REIDER PART 2
01

Chaptkr 7_Lower Leg, Foot, and Ankle 261

Figurę 7-22. lnverting the foot against resistance to demonstrate the posterior tibial tendon.

due to tinea pedis, or athletes foot. This fungal infection produces characteristic peeling of the skin between the toes and a dry red scaly appearance on the sole of the foot that, in extreme cases, may involve the entire plantar sur-face or spread onto the dorsum (Fig. 7-27C).

Alignment

Inspection of the foot and the ankle for malalignment begins with the patient standing and facing the examiner. Any gross abnormalities or deformities such as bumps or swclling are usually notcd immediately from this perspective.

Anterior Aspect

Great Toe. Detailed examination begins with inspection of the hałlux, or great toe. Normally, the great toe should point directly forward when the patient is standing with the feet together. Hallux valgus is by far the most com-mon abnormality of the great toe. In this condition, a val-gus deformity occurs at the first metatarsophalangeal joint, which causes the great toe, the hallux, to deviate away from the midlinc (Fig. 7-28A). In severe cases, the great toe may be pronated or even overlap the second toe. A pronated hallux is one that is rotated along its longitu-dinal axis, so that the toenail faces supramedially instead of directly superior.

Hallux valgus may be associatcd with a bunion deformity, although the two terms are not synonymous. The term bunion specifically refers to the accumulation of bonc and thickened soft tissue on the mcdial aspect of the First metatarsal head that results in a large prominent bump, whereas the term hallux valgus describes the deviation of the great toe away from the midline. Hallux valgus may also be associated with a splayfoot or metatarsus primus

varus. Splayfoot is a condition in which the metatarsals tend to spread broadly during weightbearing, whereas the term metatarsus primus varus refers specifically to a first metatarsal that angles excessively toward the midline.

The opposite deformity, hallux varus, almost never occurs spontaneously, but it may bc found as an unwanted complication of surgery to correct hallux val-gus. In hallux varus, the great toe deviates away from the rest of the toes toward the midline (see Fig. 7-28B). This deformity can cause severe difficulties with shoe wear.

Lesser Toes. The remaining four toes are often collec-tively referred to as the lesser toes. Normally, the second through fourth toes should be straight and the fifth toe should be slightly supinated and curved in toward the fourth. Common deformities of the lesser toes include hammer, claw, and mallet toe.

Hammer toe usually involves a single digit and con-sists of hyperextension of the metatarsophalangeal and distal interphalangeal joints combined with hyperflexion of the proximal interphalangeal joint (Fig. 7-29A). In hammer toe deformity, a callus often dcvelops on the dorsal aspect of the proximal interphalangeal joint due to friction from the top of the shoe.

In claw toe deformity, both the proximaI and the distal interphalangeal joints are held in flexion and multiple toes are usually involved (see Fig. 7-29B). In the presence of a claw toe deformity, a callus may develop both over the proximal interphalangeal joint and at the tip of the toe, which is pressed into the bottom of the shoe. At times, even the ha!Iux may be clawed. Although clawing may be idiopathic, widespread clawing may signify a neurologie disorder, such as Charcot-Maric-Tooth disease, or an adaptive change from a longstanding rupture of the Achilles tendon.

The term mallet toe is usually applied to a digit with an isolated flexion deformity of the distal interphalangeal joint. This deformity results in excessive pressure on the tip of the involved toe, often producing a callus (see Fig. 7-29 C).

A major factor in the production of ali these deformities is thought to be the Iongterm use of ill-fitting footwear because they occur morc commonly in shoe-wearing soci-eties than in unshod populations. Another important factor in the etiology of these deformities is thought to be the overpowering of weak or nonfunctional intrinsic muscles of the foot by the long flexors and extensors of the toes. A spe-cific underlying cause is rarely identified, although occa-sionally a diagnosable neurologie disorder such as muscular dystrophy, polio, or Charcot-Marie-Tooth disease may be present. Rheumatoid arthritis can produce an amazing variety of abnormalities of toe alignment (Fig. 7-30).

Foot. The examiners attention should now move proxi-mally to the metatarsals. Normally, all the metatarsal heads should appear to bear weight evenly, and the