Sesamoid problems

Last evidence check May 2011.

Pain related to the great toe sesamoids is uncommon in a general foot and ankle practice, but may be commoner where there is a large sports medicine component to the practice.

The hallux MTP sesamoids are embedded in the tendons of flexor hallucis brevis. They are subjected to the stresses of muscle contraction and MTP joint movement, and also to ground reaction force.

Pathology

Figures for the prevalence of symptomatic and asymptomatic multipartite sesamoids vary widely, from 3-33%. Prieskorn et al found bipartite sesamoids in 13.5% of 200 feet, bilateral in 34% of these. The tibial sesamoid was bipartite ten times more often than the fibular.

Sesamoid problems are commoner in athletes of any age. The tibial sesamoid is the commoner source of pain.

The main pathologies include:

Clinical features

Patients usually complain of pain under the 1st MTP joint and can often localise it, usually to the tibial sesamoid, with a finger. However, the problem may be referred with a much more vague label, such as “bunion”, “arthritis” or “metatarsalgia” because the referring clinician is not aware of the entity of sesamoid pain.

There is often a history of dorsiflexion or local impact trauma or a change in activity leading to greater forefoot loading. However, some patients have a spontaneous onset of pain. It is also important to ask about systemic arthropathy and neurological disease including peripheral neuropathy.

Examination may show a plantarflexed first ray, with or without an overall cavus deformity. If so, a neurological examination should be carried out. Sesamoid problems may be commoner in patients with hallux valgus. There may be evidence of degenerative change throughout the MTP joint (hallux rigidus). A callus is often present under the MT head.

There is usually point tenderness over the affected sesamoid which may be exacerbated by compression or friction against the metatarsal head. Allen et al (2001) described an axial compression test to reproduce symptoms. The sensitivity and specificity of this test have not been measured.

Investigation

Generalised arthropathy may require appropriate investigation. Otherwise, imaging techniques are the main investigations.

Standing AP and lateral forefoot films show bipartite sesamoids and OA, but a better view is usually obtained with an axial skyline view of the sesamoids with the MTPJ in dorsiflexion. An isotope bone scan will usually show a stress fracture and may be more accurate than an MR, although there is no real comparative data. MR will show articular problems in the MTP joint and any soft tissue element to the problem, but this is often not relevant.

Management

A few patients may need only explanation and simple advice about shoes and analgesia. Most respond well to an insole with a cut-out or pad (Axe and Ray 1988), or a modified rocker shoe (Rosenfield and Trepman 2000). An injection of local anaesthetic and depot steroid into the sesamoid-metatarsal joint may also be useful.

Only a few patients will have continuing problems after orthotic treatment, and surgery may be offered to these patients. Surgical options include: