Hallux valgus

This is a deformity of the forefoot involving the great toe. The great toe deviates laterally crowding the lesser toes. It may be unilateral or bilateral. It is often associated with a bunion or painful callosity over the medial aspect of the first MTP joint. This is generally due to a large osteophyte at the base of the proximal phalanx or head of the first metatarsal.

The aetiology is unknown but may be familial. Poor footwear is often blamed as the cause, but this usually aggravates the symptoms rather than initiating the problem.

Clinical examination reveals a valgus deformity of the great toe. If this is severe, there can be resultant deformity of the second toe with it eventually overriding the great toe. There may be a large prominence over the medial aspect of the first metatarsal head with associated callosities. It is often irritated by footwear and there may be an underlying bursa. There may be mild irritability of the first MTP joint.

Plain X-rays may reveal an increased intermetatarsal angle between the first and second metatarsal. There is also a val-gus malalignment of the great toe relative to the axis of the forefoot (Fig. 22.27). There may be mild degenerative changes within the first MTP joint and the possibility of an exostosis over the medial aspect of the first metatarsal heads.

Various splints and braces have been tried to passively hold the great toe in alignment if it is passively correctable. Patients often find them cumbersome and a hindrance. The most appropriate management, having initially enquired about the patient's footwear, is recommendation of the use of flat shoes that have a broad toe box. This particularly applies to women who tend to wear high-healed shoes with a narrow toe box. Most patients find that this alleviates the symptoms but they must be warned that this will not correct the deformity.

Figure 22.27. Bilateral hallux valgus.

There are five main methods of surgical treatment:

• Soft-tissue procedures like the McBride operation: involves release of adductor hallucis, transverse metatarsal ligament and lateral capsule combined with excision of medial eminence and plication of the capsule medially.

• Excision arthroplasty (Keller's arthroplasty; Fig. 22.28): involves excising the proximal third of the proximal phalanx of the great toe and forming a medial exostosectomy of the prominence of the first metatarsal head. Due to the bowstring effect of the extensor hallucis longus tendon, this is lengthened by Z-plasty so as to allow correction of the valgus deformity. However this procedure must be reserved for the elderly population with very limited demands as the results of this procedure in high-demand patients are not good.

• Arthrodesis: is more commonly performed in patients with hallux rigidus (Fig. 22.29), but is also more appropriate than excision arthroplasty if there are significant degenerative changes within the first MTP joint or the patient falls into the younger age group. The first MTP joint is usually transfixed with a single screw. It is important when performing this procedure that the valgus malalignment of the great toe is not overcorrected, which can result in an extremely disabling hallux varus deformity. It is also important to determine the nature of the shoes the patient will be wearing on a regular basis, so that the great toe may be fused in an appropriate degree of dorsiflexion.

• Metatarsal osteotomy: involves the first metatarsal shaft and can either be proximally or distally based. The advantage is that there is no disruption to the MTP joint. This option is often reserved for patients who have a markedly increased angle between the first and second metatarsals. In younger patients basal osteotomies are favoured where the aim is to lateralize the distal segment of the first metatarsal so as to achieve secondary correction of the obstacle near the great toe. Many different procedures have been described and they are often combined with

Figure 22.28. Keller's arthroplasty.
Figure 22.29. Hallux rigidus.

soft-tissue procedures, particularly around the first MTP joint.

• MTP joint Arthroplasty, involves patients who undergo metatarsal osteotomies or arthrodesis need to be immobilized in a plaster boot for up to 6 weeks. It is important that the patient is observed carefully so as to avoid any pressure sores developing from the plaster boot. The patient should be able to fully weight bear if the plaster boot is comfortable. Patients who undergo an excisional arthroplasty do not require such immobilization other than appropriate strapping of the foot until the wound is healed. These patients must be warned preoperatively that the great toe will remain floppy after the procedure.

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