A bunion (medical term: hallux valgus) is a painful bony bump that develops on the inside of the foot at the big toe joint. It is one of the most common foot deformities. Anyone can get a bunion, but it is more likely to happen in women. Many women wear tight, narrow shoes that squeeze the toes together, which make it more likely for a bunion to develop, worsen and cause painful symptoms.
The main biomechanical factor in the development of a bunion is excess pronation of the subtalar joint.
As the foot pronates, the centre of gravity moves towards the midline, more forces are loaded on the inner forefoot area. This action puts excessive weight on the big toe during the toe off phase of gait, increasing the load on the first metatarsal shaft in an adductory direction, causing rotation of the shaft, which then causes the big toe to compensate by deviating towards the lesser digits (abduction) and the joint enlarges to accommodate the additional loads.
It is not necessarily a hereditary condition. Bunions can run in a family but it is the biomechanical structure (excessive pronation) that is passed through the family. In some cases, bunions are caused by arthritis, trauma or fractures in the joint. These may lead to arthritic changes and the development of bunion deformities whilst limiting the range of motion in the joint.
Contrary to popular belief footwear is not the common cause of bunions. Although poor footwear in combination with causative biomechanical factors can cause bunions to progress further.
Bunions can be developed in 3 stages which are primary, secondary and tertiary. These stages refer to the progressive deviation of the big toe towards the midline of the body. Often, bunions in the tertiary stage cause the big toe to overlap or underlap the second toe, usually limiting the patient’s mobility and causing pain.
Bunions can be removed by surgery, which can reduce pain and improve your ability to walk and exercise, but up to 15% of bunions return. Weak muscles may play a role in bunion-related pain and movement problems.
Exercises to Strengthen Foot Muscles
Short foot exercise
- This exercise recruits the flexor hallucis brevis and adductor hallucis oblique head.
(a) Keep the heel and forefoot on the ground, without curling your toes into the floor.
(b) Push the base of the big toe forcefully into the ground, while pulling the forefoot back toward the heel at the same time.
(c) The toes are held suspended above the ground when done it correctly while the activation of muscles elevates the arch.
(d) Hold it for 5 sec, repeat it for 10 reps, 2-3sets.
Toe spread out
– This exercise activates the abductor hallucis along the inside of the arch.
(a) Lift and spread your toes while keeping the forefoot and heel on the floor.
(b) Now, with your toes spread apart, push the little toe downward and outward into the floor.
(c) Next, push the big toe down towards the inside of the foot.
(d) Hold it for 5 sec, repeat it for 10 reps, 2-3sets.
Heel raise
– The exercise recruits the tibialis posterior muscle that supports the ankle and foot.
(a) Hold your knee steady in slight bending to reduce the contribution from the gastrocnemius muscle.
(b) Elevate your arch while keeping your heel turned in.
(c) Raise your heel off the ground while keeping the pressure on your big toe.
(d) Hold it for 5 sec, repeat it for 10 reps, 2-3sets.
*Perform all exercises barefoot. Exercises are progressed from sitting, to standing on both feet, to performing the exercises standing on just one leg.
References:
https://www.icbmedical.com/treatable-conditions/hallux-abducto-valgus/
Ward M. Glasoe. 2016. Treatment of Progressive First Metatarsophalangeal Hallux Valgus Deformity: A Biomechanically Based Muscle-Strengthening Approach. Journal of Orthopaedic & Sports Physical Therapy 46(7): 596-606.
S.E. Nix, B.T. Vicenzino, N.J. Collins, M.D. Smith. 2012. Characteristics of Foot Structure and Footwear Associated with Hallux Valgus: A Systematic Review. Osteoarthritis and Cartilage 20: 1059-1074.
Sheree E Nix, Bill T Vicenzino, Natalie J Collins and Michelle D Smith. 2013. Gait Parameters Associated with Hallux Valgus: A Systematic Review. Journal of Foot and Ankle Research 6(9): 1-12.
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