Ganglion Cyst of the Foot

ganglion

A ganglion cyst is a mass or lump that forms below the surface of the skin. It is a benign cyst that is filled with a jelly-like fluid. The term ganglion means “knot”. It is not a malignant tumor, but a soft tissue benign mass. Ganglion cysts can occur anywhere; however, they usually occur at the wrist area and may occur at the foot (usually on top). This mass can change in size, vary in size, and may grow slowly.

wrist and footPresentation

The mass is usually asymptomatic and typically, the patient will find the mass at the top of the foot. The patient may have a burning sensation due to nerve irritation or compression of the nerve. Sometimes, a ganglion cyst mass occurs in the tarsal tunnel area, causing tarsal tunnel syndrome. If this is the case and the pain and burning sensation is not resolved with in tarsal tunnelconservative treatment, excision of the mass is probably the best option. The patient may have skin irritation, as well as difficulty in walking and wearing shoes. If the ganglion is pushing on a nerve and causing irritation, something surgical needs to be done, such as aspiration or removal. Usually, the patient’s symptoms become better after these treatments.

The physician will need to differentiate a ganglion cyst from plantar fibromatosis. Remember, ganglion cysts tend to occur at the top of the foot. Plantar fibromatosis occurs at the bottom of the foot. A ganglion cyst will transilluminate, while plantar fibromatosis will not.

tansilluminateTreatment

Treatment typically consists of observation, shoe modification, and aspiration/injection of steroids. Surgery is performed as the last resort.

The Lateral Plantar Nerve

more nerves

The lateral plantar nerve is branch of the posterior tibial nerve, which originates from the sciatic nerve. Around the medial side of the ankle, close to the tarsal tunnel, the posterior tibial nerve divides into the medial and lateral plantar nerves. anatomy

Thickening of the flexor retinaculum will cause compression of the posterior tibial nerve, which is called tarsal tunnel syndrome. When drawing a line between the medial malleolus and the calcaneus, the posterior tibial nerve divides into branches within 2 cm from this axis. The lateral plantar nerve is interesting because its branches give innervation to most of the intrinsic muscles in the foot—similar to the ulnar nerve in the hand. The lateral plantar nerve is also important due to its first branch being the Baxter’s nerve. baxter

This nerve is always mentioned in nerve entrapment in running athletes and is associated with chronic heel related pain. The pain associated with the Baxter’s nerve is very similar to the pain associated with plantar fasciitis; the pain is in the same location, the mechanical symptoms are the same, and there is nerve pain unassociated with weight-bearing.

The first branch of the lateral plantar nerve gets compressed between the fascia of the abductor hallucis muscle and the medial side of the quadratus plantae muscle. This condition may require surgical release of the abductor hallucis fascia if conservative treatments and injections do not produce any effect.

In summary, the lateral plantar nerve:

  • Is similar to the ulnar nerve in the hand
  • Supplies most of the intrinsic muscles of the foot
  • Supplies the Baxter’s nerve branch
  • Can be injured during surgery (rod placement from the heel).

sustainAnother point of interest when it comes to the lateral plantar nerve is the hardware placement. Hardware placement prominent to the sustentaculum tali can injure the flexor hallucis longus tendon and the lateral plantar nerve.

Tarsal Coalition

Tarsal coalition is a congenital anomaly in which the tarsal bones fuse together, leading to a rigid flat foot, foot pain, and multiple ankle sprains. There are two types of tarsal coalition. The first is known as a Talocalcaneal Coalition, which is a coalition between the talus and the calcaneus. The second is referred to as a calcaneonavicular coalition which is a coalition between the calcaneus and the navicular. When talocalcaneal coalition occurs, it usually happens around 12-15 years of age. The calcaneonavicular coalition presents at an earlier age. About 50% of coalitions are bilateral, and around 20% have multiple coalitions in the same foot. Coalition may be fibrous, cartilaginous, or bony and occurs due to failure of segmentation. It could be associated with fibular hemimelia or Apert’s syndrome.

tarsal anatomy

Symptoms typically consist of patient’s complaining of a painful foot, a history of repeated ankle sprains, and a flat foot deformity. Tarsal coalition may result in a peroneal spastic flat foot. During the physical examination, the physician may find hindfoot valgus. On toe standing, the arch does not reconstitute and heel cord contracture may also be evident during the exam. Furthermore, there may be restriction in the subtalar joint’s range of motion. It is important to check both feet as the condition may be bilateral.

hindfoot

The best imaging study is a CT scan. It can determine the size and location of the coalition. And MRI is also useful in detecting a fibrous or cartilaginous coalition. AP, Lateral, and Oblique view x-rays should be ordered. On a lateral view x-ray, the Calcaneonavicular Coalition can be identified by the “anteater nose sign” and the elongation of the anterior calcaneal process.

ant

A lateral view of a Talocalcaneal Coalition may show talar beaking which is a traction spur that occurs due to the limited motion of the subtalar joint. Additionally, the C sign may be seen which is a radiological sign outlining the talar dome and the sustentaculum. A 45° oblique view is the best for showing calcaneonavicular coalitions.

45oblique

Nonoperative treatment usually consists of anti-inflammatory drugs, modified activities, or the use of a brace or cast. Surgical treatment for the calcaneonavicular coalition usually consists of resection with an interposition of the extensor digitorum brevis muscle or a fat graft no matter the size of the coalition. Similarly, Talocalcaneal coalitions that involve less than 50% of the subtalar joint are also resected. A triple arthrodesis procedure is performed for large coalitions, failed resections, or advanced conditions.