A majority of leg pains result from muscle wear and tear, injuries, and trauma. Some however, could signal major underlying diseases requiring immediate attention. Here, Dr. YK Amdekar provides a quick clinical approach guide to deduce cause of leg aches in children and appropriate management.

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Leg ache is a common complaint - it is so because we use our legs more than our upper limbs and hence leg ache may be a part of generalised body pain though maximally felt in the legs. Thus, a justification to leg ache! But it refers commonly to limb pain.

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Pathogenesis of pain – Practice point

1. Pain is commonly a result of inflammation but also may be due to stretch or affection of blood vessels or nerves and could be referred from a distant site. Inflammation is easy to make out as it is accompanied with swelling, redness, tenderness and warmth besides pain. Not all the features would be present in each case but majority would be evident. Inflammation may be caused by infection or non-infective conditions as in collagen vascular disorders.
2. Vasogenic and neurogenic pain is typically along the anatomical site related to the affected blood vessel or nerve. Besides, neurogenic pain may be described as shooting or burning pain.
3. Stretching of a capsule as happens in case of enlarged liver or lymph node also causes pain.
4. Pain originating from a particular site may be referred to another distant site that shares same nerve segment supply as in case of knee pain arising from hip affection or left shoulder pain due to myocardial infarction.

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Anatomical parts of a leg (or any limb)

It consists of skin, soft tissue, muscles, bones, tendons, ligaments, joints, blood vessels, and nerves. Obviously pain may arise from any of these parts or may involve more than one part. It is important to define anatomy of the disease as pathology and aetiology are different in affection of each part.

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Common causes of pain in the limbs

• Trauma – impacted foreign body or splinter, injection site, sports injuries to muscle, tendon, bone or joint
• Infection – cellulitis, abscess, osteomyelitis, arthritis, viral myositis, syphilis
• Non-infective inflammation – rheumatic fever, juvenile idiopathic arthritis, and other rheumatological disorders, dermatomyositis, bone malignancy
• Vitamin deficiency – rickets, osteomalacia, scurvy
• Vascular – vasculitis, sickle cell disease, deep vein thrombosis, aseptic necrosis of bone, osteochondrosis
• Haematological – leukemia, hemophilia
• Neurogenic – herpes, peripheral neuritis of different causes
• Idiopathic – growing pain, restless leg syndrome
• Psychogenic or functional – pain amplification syndrome
• Referred pain – hip joint pain from psoas abscess

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Clinical approach to pain in the limbs

History

Age group

Children are at risk of injuries. Young infants present with accidental birth injury or one caused by vigorous massage or pulled elbow while lifting the child. However, pain can be localised only after the age of around 4 years and so, the most common age of presentation of leg ache is at an older age among children.

Localised or generalised pain

Trauma, bacterial infection, herpes, haemophilic arthritis often cause local pain while viral infection and other conditions result in more widespread pain.

Origin

Acute onset is typical of trauma or at times vascular or neurogenic pathology. Infection and inflammation are never very acute; they manifest over 2 to 3 days or even longer.

Duration and progress

Traumatic and infective conditions are usually short as they get diagnosed and treated early. Other conditions may have prolonged course. Most conditions result in continuous pain but growing pain manifests in the later part of the evening. Haemophilia may cause recurrent arthritis.

Relation to rest and activity

Morning stiffness or pain is typical of inflammatory arthritis while pain in the evening after daily activity suggests degenerative arthritis (not seen in children). Similarly, growing pain manifests after a day’s activity and is relieved by massage and rest. Generally pain is aggravated by touching or pressing but if it is relieved by massage, it denotes pain arising from tired muscles as in case of growing pain.

Degree and type of pain

Severe pain suggests severe inflammation as in fracture or acute cellulitis or osteomyelitis. In fact, in children, cellulitis should be viewed as probable osteomyelitis. Burning pain is characteristic of herpes zoster while dull ache may suggest mild inflammation or non-inflammatory disorders.

Accompanying symptoms

1. Swelling suggests inflammatory disease- either trauma, infection or non-infective disorders.
2. Fever indicates widespread disease as viral myositis or severe localised inflammation as in osteomyelitis or abscess.
3. Significant pallor or purpura denote haematological disorder.

Past history

Similar illness is seen in few rheumatological disorders and haemophilia

Family history

It may guide to genetic or familial disorders such as haemophilia, sickle cell disease or some of the rheumatological disorders.

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Physical examination

Sick or not sick?

• The child would be sick-looking in case of infection and non-infective inflammation while trauma, haemophilia, growing pain etc. do not present with significant sick look
• Local swelling denotes local inflammation. Generalised pain is not accompanied with swelling except in polyarticular disease
• Localised bony swelling is seen in osterochondrosis and also in bone tumours
• Local warmth and tenderness signifies severe inflammation as in case of septic arthritis or osteomyelitis

Restriction of movement

1. Severe painful conditions do not permit any movement of affected limb.
2. Pain due to periarticular disease is evident on active movement of the affected joint but not on passive movement. It differentiates articular from periarticular disease.
3. Pain in arthritis is aggravated by active as well as passive movement. Localised muscle wasting signifies chronic pathology as seen in wasting of quadriceps in chronic arthritis of knee. Similarly, deformities and contractures are seen in chronic arthritis.
4. Haematological signs such as pallor or purpura denotes proable leukaemia. It often presents as vague limb pain but sickness and other signs including hepatosplenomegly would suggest correct diagnosis. It is often missed as rheumatological disorder and the patient is wrongly prescribed steroids which is a fatal mistake. In fact, steroids are rarely necessary in the management of limb pain.
5. Bleeding gums suggest scurvy though it may also be a manifestation of other haematological disorders such as leukaemia.
6. Cardiac signs may be seen in rheumatic fever and at times in other rheumatolgical disorders.
7. Absence of any abnormal signs may suggest diagnosis of growing pain, pain amplification syndrome or functional pain.

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Investigations

• CBC helps in suspected acute osteomyelitis or arthritis as well as haematological disorders such as leukaemia or sickle cell disease
• ESR/CRP detects degree of inflammation but not the cause
• Suspected rheumatological diseases need specific tests and it is not rational to ask for ANA unless one is suspecting lupus or RA factor unless one has an older female child with polyarticular disease (such tests are better reserved for specialists)
• X-ray detects signs of rickets and also bone injury

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Management

Specific treatment depends on final diagnosis. However, symptomatic treatment with analgesic may be tried until then. Neurogenic pain such as in case of herpes zoster is not easy to control with analgesics. Steroids should never be used in undiagnosed limb pain lest leukaemia is missed with dire consequences of poor outcome.

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In summary, limb pain can be as benign as growing pain or simply treatable vitamin D or C deficiency or as dangerous as leukemia or chronic persisting rhematological disorder. One must be cautious to make a correct diagnosis and not hesitate to refer for better opinion.

Disclaimer- The views and opinions expressed in this article are those of the author's and do not necessarily reflect the official policy or position of M3 India.