Foot
The foot is a highly complex mechanical device, comprising 26 bones and 33 joints. Its function is to provide a stable and painless step on different surfaces. It is very important to respect your feet and if there are any symptoms or deformity, such as deviation of the toes, collapsed arches, bony prominences, deviated heels or hard, painful skin or corns, you should seek advice from a foot and ankle specialist.
Toe Abnormalities
Most toe abnormalities are either due to inherited conditions (familial), muscular imbalance or inappropriate footwear.
The function of the toes is to grip the ground, to push-off at the end of the step and to provide stability. Toe abnormalities disrupt this function. Most of the pain in these cases occurs from pressure from footwear and corns and callus can also develop over the tops and tips of the toes, causing further pain.
Bunions (Hallux Adducto Valgus)
Hallux adducto valgus (HAV) is a progressive condition, which can be inherited or acquired. As HAV develops, the function of the big toe joint is badly affected, so that the body’s weight transfer through the foot is disrupted and the big toe joint is unable to bend as it should do at the end of the step.
This changes the normal gait cycle and has a secondary effect on the back and lower limbs, as well as increasing pressure over the outer side of the forefoot, causing conditions such as metatarsalgia, as can be seen below.
Unlike larger arthritic joints, such as the hip, it is better to treat HAV early as otherwise it will progress and require more extensive surgical treatment later. For patients unable to undergo surgery, pain relief may be possible through the use of custom-made foot orthoses, exercises and gait re-training (see the Podiatry section for more details on foot orthoses).
The aim of this surgery is achieve a normal gait cycle. It is not cosmetic surgery.
Forefoot pain
Pain, usually under the front of the foot (around the heads of the metatarsals), can be due to a number of different conditions. As seen in the bunion (HAV) section, having HAV can contribute to pressure over the lesser metatarsals (2-5), but it can also be caused by having genetically altered metatarsal lengths.
Incorrect metatarsal lengths:
In this picture, the lesser metatarsals (2-5) are longer in relation to 1st metatarsal. Although the toes appear malaligned, this is actually a disorder of the metatarsal bones and not the toes.
If the metatarsals are of an altered length as described above, weight transfer through the forefoot is altered and increased pressure is put on the longer metatarsals.
Arthritis of the big toe joint (hallux rigidus)
The big toe joint is extremely important for mobility, balance and weight-transfer in normal gait. Arthritis can develop in this joint through trauma, sport, inappropriate footwear or due to an abnormal gait cycle. This causes pain and loss of function in the affected joint, leading weight being transferred away from the arthritic joint and onto the outer side of forefoot.
In the early stages of arthritis, the joint can be cleared out and cleaned (Cheilectomy). However, in later stages, when pain is continuous the joint can be replaced. It is better to replace the joint with a prosthesis which mimics the anatomical function of the joint, as it will restore normal function and gait cycle, whereas fusion of the joint disrupts normal gait.
In the case below, joint replacement surgery, with another team, using a silastic joint implant (does not mimic normal joint anatomy) failed. After building up the bone stock, it was possible to replace this joint with a superior joint replacement, which replicates normal joint function.
Morton’s Neuroma
Morton’s neuroma is an entrapment neuropathy of one of the common plantar digital nerves, which run between the metatarsal bones in the foot. It is a slow degeneration of nerve fibres, causing pain and numbness in, commonly, the 3rd and 4th toes, although it can also affect the nerve between the 2nd and 3rd metatarsals, causing symptoms in the 2nd and 3rd toes.
The exact cause of Morton’s Neuroma is not known, but it is widely thought to be related
to the size and shape of the space between the metatarsal bones concerned, leading to
pressure on the nerve, with resultant inflammation and thickening, which, in turn, takes
up more space in the inter-metatarsal area and subsequent increased pressure on the
nerve, leading to symptoms.
Anything that increases the pressure between these metatarsals such as tight-fitting shoes,
will make the pain worse.
In the early stages, changes in foot and gait abnormalities via foot orthoses can be
helpful, but, if symptoms persist, the neuroma must be removed surgically.
Rheumatoid foot problems
Rheumatoid arthritis can have profound effects on the foot. As the disease process
attacks joints, the potential for some of the 33 joints in each foot to be affected is very
high.
Commonly, the front of the foot is affected, causing the development of a severe forefoot
deformity and a feeling like walking on pebbles, which is caused by the heads of the
metatarsals dropping down under the foot and causing more pressure. The lesser digits
can become very retracted and actually dislocate from the metatarsals, causing problems
with corns, callus and, sometimes, ulcers on the tops of the toes and balls of the feet, as
well as problems with getting footwear to fit comfortably.
Distorted Rheumatoid forefoot prior to reconstructive surgery
The back of the foot can also be affected, with the heel going outwards and causing the foot to roll in, which then puts more pressure on the bunion and the metatarsal heads at the front of the foot. It is now possible to correct this type of foot surgically, allowing a return to painless walking and less pressure on the balls of the feet.
For those patients not suitable for surgery, footwear modifications and foot orthoses (Walkrite) can also help to reduce pain when walking with this foot type.
Flat foot
A foot that flattens in standing, caused by flexible ligaments (hypermobility) can be normal for that person.
Surgical intervention is not indicated in these cases. Good, supportive footwear is adequate. If pain is present, then orthoses and exercises are indicated (Walkrite).
A rigid flat foot however, (a foot that does not regain its normal arch shape when not
standing on the foot) is a serious condition, which will completely disrupt the normal
functioning of the foot.
In children, this can be due to a tarsal coalition (bones of the rearfoot fused together).
When this is the case, surgery is indicated to remove the fused area of bone and restore
normal rearfoot function, followed by wearing custom-made foot orthoses to maintain restored foot function and Physiotherapeutic exercises to maintain restored movement.
There are various causes of flat foot, such as tibialis posterior dysfunction and arthritis.
In arthritis, the bones of the rearfoot are prevented from moving adequately due to the
arthritic changes. Tibialis posterior dysfunction, however, is a progressive deformity,
caused, initially by dysfunction of the tibialis posterior tendon.
In a foot with a healthy tibialis posterior tendon, it is possible to stand on one leg and go onto tip toe. When this is done, the heel should swing inwards (varus)
Early diagnosis and treatment is essential. In stage I and early stage II, it may be possible to treat pain and dysfunction with custom-made functional foot orthoses. If pain persists and in stage II, it is recommended to correct the problem surgically, as the extent of the soft tissue damage is too great to correct non-surgically.
The surgical gold standard is to restore normal biomechanics of the foot by medial displacement calcaneal osteotomy (reshaping the heel), FDL (tendon) transfer to navicular bone of the foot, plus repair of the spring ligament (under the arch of the foot).
2nd line surgical treatment is to restore the shape, but not normal function, by fusion of the sub-talar joint or lengthening of the outer border of foot by fusion of the calcaneocuboid joint with bone grafting.
Early diagnosis of this condition can avoid surgery and prevent progressions to stage III, where normal function cannot be restored, even surgically. Custom-made foot orthoses are essential in all the patients with tibialis posterior dysfunction, before or after surgery (Walkrite).