Lesser Toe Deformity
The smaller toes of the foot can sometimes deform in a number of ways. Depending on the underlying cause and pattern of deformity they can fall into one of three categories:
Claw toe is usually not isolated with several toes being affected. The underlying cause can be due to a neuromuscular disorder.
Hammer toes are the most common lesser toe deformity and occur as a result of mechanical overload of the plantar soft tissue restraints of the main lesser toe joint, the metatarsophalangeal joint (MTPJ). It can occur in conjunction with a hallux valgus or 'bunion' or any condition giving rise to forefoot overload.
Mallet toe is more unusual and describes the deformity when only the terminal phalanx appears flexed usually due to rupture of the toe's extensor tendon as a consequence of injury.
Symptoms and Progression
The altered position of the toe usually leads to discomfort as the skin of the foot begins to rub inside the shoe. This in turn leads to callous buildup or even ulceration in the affected area. Callosity can also occur on the ball of the foot as a response of the skin cells to increased forefoot pressure. The pain felt in the forefoot is often described as metatarsalgia.
Deformities of the lesser toe tend to progress slowly when left untreated. Callosities will sometimes become ulcers given enough time and wear, and the flexibility of the affected toes will also diminish over time.
The diagnosis of lesser toe deformity is purely clinical and evident on examination. However, to accurately determine and treat the underlying cause a weight-bearing X-ray of the foot is almost always required. Depending on the findings it may be necessary to conduct further detailed imaging such as ultrasound or MRI.
Specialised footwear is a common treatment for lesser toe deformity. Rather than seeking to correct the shape of the toe, this approach involves accommodating the condition by having the patient wear custom-made shoes with a heightened toe-box that avoids the toes rubbing internally. Sometimes an insole is used to reduce the pressure under the ball of the foot.
If a toe has a flexible, fully-correctable deformity then a tendon transfer (utilising a flexor side to extensor side transfer) can pull the toe straight again. This procedure is usually reserved for children as adults tend to have more fixed or not fully-correctable deformity. Sometimes simple tenotomy (dividing fixed tendon contractures) is all that is required.
A more common technique for correcting lesser toe deformity involves fusing the small joints of the toe together in the corrected position. This involves removing joint cartilage and using a metal implant to support the healing in the corrected position. This permanently straightens the toe, the loss of movement being easily tolerated and leaving the patient with a high degree of function.
In cases of mechanical forefoot overload it may be appropriate to address other pathology such as a tight gastrocnemius muscle (calf muscle) with a lengthening of the muscle. When a hammer toe is dislocated from its MTP joint the tension in the surrounding soft tissues and forefoot callosity may necessitate undertaking a shortening and elevating Weil osteotomy (boney cut) of the lesser metatarsal.
Hammer toes are often accompanied by a bunion (Hallux Valgus Deformity) of the Great toe. As the Great toe deviates from the midline, it becomes a poor weight-bearing strut and so weight is transferred to the smaller metatarsals and lesser toes causing the hammer toe deformity. The surgical solution in these cases must include correction of the Hallux Valgus.