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The painful foot

The foot does not simply bear the weight of the whole body but the weight springs off it many times a minute in walking, running or jumping and it helps to absorb the impact of landing. The bones, ligaments and muscles absorb an enormous amount of impact over a lifetime, especially in an athlete but perhaps more so in the obese.

The foot is a dynamic piece of engineering. It has both a longitudinal and a transverse arch. The longitudinal arch is higher on the medial side. The foot may be inspected with the patient seated and the foot elevated to facilitate inspection, especially of the sole but it is essential to examine the foot in a weight bearing mode. This is when almost all the problems occur in this dynamic structure and failure to do so will result in missing the correct diagnosis in most cases. Problems of the ankles, knees, hips and back also merit examination of the feet.

Epidemiology: Painful feet is a very common problem.

Risk factors: Advancing age, obesity, injudicious footwear.

Aetiology: There are many causes of painful feet:

• Painful polyneuropathies
• Ischaemia from peripheral vascular disease or embolism
• Skin lesions may be painful including blisters
• Arthritis affecting the feet, especially rheumatoid arthritis or the exquisitely painful 1st MTP joint in acute gout.
• Ingrowing toenails, especially if infected
• Abnormalities of the joints, ligaments and tendons of the foot. This will be the prime concern of this article. Often there appears to be an inherent predisposition but other factors include poor footwear, obesity and hypermobility syndromes.

History:

• When did it start?
• Is it getting worse?
• Is the pain diffuse or at a point?
• Aggravating and relieving factors.
• Occupation, sport, training routines, recent injury?
• Is there pain elsewhere? Poor posture of the feet can cause pain in the ankles, knees and back.

Examination:

• Look at the shoes. What type of shoes does the patient choose to wear? Are they fashionable shoes that distort the foot? Trainers are unique in the history of footwear in being designed for feet but when did he last get a new pair? If he trains seriously does he have several pairs? Just as cars need to have tyres and shock absorbers replaced periodically, so too trainers need replacing.
• Is there abnormal or uneven wear of the shoes?
• Note any obesity.
• Does the shape of the foot look normal? Look at the sole. Is there abnormal callus? Weight should be taken over the 1st and 5th metatarsal heads. Callus over other metatarsal heads means fallen transverse arch.
• Is there local tenderness?
• Now examine the feet standing with both feet bare. Are the longitudinal aches normal? Can you get your finger under the medial arch? Look at the feet from behind. Fallen arches cause hyperpronation and upset the line of the Achilles tendon.
• If there is a postural problem such as a fallen arch it is often possible to put something underneath it, like a small pile of leaflets, to correct the abnormality and to prove that posture can be corrected.

Children rarely complain of painful feet and if they do, think of a foreign body. Pressure from shoes on a prominent navicular bone, or sometimes an accessory bone, or a prominent posterosuperior os calcis may require surgical trimming. Osteochondritis and similar conditions may affect the bones of the foot. An x-ray will aid diagnosis. A podiatrist can help. Usually an insertion into the shoe is satisfactory but occasionally a plaster casts is required.

Metatarsus primus varus: The 1st metatarsal shows angulation towards the midline. It usually affects teenagers and may run in families. If deformity is marked, a metatarsal or proximal wedge osteotomy may be beneficial.¹

Hallux rigidus: The 1st MTP joint has arthritis, pain and restricted movement. A dorsal ring of osteophytes may occur. In early cases manipulation and injection of the joint with steroid and local anaesthetic may offer relief² but in more advanced cases, arthrodesis, Keller's operation, or distal oblique osteotomy may be required.³

Ingrowing toenails: Some people seem to have an inherent predisposition but bad cutting of nails and tight socks and shoes contribute. The nail should be cut in a straight line and not cut down at the edge. Correct nail cutting, avoidance of tight footwear and pushing back the overgrowing skin when it is soft in the bath may suffice but wedge resection is often required. This may be performed under the enhanced service of minor surgery in general practice. It is almost invariably the hallux that is affected. If there is infection it should be treated first to reduce excessive vascularity. Under ring block a wedge of nail is cut away, cutting right down to the nail bed. Phenol is used to destroy that part of the bed or regrowth will probably result in the recurrence of the condition.⁴ Simple avulsion of the nail will probably lead to recurrence as the nail regrows. Avulsion with total destruction of the nail bed with phenol is a drastic procedure that gives a poor cosmetic result. Wedge resection is the procedure of choice.

Flat feet, also known as pes planus and fallen arches is a common problem, perhaps affecting as many as 20% of the adult population. As the arches start to fall the ligaments and muscles that maintain them are put at increasing mechanical disadvantage, accelerating the condition. This can cause pain in the feet after long marches and hence the fact that flat feet were a cause for rejection for National Service in otherwise healthy young men. The fallen arch causes hyperpronation and this affects the ankle joint and the line of the Achilles tendon. It also tends to cause valgus deformity at the knee and malalignment of the angle of pull of the quadriceps tendon. This can cause knee pain and swollen knees after exercise and even predispose to medial subluxation of the patella. It can also cause scoliosis and back pain. Hence the feet should be examined when pain presents in higher joints. The feet must be examined when weight bearing. Look first for abnormal callus then inspect the arches of both feet with the patient standing. Arches may seem satisfactory when sitting but collapse when bearing weight.

