no one wants to be faced with the decision to have a fibular sesamoidectomy, but out goal with my patient today is to have him non-weight bearing for 3 weeks.  This is customary during the first few weeks of healing with a plantar incision.  Pedestrian activities will follow for 3 weeks and hopefully we’ll see this patient back and running at about 8 weeks post-op.

Jeffrey A. Oster, DPM
Medical Director


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