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growing pains

Growing Pains

When a child persistently complains of vague knee pain, they may end up in a sports therapy clinic. Patrick Lusty and Deborah Eastwood explain what to look out for.

‘Diseases or complaints of growth’ were first described by Duchamp (1) in his treatise ‘Maladies de la Croissance’ in 1832. These aches and pains were initially thought to be manifestations of rheumatic fever requiring prolonged bed rest, a notion that gave way to the ‘fatigue theory’ proposed by Bennie in 1894 (2). This declared that ‘little legs have performed an unusual amount of work during the day’ and may therefore hurt at the end of the day. In 1939 Hawksley (3) emphasised the occurrence of limb pains in healthy children at night or at the end of the day, and by 1951 Naish and Apley (4) had developed clear diagnostic criteria for growing pains (see Table 1 below) to explain the vague, nebulous discomfort in the lower limbs of which children frequently complain and for which no cause can be found.

Symptoms can range from mild aches at night to severe cramp-like pain waking the child from sleep. The pain is normally felt in the thighs and/or the calves and very rarely involves upper limbs. The pain is bilateral, and is not usually localised to a joint such as the knee. Daytime activities and sports do not obviously exacerbate the pain. Clinical examination and investigations prove normal.

Who gets growing pains

How common these symptoms are depends on the diagnostic criteria used and the population studied. Naish and Apley (4) examined 720 healthy English children and found that, defined by their strict criteria, 4.2% had a history of growing pains. Other researchers came up with rather different results (see Table 2 below). The age group most commonly affected is three to five year olds and symptoms are rare beyond the age of 12. A higher incidence is reported in girls (although this is not statistically significant).

What are growing pains?

Growing pains are not caused by growth, but they do cease when growing stops. The growth rate slows from three years of age onwards and only picks up again with the onset of puberty, so it is declining at the time when most of these patients present. The growth rate of children who have growing pains is no different from that of those who do not (5). Hawksley, in 1938 (3), suggested that there may be an anatomical basis for these pains and if the children were properly examined for scoliosis, a foot deformity or rotational abnormalities of the lower limbs, an anatomical cause for the pains would be found. However, this theory has fallen out of favour because numerous other authors, on close examination of their patients, have failed to find any such significant anatomical variations.

Table 1: Growing pains in children: the Naish and Apley criteria
History of pain lasting for three months or more
Symptom-free intervals of days, weeks or months
Pain at the end of the day or waking the child at night
Pain of significant severity to interrupt activity such as sleep
Pain not specifically related to the joint
Normal physical examination
Normal laboratory tests and X-rays

In 1951 Naish and Apley said: ‘Physical growth is not painful but emotional growth can hurt like hell.’ They described a triad of abdominal pains, headaches and limb pains, with psychological profiles showing emotional disturbances in all their patients. More recently, it has been suggested that the muscle pain arises from local ischaemia (shortage of oxygen) in a muscle, causing muscle contraction which leads to capillary constriction, a build-up of irritative metabolites and further local ischaemia and pain, all setting up a vicious circle of spasm and pain. Hashkes (8) looked at 44 patients and 46 controls and found a lower pain threshold in children with growing pains, with increased muscle tenderness similar to fibromyalgia. He suggested that growing pains may be a variant of a non-inflammatory pain syndrome.

Diagnosis by exclusion

The real difficulty with growing pains is not in making the diagnosis but rather in mistaking the diagnosis and labelling a far more serious pathological process as growing pains (see Table 3, below). Growing pains is, in essence, a diagnosis by exclusion, and common sense (rather than exhaustive investigations) will exclude most worrying diagnoses. But Bennie (2) was correct when he wrote: ‘the longer an MD practises the less the diagnosis of growing pain is made as his diagnostic acumen increases’.

