How Does Turner Syndrome Affect the Bones?

It’s important to be aware of the skeletal system abnormalities in Turner syndrome as they are common and vary from person to person.  Bone irregularities may be present at birth or may develop across the lifespan.

Women and girls with TS are at a higher risk of developing osteoporosis, a condition caused by a reduction of calcium and collagen in the bones. This "thinning" of the bones can lead to an increased risk of fractures. The risk is doubled in women with TS, and the wrist is the most vulnerable site.

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Risk of fracture is increased even with normal bone strength (bone mineral density- BMD). The increase of falls may be related to older age and/or hearing impairments.

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Common skeletal differences in TS

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The lower jaw is set back from the upper jaw and appears recessed when the face is viewed from the side. (Retrognathia)

• babies may struggle to properly latch onto a nipple when feeding

• biting or chewing food may be difficult

• teeth may become crowded or irregularly positioned

• Snoring and sleep apnea may be related to a recessed jaw.

A short neck may result from small and/or fused cervical vertebrae. (Hypoplasia)

Broad shoulders and pelvis lend to a stocky appearance

Arms may turn out at the elbow (Cubitus valgus).

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The spine

• Scoliosis (curvature of the spine) occurs in 10% of those with TS during early childhood or adolescence. It may progress or develop during growth hormone therapy. 

• Kyphosis (spine bending forward)

• Irregular shaped bones called vertebral wedging result from deterioration of the spine.

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The hips

• Infants have an increased risk of congenital hip dislocation called dysplasia. If detected early, it can easily be treated within a few weeks.

• In rare cases the hip(s) can be dislocated at birth

• The top of the hip bone can slip off the long-bone during later years of growth (slipped capital femoral epiphysis).

• congenital hip dislocation increases the risk of osteoarthritis in the hips of older women

Although rare the bones between the wrist and elbow may bow out a bit, the condition is called a Madelung deformity.

Some have a toe deformity of the 4th toe called brachymetatarsia.

Knees (60-80%)

The knees may touch each other when the legs are straightened and is commonly referred to as "knock-kneed" (Genu valgum). Those unable to touch their feet together while straightening the legs may experience knee instability or body alignment abnormalities.

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Feet

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• Toes spreading out create a wide or splaying of the front of the foot. Treatment is important to prevent foot weakness. https://www.physio-pedia.com/Splay_foot

• “Flat feet” usually develop during childhood due to the arch collapsing downward and/or inward (overpronation) and may cause pain if the foot is not structurally supported.

• The subtalar joint (ankle/heel area) may be weak and is vital to movement as it helps to readjust the lateral (side-to-side) position of your foot as you navigate uneven or shifting terrain.

Care and treatment

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• Proper estrogen treatment improves bone mineral density (BMD) and helps protect bones.

• Adequate calcium and vitamin D intake are essential to prevent osteoporosis.

• Knee, shoulder and hip alignment are important to measure.

• A DEXA scan should be performed every 3-5 years and annually at the start of specific treatment like estrogen and GH. Bone mass density tests must consider small bone size related to short stature.

• Physical therapy supports misalignment issues for the shoulders, hips, knees, ankles and as well as how the body carries its weight.

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Resources

Exercises to reduce or prevent falling (National Osteoporosis Foundation)