Anatomy and Normal Development in Children Understanding growth and development is core knowledge in pediatric orthopaedics. This chapter summarizes clinically relevant anatomy and developmental norms. It also contains a description of normal gait and guidelines for interpreting a gait study. When evaluating a patient at risk of developmental delay, appropriate norms help determine whether a delay is present. This section presents the chronological appearance of key motor, social, and language skills. ▶ Table 1.1 provides the norms for motor milestones. Skill Mean age (mo) Std Dev Roll from back to stomach 3.6 1.4 Roll from stomach to back 4.8 1.4 Sit tailor style 5.3 1.0 Sit unsupported 6.3 1.2 Crawl (many never crawl) 7.8 1.7 Pull to stand 8.1 1.6 Cruise 8.8 1.7 Walk 11.7 2 Run 15 3 Source: Used with permission from Palmer F, Capute A. Keys to developmental assessment. In: McMillan J, ed. Oski’s Pediatrics. 3rd ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2006:789. Neonatal period (first month): Supine: Generally flexed and tone a little low. 2 Months: Prone: Head sustained in plane of body in ventral suspension. Social: Smiles on social contact. 4 Months: Supine: Reaches and grasps objects and brings them to mouth. Sitting: No head lag on pull to sitting position. 4 to 6 Months: Prone: Rolls over to supine. Semantics: Turns to his or her own name. 6 to 7 Months: Sitting: Sits initially with support of pelvis, then independently. Adaptive: Transfers objects from hand to hand. 10 Months: Standing: Pulls to standing position. Motor: Creeps or crawls. 12 to 18 Months: Syntax: Speech generally consists of single words). 12 Months: Motor: Walks with one hand held, “cruises” or walks holding on to furniture. Language: Two “words” besides mama and dada. 15 Months: Motor: Walks alone, crawls up stairs. 18 Months: Motor: Runs stiffly. Social: Feeds self. 24 Months: Motor: Opens doors. Syntax: Uses two- and three-word combinations (telegraphic speech). 30 Months: Motor: Jumps. 36 Months: Motor: Goes up stairs alternating feet, stands momentarily on one foot. 48 Months: Motor: Hops on one foot, throws ball overhand. 60 Months: Motor: Skips. Referral to a developmental pediatrician or neurologist should be made if the infant is displaying any of the following: Not rolling by 6 months. Not sitting independently by 8 months. Handedness develops too early (by 12 months): may indicate abnormality of opposite side. Not walking by 18 months. No words by 14 months. Bibliography 1. Richter SB, Howard BJ, Sturner R. Normal infant and childhood development. In: McMillan J, ed. Oski’s Pediatrics. 4th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2006:593–601 2. WHO Multicentre Growth Reference Study Group. WHO Motor Development Study: windows of achievement for six gross motor development milestones. Acta Paediatr Suppl 2006;450:86–95 There is some variation and overlap between levels. This is why injury to a single nerve root may not produce complete loss of sensation within a dermatome. The sensation of proprioception and vibration is carried in the dorsal column of the spinal cord: light touch in the ventral spinothalamic tract and pain and temperature in the lateral spinothalamic tract. During neurologic root recovery, pain sensation returns before light touch (▶ Fig. 1.1). Fig. 1.1 Dermatomes. Even though most muscles have innervation from multiple segments, each root has specific muscles and sensory regions for which it is critical. The image shown in ▶ Fig. 1.2 is helpful for diagnosing cervical root lesions and spinal cord injury. Motor testing can be performed in one coordinated sequence, from proximal to distal: deltoid (C5), biceps (C5), wrist extension (C6), finger extension (C7), finger flexion (C8), and finger abduction and adduction (T1). Fig. 1.2 Sensory and motor innervation C6 to T1. Note that only sensory loss is shown in the shaded hand, and only muscle involvement is shown in the arm. (Used with permission from McQueen JD, Khan MI. Neurologic evaluation. In: Sherk HH, Dunn EJ, Eismont FJ, et al, eds. The Cervical Spine. 