02/02/2025
Uwięźnięcie nerwu Baxtera 🦶🧐
Baxter’s nerve entrapment 🦶
🦶 Plantar heel pain is one of the most prevalent and recalcitrant podiatric conditions. Previous studies have estimated that 10–15% of the population experiences this condition during their lifetime (https://pubmed.ncbi.nlm.nih.gov/17400020/, https://pubmed.ncbi.nlm.nih.gov/18574754/). However, making a correct diagnosis is challenging because of numerous etiologies, including plantar fasciopathy, heel pad atrophy, and nerve entrapment, which produce overlapping symptoms (https://pubmed.ncbi.nlm.nih.gov/1600660/, https://pubmed.ncbi.nlm.nih.gov/24860133/)
🦶 Among these etiologies, entrapment of the first branch of the lateral plantar nerve, also known as Baxter’s nerve (BN) or inferior calcaneal nerve, is thought to be one of the main causes of neuropathy, accounting for approximately 20% of chronic heel pain (https://pubmed.ncbi.nlm.nih.gov/23980227/).
🦶 Initially described in 1984 by Baxter and Thigpen, it is often overlooked as a cause of medial heel pain, particularly in athletes, where it may coexist with plantar fasciopathy (https://doi.org/10.29328/journal.aceo.1001012).
🦶 Usually emerging from the lateral plantar nerve (LPN) just distal to its origin from the tibial nerve, the BN is a mixed motor and sensory nerve. The nerve has a motor branch to the abductor digiti minimi muscle (ADM) and a sensory branch (also known as calcaneal branch of the inferior calcaneal nerve) to the periosteum of medial calcaneal tuberosity and long plantar ligament (https://pubmed.ncbi.nlm.nih.gov/17400020/).
👉 There are two well-known entrapment sites of the BN (https://pubmed.ncbi.nlm.nih.gov/32500156/).
1️⃣ The first site is where the nerve crosses the deep fascia of the abductor hallucis between the abductor hallucis and medial caudal margin of the quadratus plantae (https://pubmed.ncbi.nlm.nih.gov/22526881/); contributory factors include altered biomechanics such as pes cavus or excessive pronation as well as muscle hypertrophy.
2️⃣ The second is where the nerve passes just anterior to the medial calcaneal tuberosity. Contributory factors include plantar fasciopathy or a plantar calcaneal spur (https://pubmed.ncbi.nlm.nih.gov/23980227/, https://pubmed.ncbi.nlm.nih.gov/28369929/).
👉 Clinically, patients with Baxter's nerve entrapment complain of plantar heel pain, but there are subtle differences between these patients’ symptoms and those with plantar fasciitis.
✅ Patients with Baxter's nerve entrapment describe the pain as located more medially than the pain in plantar fasciopathy.
✅ Additionally, the pain is often described as a burning pain on the medial side of the heel, and it is worse in the evenings and after activities rather than during the patients’ first steps in the morning (typically described in plantar fasciopathy, (https://pubmed.ncbi.nlm.nih.gov/29763043/, https://doi.org/10.1016/j.otsm.2021.150854).
✅ A positive Tinel sign and maximal tenderness of nerve entrapment can be elicited at the two points mentioned above (https://www.ncbi.nlm.nih.gov/books/NBK499868/). Patients may report numbness or paresthesias on the lateral aspect of their foot especially in chronic cases (https://doi.org/10.1016/j.jbspin.2016.02.005).
✅ Examining these nerve entrapments should include a biomechanical exam to evaluate the contribution of hindfoot varus/valgus position, equinus, or pes planus.
💡 A combination of load management, non-steroidal anti-inflammatory medication (NSAIDs), orthoses, and physical therapy (strengthening of the foot intrinsics, neural mobilization, https://doi.org/10.1016/j.eujim.2022.102201, https://pubmed.ncbi.nlm.nih.gov/21875518/, https://pubmed.ncbi.nlm.nih.gov/17400020/) is recommended in the initial management of Baxter's neuropathy (https://pubmed.ncbi.nlm.nih.gov/24860133/), based on very weak evidence.
📸 https://pubmed.ncbi.nlm.nih.gov/39773256/: Gross dissection of the Bn, which diverges from the lateral plantar nerve. it travels vertically and turns horizontally (red arrowhead) towards the abductor digiti minimi muscle. Bn: Baxter nerve, lPn: lateral plantar nerve, MPn: medial plantar nerve, fHl: flexor hallucis longus muscle, fdl: flexor digitorum longus muscle.
