Medically reviewed by Dr. Tom Biernacki, DPM
Board-certified podiatric surgeon | Balance Foot & Ankle, Howell & Bloomfield Hills, MI
Last reviewed: May 2026
Sural nerve injury at the ankle is more common than most patients realize after ankle sprains — and the laterality of numbness versus pain on the outer foot is the key clue that distinguishes it from a peroneal issue. Call (810) 206-1402 — expert podiatric care across Michigan.
The sural nerve is a pure sensory nerve formed by contributions from the tibial nerve (medial sural cutaneous nerve) and the common peroneal nerve (lateral sural cutaneous nerve), running subcutaneously along the posterolateral lower leg and curving behind and below the lateral malleolus to supply sensation to the lateral heel, lateral foot, and small toe. Because of its predictable superficial course, the sural nerve is susceptible to injury in several common clinical scenarios: lateral ankle sprains (traction or contusion), calcaneal fracture surgery (direct injury during extensile lateral approach), peroneal tendon surgery, ankle arthroplasty, and nerve entrapment from peroneal tunnel adhesions, ganglion cysts, or tight footwear pressing against the lateral ankle. Sural nerve pathology produces characteristic lateral foot numbness, burning, or hypersensitivity that is often misattributed to lateral ankle sprain sequelae, peroneal tendon pathology, or radiculopathy — accurate diagnosis requires understanding the sural nerve distribution and targeted clinical examination.
Sural Nerve Injury: Causes, Clinical Features, and Differential Diagnosis
| Condition | Mechanism | Symptoms | Exam Findings | Diagnosis |
|---|---|---|---|---|
| Sural nerve contusion (ankle sprain) | Inversion ankle sprain stretches or contuses the sural nerve as it courses posterior to the lateral malleolus; nerve lies directly in the path of maximum soft tissue disruption in lateral ankle sprains | Lateral heel and foot numbness or burning after ankle sprain; often coexists with ATFL/CFL sprain symptoms; tingling along lateral border of foot and fifth toe | Decreased sensation lateral heel and lateral foot; positive Tinel sign behind lateral malleolus; normal peroneal strength (sural is sensory only); symptoms along sural distribution (not fibular head area) | Clinical: nerve distribution + mechanism. EMG/NCS: sural nerve sensory action potential reduced or absent. MRI ankle: no nerve lesion typically visible; rules out other pathology |
| Sural nerve entrapment | Fibrous adhesion at lateral ankle from prior surgery or trauma; ganglion cyst compressing nerve in peroneal tunnel; tight footwear or ankle brace pressing on nerve; fibula peroneal groove adhesions after peroneal tendon surgery | Persistent burning, tingling, or hypersensitivity of lateral foot after surgery or ankle injury; pain aggravated by shoe pressure on lateral ankle; worse with activity, relieved by rest and removing shoe | Positive Tinel sign at entrapment point; focal tenderness at point of nerve compression; sensory deficit distal to entrapment; no motor deficit (pure sensory nerve) | Ultrasound: nerve thickening or perineural scarring at entrapment site; ganglion cyst. NCS: reduced sural SNAP. Diagnostic nerve block at entrapment site → symptom relief confirms diagnosis |
| Sural nerve injury (surgical) | Direct injury during calcaneal fracture ORIF (extensile lateral approach), peroneal tendon repair, ankle arthroplasty, or Achilles tendon surgery; nerve transection or stretch causing neuroma formation at surgical site | Postoperative lateral foot numbness (transection) or burning hypersensitivity (neuroma); symptoms begin immediately postoperatively or weeks later as neuroma matures; allodynia at scar | Scar tenderness; positive Tinel at neuroma site; sensory deficit in sural distribution; allodynia (light touch painful); neuroma palpable in some cases | Ultrasound: spindle-shaped nerve thickening (neuroma) at scar. NCS: absent or reduced sural SNAP distal to injury. Clinical distribution confirms sural vs peroneal vs saphenous |
| S1 radiculopathy | L5-S1 disc herniation or foraminal stenosis compressing S1 nerve root — S1 root contributes to sural nerve formation; can mimic isolated sural neuropathy but with additional features | Lateral foot numbness + heel pain; may have low back pain; calf weakness; loss of Achilles reflex; symptoms extend to posterior calf (sural proper) and lateral foot (S1 distribution) | Reduced or absent Achilles reflex; weakness of plantarflexion; sensory loss extends above ankle into calf (beyond sural nerve territory); positive straight leg raise | MRI lumbar spine: disc herniation or foraminal stenosis at L5-S1. EMG: S1 denervation in multiple muscles (gastrocnemius, peronei, gluteus medius) vs isolated sural neuropathy |
Sural Nerve Treatment: Conservative and Surgical Options
| Treatment | