Do flat feet cause heel pain and plantar fasciitis?

The human foot is consists of 26 bones, 30 joints and is moved by 22 intrinsic and extrinsic muscles. It has two important functions; to provide support to the body weight and to act as a lever to propel the body while walking or running. Since this arm of the lever has multiple components as bones, it is arranged as an arch so as to handle body weight. This also helps the foot to mould to uneven surfaces while walking. The foot is divided into three parts:

1. Forefoot (toes and adjacent part) – metatarsals & phalanges

2. Midfoot (middle part) – navicular, cuboid & 3 cuneiforms

3. Hindfoot (including heel) – talus & calcaneus

The arches of the foot
The foot has three arches. They are as below:

1. Medial or Inner longitudinal arch (inner arch in the long axis of the foot). This arch consists of the calcaneus, the talus, the navicular bone, the three cuneiform bones, and the first three metatarsal bones. The centre of the arch is formed by navicular bone. The inner arch is higher than the outer longitudinal arch.

2. Lateral or Outer longitudinal arch (outer arch in the long axis of the foot). It consists of fourth and fifth metatarsals, cuboid and calcaneus.

3. Transverse arch extends across the midfoot and consists of metatarsals.

The arch support
The arch support can be described as consisting of two components, static and dynamic. The static component consists of ligaments and plantar fascia; and the dynamic component is due to the tone and contraction of the muscles of the foot. These arches are also maintained by the shape of bones.

The Plantar fascia is a sheath of fibrous connective tissue which stretches between the ends of the longitudinal arch thereby acting as a tie beam. It extends from medial tuberosity on the lower surface of calcaneus to the metatarsal heads. The transverse arch is present along the transverse axis of the middle part of the foot. Because of this arrangement of bones, the body weight on standing is exerted on the ground through six contact points which includes heel (calcaneus) and heads of five metatarsals. These arches are present at birth though the foot of the child appears to be flat because of fat under the sole.

Flat foot
Flat foot or Pes planus is a condition in which the inner longitudinal arch is depressed or collapsed resulting in contact of the complete sole with the floor (including the inner part which usually is raised from the floor). While standing or walking, it is the tone of muscles which has an important role in supporting the arches of the foot. When these muscles are fatigued by prolonged exercise (a long route march by an army recruit), by standing for long time (nurse or security guards), by obesity or by certain other diseases, the muscular support weakens and the ligaments are overstretched.

Clinical features of flat foot
Flat foot in adults can be asymptomatic or presents with pain, instability of foot and severe functional restrictions. The clinical evaluation of the foot requires the following:

• Appearance of the foot with and without weight bearing. Everted or valgus angulation of the heel is observed from behind. The collapse of the medial arch is also associated with abduction (outward movement) of the forefoot. ‘Too many toes’ sign indicates forefoot abduction deformity. When seen from behind, more toes are seen lateral (outside) to the leg in comparison to normal foot. The arch height can be compared with the opposite foot in unilateral cases.

• Areas of tenderness especially on the inner side of the heel, is seen in these patients.

• Range of movements to see whether the foot is flexible or is rigid.

• Navicular drop test: with the person sitting on chair and foot placed flat on ground, the distance between navicular tuberosity and the ground is assessed with the help of a scale. Then the person is asked to stand and the same distance on weight bearing is checked. A drop in the height of navicular tuberosity of more than 10 mm is indicative of hyper-pronation of the forefoot. It has been seen that more is the navicular drop, higher are the chances of plantar fasciitis and heel pain.

• Check tone of muscles.

• Observing gait of the person with and without shoes. Also observe the pattern of wearing of the shoes. It may show delayed or absent supination of the foot and decreased propulsive action.

• Imaging: weight bearing x-ray imaging aids in the diagnosis.

So the flat foot in an adult can be described as a three dimensional deformity with three components:

1. Abduction and excessive pronation of the forefoot.

2. Collapse of the medial longitudinal arch.

3. Valgus deformity of the hindfoot.

These deformities alter the biomechanics of the foot and ankle. This results in altered gait pattern and pain. This condition tends to be progressive. Once the arch integrity is lost and collapse begins, gravity and body weight act as forces to amplify complete collapse and destabilization of the foot.

