How Your Back May Be Causing Your Bunions and a Bunion Surgery Alternative

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Bunion surgery is big business. Is there a bunion surgery alternative? To see if that’s possible, we first have to understand why bunions occur in the first place. In my clinical experience, a big cause is a back problem that causes the stabilizing muscles of the foot to weaken. How does that work?

The nerves in your back power your leg muscles that stabilize the foot. These nerves are numbered. The two lowest nerves are L5 and S1. The L5 spinal nerve goes to the muscles that help support the inside of the foot, while the S1 nerve goes to muscles that support the outside of the foot (see above).

Medical illustration showing neutral human foot, a foot with pronation and a foot with over pronation


When a nerve in your back is chronically irritated, a few other things happen. First, you may or may not feel back pain. Second, the local muscles that stabilize the spine begin to atrophy (read get weaker) and this leads to an unstable spine. Finally, the muscles that the nerve powers (in this case in the leg), also get weaker. So if you have an irritated S1 nerve in the back, you may feel tightness in your hamstring or calf, pain in your heel, or if it’s really bad-numbness in the outside or bottom of your foot. In addition, as shown above, the muscles that support the outside of the foot as you walk, run, or stand won’t be able to do their job (due to less signals from the S1 nerve). This causes the foot to pronate. What does the pronation cause?

bunion surgery alternatives

The big toe is drawn above with very simple blocks. Normal big toe bones are aligned straight in a row. A pronated foot causes the tendon on top of the foot to move toward the outside as the foot rolls (blue line above). This outside pulling from the important EHL tendon causes the big toe bones to tilt (the inward direction of the big toe seen with a bunion). Finally, a bunion forms (which is really just a bone spur) to fill this gap. This happens because bone is constantly remodeling to deal with forces.

In summary, a bad S1 nerve in the back leads to weakness in the outer foot muscles which causes the foot to pronate. This causes the main big toe tendon to become misaligned and the pull of this tendons on the big toe bones causes them to collapse inwards. This funky alignment ultimately causes a bone spur to form, which we call a “bunion”.

What can you do? First, get your back checked if you have a bunion. We often use the Regenexx-PL-Disc procedure as a bunion surgery alternative with these patients. Second, getting a good pair of orthotics may help, as they will deal with the pronation. Third, once the bunion has formed, consider getting a device to move the bones back in the other direction. Finally, if the joint is really bad, it may take a platelet or stem cell injection to help it remodel back the other way. In addition, some joints left this way for many years may not be able to be fixed with just the simple techniques described above, so act early!

Learn about Regenexx procedures for foot & ankle conditions.
Chris Centeno, MD is a specialist in regenerative medicine and the new field of Interventional Orthopedics. Centeno pioneered orthopedic stem cell procedures in 2005 and is responsible for a large amount of the published research on stem cell use for orthopedic applications. View Profile

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NOTE: This blog post provides general information to help the reader better understand regenerative medicine, musculoskeletal health, and related subjects. All content provided in this blog, website, or any linked materials, including text, graphics, images, patient profiles, outcomes, and information, are not intended and should not be considered or used as a substitute for medical advice, diagnosis, or treatment. Please always consult with a professional and certified healthcare provider to discuss if a treatment is right for you.

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