Table 2: The incidence of growing pains in various populations
Author No in sample Age Sample type Incidence
Hawksley, 1939 (3) 505 4 to 14 Hospital patients 33.6%
Naish and Apley, 1951 (4) 721 4 to 11 Schoolchildren 4.2%
Brenning, 1960 (7) 676 6 to 11 Schoolchildren 19.8%
Oster and Neilsen, 1972 (5) 2178 6 to 19 Schoolchildren 15.5%
Evans and Scutter, 2004 (6) 1445 4 to 6 Schoolchildren 36.9%

The clinician’s most important diagnostic tools are a full history and a complete examination of the child. The investigations that are most frequently requested include:

  • full blood count (FBC)
  • erythrocyte sedimentation rate (ESR)
  • appropriate radiographs (X-rays).

The full blood count will pick up some cases of leukaemia (although a normal test does not rule this out) and most cases of infection, while an ESR will be elevated in inflammatory and infectious diseases. An X-ray will only show changes in the bone 10 to 14 days after the start of the pathological process unless there is a fracture.

In MacArthur’s study (9) of why physicians ordered tests in growing pains, one of the main reasons given was ‘family reassurance’. Investigations, however, should be used primarily to help answer a question and lead to a diagnosis. If there is diagnostic uncertainty then, depending upon the individual child’s mode of presentation, various specialist tests may also be requested including additional blood tests, radio-isotope bone scans, computer tomography and MRI scans.

Treatment

Growing pains are benign, self-limiting conditions usually resolving within two years. Many treatments have been advocated, including simple reassurance, vitamins, salicylates (such as aspirin), friction rubs and psychiatric counselling. The most popular treatment regimes are reassurance, ‘home’ massage programmes and analgesia. Baxter (10) suggested that parents perform a 10-minute, twice-daily programme of stretches to the quadriceps, calf muscles and hamstrings. She demonstrated an impressive improvement in the number of episodes of pain per month and the time to resolution. Whether this was the result of a physiological change in the muscles by stretching promoting improved blood supply, or increased parental-child interaction and psychological support is not clear. However, it is a benign intervention with good reported results that can certainly be recommended.

What to watch out for

It is beyond the scope of this article to discuss every possible differential diagnosis for knee pain in the growing child. However, there are a few important conditions that must be recognised.

Table 3: Potential knee pain diagnoses in the growing child
Trauma
  • Meniscal injury/discoid meniscus
  • ACL complex or ligamentous disruption
  • Fracture including stress and pathological fractures
  • Battered child
  • Contusion/bone bruising
Collagen disorders
  • Benign hypermobility (see SIB 49)
  • Juvenile arthritis
  • Rheumatic fever
  • Dermatomyositis
  • Scleroderma
Infection
  • Osteomyelitis
  • Septic arthritis
  • Reactive arthropathy
  • Parasites causing myalgia
Neoplasia
  • Osteoid osteoma
  • Unicameral bone cyst
  • Aneurysmal bone cyst
  • Giant cell tumour
  • Osteogenic sarcoma
  • Ewing’s sarcoma
  • Metastatic neuroblastoma
  • Soft tissue sarcomas
  • Leukaemias/lymphomas
Vascular
  • Sickle cell infarcts
  • Haemophilia–haematomas/joint effusions/pseudotumours
  • Compartment syndromes
  • Vascular malformations
Anterior knee pain
  • Patello-femoral joint pain syndrome
  • Osgood-Schlatter disease
  • Sinding-Larson-Johansson disease
Pain referred from the hip
  • Perthes (temporary loss of blood supply to femoral epiphysis)
  • Slipped upper femoral epiphysis
  • Other pathologies affecting the hip
Miscellaneous
  • Somatisation disorders
  • Restless leg syndrome

Pain referred from the hip

Hilton’s Law states that the nerves that supply the muscles that move a joint also supply sensation to the joint itself. The muscles that move the hip also move the knee, so pain in the knee may be felt in the hip and vice versa. Every orthopaedic trainee has drummed into them the need to examine the hip when a patient complains of a knee problem but we still see too many missed diagnoses at tertiary referral centres (see case study below).

