Musculoskeletal disorders

Features of musculoskeletal disorders in children are:

• Although musculoskeletal presentations are common and often benign and self-limiting, they can be caused by a serious underlying condition such as infection, malignancy or non-accidental injury

• Many concerns of parents about their children’s posture are variations of normal alignment in the growing skeleton

• Juvenile idiopathic arthritis (JIA) is the most common cause of chronic arthritis in children.

Assessment of the musculoskeletal system

This should, as a minimum, include the pGALS (paediatric Gait, Arms, Legs, Spine) screen (see p. 25) to identify and localise musculoskeletal problems; any suggestion of a musculoskeletal problem should be followed by more detailed regional musculoskeletal examination (called pREMS, see p. 26).

Variations of normal posture

Variations are common and may be noticed by parents or on routine developmental surveillance. Most resolve without any treatment but if severe, progressive, painful or asymmetrical, they should be referred for specialist opinion.

Bow legs (genu varum)

The normal toddler has a broad base gait. Many children evolve leg alignment with initially a degree of bowing of the tibiae, causing the knees to be wide apart – best observed while the child is standing with the feet together (Fig. 26.1). A pathological cause of bow legs is rickets; check for the presence of other clinical features (see Ch. 11). Severe progressive and often unilateral bow legs is a feature of Blount disease (infantile tibia vara), an uncommon condition predominantly seen in Afro-Caribbean children. Radiographs are characteristic with beaking of the proximal medial tibial epiphysis.

Knock-knees (genu valgum)

The feet are wide apart when standing with the knees held together (Fig. 26.2). It is seen in many young children and usually resolves spontaneously.

Flat feet (pes planus)

Toddlers learning to walk usually have flat feet due to flatness of the medial longitudinal arch and the presence of a fat pad which disappears as the child gets older (Fig. 26.3). An arch can usually be demonstrated on standing on tiptoe or by passively extending the big toe. Marked flat feet is common in hypermobility. A fixed flat foot, often painful, presenting in older children, may indicate a congenital tarsal coalition and requires an orthopaedic opinion. Symptomatic flat feet are often helped with footwear advice and, occasionally, an arch support may be required.

Variants of normal

In-toeing and out-toeing

There are three main causes of in-toeing:

• Metatarsus varus (Fig. 26.4a) – an adduction deformity of a highly mobile forefoot

• Medial tibial torsion (Fig. 26.4b) – at the lower leg, when the tibia is laterally rotated less than normal in relation to the femur

• Persistent anteversion of the femoral neck (Fig. 26.4c) – at the hip, when the femoral neck is twisted forward more than normal.

The clinical features are described in Box 26.1.

Out-toeing is uncommon but may occur in infants between 6 and 12 months of age.

When bilateral, it is often due to lateral rotation of the hips and resolves spontaneously.

In-toeing

Box 26.1

Clinical features of in-toeing in children

Metatarsus varus

• Occurs in infants

• Passively correctable

• Heel is held in the normal position

• No treatment required unless it persists beyond 5 years of age and is symptomatic

Medial tibial torsion

• Occurs in toddlers

• May be associated with bowing of the tibiae

• Self-corrects within about 5 years

Persistent anteversion of the femoral neck

• Presents in childhood

• Usually self-corrects by 8 years of age

• May be associated with hypermobility of the joints

• Children sit between their feet with the hips fully internally rotated (‘W’ sitting)

• Most do not require treatment but femoral osteotomy may be required for persistent anteversion.

Toe walking

Common in young children and may become persistent, usually from habit; can walk normally on request. Needs to be distinguished from mild cerebral palsy or tightness of the Achilles tendons or inflammatory arthritis in the foot or ankle. In older boys, Duchenne muscular dystrophy should be excluded.

Summary

Variations of musculoskeletal normality and differential diagnosis

Perceived disorder	Normal age range	Differential diagnoses to consider
Bow legs	1–3 years	Rickets osteogenesis imperfecta, Blount disease
Knock-knees	2–7 years	Juvenile idiopathic arthritis (JIA)
Flat feet	1–2 years	Hypermobility, congenital tarsal fusion
In-toeing	1–2 years	Tibial torsion, femoral anteversion
Out-toeing	6–12 months	Hypermobility, Ehlers–Danlos and Marfan syndromes
Toe walking	1–3 years	Spastic diplegia, muscular dystrophy, JIA

Abnormal posture

Talipes equinovarus (clubfoot)

Positional talipes from intrauterine compression is common. The foot is of normal size, the deformity is mild and can be corrected to the neutral position with passive manipulation. Often the baby’s intrauterine posture can be recreated. If the positional deformity is marked, parents can be shown passive exercises by the physiotherapist.

