Foot and Ankle cases 11

A 45-year-old woman presents to your office and notes that she has had a several years history of pain at the plantar medial hindfoot. She reports that the pain is present throughout the day and seems to be worse when she is active. She denies any trauma or recent change in shoewear. A lateral foot radiograph is reviewed (Fig. 5–22).

 

 

 

Figure 5–22 Lateral weight-bearing radiograph of the foot.

 

Your differential diagnosis includes all of the following except:

1. Plantar fasciitis

2. Entrapment first branch lateral plantar nerve (Baxter’s nerve)

3. Noninsertional Achilles tendinosis

4. Calcaneal stress fracture

 

Discussion

The correct answer is (C). The patient presents with heel pain. While plantar fasciitis is far and away the most common cause of heel pain, one must also consider less common diagnoses including calcaneal stress fracture, entrapment of the first branch of the lateral plantar nerve, and central heel pain (fat pad atrophy). Noninsertional Achilles tendinosis would not cause pain in this location.

Upon examination she is focally tender at the site marked with the dot and black arrow (Fig. 5–23). Based upon this site of tenderness, you suspect which of the diagnoses?

1. Plantar fasciitis

2. Entrapment first branch lateral plantar nerve (Baxter’s nerve)

3. Central heel pain

4. Calcaneal stress fracture

 

 

 

Figure 5–23 Photograph showing site of tenderness (dot with black arrow).

 

Discussion

The correct answer is (B). The first branch of the lateral plantar nerve can be entrapped by the deep fascia of the abductor hallucis muscle at the site where this patient is tender. It is important to distinguish between this site of pain and other sites of heel pain. Plantar fasciitis typically causes pain at the origin of the plantar fascia (white arrow). Central heel pain typically causes pain at the plantar aspect of the heel (red arrow), and a calcaneal stress fracture at the medial and lateral hindfoot (blue arrow).

Terminal branches of the tibial nerve distal to the tarsal tunnel include which of the following?

1. Lateral plantar nerve, deep peroneal nerve, medial calcaneal nerve

2. Lateral plantar nerve, sural nerve, medial calcaneal nerve

3. Lateral plantar nerve, medial plantar nerve, superficial peroneal nerve

4. Lateral plantar nerve, medial plantar nerve, medial calcaneal nerve

Discussion

The correct answer is (D). The superficial and deep peroneal nerves are branches of the common peroneal nerve. The sural nerve originates typically at the level of the knee or proximal calf.

Your initial treatment for Baxter’s nerve entrapment should involve which of the following?

1. Medial posting accommodative hindfoot orthotic, anti-inflammatory medications, activity modification

2. Surgical release of the nerve

3. Nerve transection and burial

4. Lateral posting accommodative hindfoot orthotic, anti-inflammatory medications, activity modification

Discussion

The correct answer is (A). The initial goal of treatment is to reduce local inflammation and also to attempt to remove pressure from the site of nerve entrapment. An accommodative arch support orthotic (medial hindfoot post), may help to push the hindfoot into varus a bit, taking pressure off structures stretched at the medial hindfoot. This type of orthotic would be of particular use if the hindfoot were in valgus.

Your patient undergoes an extensive course of nonoperative treatment, including activity modification, anti-inflammatory medications, icing, and physical therapy yet has persistent pain that she finds to be very limiting.

You discuss operative treatment, specifically planning for which of the following procedures?

1. Transection and burial of the first branch of the lateral plantar nerve

2. Open decompression of the first branch of the lateral plantar nerve

3. Endoscopic plantar fascia release

4. Excision of the first branch of the lateral plantar nerve and intercalary sural nerve grafting

Discussion

The correct answer is (B). The goal of this operation is to decompress the entrapped area of nerve. This often involves transecting the deep fascia of the abductor hallucis muscle. Transection of the nerve is not recommended as maintenance of

plantar sensation is critical.

 

Objectives: Did you learn...?

 

Describe the anatomy of the plantar-medial hindfoot and common sources of pain?

 

Discuss nonoperative and operative treatment for Baxter’s nerve entrapment?