Inflammation and swelling of the peri-sesamoid structures – position of sesamoid bones make them prone to injury, especially during the repetitive loading during sporting activities.
Generally considered to be an ‘overuse’ type of problem.
More common in feet with plantarflexed first ray/forefoot valgus and a limited range of motion at the midtarsal joint (cavus feet).
Painful/aching on walking. Local tenderness to palpation. May have limitation of first MPJ motion. May be painful on dorsiflexion against resistance. May be thickening or inflammation of a bursa on the plantar surface. X-rays are generally normal.
Peroneal tendonitis may develop due to changes in gait from the pain.
Correct diagnosis is crucial (see below). Treat inflammation – RICE; Activity modification; NSAID’s; Low heel shoes; strapping to prevent first MPJ dorsiflexion; manipulation/mobilisation of first ray; physical therapy; accommodative padding on the foot (Dancers pad); accommodative insole/orthoses (inverting orthoses can improve MPJ function and relieve pressure); soft top cover on orthoses; rocker sole shoe; below knee casts for intractable cases; proper biomechanical control considered important to prevent recurrence, especially if patient has a plantarflexed first ray – rearfoot will need inverting to help offload the medial column;
Surgical – removal
– shaving a prominent sesamoid
Other Causes of Sesamoid Pain
Osteoarthritis may occur in the sesamoid articulation. Erosion of cartilage in case of sesamoid chrondomalacia have been reported and may be an early stage of osteoarthritis. Swelling is often present on examination. MPJ motion may be restricted; pain on palpation and forced dorsiflexion of the joint. On x-ray there may be osteophytes, non-uniform loss of joint space, subchondral sclerosis, and a flattening of a portion of the sesamoid bones.
Rheumatoid arthritis typically causes bone resorption and erosions, uniform joint space narrowing and soft tissue swelling
Gout may also affect the joint
Osteomyelitis may occur following a puncture wound.
The digital nerves in the region of the sesamoid may be impinged and the pain may be difficult to differentiate from localised sesamoid pain. A positive Tinel’s sign and decreased sensation may be present. Surgical excision may be needed.
Bipartite Sesamoids and Fractures:
Reports of the prevalence of bipartite sesamoids ranges from 6% to 30%, with most being medial sesamoids. Medial sesamoids can be in up to 4 parts, but it is rare for lateral sesamoids to be in more than 2 parts. Fractures are rare and it is often difficult to differentiate a fracture from bipartite sesamoids.
A painful bipartite sesamoid will often be related to minor trauma with gradual onset, whereas a fracture will have an acute onset. Fractures are more likely to involve the medial sesamoid.
Bone scintigraphy may distinguish between a fracture and other causes.
Fractures will need 4-8 weeks of immobilisation.
Stress fractures can occur in the sesamoids can occur. Onset will be gradual. X-rays will generally be negative and bone scintigraphy may be positive.
Osteochondritis/avascular necrosis/Treve’s disease:
Characterised by pain, tenderness to palpation and osseous mottling or fragmentation on x-ray. The cause is unclear, may be post-traumatic. MRI will show low marrow signal intensity. Management is immobilisation for 4-8 weeks. May need surgical excision if conservative management is ineffective.
Callus beneath the metatarsal head can cause pain in the region and may co-exist with a sesamoid problem.
Flexor Hallucis Longus Tendonitis:
The tendon may become inflamed in the region of the sesamoids. It is more common in ballet dancers, due to the forced range of dorsiflexion of the first MPJ during some positions. Physical therapy modalities are much more effective for FHL tendonitis (not so effective against sesamoiditis).
Myofascial pain syndrome:
Pain referred to sesamoid area from trigger point in intrinsic muscles
“Sesamoiditis is most of the associated with inhibition of the peroneals longus. Manipulation of the ankle and cuboid can often create immediate relief.”