Talipes equinovarus is a complex abnormality (Figs 26.5, 26.6). The entire foot is inverted and supinated, the forefoot adducted and the heel is rotated inwards and in plantar flexion. The affected foot is shorter and the calf muscles thinner than normal. The position of the foot is fixed, cannot be corrected completely and is often bilateral. The birth prevalence is 1 per 1000 live births, affects predominantly males (2 : 1), can be familial and is usually idiopathic. However, it may also be secondary to oligohydramnios during pregnancy, a feature of a malformation syndrome or of a neuromuscular disorder such as spina bifida. There is an association with developmental dysplasia of the hip (DDH).

Treatment is started promptly with plaster casting and bracing (‘Ponsetti method’), which may be required for many months. It is usually successful unless the condition is very severe, when corrective surgery is required.

Vertical talus

Talipes equinovarus needs to be differentiated from the rare congenital vertical talus, where the foot is stiff and rocker-bottom in shape. Many of these infants have other malformations. The diagnosis can be confirmed on X-ray. Surgery is usually required.

Talipes calcaneovalgus

The foot is dorsiflexed and everted (Fig. 26.7). It usually results from intrauterine moulding and self-corrects. Passive foot exercises are sometimes advised. There is an association with developmental dysplasia of the hip.

Talipes

Summary

Regarding talipes equinovarus

• Needs to be differentiated from positional talipes

• Check for neuromuscular disorder or spinal lesion and for developmental dysplasia of the hip (DDH).

Developmental dysplasia of the hip (DDH)

This is a spectrum of disorders ranging from dysplasia to subluxation through to frank dislocation of the hip. Early detection is important as it usually responds to conservative treatment; late diagnosis is usually associated with hip dysplasia, which requires complex treatment often including surgery. Neonatal screening is performed as part of the routine examination of the newborn (see Fig. 9.15), checking if the hip can be dislocated posteriorly out of the acetabulum (Barlow manoeuvre) or can be relocated back into the acetabulum on abduction (Ortolani manoeuvre). These tests are repeated at routine surveillance at 8 weeks of age. Thereafter, presentation of the condition is usually with a limp or abnormal gait. It may be identified from asymmetry of skinfolds around the hip, limited abduction of the hip or shortening of the affected leg.

On neonatal screening, an abnormality of the hip is detected in about 6–10 per 1000 live births. Most will resolve spontaneously. The true birth prevalence of DDH is about 1.3 per 1000 live births. Clinical neonatal screening misses some cases. This may be because of inexperience of the examiner, but in some it is not possible to clinically detect dislocation at this stage, e.g. where there is only a mildly shallow acetabulum. To overcome these problems, some centres perform ultrasound screening on all newborn infants. It is highly specific in detecting DDH but is expensive and has a high rate of false positives, and is not recommended in the UK. It is performed in some centres in infants at increased risk (family history, of breech presentation).

If developmental dysplasia of the hip is suspected, a specialist orthopaedic opinion should be obtained. An ultrasound examination allows detailed assessment of the hip, quantifying the degree of dysplasia and whether there is subluxation or dislocation. If the initial ultrasound is abnormal, the infant may be placed in a splint or harness to keep the hip flexed and abducted for several months. Progress is monitored by ultrasound or X-ray. The splinting must be done expertly as necrosis of the femoral head is a potential complication.

In most instances, a satisfactory response is obtained. Surgery is required if conservative measures fail.

Scoliosis

Scoliosis is a lateral curvature in the frontal plane of the spine.

In structural scoliosis, there is rotation of the vertebral bodies which causes a prominence in the back from rib asymmetry. In most cases, the changes are mild, pain-free and primarily a cosmetic problem; however, in severe cases, the spinal curvature can lead to cardiorespiratory failure from distortion of the chest.

Causes of scoliosis are:

• Idiopathic. The most common, either early onset (<5 years old) or, most often, late onset, mainly girls 10–14 years of age during their pubertal growth spurt

• Congenital. From a congenital structural defect of the spine, e.g. hemivertebra, spina bifida, syndromes (e.g. VACTERL association – Vertebral, Anorectal, Cardiac, Tracheo-oEsophageal, Renal and Limb anomalies).

• Secondary. Related to other disorders such as neuromuscular imbalance (e.g. cerebral palsy, muscular dystrophy); disorders of bone such as neurofibromatosis or of connective tissues such as Marfan syndrome, or leg length discrepancy, e.g. due to arthritis of one knee in JIA.

Examination should start with inspection of the child’s back while standing up straight. In mild scoliosis, there may be irregular skin creases and difference in shoulder height. The scoliosis can be identified on examining the child’s back when bent forward (Fig. 26.8). If the scoliosis disappears on forward bending, it is postural although leg lengths should be checked.

Figure 26.8 Structural scoliosis with vertebral rotation shown by rib rotation on bending forward.

