Sesamoiditis

Sesamoiditis

A complaint by distance runners or running based sports seen less commonly in the clinical environment is medial forefoot pain on the metatarsal head otherwise known as sesamoiditis. This is generally acutely painful with a short build up bought on by increases in load through the forefoot, typically volume, intensity and sprint type work including hill sprints.

The sesamoid bones are actually two small bones embedded within the tendon of the flexor hallicus longus (tendon that inserts underneath the great toe). The function is to increase the mechanical advantage during great toe extension acting as a fulcrum.

Under normal circumstances the forefoot spreads the load over the foot including the plantar fascia and also absorbs load through the fat pad covering the ‘ball of the foot’. There are several reasons this injury may present such as;

·      Increase in volume

·      Increase in intensity

·      Increase in hill sprints (forefoot load)

·      Increased pronation

·      Valgus great toe

·      Decreased great toe extension

·      Decreased dorsiflexion

·      Pelvic instability – causing changes in the foot strike

Fig 1. Location of the two sesamoid bones, overuse can cause friction between the tendon bone interface or between the bones themselves.

Treatment

Addressing the factors that promote dysfunction or increase the load on this area is paramount. As usual addressing the symptom alone is a poor choice of treatment, hence outcome.

Soft tissue therapy to areas of focal thickening in the calf and joint mobilization addressing portions of stiffness in the ankle and first MTP (metatarsophalangeal joint) are often helpful.

Pelvic positioning and firing of pelvic stabilisers often addresses foot position decreasing load on the area Runners who overstride and attempt to land on the mid to forefoot (as is all the rage at the moment) are at risk of increased eccentric load over a longer period with increased ground contact times.

Anti-inflammatories may be helpful in the short term after the initial acute inflammatory process has calmed down. A period of 3-5 days often provides a benefit where further treatment can progress. It is contraindicated to treat a joint or an area that is acutely inflamed. A small donut shaped foam padding may decrease pressure on the forefoot allowing the joint to settle down.

Taping the great toe out of valgus and applying soft tissue treatment to flexor hallucis brevis and abductor hallucis (these are small intrinsic muscles in the mid to forefoot) often allows the joint to improve mobility and helps to re-educate the toe position.

Fig 2. A valgus toe angle may represent changes in hip stability further up the kinetic chain. This places undue strain on the medial joint capsule and further loads the sesamoids.

Modifying the training load including speed work and hill efforts should be a consideration with a gradual build up on return.

Prognosis

If caught early and with the appropriate treatment a successful outcome is often the case. In recalcitrant cases and after 6 months of conservative treatment further investigation may be warranted.

Jimmy