2nd ed. Philadelphia, PA: J.B. Lippincott; 1989:206 [Figs. 4, 5].) Because most muscles are innervated by multiple segments, it is necessary to know all the roots controlling a given muscle. ▶ Fig. 1.3 indicates the roots contributing to a given muscle in the upper extremity. For strength grading, the five-grade scale of the MRC (Medical Research Council) has been widely used: Grade 1: Flicker. Grade 2: Less than antigravity. Grade 3: Maintains position against gravity. Grade 4: Moves against submaximal resistance. Grade 5: Full strength. Fig. 1.3 Innervation of muscles of upper extremity. The anatomy is depicted here to understand injuries from birth and later trauma. Most traction injuries involve the upper roots (▶ Fig. 1.4). Fig. 1.4 Formation of the brachial plexus. The median nerve may be tested by grip or finger flexion and the anterior interosseous nerve (a branch of the median that can be selectively injured) by testing distal interphalangeal flexion of the index finger and thumb, forming an “O.” Radial nerve: By extending the thumb, the wrist or the metacarpophalangeal joints. Ulnar nerve: By crossing fingers, abducting fingers, or flexing the distal interphalangeal joint of the fifth finger (▶ Fig. 1.5). Fig. 1.5 Documentation of the status of all nerves and circulation before treatment of supracondylar humerus fractures. This involves (a) checking active palmar flexion (median nerve); (b) flexion of distal interphalangeal joints of the index finger and thumb—anterior interosseous nerve; (c) dorsiflexion of the metacarpophalangeal joints—posterior interosseous nerve; (d) flexion of the fifth finger distal interphalangeal joint; or (e) crossing of index and second fingers—ulnar nerve. Knowledge of lower extremity motor innervation is important for understanding spina bifida, lumbar disk herniation, spinal cord injury, and other conditions. Innervation of muscles is by descending spinal segments at progressively distal levels of the limb, with the notable exception of gluteus maximus, medius, and minimus (L5 through S2). The most important motor innervations to know are iliopsoas (L1 through L3), adductors (L2 through L4), quadriceps (L2 through L4), hamstrings (L4 through L5), anterior tibialis (L4 through L5), gastrocnemius (S1), and glutei (L5 through S2) (▶ Fig. 1.6). Fig. 1.6 Segmental innervation of muscles of the lower limb. In many situations, it is important to know whether an epiphysis should be ossified at a given age, such as in evaluating a patient with a hip dislocation, skeletal dysplasia, or elbow fracture. Normal times for appearance and closure of the long bones are given in ▶ Fig. 1.7; for the hand and foot, see ▶ Fig. 1.8. The following are 11 important milestones: The distal femoral epiphysis is the first to ossify, at ~39 weeks’ gestation; the proximal tibia ossifies 1 week later. The mean time for ossification of the proximal femoral epiphysis is 4 months, but normal may be up to 11 months. The greater trochanter ossifies at 4 to 6 years. The triradiate cartilage closes before Risser I. The tarsal navicular does not ossify until 3 to 4 years, so its location must be inferred from the position of the first metatarsal. The last physis to close is that of the medial clavicle, at age 20 to 25 years. The sequence of ossification about the elbow can be remembered by the mnemonic CRITOE (▶ Fig. 1.9): Capitellum (age 2). Radial head (age 5). Internal epicondyle (age 7). Trochlea (age 9). Olecranon (age 10). External epicondyle (age 11). Angle of distal humeral articular surface: This angle is key to understanding any angular change about the elbow. It is best followed by the Baumann angle, between the humeral shaft and the lateral condylar physis (▶ Fig. 1.10). Its normal value is 72 ± 4 degrees. There is no difference between genders or ages from 2 to 13 years. Determination of skeletal age using the elbow: This can be determined by the olecranon or modified Sauvegrain method (▶ Fig. 1.11). The five stages are (1) bipartite olecranon; (2) half-moon–shaped olecranon; (3) rectangular olecranon; (4) partially fused; or (5) fully fused. They occur at 6-month intervals of skeletal age from 11 years in girls and 13 years in boys. The rectangular shape of the olecranon marks the early part of the peak growth velocity. The fully fused olecranon occurs at skeletal age of 13 in girls and 15 in boys, marking the deceleration of growth velocity. Determination of skeletal age using the Sanders Skeletal Maturity Staging System (▶ Table 1.2; ▶ Fig. 1.12). Patients with curves over 30 degrees at stages 3 to 4 are at high risk of progression to surgery, and patients with curves less than 20 degrees at these stages are at low risk. Skeletal age can also be assessed more simply by use of the Thumb Ossification Composite Index or TOCI (▶ Fig. 1.13). Determination of skeletal maturity using the calcaneal apophysis: this occurs in six stages, four of them prior to peak height velocity (PHV). Thus, it is ideal for predicting the PHV, which occurs between stages 3 and 4. Stage 2 occurs about 2 years before PHV, stage 3 about 1 year prior, and stage 4 just after (▶ Fig. 1.14). Fig. 1.7 Age of appearance of secondary ossification centers (a,b) and physeal closure (c,d) in the long bones. (Used with permission from Ogden JA. Radiologic aspects. In: Ogden JA, ed. Skeletal Injury in the Child. 