Plantar fasciitis and heel pain
Heel pain is one of the commonest symptoms in the foot problems. The plantar heel pain is most commonly caused by plantar fasciitis. This condition occurs due to inflammation (swelling) of the proximal (nearer to the heel) part of the plantar fascia or at the medial tubercle of the calcaneus. Sometimes it is also referred to as ‘calcaneal or heel spur’. This is a misnomer as only 50% of the patients with plantar fasciitis have plantar spur and about 15% of asymptomatic people may have a spur. It mostly affects one foot though in about 15 to 30% cases it can be bilateral.

It is commonly seen in long distance runners and in military personnel after route march. It may also occur in ballet dancers, tennis or basketball players. Sometimes plantar fasciitis is associated with underlying systemic conditions like rheumatoid arthritis, ankylosing spondylitis, gout, psoriatic arthritis and systemic lupus erythematosus.

It occurs due to repetitive and prolonged irritation or stretching of plantar fascia as seen in flat foot. Excessive pronation of the forefoot associated with collapse of the medial arch results in strain on the plantar fascia due to pull at its insertion in the heel (calcaneus). This pull is directly proportional to the severity of arch collapse (navicular drop as described above) that overloads the plantar fascia and corresponds with severity of plantar fasciitis and heel pain.

The pain is of gradual onset and progression. It is usually pinpointed at the medial tubercle of calcaneus. Rarely, swelling over this area may be present. The pain starts as one begins to walk but reduces on continuation of walking. Later on the pain becomes continuous. Passive dorsiflexion of the great toe stretches the plantar fascia and causes pain.

Treatment of heel pain
Prevention is very important. This can be achieved by early identification of the condition, use of proper footwear and following correct physical training methods. Weight reduction also helps significantly by reducing stress on all weight bearing joints.

In cases requiring treatment there are many options.

1. Rest to the foot. It reduces the inflammation and pain.

2. Local application of ice.

3. Anti-inflammatory drugs – ibuprofen, piroxicam or diclofenac. They reduce swelling and relieve pain by reducing inflammation.

4. Wearing shoes with good support for the medial arch provides relief.

5. Orthotic management - foot orthoses including custom-made devices are used to accommodate any degree of deformity present in the individual. Some of these orthoses are medial arch flange, deep heel seat and full AFO (ankle-foot orthosis) that will support the entire ankle-tarsal complex.

6. Strapping of foot – Correction of biomechanical deformities of the foot can also be achieved with adhesive strapping.

7. Stretching exercises – Regular daily stretching of plantar fascia, foot muscles including gastrocnemius-soleus muscle complex and Achilles tendon helps in improvement of symptoms. It is prescribed for ten minutes per session, 5 to 6 times daily.

8. Corticosteroid injections act as anti-inflammatory agents. Though the improvement in symptoms is dramatic, repeated injections can result in rupture of plantar fascia, heel fat pad atrophy (wasting) and calcaneal osteomyelitis (infection of calcaneus). This may aggravate the symptoms.

9. Immobilization using splint or cast gives rest to the foot and helps in correction of the foot deformities. Plantar fascia night splints are useful and prevent shortening of fascia. This also reduces the morning pain considerably.

10. Extracorporeal shock wave therapy (ESWT) – Some studies have shown benefit from this modality of treatment. It has been found that ESWT reduces swelling, promotes formation of new bone and blood vessels. The duration of this therapy may extend from 3 to 12 months.

11. If the patient remains symptomatic for more than one year and the above modalities of treatment have failed, then surgery may be considered. Plantar fasciotomy is the surgery done for this condition. In this operation plantar fascia is divided 1 cm distal to its attachment to medial tuberosity of calcaneus. Sports can be restarted after about two months of surgery. This surgery is performed by open or by endoscopic methods. The endoscopic approach is less traumatic and results in earlier return to work or activity. The functional results are also better. Correction of foot deformities associated with flat foot can also be done surgically.

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