Paediatric Musculoskeletal Development

Introduction

As an infant grows, movement patterns develop that affect their bony alignment. As movement patterns are practiced thousands of times a day any abnormal muscle pull can create atypical alignment. Abnormal muscle pulls can be caused by genetic conditions and impairments with abnormal tone. Atypical alignment can directly affect form and functional activities and participation.

The following sections will highlight typical musculoskeletal development for an infant as well as changes that progress over time.

Rib Cage

Rib Cage	Shape	Location of Ribs	Other
Infant	Barrel-Shaped	Elevated; Perpendicular to Spine	Rigid
2 years old	Oblong-Shaped	Depressed due to diagragm pull and sitting/standing/walking	Lateral Expansion
Abnormal	Persistence of Barrel-Shape

Trunk

• begins with kyphotic spine moving into a more neutral spine
• prone push-up and sitting activates posterior chain musculature
• crawling creates co-contraction of anterior and posterior muscles

** Abnormal muscle pull can change spine position

Pelvis

• begin with rounded pelvis and posterior tilt
• sit and stand: activates core muscles and anterior pelvic tilt
• 12 months: 12 degrees of anterior pelvic tilt
• 30 months: 15 degrees of anterior tilt
• with increased gluteal activity, anterior tilt decreases slightly until age 8
• adult: 10 degrees of anterior pelvic tilt

Lower Extremity

Lower extremity normal infant pattern:

• hip: flexion, abduction and lateral rotation
• knee: flexion, genu varum, medial rotation of tibia
• ankle: dorsiflexion, slight pronation

Hip

• infants:
  • hip adduction limitation
  • high external rotation which decreases over time
  • 34 degrees of hip extension limitation
    • as they spend more time in prone 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 adult - 126 degrees.
  • more ambulatory, lower femoral neck angle
• newborn: anterversion of the femur - 40 degrees
  • adult- 16 degrees

** Abnormal: femoral neck angle remains high: high femoral anteversion: increase risk of posterior hip dislocation (especially cautious of this with non-walkers at 30 months

Increased anterior pelvic tilt:

• abdominals and hip extensors are too long
• hip flexors and lumbar extensors are too short
• results: unable to have appropriate muscle pull of both abdominals and gluteus muscles when you're performing functional activities.

Decreased anterior pelvic tilt

• iliopsoas and anterior hip capsule is stretched out
• anterior hip capsule is stretched out
• gluteus maximus is shortened
• results: hip laxity in the front and hip instability.

Pelvic obliquity

• common in patients with hemiplegia and diplegia
• lower side (hip depressed)
  • shorter lower extremity or
  • increased pronation of the foot on that extremity
  • reduced stance time
  • reduced loading
  • functional ankle plantarflexion
• long side
  • foot pronation as a compensatory mechanism
  • medial rotation of the lower extremity
  • knee flexion to compensate.
• Results: gait asymmetry and pelvis rotation on short side.

Knee

• newborn: genu varum
• toddler: genu valgus
  • maximum around 2 1/2 years old
  • decreases over time
• adult: neutral
• newborn: 30 degree knee flexion contracture
  • resolves first few months of life
• infant: 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

• crouched posture

Increased genu valgus

Possible issues:

• calf, thigh and knee pain
• 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

• infant: feet straight forward or slight toeing out
• adulthood: toeing out increases
• newborn: arch
• adult: flat feet
• newborn: hindfoot varus
  • with standing moves it into valgus

Physiotherapy Role

Malalignment reinforces faculty aberrant pull resulting in atypical movement patterns. Physiotherapists can facilitate correct movement patterns to attain proper biomechanical alignment. The earlier the interventions are applied, the better the functional outcome will be. Some of the interventions that help with appropriate alignment are listed below:

• Weight shifts/Loading
• Static positioning devices
• Splinting/Bracing

So for children that are unable to stand by the age of five, we want to have imaging of their spine. Do they have scoliosis that's developing? What is their ribcage doing? Are they able to maintain appropriate alignment? Because if you have too much curvature in your spine, it affects your breathing. It can affect your lung position, it can affect where your heart is at. So it can affect visceral function if they have too much compression on those organs due to a curved spine.it's really important to make sure that you know what that child is doing and what they look like functionally because it can have significant impact on pain, on mobility, and even on things like breathing and cardiac function as they continue to grow and develop.