2nd ed. Philadelphia, PA: W.B. Saunders; 1990:84 [Figs. 3–28, 3–29].) Fig. 1.8 Age of appearance of secondary ossification centers and physeal closure in the hand (a) and foot (b). m.i.u., months in utero. (a is used with permission from O’Brien ET. Fractures of the hand and wrist region. In: Rockwood CA Jr, Wilkins KE, King RE, eds. Fractures in Children. 3rd ed. Philadelphia, PA: J.B. Lippincott Co.; 1991:320 [Fig. 4–1]. b is used with permission from Aitken JT, Causey G, Joseph J, Young JZ. The foot. In: Aitken JT, Causey G, Joseph J, Young JZ, eds. A Manual of Human Anatomy: Vol IV, Lower Limb. 2nd ed. Edinburgh: E & S Livingstone; 1966:80 [Fig. 30].) Fig. 1.9 Appearance of age of ossification centers about the elbow can be summarized by the mnemonic “CRITOE.” (Used with permission from Sponseller PD. Orthopaedic injuries. In: Nichols DG, Yaster M, Lappe DG, Buck JR, eds. Golden Hour: The Handbook of Advanced Pediatric Life Support. St. Louis, MO: Mosby Year Book; 1991:350 [Fig. 18–3].) Fig. 1.10 (a–c) Differing configuration of the distal humerus and landmarks used for measurement of the Baumann angle. Fig. 1.11 Simplified Sauvegrain method for skeletal maturity assessment. Fig. 1.12 Simplified Tanner-Whitehouse III (Sanders) maturation scale for skeletal maturity assessment. Note that the distal phalangeal epiphyses are the key to the curve acceleration phase (CAP). When they are capped, the phase is beginning, and when they are all closed, the phase has ended. Stage 1: All digital epiphyses not covered (epiphyses not as wide as metaphyses). Stage 2: All digital epiphyses are covered. Stage 3: Most epiphyses cap their metaphyses. Capping is a small bend over the metaphyseal edge. This is also the beginning of the CAP. Stage 4: At least one of distal phalanges closed. Stages 5 to 8: Descending phases of growth. (Adapted with permission from Sanders JO, Khoury JG, Kishan S, et al. Predicting scoliosis progression from skeletal maturity: a simplified classification during adolescence. J Bone Joint Surg Am. 2008;90(3):540–553.) Fig. 1.13 The thumb axis provides similar information to the whole hand. Thumb Ossification Composite Index (TOCI) stages 1 through 8 are based on the appearance of the ulnar sesamoid and the maturation of the phalangeal physes. Peak height velocity occurs between TOCI stages 4 and 5, and menarche occurs in TOCI stage 6. TOCI stage 8 matches Sanders 7, with less than 1–2 cm growth remaining. Stage Key features Tanner–Whitehouse III stage Greulich and Pyle reference Related maturity signs 1. Juvenile slow Digital epiphyses not covered Some digits are at stage E or lower Female 8 y + 10 mo, male 12 y + 6 mo (note fifth middle phalanx) Tanner stage 1 2. Preadolescent slow All digital epiphyses covered All digits at stage F Female 10 y, male 13 y Tanner stage 2, starting growth spurt 3. Adolescent rapid-early Preponderance of digits is capped. The 2nd through 5th metacarpal epiphyses wider than their metaphyses All digits are at stage G Female 11 and 12 y, male 13 y + 6 mo and 14 y Peak height velocity, Risser stage 0, open pelvic triradiate cartilage 4. Adolescent rapid-late Any distal phalangeal physes are clearly beginning to close Any distal phalanges are at stage H Female 13 y (digits 2, 3, 4), male 15 y (digits 4, 5) Girls typically in Tanner stage 3, Risser stage 0, open triradiate cartilage 5. Adolescent steady-early All distal phalangeal physes closed; others are open All distal phalanges and thumb metacarpal are at stage I; others remain at stage G Female 13 y + 6 mo, male 15 y + 6 mo Risser stage 0, triradiate cartilage closed, menarche only; occasionally starts earlier 6. Adolescent steady-late Middle or proximal phalangeal physes are closing Middle or proximal phalanges are at stages H and I Female 14 y, male 16 y (late) Risser sign positive (stage 1 or more) 7. Early mature Only distal radial physis is open; metacarpal physeal scars may be present All digits are at stage I. The distal radial physis is at stage G or H Female 15 y, male 17 y Risser stage 4 8. Mature Distal radial physis completely closed All digits are at stage I Female 17 y, male 19 y Risser stage 5 Source: Used with permission from Sanders JO, Khoury JG, Kishan S, et al. Predicting scoliosis progression from skeletal maturity: a simplified classification during adolescence. J Bone Joint Surg Am 2008;90(3):541 (Table 1). Bibliography 1. Nicholson AD, Liu RW, Sanders JO, Cooperman DR. Relationship of calcaneal