REIDER PART 218

278_Chapter 7 Lowcr Leg, Foot, and Anklc

Figurę 7-49. Ąctiye abduction of the toes.

resistance and stability while palpating with the other hand. A common mistake is to use too littlc or too much force when palpating. Our rule of thumb is to use just enough force to blanch the examiner s nailbed.

Anterior Aspect

Lower Leg and Ankle. Palpation can be helpful in diagnosing several unusual conditions of the anterior leg (see Fig. 7-10). Although stress fractures morę com-monly occur on the posteromedial aspcct of the tibia, they occasionally arise on the anterior tibial crest. These lesions are usually associated with point tender-ness at about the midpoint of the anterior tibial crest and sometimes a smali visible bump at this location. These fractures are important to detect because they may progress to nonunion or even a completely dis-placed fracture.

Another cause of anterior leg pain in athletes is an exercise-induced anterior compartment syndrome. In such indmduals, the anterior compartment muscles seem normal at rest but tender and abnormally firm if the examiner palpates them immediately after the patient has exercised. The physical findings of the exercise-induccd anterior compartment syndrome are transient and subtlc compared with those of the classic acute compartment syndrome, in which the anterior compartment muscles are extremely firm and tender.

The anterior inferior tibiofibular ligament con-nects the distal fibula and tibia just proximal to the ankle joint (see Fig. 7-8). It forms the anterior portion of the syndesmotie complex, which stabilizes the ankle mortise. Tendcrness over the anterior-inferior tibiofibular ligament may be associated with a syndesmosis sprain or a Maisonneuve fracture. In the morę severe injuries, the tenderness continues up the leg owing to injury of the interosseous membranę.

The tibialis anterior tendon may be easily identified by asking the patient to actively dorsiflex the ankle. At the level of the ankle joint, the tendon is closer to the medial malleolus than to the latcral malleolus, but the muscle itsclf lies lateral to the tibial crest in the anterior compartment. Peritendinitis, or inflammation of the tissue around the tibialis anterior tendon, occasionally occurs where the morę proximal portion of the tendon courscs over the anterior surface of the tibia (see Fig. 7-10). In the presence of this condition, the tibialis anterior is tender about a hands breadth proximal to the ankle joint. If the examiner lightly palpates the tendon at this point while the patient alternately dorsiflexcs and plantar flexes the ankle, soft tissue crepitus surrounding the tendon is often appreciated.

Acute or chronic degenerative ruptures of the tibialis anterior tendon occasionally occur. In complete ruptures, the retracted tendon stump is felt as a firm, palpable mass just proximal to the joint linę of the ankle. In such cases, active dorsiflexion of the ankle is accompanied by invol-untary eversion of the foot due to overpull of the exten-sor hallucis longus and the extcnsor digitorum communis. In longstanding undiagnosed tears, this over-pull of the toe extensors may cause all the toes to become clawed, and the unbalanced activity of the muscles of plantar flexion may lead to contracture of the Achilles tendon and ankle eąuinus.

Rarely, the superficial peroneal nerve may be com-pressed at the point where it pierces to the dccp fascia of the ankle to supply sensation to the dorsum of the foot. In such cases, percussing the nerve about 12 cm proximal to the lateral malleolus may reproduce the patient s pain or produce dysesthesias. Laceration of the superficial peroneal ncrve is a morę common occurrence that results in numbness of the majority of the dorsum of the foot. Foot. As the anterior tibial artery courses across the anklc into the foot, it becomes the dorsalis pedis artery (see Fig. 7-1). The extensor hallucis longus tendon crosses the artery at about the level of the ankle, so that in the ankle and the foot, the artery is located immediately lateral to the extensor hallucis longus tendon. The best place for palpating the dorsalis pedis pulse is on the dorsum of the foot at a point just lateral to the extensor hallucis longus tendon and just proximal to the prominence of the metatarsal-cuneiform joints (Fig. 7-50).

The deep peroneal nerve, which travels with the dorsalis pedis artery, may become entrapped under the