REIDER PART 225

Chaptp.r 7_Lower Leg, Foot, and Ankle 285

knot of Henry, the point in the medial plantar arch where thc flexor hallucis longus and flexor digitorum longus tendons cross. In the presence of medial plantar nerve entrapment, the most characteristic place for tenderness is on the medial plantar aspect of the arch distal to the navicular tuberosity (Fig. 7-56). Palpating the nerve at this point may cause aching in the arch and dysesthesias in the medial plantar portion of thc foot; TinePs sign may also be prcsent. Passively everting the patient s hcel or asking the patient to stand on the toes may also repro-duce the symptoms of medial plantar nerve entrapment. This syndrome may be associated with excessive adduc-tion or abduction of the forefoot at the talonavicular joint, which may cause the medial plantar nerve to be compressed underneath the master knot of Henry. Other conditions that may be associated with medial plantar nerve entrapment include hallux valgus or hyperprona-tion of the foot. Medial plantar nerve entrapment is sometimes called joggers foot. Decreased sensation may be found in such patients if the examination is conducted immediately after running.

The first branch of the lateral plantar nerve is morę likely to bccome compressed than the entire lateral plantar nerve itself. This branch may become entrapped between the fascia of the abductor hallucis and the quad-ratus plantae muscles. Patients with this condition usually complain of chronic heel pain, often inereased by running. This pain is often worsc in thc morning and may radiate to the inferomedial aspect of the heel and proxi-mally into the medial ankle. In such patients, digital com-pression of the first branch of the lateral plantar nerve on

Figurę 7-56. Typical sitc of tenderness in medial plantar nerve entrapment.

the medial aspect of the heel should reproduce the patients symptoms, including pain radiation (Fig. 7-57). No numbness should be associated with this syndrome.

Pij\ntar Aspect

Examination of the plantar surface of the foot should include palpation of any abnormal callosities noted dur-ing inspection. Callosities reflect the weightbearing pat-tern of the foot, but they may not always be symptomatic. When a callosity is tender, particularly in areas such as beneath the metatarsal heads or abnormal bony promi-nences, it is likely that the tender area is a source of pain for the patient. F.xtreme tenderness suggests the possibil-ity of an infection, particularly in the diabetie patient.

The plantar surface under the first metatarsal head should be palpated for tenderness of the sesamoids (see Fig. 7-24). These two smali oval bones are embedded in the flexor hallucis brevis tendon beneath the first metatarsal head. The exact outlines of the sesamoids can-not be distinctly felt, but firm palpation should reveal the sensation of steady resistance provided by these bones. They are located about 15 mm apart underneath the medial and lateral borders of the first metatarsal head. Normally, the sesamoids should not be significantly tender to palpation. Tenderness localized to one of these sesamoids may be due to a variety of conditions including fracture, sesamoiditis, and avascular necrosis. The medial sesamoid is morę commonly involved in such pathology.

Palpation of the middle portion of the plantar foot is directed primarily at detecting abnormal conditions of the plantar fascia. The plantar fascia is a sheath of tough tendon-like tissue that extends from the plantar surface of the calcaneal tuberosity anteriorly to the metatarsal heads

Figurę 7-57. Digital compression of the first branch of the lateral plantar nerve.