and iliac apophyseal ossification to peak height velocity timing in children. J Bone Joint Surg Am 2015;97(2):147–154 The cervical spine in children is characterized by increased mobility at C2–C3, termed pseudosubluxation, which should not exceed 3 mm. The tip of the odontoid should not be more than 1 cm from the basion of the skull (anterior rim of the foramen magnum). The physis of the odontoid normally fuses between 3 and 6 years. The atlas–dens interval should be less than 4 mm. The power ratio is the ratio of the distance from basion to the posterior arch of C1 divided by the distance from the opisthion to the anterior arch of C1. This ratio should be less than 1. The retropharyngeal space should not exceed 8 mm; if greater, it could signify bleeding from a fracture or a dislocation. The spinal laminae should form a smooth line posteriorly. The vertebral bodies may be wedged anteriorly, especially on their superior surfaces, until age 10 years (▶ Fig. 1.15). Fig. 1.15 Normal values of cervical spine alignment for children. (Used with permission from Sponseller PD. Orthopaedic injuries. In: Nichols DG, Yaster M, Lappe DG, Buck JR, eds. Golden Hour: The Handbook of Advanced Pediatric Life Support. St. Louis, MO: Mosby Year Book; 1991:353 [Fig. 18–4].) Body: Not ossified at birth; the center (occasionally two centers) appears during the first year after birth. Neural arches: Appear bilaterally at approximately the seventh fetal week; most of the anterior portion of the superior articulating surface is usually formed by the body. Synchondrosis of posterior arch: Unites by the third year. Union rarely is preceded by the appearance of a secondary center within the synchondrosis. Neurocentral synchondrosis: Fuses at approximately the seventh year (▶ Fig. 1.16). Fig. 1.16 Axial, coronal, and sagittal views of the developing atlas. The first cervical vertebra is formed by three ossification sites: the anterior arch (gray), or centrum, and the two neural arches (white). (Used with permission from Oh BC, Wang MY. Cervical anatomy and surgical approaches. In: Kim DH, Betz RR, Huhn SL, Newton PO, eds. Surgery of the Pediatric Spine. New York: Thieme; 2008:95 [Fig. 8–1].) Body: One center (occasionally two) appears by the fifth fetal month. Neural arches: Appear bilaterally by fetal month 7. Neural arches fuse posteriorly by year 2 or 3. Bifid tip of spinous process: Occasionally a secondary center is present in each tip. Neurocentral synchondrosis: Fuses at 3 to 6 years. Inferior epiphyseal ring: Appears at puberty and fuses at around 25 years. “Summit” ossification center for odontoid: Appears at 3 to 6 years and fuses with the odontoid by 12 years. Odontoid (dens). Two separate centers appear by fetal month 5 and fuse with each other by month 7. Synchondrosis between odontoid and neural arch: Fuses at 3 to 6 years (▶ Fig. 1.17). Fig. 1.17 Coronal and sagittal views of the developing axis. There are four ossification centers present at birth: one center for each neural arch (white), one for the odontoid process (gray), and one for the body (black). (Used with permission from Oh BC, Wang MY. Cervical anatomy and surgical approaches. In: Kim DH, Betz RR, Huhn SL, Newton PO. Surgery of the Pediatric Spine. New York: Thieme; 2008:96 [Fig. 8–2].)
1.1 Introduction
1.2 Neurodevelopmental Norms
1.2.1 Psychomotor Skills in Children during Years 1 through 5
1.3 Referral Criteria
1.4 Neurologic Anatomy
1.4.1 Sensation
1.4.2 Upper Extremity Motor Examination
1.4.3 Upper Extremity Muscle Innervation
1.4.4 Formation of the Brachial Plexus
1.4.5 Peripheral Nerve Testing in the Upper Extremity
1.4.6 Lower Extremity Motor Innervation
1.5 Skeletal Development
1.5.1 Appearance of Secondary Ossification Centers and Physeal Closure
![(c,d) in the long bones. (Used with permission from Ogden JA. Radiologic aspects. In: Ogden JA, ed. Skeletal Injury in the Child. 2nd ed. Philadelphia, PA: W.B. Saunders; 1990:84 [Figs. 3-28, 3-29].)](https://i0.wp.com/musculoskeletalkey.com/wp-content/uploads/2020/03/9781626234321_c001_f007cd.tif_epub1.jpg?w=960)
Fig. 1.14 Determination of skeletal maturity using the calcaneal apophysis:
Stage 0: no apophysis.
Stage 1: <50% coverage.
Stage 2: >50% coverage.
Stage 3: Complete coverage within 2 mm of plantar edge. ~1 year before peak height velocity (PHV).
Stage 4: Beginning fusion; just after PHV.
Stage 5: Complete fusion.
1.5.2 Cervical Spine Radiographic Normal Values for Children
1.5.2.1 Alignment
1.5.3 Development of the Cervical Spine
1.5.3.1 First Cervical Vertebra (Atlas)
1.5.3.2 Second Cervical Vertebra (Axis)
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