Insoles can correct the anatomical deformity. Exercises of the intrinsic muscles of the feet help to maintain the arch. It is possible to buy insoles in many pharmacies but for difficult cases referral to a podiatrist is advised.

Images of flat feet

Fig.1.Underneath of feet Note the callus over the 2nd, 3rd and 4th metatarsal heads

Fig.2.View from in front Note the flattened arch, hallux valgus and livedo suggesting poor circulation too

Fig.3.View from behind Note the fallen arches, hyperpronation and hence lateral deviation of achilles tendon

Stress (march) fracture: Route marches, long hikes and excessive running can produce stress fractures that are sometimes compared with metal fatigue. They tend to affect the metatarsal bones, most often the 2nd or 3rd but also the calcaneum. There is usually a complaint of pain on training that may progress to pain at rest. There may be tenderness over the lesion. An x-ray may show the fracture but often it does not. A repeat in a week or two may show callus formation where the fracture is healing. If there is clinical suspicion of a stress fracture but x-rays are unhelpful, it may be worth discussion with the Nuclear Medicine Department as scintillation scanning is a far more sensitive technique, the fracture showing as a hot spot or MRI is often valuable.⁵

Treatment is rest whilst the fracture heals. A plaster cast is rarely required. Classification of injured athletes as high or low risk is helpful as inadequate rest puts the athlete at risk whilst excessive rest causes deconditioning and undue exclusion.⁶

Metatarsalgia: This is pain across the metatarsal heads. It is often due to collapse of the transverse arch. A metatarsal pad will often reform the arch and give relief. If there are difficulties, ask a podiatrist to help. In rheumatoid arthritis, metatarsalgia may require operation.⁷

Morton's metatarsalgia: There is pain is from pressure on an interdigital neuroma between the metatarsals. Fashionable shoes often contribute. Pain usually radiates to the lateral side of one toe, and the medial side of its neighbour. Pressure on the affected web space reproduces the pain. Excision of the neuroma may be needed.⁸

Pain in the heel: This is a common problem with a variety of causes.

• As mentioned earlier a stress fracture may be present and MRI or scintillation scan may be required for diagnosis.
• Arthritis of the subtalar joint
• Rupture of the Achilles tendon. This usually arises in middle aged men as they take unaccustomed exercise and there is a sudden local pain but usually a little above the foot. Extension of the ankle is weak. There may be incomplete rupture of the tendon. If it is complete there is still some force from soleus.
• Post calcaneal bursitis
• Tender heel pad
• Anterior to the calcaneum, plantar fasciitis. It affects adults of all ages but especially the obese and those who are on their feet all day. Treatments have been reviewed both in the USA⁹ and by a Cochrane review¹⁰ and both found poor evidence of efficacy of the various available treatments. Steroid injection is often used but injecting through such tough skin is very painful and any benefit is in the short term only. There is much to be said for an expectant approach. NSAIDs or insoles are simple, cheap and probably as effective as any treatment.

References:

1. Fox IM, Caffiero L, Pappas E; The crescentic first metatarsal basilar osteotomy for correction of metatarsus primus varus.;J Foot Ankle Surg. 1999 May-Jun;38(3):203-7.[abstract]
2. Solan MC, Calder JD, Bendall SP; Manipulation and injection for hallux rigidus. Is it worthwhile?;J Bone Joint Surg Br. 2001 Jul;83(5):706-8.[abstract]
3. Ronconi P, Monachino P, Baleanu PM, et al; Distal oblique osteotomy of the first metatarsal for the correction of hallux limitus and rigidus deformity.;J Foot Ankle Surg. 2000 May-Jun;39(3):154-60.[abstract]
4. Rounding C, Hulm S; Surgical treatments for ingrowing toenails.;Cochrane Database Syst Rev. 2000;(2):CD001541.[abstract]
5. Spitz DJ, Newberg AH; Imaging of stress fractures in the athlete.;Radiol Clin North Am. 2002 Mar;40(2):313-31.[abstract]
6. Kaeding CC, Yu JR, Wright R, et al; Management and return to play of stress fractures.;Clin J Sport Med. 2005 Nov;15(6):442-7.[abstract]
7. Hughes J, Grace D, Clark P, et al; Metatarsal head excision for rheumatoid arthritis. 4-year follow-up of 68 feet with and without hallux fusion.;Acta Orthop Scand. 1991 Feb;62(1):63-6.[abstract]
8. Wu KK; Morton neuroma and metatarsalgia.;Curr Opin Rheumatol. 2000 Mar;12(2):131-42.[abstract]8
9. Cole C, Seto C, Gazewood J; Plantar fasciitis: evidence-based review of diagnosis and therapy.;Am Fam Physician. 2005 Dec 1;72(11):2237-42.[Full text]
10. Crawford F, Thomson C; Interventions for treating plantar heel pain.;Cochrane Database Syst Rev. 2003;(3):CD000416.[abstract]

Internet:

• wheelessonline.com Morton's neuroma. Interdigital perineural fibrosis
• New Jersey Sports Medicine Clinic correction of flat feet by insoles
• Arthritis Research Campaign Feet, footwear and arthritis

Acknowledgements EMIS is grateful to the Mentor authoring team for writing this article. The final copy has passed peer review of the independent Mentor GP authoring team. ©EMIS 2006.

Last issued 08 May 2006