REIDER PART 2
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Chapter 7_Lower Leg, Foot, and Anklc

fracture. Such fractures are difficult to diagnose radi-ographically. In children, a tender navicular may signify Kohler^ys disease_y or navicular osteochondrosis.

The medial, intermediate, and lateral cuneiforms articulate with the distal navicular. Tracing the tibialis anterior tendon distally to its insertion leads the exam-iner to the medial cuneiform. The othcr two cuneiform bones are lateral to it. Tcndcrness in these bones is usually attributable either to posttraumatic arthrosis or to inflammatory arthritis. Prominent osteophytes may be identified in these circumstances.

Further distally, the examiner palpates the articula-tions of the five metatarsals with the cuneiforms and the cuboid. These articulations are collectively called the tar-sometatarsal joint or Lisfranc’s joint. Tenderness and swelling in the vicinity of Lisfranc s joint suggcsts a sprain, or in its morę severe forms, a subluxation or even dislocation. The subtler forms of these injuries are difficult to diagnose radiographically. In a chronic situation, tenderness of Lisfrancs joint usually signifies arthritis, whether posttraumatic, inflammatory, or idiopathic. Palpable tender osteophytes are a frequent finding. Arthritis of Lisfranc s joint can cause deformities includ-ing forefoot abduction and arch collapse.

The individual metatarsals should be identified and palpated for tenderness. Localizcd tenderness suggcsts the possibility of a stress fracture. These stress fractures occur most commonly in the shafts of the second and the third metatarsals about two fmgerbrcadths proximal to the metatarsophalangeal joints. Early in their course, these stress fractures may be associated with local edema or even ecchymosis. In morę longstanding cases, a palpable lump of callus may be detectable. Stress fractures of the fifth metatarsal tend to occur in the proximal metaphysis about 2 cm distal to the palpable base of the metatarsal. Such stress fractures are often called Jones fractures, although Jones fractures may also occur owing to acute trauma as well as recurrent stress. Metatarsophalangeal Joints. The first metatarsophalangeal joint may be tender medially in the prcsence of a bunion or hallux valgus deformity, although in such cases the associated deformity should be obvious. Osteo-arthritis of the first metatarsophalangeal joint may pro-duce a subtler finding of palpable osteophytes on the dorsum of the joint without associated angular deformity. These osteophytes may be tender and may limit joint motion. Extreme tenderness, especially when associated with swelling, warmth, and erythema around the joint, is morę suggestive of acute gout or septic arthritis.

The four lesser metatarsophalangeal joints should also be palpated for tenderness. These joints may be painful and swollen in the prescnce of active synovitis. Synovitis can occur owing to activc rheumatoid arthritis, or it can be the result of pressure overload in a foot with a shortened, hypermobile first metatarsal that inereases pressure distribution to the lesser metatarsophalangeal joints. Isolated tenderness of the second metatarsophalangeal joint may signify overuse synovitis or, less commonly, Freiberg’s infraction, which is avascular necrosis of the second metatarsal head. Freibergs infraction may occasionally involve multiple toes. Isolated tenderness of the fifth metatarsophalangeal joint may be associated with a tailors bunion, or bunionette. Although this deformity is not always tender, active bursitis may occur over the prominence in extreme cases.

The spaces between the metatarsal heads should be firmly palpated for tenderness. The examiner may either compress the tissue between the thumb and the index fin-ger of one hand or support the forefoot with one hand while compressing with the index finger of the other (Fig. 7-52). Tenderness between the metatarsal heads, which reproduces the patienfs pain, is most commonly due to an interdigital neuroma, also known as Mortons neurorna. If the neuroma is very large, the examiner may actually be able to feel a firm nodule between the metatarsal heads. The intcrspace between the third and the fourth metatarsal heads is the most common location for such neuromata. In advanced cases, the patient also reports hypoesthesia or dysesthesia in response to light touch on the side of the toes adjacent to the interspace. For exam-ple, a neuroma in the interspace between the third and fourth metatarsal heads may be associated with sensory changes of the lateral side of the third toe and the medial side of the fourth toe. If an interdigital neuroma is sus-pcctcd, the examiner should also perform Morton’s test, described in the Manipulation section.

Toes. In the toes, the deformities already described may be associated with tender calluses. The toes should be spread so that heloma molle, soft interdigital corns, may

Figurę 7-52. Palpation for interdigital neuroma.