What is Baxter’s nerve entrapment?
Heel pain is arguably the most common complaint a podiatrist hears. Though most of these complaints are linked to plantar fasciitis, it is important to recognise that there are numerous conditions that can cause heel pain. When plantar fasciitis does not respond to treatment, heel pain may, in fact, be associated with the entrapment of Baxter’s nerve.
Baxter’s nerve entrapment results from compression of a nerve that supplies the plantar surface (underneath) of your foot. This nerve is also known as the inferior calcaneal nerve which snakes around the front of the heel bone. When this nerve is entrapped it can result in pain and numbness being experienced in the heel and bottom of the foot. According to Baxter, as much as 20% of heel pain is actually caused by entrapment of the inferior calcaneal nerve.
Signs and symptoms of Baxter’s nerve entrapment
The main reason why plantar fasciitis and Baxter’s nerve entrapment get confused is due to the similarity in the location of pain. In Baxter’s nerve entrapment, distinct tenderness is felt at the origin of the abductor hallucis muscle (a small muscle along the inside of the foot), whereas the most intense site of pain in plantar fasciitis is commonly more towards the bottom of the heel.
Additionally, unlike plantar fasciitis, pain associated with entrapment tends to get worse with physical activity, rather than better. This is clinically known as post-kinetic dyskinesia. With entrapment, the pain is also more localised and is pressure sensitive. Consequently, in some cases, orthotic therapy may aggravate the pain if they have been prescribed to address a different diagnosis. This will be due to the orthotic further compressing the nerve. Other symptoms include burning and sharp shooting pain. Patients occasionally also locate the pain at the edges of the heel, either the outer or inner edge.
Causes of Baxter’s nerve entrapment
There are two main causes of Baxter’s nerve entrapment:
The first, and most common, is when the nerve becomes entrapped between two muscles, known as abductor hallucis muscle and the quadratus plantae muscle. These muscles are located along the lower aspect of the inside (medial-plantar) of the heel.
The second is when the nerve becomes compressed against the heel bone on the under (plantar) side of the foot. Heel spurs (calcaneal plantar enthesophytes) and swelling of the plantar fascia may contribute to nerve entrapment at this location.
Risk factors for development of Baxter’s nerve entrapment include:
- Over-pronation (flat feet)
- Calcaneal spur
- Advancing age
- Plantar fasciitis
- Underlying mass
- Vascular enlargement
- Muscular enlargement (such as in athletes)
Diagnosing Baxter’s nerve entrapment
Due to the complexity of the foot and symptoms that are often indistinguishable to plantar fasciitis, diagnosing Baxter’s nerve entrapment requires a high degree of clinical suspicion and knowledge. Comprehensive history taking and clinical examination should be performed to assess for possible nerve related symptoms. This is extremely important as there is no definitive test to diagnose Baxter’s nerve entrapment. X-ray, ultrasound and MRI can be used, but only to rule out other possible conditions and risk factors. An effective diagnostic technique is to inject local anaesthetic to numb the possible offending nerve. If symptom relief is gained with the injection, it provides good evidence that Baxter’s nerve entrapment is present. Our podiatrists at OnePointHealth are able to perform this injection technique.
Conservative Treating Baxter’s nerve entrapment
Conservative treatment aims to reduce the causative factors of entrapment. Treatment may include:
- Activity modification. An initial change to your exercise regime or daily activities may be needed to avoid the condition getting worse. The introduction of a low impact alternate activity may also be of benefit such as swimming.
- Icing: to reduce possible inflammation.
- Strengthening/Isometric loading. It is important that strength is addressed for this condition so that the affected area can tolerate more load. This is done initially with isometric loading to load up the affected area in a pain-free way.
- Massage: to help release excessive tight soft tissue structures that surround the nerve.
- Taping/splinting: to control poor foot motion and function.
- Orthotic therapy: can be used to address causative biomechanical factors such as flat feet, over-pronation.
- Injection therapy: local anaesthetic and corticosteroid can help bathe the nerve and reduce symptoms.
Some of the conservative treatment options are similar to those used for plantar fasciitis. However, with plantar fasciopathy pain levels tend to improve within weeks of a good treatment plan. In those that are non-responsive to conservative treatment, a diagnosis of Baxter’s nerve entrapment is further supported.
Surgery for Baxter’s nerve entrapment
Surgery is often indicated when pain levels fail to improve with conservative treatment. Additionally, if pain levels cease after an injection only for a short time before returning, surgery is also warranted. Surgery for Baxter’s nerve entrapment is known as neurolysis and may also be combined with a plantar fascia release.