Case study: hips and knees

A 13 year old boy referred to the clinic gave a 12-month history of pain in his left knee, exacerbated by playing football. Prior to his referral, he had presented several times to his GP, who eventually arranged for an X-ray of his knee that apparently showed no abnormality. He was treated with physiotherapy and painkillers for his ‘growing pains’ and allowed to continue with his activities. However, his pain persisted and he said he could no longer run so well. Eventually his GP arranged for an orthopaedic opinion.

His knee examination was normal, but the boy walked with an out-toeing gait because of the external rotation deformity of his lower limb. Flexion of the hip brought his leg up into abduction and external rotation and an X-ray of the hip showed that the upper femoral epiphysis had slipped. This is a rare condition seen possibly only once in a GP’s career. It occurs in the adolescent growth spurt and the proximal femoral epiphysis ‘slips off’ the femur. It can result in hip deformity and avascular necrosis of the hip. In this case, the boy required a femoral osteotomy to correct his deformity.

It is clear from this child’s history that he did not have growing pains, and a proper physical examination at initial visit would have localised the pathology to the hip, enabling the deformity to have been identified far sooner and corrected with a more minor procedure and better long-term prospective outcome.

Tumour and infection

A practitioner rarely misses a child with an infection who is acutely unwell, but children may present with knee pain shortly after having had a respiratory illness treated with antibiotics and much more subtle signs of their bone or joint infection, which can be easily missed.

Pain that is not localised to a joint, but is well localised to one part of the bone such as the distal femur or proximal tibia may indicate an infection or tumour. Soft- tissue changes may be present, although true cellulitis is uncommon. If the pain is localised to a joint and if that joint is irritable, an infection of the joint (septic arthritis) must be considered. A Brodie’s abscess (a small chronic localised bone infection), an osteoid osteoma (benign bone tumour) and some malignant tumours will all give night pain. The pain from osteoid osteoma is very responsive and specifically so to anti-inflammatory medication. Important tests for diagnosis include a full blood count and ESR, as well as X-rays and occasionally a bone scan.

Anterior knee pain syndromes

These conditions are readily diagnosed with history and examination and, in the typical patient, require no further tests. There should be no history of trauma, and the knee pain should be well localised. It is often bilateral, although not symmetrical (see fig 1 below).

Figure 1: Anterior knee pain syndromes

Figure 1: Anterior knee pain syndromes

i) Patellofemoral pain:

This used to be called chondromalacia patellae. Patients have anterior knee pain localised to the patellofemoral joint. They may have crepitus from the joint and complain of giving way. Swelling is not a prominent feature. Patients usually respond to a stretching and strengthening programme concentrating on the quadriceps and hamstring muscle groups, perhaps particularly the vastus medialis group.

ii) Osgood-Schlatter disease:

In reality this is a condition rather than a disease. Patients present with pain, tenderness and swelling localised to the proximal tibial tuberosity. The pain is exacerbated after activity and resisted knee extension. It is thought to be caused by a repeated traction injury on the developing ossification centre of the tibial tuberosity, which causes inflammation and structural change. However, MRI studies have shown changes within the patellar tendon consistent with tendinitis. Treatment is controversial. The currently recommended treatment is RICE: rest, ice, compression and elevation, with the use of analgesic and non-steroidal anti-inflammatory medication as necessary. The condition should resolve within two years.

