The bump on the inside border of your forefoot is caused by prominence of the end or head of the first metatarsal bone. The first metatarsal has assumed an abnormal position, its head no longer lying beside the adjacent second metatarsal head. Thickening of the underlying bone (hypertrophy), in combination with swelling of the overlying tissues and thickening of the skin, make the bunion prominence worse.
A bunion can be caused by wearing close-fitting high-heeled shoes, excess motion at the joint at the base of the first metatarsal or flat-footedness, or it can be an inherited problem. Some people have a combination of these “risk factors”. The angled position of the big toe is caused by the abnormal position of the first metatarsal. Pressure from shoes, particularly when the toe box is constrictive, pushes the big toe across into this “valgus” position. Some rotational deformity of the big toe is common, the result of abnormal eccentric muscle pull.
Some people with severe bunions develop osteoarthritis in the joint at the base of the toe. A bunion can also result in relative overload of the heads of the other adjacent metatarsal heads. This can cause pain in the ball of the foot (metatarsalgia). A severe bunion can put pressure on the second toe and cause it to also become deformed.
Initial treatment is non-operative, and involves addressing footwear. If pain about the bunion is purely the result of pressure from shoes, broader toe-box shoes should be worn, in an attempt to accommodate deformity. Round or square toe boxes are usually more comfortable. Soft uppers, such as those found in athletic shoes, or specialised material such as deer skin, also reduce pressure upon painful bunions. Sometimes, a contoured insole may be of benefit.
When modified shoes fail to relieve bunion pain, and there is consequent disability, operative management may be required.
Advanced age, diabetes, peripheral vascular disease, significant systemic disease and the long-term use of corticosteroid medication, such as Prednisone, are some of the relative contraindications for bunion surgery.
To correct a bunion deformity, surgery on both the first metatarsal and the big toe is usually required.
To correct the abnormally positioned first metatarsal, this bone must be osteotomised (cut) and repositioned. It is held in its new position with small specially-designed bone screws. The prominent bone on the inside of the first metatarsal head is also trimmed, to smooth its profile.
To correct the angled position of the big toe, contracted tissues on one side of the joint are lengthened and stretched tissues over the inside border of the joint are tightened. Sometimes, it is necessary to remove a small wedge of bone from the base of the toe to help correct its position. This is called an Akin osteotomy. It is held in position with a small bone staple.
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During the operation, a local anaesthetic is infiltrated, to lessen post-operative pain, and a bulky well-padded dressing applied. Post-operatively, your foot will be elevated, to improve comfort and lessen swelling, and further analgesia will be given by vein, frequently in the form of PCA (patient-controlled analgesia). Oral medications will also be used, In spite of these measures there will still be some pain. This improves rapidly after the first 12 hours.
Intravenous antibiotics will be given prophylactically for 24 hours, together with Clexane, a blood-thinning drug given via a small subcutaneous injection, which lessens the risk of thrombosis (DVT).
The day after the operation you will usually be allowed to stand up and walk, and when you are safely and comfortably able to move around you may go home. You will be fitted with a post-operative shoe. It allows you to walk on your heel, making it easier to keep your forefoot off the ground. This is necessary for 6 weeks, whilst the bone and soft tissues heal.
When you go home, you must keep your foot elevated, at hip height or above, as much as possible. This will lessen post-operative pain and swelling. Your dressings must remain in place, and to keep them dry you should put a plastic bag over your foot when showering.
Two weeks after the operation you will return for removal of dressings and wound sutures. Thereafter, a “bunion bandage” will remain in place for the next four weeks, although it can be removed for bathing and re-secured every day. During this period, you will continue to walk with the bunion shoe.
At the six week post-operative visit, Xrays will be performed to confirm healing of the metatarsal osteotomy. You will then be allowed to begin bearing weight fully on your foot, but you must wear soft-uppered broad toe-boxed shoes for the next few months, both for comfort and to prevent recurrence of deformity. High fashion footwear must be strictly avoided.
All surgical procedures involve risks. The information provided here is for general educational purposes only. For specific advice regarding a bunion (hallux valgus), please book an appointment with Dr Newman.