Baxter's neuropathy, also known as inferior calcaneal nerve entrapment, is a relatively underdiagnosed cause of heel pain, frequently confused with plantar fasciitis. Though less common, it plays a significant role in chronic heel discomfort, especially in patients unresponsive to conventional treatments for more typical causes.

The inferior calcaneal nerve, commonly referred to as Baxter’s nerve, is the first branch of the lateral plantar nerve, which itself branches from the tibial nerve. This small nerve courses around the medial aspect of the ankle and enters the medial calcaneal area, where it innervates the abductor digiti minimi muscle. Pathophysiology involves entrapment or compression of Baxter's nerve as it passes between the abductor hallucis muscle, quadratus plantae, and the medial calcaneal tuberosity. This compression leads to localized nerve irritation and chronic pain.

Causes and Risk Factors

Several factors may contribute to the entrapment of Baxter’s nerve such as anatomical variations (eg tight fascial bands or hypertrophied muscles can compress the nerve); repetitive microtrauma from activities involving excessive standing, running, or jumping increase strain on the heel; biomechanical abnormalities such as flat feet (pes planus), overpronation, or cavus feet can alter the mechanics of foot motion, increasing nerve compression risk; space-occupying lesions which are rare, but includes possible tumors or cysts in the region can compress the nerve; obesity amplifies pressure on the heel and associated structures; there could be scar tissue formation from previous surgery or injury that may entrap the nerve following trauma or surgery.

Clinical Presentation

Patients typically present with:

• a medial heel pain: Deep, burning, or aching pain on the inside of the heel.

• pain aggravated by activity: Especially after prolonged standing, walking, or athletic activities.

• night pain: Unlike plantar fasciitis, which often presents with morning pain, Baxter’s neuropathy may cause discomfort at night.

• minimal tenderness on palpation: Direct palpation may not always reproduce the pain.

• weakness or atrophy: In chronic cases, wasting of the abductor digiti minimi may occur.

Baxter's neuropathy can mimic or coexist with several other conditions with the most common being plantar fasciitis. Other possible differentials include tarsal tunnel syndrome, lumbar radiculopathy (especially L5/S1 nerve roots), stress fractures, fat pad atrophy. Accurate diagnosis requires careful differentiation to ensure appropriate treatment. The diagnosis is often clinical, supported by a physical examination showing tenderness over the medial heel, positive Tinel’s sign over Baxter’s nerve course, and specific provocative maneuvers may suggest entrapment. MRI can visualize muscle atrophy, fascial thickening, or space-occupying lesions and an ultrasound may detect nerve compression and dynamic changes during movement.

Treatment Options

Conservative management starts with activity modification, reducing high-impact activities to allow nerve recovery. Custom insoles can be used to correct biomechanical abnormalities. Stretching, strengthening, and nerve mobilization exercises can be helpful. NSAIDs can be used for inflammation and pain relief. Targeted corticosteroid injection near the nerve can be used to reduce inflammation and swelling. A surgical decompression is reserved for refractory cases which involves a surgical release of the nerve may be performed to alleviate chronic compression. With appropriate management, many patients experience significant relief. Early diagnosis greatly improves outcomes, while delayed treatment may lead to chronic pain and muscle atrophy.

Conclusion

Baxter’s neuropathy remains an often overlooked source of heel pain. Its clinical overlap with plantar fasciitis and other heel disorders makes accurate diagnosis challenging but essential. A comprehensive understanding of its anatomy, risk factors, clinical features, and management options allows for tailored, effective treatment strategies and improved patient quality of life.