An important concept in management is that of ‘relative rest’. We allow our patients to continue playing sport as symptoms permit. We have no objections to the intermittent use of strapping or bracing, particularly if some limitation of flexion may give symptomatic relief during sport. Occasionally a short period of immobilisation will be needed. Persistent cases may have a symptomatic mobile ossicle within the tendon This can be removed surgically but only in exceptional cases as the risks of surgery can outweigh the benefits.

iii) Sinding-Larsen-Johansson disease:

This condition is analogous to Osgood- Schlatter disease but affects the inferior pole of the patella. It, too, usually responds to non-steroidal medications and RICE, but stretching and strengthening regimes may also help.

iv) Discoid meniscus:

In about 2% of Western populations, the meniscus, rather than having a normal semi-lunar structure, is disc-shaped. Most patients present in childhood; a few as adults, and a few remain symptom-free. Children present between the ages of six and 12 years, complaining of popping, snapping or instability in the knee. If symptoms are troublesome, these patients need to be investigated with X-rays and MRI scans. The treatment involves arthroscopic surgery.

v) Meniscal cysts:

Patients present with symptoms and signs typical of meniscal pathology. They often have pain over the joint line and sometimes associated swelling. Classically the swelling from the cyst decreases in size with knee flexion and increases with extension. MRI can confirm the presence of a cyst and identify whether there is a concomitant meniscal tear, as well as excluding other pathologies.

History of trauma

If the patient has a history of significant trauma prior to the onset of their growing pains, they should undergo a thorough examination, possibly in a hospital setting, to rule out fractures, meniscal injuries and disruption to the ACL complex. Ligament injuries are unusual in this age group, as ligaments are stronger than the bones they insert into, under most conditions.

Restless leg syndrome

There is evidence that cases of persistent growing pains are being diagnosed in later life as restless leg syndrome (11), an autosomal dominant condition (it runs in families) originally thought mainly to affect the middle aged and elderly. Patients complain of leg discomfort and the urge to move their legs. Symptoms are worse at rest or at night. Patients have periodic involuntary limb movements in their sleep and when awake. These movements, when recorded on polysomnography, are diagnostic. Caffeine and chocolate have been reported to exacerbate the condition; some patients respond to antiepileptic or dopaminergic drugs.

Patrick Lusty is an orthopaedic specialist registrar based at the Royal National Orthopaedic Hospital in London

Deborah Eastwood MB FRCS is a consultant paediatric orthopaedic surgeon, based at the Hospital for Sick Children, Gt Ormond St, London and the Royal National Orthopaedic Hospital. Her special interest is in working with disabled children in sports and non-sporting contexts

Illustrations by Viv Mullett

References

  1. Duchamp (1823), Maladies de la croissance. In Levrault, FG (ed) (1832) Memoires de Médecine Practique Paris, Jean-Frederic Lobstein
  2. Bennie B, Growing pains. Arch Paediatr 1894; 11:337
  3. Hawksley JC, The nature of growing pains and their relation to rheumatism in children and adolescents. Br Med J 1939; 1:155-157
  4. Naish J, Apley J, ‘Growing pains’: a clinical study of non-arthritic limb pains in children. Arch Dis Child 1951; 26:134-140
  5. Oster J, Nielsen A, Growing pains. A clinical investigation of a school population. Acta Paediatr Scand 1972; 61:329-334
  6. Evans AM, Scutter SD, Prevalence of ‘growing pains’ in young children. J Pediatr 2004; 145:255-258
  7. Brenning R, ‘Growing pains’. Sven Lakartidn 1960; 57:85-103
  8. Hashkes DJ, Friedland O, Jaber L, Cohen HA, Wolach B, Uziel Y, Decreased pain threshold in children with growing pains. J Rheumatol. 2004; 31:610-613
  9. MacArthur C, Wright JG, Srivastava R, Rosser W, Feldman W, Variability in physician reported ordering and perceived reassurance value of diagnostic tests in children with growing pains. Arch Pediatr Adolesc Med 1996; 150:1072-1076
  10. Baxter MP, Dulberg C. ‘Growing pains’ in childhood – a proposal for treatment. J Pediatr Orthop 1988; 8:402-406
  11. Rajaram SS, Walters AS, England SJ, Mehta D, Nizam F. Some children with growing pains may actually have restless legs syndrome. Sleep 2004; 27:767-773

growing pains