Mild scoliosis will resolve spontaneously, or progresses minimally. If more severe, the severity and progression of the curvature of the spine is determined by X-ray. Severe cases are managed in specialist spinal centres where the place of non-medical treatment such as bracing will be considered, with surgery indicated only if severe or there is coexisting pathology such as neuromuscular or respiratory disease.

Torticollis

The most common cause of torticollis (wry neck) in infants is a sternomastoid tumour (congenital muscular torticollis). They occur in the first few weeks of life and present with a mobile, non-tender nodule, which can be felt within the body of the sternocleidomastoid muscle. There may be restriction of head turning and tilting of the head. The condition usually resolves in 2–6 months. Passive stretching is advised, but its efficacy is unproven.

Torticollis presenting later in childhood may be due to muscular spasm or secondary to ENT infection, spinal tumour (such as osteoid osteoma), cervical spine arthritis or malformation or posterior fossa tumour.

The painful limb, knee and back

Growing pains

Episodes of generalised pain in the lower limbs, referred to as ‘growing pains’ or nocturnal idiopathic pain, are common in preschool and school-aged children. The pain often wakes the child from sleep and settles with massage or comforting. The condition is poorly understood, but features to be fulfilled for this diagnosis are:

• Age range 3–12 years

• Pains symmetrical in lower limbs and not limited to joints

• Pains never present at the start of the day after waking

• Physical activities not limited; no limp

• Physical examination normal and otherwise well (with the exception of joint hypermobility in some).

Hypermobility

Older children or adolescents with hypermobility may complain of musculoskeletal pain mainly confined to the lower limbs, often worse after exercise. Joint swelling is usually absent or is transient. Hypermobility may be generalised or limited to peripheral joints (such as hands and feet). There is symmetrical hyperextension of the thumbs and fingers that can be hyperextended onto the forearms (Fig. 26.9), elbows and knees can be hyperextended beyond 10°, and palms can be placed flat on the floor with knees straight. Lower limb findings associated with hypermobility are hyperextensibility of the knee joint and flat feet with normal arches on tiptoe, which are over-pronated secondary to ankle hypermobility.

While mild degrees of hypermobility are a normal finding in younger female children, and many children with hypermobility are asymptomatic and find being very flexible an advantage in dancing and gymnastics, some experience recurrent mechanical joint and muscle pain, which is often activity related. These children require specialist assessment and may benefit from advice about footwear, exercises and occasionally orthotics. Hypermobility is also a feature of some chromosomal syndromes, e.g. Down syndrome and some inherited collagen disorders (e.g. Marfan and Ehlers–Danlos syndrome).

Complex regional pain syndromes

The most dramatic musculoskeletal pain is that encountered in complex regional pain syndromes (CRPS), formerly known as idiopathic pain syndromes, which may be localised or generalised. They usually present in adolescent females.

Localised forms often present with foot and ankle involvement (typically unilateral); the pain can be extreme and incapacitating, often triggered by minor trauma or without a clear precipitant. Presentation to the clinic may be in a wheelchair. In addition to severe pain, there may be hyperaesthesia (increased sensitivity to stimuli), allodynia (pain from a stimulus that does not normally produce pain), and the affected part (often a foot or hand) may be cool to touch with swelling and mottling, held in flexion with minimal if any active movement, and bizarre posturing is not uncommon. Typically, with distraction, the normal range of passive movements is possible.

Diffuse forms are characterised by severe widespread pain with disturbed sleep patterns, feeling exhausted during the day, with extreme tenderness over soft tissues. The characteristic tender points that are found in adults with fibromyalgia may be absent or fewer in number in children.

The child or adolescent with complex regional pain is otherwise well and physical examination is otherwise normal.

Organic pathology needs to be excluded. The aetiology is unknown, but affected children often have significant associated stresses in their lives.

A multidisciplinary rehabilitation regimen is required, predominantly physical therapy-based, either community or inpatient.

Acute-onset limb pain

Limb pain of acute onset has a number of causes. Trauma is the most common, usually accidental from sports injuries or falls, but occasionally non-accidental. Osteomyelitis and bone tumours are uncommon, but need urgent treatment.

Osteomyelitis

In osteomyelitis, there is infection of the metaphysis of long bones. The most common sites are the distal femur and proximal tibia, but any bone may be affected (Fig. 26.10). It is usually due to haematogenous spread of the pathogen, but may arise by direct spread from an infected wound. The skin is swollen directly over the affected site. Where the joint capsule is inserted distal to the epiphyseal plate, as in the hip, osteomyelitis may spread to cause septic arthritis. Most infections are caused by Staphylococcus aureus, but other pathogens include Streptococcus and Haemophilus influenzae if not immunised. In sickle cell anaemia, there is an increased risk of staphylococcal and salmonella osteomyelitis. Infection may be from tuberculosis; although rare in the UK, it needs to be considered, especially in the immunodeficient child.

Osteomyelitis