Arthritis

Arthritis affecting the foot is a common event in an ageing population. The vast majority will be osteoarthritis. The most common joint affected is the first metatarso­phalangeal joint.

Inflammatory arthropathies frequently produce foot problems. In rheumatoid arthritis the forefoot is the first part affected. Up to 40 per cent of patients suffering with rheumatoid arthritis regard their feet as being their most troublesome area. Other forms of inflammatory arthritis are also seen in the foot. Of particular note is psoariatic arthritis, which is commonly missed. It is a particular cause of symptoms following minor trauma. Gout is also a cause of a sudden acute arthritis.

Rheumatoid changes

Rheumatoid arthritis creates symptoms in three ways. In the early stages of the disease, pain may be caused by the presence of inflamed synovium, usually in the forefoot and the subtalar joint. It can also affect the tendon sheaths. If the synovitis persists the ligaments and tendons can be damaged and rupture. This means that the joints become unstable, and deform. The toes dislocate at the metatarsophalangeal joints (Fig. 31.7). This produces fixed clawing, with the metatarsal heads being prominent in the sole of the foot. In the hindfoot a combination of instability of the subtalar joint and rupture of the tibialis posterior tendon will produce a progressive planovalgus foot. The synovitis also damages the joint surface.

Patients suffering from an inflammatory arthropathy will complain of pain and swelling in the affected joints. Sub­sequently, progressive deformity and arthritic change result in metatarsalgia. Pain over the medial side of the foot due to the progressive lateral tilt of the foot is common. Impinge­ment between the calcaneum and the lateral malleolus produces pain on the lateral side. Stress fractures of the lateral malleolus can occur. The secondary osteoarthritis will cause pain in its own right.

Treatment

During the early stages the aim of treatment is to reduce the synovitis and to manage associated pain. Nonsteroidal anti-inflammatory agents are the first-line drugs. Additional pain relief can be obtained from well-cushioned shoes. If drugs do not bring swelling under control, synovectomy should be considered. Once deformity has occurred the treatment is aimed at controlling symptoms. Shoes with cushion insoles and extra depth to allow for toe deformities should be used. If forefoot symptoms persist, surgical correction of the toe deformities should be undertaken, aimed at reducing the symptoms of metatarsalgia. The exact technique used for correcting the forefoot remains controversial. The principles of surgery are to correct the alignment of the toes over the end of the metatarsals. This provides cover for the ends of the prominent metatarsals. The most common technique practised is to excise the metatarsal heads through either a plantar or dorsal approach. At the same time, the first metatarso-phalangeal joint is fused to restore the position of the great toe and allow it to take weight.

Progressive deformity of the hindfoot is probably best treated by surgery to correct the position and stabilise the foot; this usually involves fusion of one or the more hindfoot joints (Fig. 31.8). Bone grafts are frequently necessary to help correct the deformity. Reduction of deformity has to be dir­ected towards keeping the foot flat to the floor. Involvement of the ankle can further complicate matters, the ankle frequently tilting into valgus. If the ankle is symptomatically involved then consideration should be given to either arthrodesis or possible arthroplasty of that joint also. The choice between surgical treatments under these conditions will depend on the general and local state of the patient, the position of the patient’s hindfoot and their expectation.

HaIIux rigidus

This is the most common arthritic condition affecting the foot.

The symptoms are those of limitation of movement and pain.

It can arise as early as the adolescent years. It is associated with various systemic causes of arthritis such as gout and psoriasis. Most commonly it arises tie novo. Pathologically it is typified by the presence of dorsal osteophytes and by damage to the articular surface centrally and dorsally. The vast majority of patients presents with severe joint involvement.

Treatment

The first line of treatment is conservative. Education about the nature of the condition is helpful. Advice about footware and stiffening of the sole of the shoe under the first ray can be helpful.

Operative treatment falls into three groups depending on the severity of the condition. In mild or moderate disease dorsal wedge osteotomy of the proximal phalanx can help to reduce pressure over the dorsum of the great toe. If there are mild to moderate changes on the joint surface hut a significant dorsal osteophyte a cheilectomy procedure, where the dorsal osteophyte and approximately the dorsal third of the metatarsal head is excised, can be undertaken. If there are severe changes two procedures can he considered. The first is to fuse the first metatarsal to the proximal phalanx. This produces the most reliable result but by definition there is a loss of the range of movement. Approximately 90 per cent of patients who undergo this procedure ultimately find it satisfactory. The second option is to undertake an arthroplasty. A variety of prostheses has been tried without consistent success.