An anatomical perspective on growing pains in children.
Definitive causes were not identified in the literature, but some of the many possibilities included muscular fatique due to excessive physical activity, postural deviations such as pes planus (flat feet), pronated feet, genu valgum (knock knees), and medical conditions and pathologies such as juvenile arthritis, osteomyelitis, Ross River virus, a fracture across the growth plate, and Osgood-Schlatter's syndrome.
A BRIEF HISTOLOGICAL DESCRIPTION OF GROWTH IN LONG BONES
Growth in long bones like the femur, tibia and humerus primarily occurs via two processes:
* Appositional growth by deposition of matrix produced by osteoblasts and resorption of matrix by osteoclasts in order to increase the width of the bone, while at the same time maintaining a medullary cavity for bone marrow to reside in, and
* Interstitial growth at a specialised area of long bone near the epiphysis known as the epiphyseal (growth) plate, where cartilage cells (chondrocytes) eventually enlarge and degenerate, and are replaced by osteoblasts and osteocytes invading from the diaphysis towards the space created at the plate by the degenerating chondrocytes. This then allows the long bone to elongate.
This growth process is stimulated by somatotrophin (growth hormone) released by the anterior pituitary gland.
Another important tissue to bear in mind is the periosteum, which is layer of connective tissue that surrounds bones except at the articular surfaces. The periosteum has both an outer fibrous (collagenous) layer and an inner osteogenic layer, which contains cells that can develop into osteoblasts that are important in fracture repair and increasing the width of bone.
[FIGURE 1 OMITTED]
The periosteum is attached to the bone by Sharpey's collagen ibers as and provides attachment for ligaments and tendons. Significantly, the periosteum contains nociceptive (pain) nerve endings, which respond mainly to mechanical and thermal changes. Figure 1 also shows spongy bone that occurs at the epiphysis and consists of trabeculae or shelves of bone. The compact bone around it and in the diaphysis is formed by a series of Haversian systems (osteons). Bone marrow residing mainly in the diaphysis consists of developing red and white blood cells as well as adipocyte (fat) cells. Articular cartilage surrounds the ends of long bones to form part of the synovial joints and is not lined by periosteum.
A paper by Noonan et al. (1) examined increased growth during recumbency in young animals. Using implanted microtransducers, bone length measurements were sampled every 167 seconds for 25 days, to reveal that 90% of bone elongation occurred during recumbency and little whilst standing or during movement. The authors suggested that the growth plates are compressed during weight bearing and that a possible mechanism of pain may be increased tension in the periosteum as the growth plates spring back from released compression, or because of some signal transduction mechanism during recumbency.
There is a distinct possibility that, during certain times in some children's growth phases, the tension across the epiphyseal plate may be released in a manner similar to a microscopic "earthquake", placing increasing tension on the periosteum, thereby triggering the firing of the pain receptors that reside in this tissue. In addition, it is well established that bone growth is influenced by the release of growth hormone from the anterior pituitary gland, so it is necessary to take into consideration that varying levels of hormone characteristically released during certain behavioural states in a child may intensify the growing pain. In 1971 Finkelstein et al. (2) examined four normal human infants to establish that during the states of crying and sleep (REM and non REM) plasma growth hormone levels were distinctly higher and more variable than normal. More recently, a paper by Lampl and Johnson (3) Johnson (3) examined the relationship of sleep and infant bone growth in length. The study concluded by suggesting that sleeping and bone length growth are related temporarily, which again supports the notion that certain behavioural states in a child could exacerbate the discomfort and pain experienced by having increased hormone output adding to the cellular forces exerted across the epiphyseal growth plate.
This analysis of the mechanical forces which may be occurring at the growth plate, as well as addressing certain behavioral states in the affected child, supports a large part of the literature encountered on this topic, which suggests that massage of the affected limb(s) would be beneficial in easing discomfort and pain. Some of the aims of massage therapy for this purpose would be to elongate the muscles by employing gentle passive or active stretches (PNF) and kneading, thereby reducing the tension of tendons on the periosteum. Other massage techniques such as effleurage and compression aim to improve soft tissue blood supply and further increase tissue elasticity. In addition, massage has the added benefit of relaxation providing comfort in this stressful period of a child's life.
(1.) Noonan, K. J., Farnum, C. E., Leiferman, E.M., Lampl, M. Markel, M. D., and Willsman N.J. Growing Pains: are they due to increased growth during recumbency as documented in a lamb model? Journal of Paediatric Orthopedics 2004; 24 (6): 726-731.
(2.) Finkelstein JW, Anders TF, Sacher EJ, Roffwarg HP, Hellman LD, authors. Behavioral state, sleep stage and growth hormone levels in human infants. J Clin Endocrinol Metab. 1971; 32: 368-71.
(3.) Lampl M. and Johnson M.L. Infant growth in length follows prolonged sleep and increased naps. SLEEP 2011; 34(5): 641-650.
Patrick de Permentier BSc (Hons), UNSW, MSc (Research), UNSW, Grad Cert H Ed (UNSW), Diploma Remedial Massage (NSW School of Massage). Lecturer, Anatomy Department, School of Medical Sciences, Faculty of Medicine, UNSW. Lecturer in Anatomy and Physiology, NSW School of Massage, Sydney. ATMS Member's Representative, Council member ANZACA (Australian and New Zealand Association of Clinical Anatomists), Member ANS (Australian Neuroscience Society)
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|Author:||de Permentier, Patrick|
|Publication:||Journal of the Australian Traditional-Medicine Society|
|Date:||Mar 1, 2012|
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