REIDER PART 229

Charter 7_Lower Leg, Foot, and Ankle 289

that the average examiner can supply. The morę common causes of gastrocsoleus weakness include lumbar radicu-lopathy, prior Achilles’ tendon rupture, and sciatic or tibial nerve injury.

The flexor hallucis longus and flexor digitorum longus are often tested together because they have tendi-nous cross-connections that make isolated testing diffi-cult. The examiner stabilizcs the patients heel with one hand and instructs the patient to curl the toes downward. After instructing the patient to maintain this position against resistance, the examiner hooks his or her fingers beneath the patient’s toes and attempts to passively dorsi-flex them (Fig. 7-63). In a normal patient, the examiner should not be able to overcome the strength of the flexor hallucis longus and the flexor digitorum longus with this maneuver. The morę common causes of weakness include lumbar radiculopathy, tendinitis, and sciatic or tibial nerve injury.

EVERTORS OF THE FOOT

Pure eversion strength is supplied primarily by the per-oneus brevis, assisted by the peroneus longus. To test eversion strength, the examiner places the patients foot in the everted position with the ankle plantar flexed. The patient is instructed to maintain the everted position while the examiner attempts to force the foot into inversion. The examiner stabilizes the limb with the palm of one hand against the mcdial aspect of the tibia just above the ankle. The examiner then pushes medially against the lateral border of the patients foot in an attempt to invert the foot (Fig. 7-64). Normally, the examiner should be unable to overcome the patients eversion strength. During this test, the peroneus brevis can normally be seen or palpated as it courses from the posterior aspect of the lateral malleolus to the fifth metatarsal.

Weakness of eversion may be due to tendinitis, insta-bility of the peroneal tendons, or, if profound, Charcot-Marie-Tooth disease. Lumbar radiculopathy and peroneal nerve injury may also cause eversion weakness.

Figurę 7-63. Assessing toe łlexion strength.

Figurę 7-64. Assessingeversion strength.

The peroneus longus is difficult to test in isolation. Because the peroneus longus passes beneath the plantar surface of the foot to insert on the plantar surface of the first metatarsal, it functions as a plantar flexor of the first metatarsal. The examiner may attempt to test this func-tion by pushing upward with a thumb beneath the head of the First metatarsal. The patient is instructed to press the medial border of the foot downward to resist this force. Unfortunately, most patients assist the peroneus longus with the toe flexors and gastrocsoleus complex. The examiner should attempt to verify that the peroneus longus is firing by palpating the tendon posterior to the lateral malleolus. Like the peroneus brevis, the peroneus longus is innervated by the superficial peroneal nerve.

lNVERTORS OF THE FOOT

Inversion of the foot is accomplished primarily by the tibialis posterior, with contributions from the tibialis anterior, flexor digitorum longus, and flexor hallucis longus. These are innervated by the tibial tierve, except for the tibialis anterior, which is innervatcd by the deep peroneal nerve.

To test inversion strength, the examiner places the patients foot in an inverted position with the ankle plantar flexed. The patient is instructed to maintain this position while the examiner attempts to push the foot into cvcrsion. The examiner supports the limb with one hand and pushes laterally against the mcdial border of the first metatarsal (Fig. 7-65). The tendon of the normal tibialis posterior sometimes can be seen and usually can be palpated between the medial malleolus and its insertion into the tuberosity of the navicular. Normally, the examiner should be unable to overcome the strength of the inver-tors. Tendinitis and rupture are common causes of tibialis posterior weakness.