Paediatric Musculoskeletal Development

Original Editor - Robin Tacchetti based on the course by Krista Eskay
Top Contributors - Robin Tacchetti, Jess Bell and Naomi O'Reilly

Introduction

The musculoskeletal system is influenced by many different factors as infants and children grow. This system adapts to the demands, or lack of demands, that are placed on it. When inappropriate forces are applied to muscles or bones, alignment may be impacted. Atypical alignment can directly affect functional activities and an individual's participation.

The following sections will highlight key stages and changes that occur during musculoskeletal development, and provide examples of atypical development.

Rib Cage

Table 1. Rib development.

Rib Cage	Shape	Location of Ribs	Other
Infant	Barrel-shaped	Elevated; perpendicular to Spine	Rigid
2 years old	Oblong-shaped	Depressed due to diaphragm pull and sitting/standing/walking	Lateral expansion
**Atypical	**Persistence of barrel-shape

Trunk

• Initially, infants have a kyphotic spine, which over time, becomes a more neutral spine (as seen in adults)
• Prone push-ups and sitting activate the posterior chain musculature (pushing into thoracic extension)
• Crawling creates co-contraction of the anterior and posterior muscles (for stability)

Increased Curvature of the Spine

Increased curvature of the spine (e.g. scoliosis) can affect:

• breathing
• lung positioning
• heart location
• visceral function

Pelvis

• Initially, infants have a rounded pelvis with a posterior tilt
• Sitting and standing activate core muscles and lead to an anterior pelvic tilt
• At 12 months old: an infant has 12 degrees of anterior pelvic tilt
• At 30 months old: a child has 15 degrees of anterior tilt
• With increased gluteal activity, the anterior tilt decreases slightly until age 8
• Adults have 10 degrees of anterior pelvic tilt

Lower Extremities

Typical joint patterns in infants are as follows:

• Hip: flexion, abduction and lateral rotation
• Knee: flexion, genu varum, medial rotation of tibia
• Ankle: dorsiflexion, slight pronation

Hip

• Infants:
  • more external rotation at birth which decreases over time
  • hip adduction limitation
  • 34 degrees of hip extension limitation
    • as infants spend more time in prone, their anterior capsule stretches
    • 6 weeks old: 19 degrees of hip extension limitation
    • toddlerhood: 7 degrees of hip extension limitation
• Newborn: increased coxa valga - 140-160 degrees
  • decreases over time to 126 degrees in adults
  • as become more ambulatory, femoral neck angle decreases
• Newborn: anteversion of the femur - 40 degrees; decreases to 16 degrees in adults

Changes in Alignment to Consider

Hip

• Femoral neck angle remains high: high femoral anteversion: increase risk of posterior hip dislocation (especially cautious of this with non-walkers aged 30 months)

Increased Anterior Pelvic Tilt

• Abdominals and hip extensors long
• Hip flexors and lumbar extensors short
• Results: unable to have appropriate muscle pull of both abdominals and gluteus muscles when performing functional activities

Decreased Anterior Pelvic Tilt

• Iliopsoas and anterior hip capsule is stretched out
• Gluteus maximus is shortened
• Results: anterior hip laxity and hip instability

Pelvic Obliquity

• Common in individuals with hemiplegia and diplegia
• Depressed hip side (shorter side):
  • increased pronation of the foot on that extremity
  • reduced stance time
  • reduced loading
  • functional ankle plantarflexion
• Longer side:
  • compensatory foot pronation
  • medial rotation of the lower extremity
  • compensatory knee flexion
• Results: gait asymmetry, pelvis rotation on the shorter side
• Significant increase in pelvic obliquity leads to a seating imbalance, pain from pelvic impingement on the ribs and ischial decubitus ulcers

Knee

• newborn: genu varum
• toddler: genu valgus
  • maximum valgus peaks around 2 1/2 years old
  • decreases over time
• adult: neutral
• newborn: 30 degree knee flexion contracture
  • resolves first few months of life
• newborn: medial rotation of the tibia
  • 12 months: medial rotation resolve

Increased Medial Tibial Torsion

• not common
• toeing in
• most likely medial rotation occurring higher up in the chain

Increased Lateral Tibial Torsion

• presents with crouched posture

Increased Genu Valgus

Possible impairments:

• pain in calf, thigh and/or knee
• increased fatigue with activities
• less efficient gait
  • decreased gait velocity
  • decreased balance
• increase Q-angle
  • quad less efficient secondary to abnormal muscle pull
• lateral subluxation of the patella
• collapse of medial foot arch
• protective in-toeing

Ankles/Feet

• newborn: hindfoot varus
  • weight-bearing changes to valgus
• newborn: feet straight forward or slight toeing out
• adulthood: toeing out increases
• newborn: high arch
• adult: flat feet

Physiotherapy Role

Physiotherapists can facilitate correct movement patterns to attain proper bio-mechanical alignment. The earlier in life the interventions are applied, the better the functional outcome will be. Some of the interventions that physiotherapist can use are listed below:

• weight shifts
• loading
• static positioning devices
• splinting
• bracing

Resources

• Biomechanics
• Infant Development
• Coxa Vara / Coxa Valga
• Valgus Knee