Down Syndrome and Neck Safety in Sport: Atlantoaxial Instability

Your son, who has Down syndrome, just joined a swim club and loves it. The registration form asks about something called atlantoaxial instability, and a friend mentioned that some kids need a neck X-ray before they can do certain events. You are not sure what it means or whether you should worry.

The good news is that most people with Down syndrome play sport safely for life. Knowing what atlantoaxial instability is, and which signs to watch for, helps you keep it that way.

What is atlantoaxial instability?

The top two bones of the neck are called the atlas (C1) and the axis (C2). Together they let the head turn. Strong ligaments normally hold them firmly in place.

People with Down syndrome often have looser ligaments and lower muscle tone. In some, the joint between C1 and C2 has more movement than usual. This is called atlantoaxial instability, or AAI. If the bones shift too far, they can press on the spinal cord.

How common is it? Numbers vary a lot between studies:

• Special Olympics Canada states that up to 15% of people with Down syndrome have a misalignment of C1 and C2
• A UK sport and exercise medicine position statement reports AAI in 6.8% to 27%, depending on age
• The same statement notes that fewer than 1% to 2% go on to develop symptoms

In other words, many people with AAI on an X-ray never have any problems. The key is watching for symptoms.

Warning signs to know

Signs that the spinal cord may be under pressure include:

• Neck pain or head pain
• A head tilt, or not wanting to move the neck
• Trouble holding the head up
• A change in walking, poor balance or new clumsiness
• Weakness in the arms or legs, or dropping things
• Numbness or tingling
• New bladder or bowel accidents
• Less interest in usual activities

Some people with Down syndrome may not be able to describe these changes. Parents, coaches and caregivers are often the first to notice that something is different.

When to call 911 or go to the emergency department

Call 911 if, after a fall, tackle or awkward landing, the person has neck pain with weakness, numbness, tingling, or trouble walking or breathing. Keep them still and do not move their neck.

Go to the emergency department the same day if new weakness, a sudden change in walking, or new bladder or bowel loss appears, even without an injury.

When to see your doctor

Contact your family doctor or pediatrician promptly for new neck pain, a stiff neck, a head tilt, or any change in walking, hand use, or bladder and bowel habits. The doctor may check reflexes, strength and balance, and may order X-rays taken with the neck bent forward and back, or an MRI. Referral to a spine surgeon may follow.

For children with no symptoms, the American Academy of Pediatrics (as summarized by the Adult Down Syndrome Center) does not recommend routine screening X-rays. Instead, it recommends a careful history and exam at every well-child visit. The UK position statement reaches a similar conclusion: plain X-rays are not reliable for screening people without symptoms.

What about sport?

Staying active matters for physical and mental health, and limiting sport for people without symptoms is unlikely to prevent injury. Still, some rules apply. Special Olympics Canada requires an initial AAI screening for all new athletes with Down syndrome. Unless a doctor's exam with flexion and extension neck X-rays shows no instability (or other written medical clearance is in place), athletes cannot take part in:

• Butterfly stroke and diving starts in swimming, and diving
• High jump and pentathlon
• Squat lifts
• Equestrian sports and artistic gymnastics
• Soccer and alpine skiing
• Warm-ups that put undue stress on the head and neck

Other sensible precautions include never tackling head first and using trampolines only with proper training and supervision.

Why your physiotherapist asks about this

When a client with Down syndrome comes to Vaughan Physiotherapy Clinic, we ask whether they have had AAI screening, whether there are any sport restrictions, and whether anything has changed recently. We also do a quick neurological screen: walking, balance, strength, reflexes and neck movement.

We adapt treatment to keep the neck safe. That means no neck manipulation, no forceful end-range neck stretching, and care with positions that push the head far back or forward. If we find any new nerve signs, we stop and refer to the family doctor or emergency department, and we share what we found with your permission.

What physiotherapy can and can't do

Physiotherapy cannot fix a loose C1 and C2 joint, and it does not replace medical screening or a surgeon's opinion. What it can do is help people stay active safely:

• Building overall strength, balance and body control
• Choosing exercises and sports that fit any medical restrictions
• Teaching safe technique for landing, falling and lifting
• Supporting rehab after neck surgery, following the surgeon's plan

Key takeaways

• Atlantoaxial instability is looseness between the top two neck bones and is more common in Down syndrome.
• Most people with it never have symptoms, and sport is encouraged.
• Watch for neck pain, head tilt, walking changes, weakness, or bladder and bowel changes.
• Neck pain with weakness or numbness after a fall or tackle means call 911.
• Special Olympics Canada has specific screening rules and restricted events.

Related reading: You may also find our guides to hypermobility and Ehlers-Danlos syndrome and cervical myelopathy helpful.

If you would like help planning safe activity, or a check after a change in walking or balance, our team can help and will work with your doctor. You can also read about our approach to cervical instability.

Call: 905-669-1221

Visit: 398 Steeles Ave W #201, Thornhill, ON

Book online: vaughanphysiotherapy.com

Sources

Chicoine, B. (2025). Atlantoaxial instability. Adult Down Syndrome Center, Advocate Health. https://adscresources.advocatehealth.com/resources/atlantoaxial-instability/

Special Olympics Canada. (2019). Eligibility for participants with Down syndrome policy. https://www.specialolympics.ca/sites/default/files/Eligibility%20for%20Participants%20with%20Down%20Syndrome%20Policy.pdf

Tomlinson, C., Campbell, A., Hurley, A., Fenton, E., & Heron, N. (2020). Sport preparticipation screening for asymptomatic atlantoaxial instability in patients with Down syndrome. Clinical Journal of Sport Medicine, 30(4), 293 to 295. https://doi.org/10.1097/JSM.0000000000000642

This article is for general information and isn't medical advice. If you have any of the warning signs above, call 911 or contact your doctor right away.