This deformity is characterized by abnormal abduction of the first metatarsal with adduction of the phalanges. It is usually present during early life but gets aggravated in later age . Injury or diseases like gout, arthritis or even bad footwear can precipitate this condition.
A false bursa may form over the first metatarsal head, which may get thickened and enlarged. This is known as 'bunion. The artic- ular cartilage may get inflamed, eroded and atrophied. New bone formation may take place on the medial side of the metatarsal head (exostosis or spur). Tendon of the extensor hallucis longus is shortened and displaced laterally. It acts with a mechanical disadvantage, increasing the deformity. Intrinsic muscles, too, cannot act effectively. These inadequacies result in dropping of the arch and eversion of the foot.
Introduction
Hallux valgus (HV), also known as a bunion, is one of the most common forefoot deformities. HV manifests with the proximal phalanx deviating laterally and the first metatarsal head deviating medially and due to the adduction of the first metatarsus, called metatarsus primus varus.
Epidemiology
HV deformity is a relatively common condition. It occurs in approximately 23% of adults aged 18 to 65 years and up 36% of adults older than 65 years. When looking at adult females, HV deformity occurs as high as 30%.The prevalence is higher in those who wear shoes or heels when compared to the barefoot population. Interestingly, when comparing women and men in barefoot populations, women are found to have HV deformity twice as often.
Pathophysiology
The pathophysiology of HV is complex, but the general assumption is that an imbalance exists between the extrinsic and intrinsic muscles of the foot with the involvement of the ligaments also. Maintenance of the first metatarsal alignment is by the tension created by the peroneus longus laterally and the abductor hallucis muscle medially. Collateral ligaments prevent movement along the transverse plane at the first MTP joint. If there is increased pressure at the head of the first metatarsal, the metatarsal will begin to move medial-dorsally. This force increases the hallux angle, which is also worsened by muscle stabilization while walking.
Diagnosis
Hallux valgus deformity is typically diagnosable through a physical exam, and imaging (X- Ray) is important as it can evaluate whether there is damage to the first metatarsophalangeal (MTP) joint.
Treatment
Mild cases are to be managed by physiotherapy and proper footwear.
Surgical Treatment
Severe cases do not respond to conservative treatment and need surgery.
1. Arthroplasty: The bunion and the exostoses are removed, shortened and the soft tissues are divided. The joint is aligned in the maximally corrected position.
2. Keller's operation: Proximal two-thirds of the proximal phalanx are removed with the bunion and the medial portion of the head of the metatarsal .
3. Mayo's operation: The head of the metatarsal is excised. Firm dressings or plaster cast are given for 2-3 weeks following surgery. Occasionally, traction may be applied through the pulp of the toe.
4. Arthrodesis: Arthrodesis of the metatarsophalangeal joint of the big toe.
Physiotherapeutic Management
1. The patient is taught to carry out relaxed passive stretching of abduction of the toe many times a day.
2. Straight inner border footwear with wedge in between the great toe and the second toe greatly helps in maintaining constant abduction stretch on the great toe. Night splint may be given.
The most important factor to be remembered with the splint or the corrective shoe is that it must not exert any pres- sure or friction over the medial aspect of the head of the first metatarsal.
3. Strong active exercises are given for strengthening the lum- bricals and interossei.
4. Proper weight bearing: Weight bearing, which tends to be more on the lateral aspect of the foot to avoid pressure and pain, should be discouraged.
5. Faradic foot bath may be necessary to relieve pain, improve circulation and induce contractions of the intrinsic muscles.
Physiotherapy following surgery: It follows the same course
as described earlier during immobilization. After the removal of stitches:
1. The patient is trained in relaxed passive stretching of the toe. It is advisable to put a soft cotton or foam wedge between the great toe and the second toe.
2. Strong exercises are given to the intrinsic muscles of the foot.
3. Active fanning of the toes in warm water with assisted abduction of great toe is to be emphasized.
4. Faradic foot bath is useful in assisting active efforts.
5. Weight transfers, gait training and ambulatory activities to be gradually added avoiding the limp.
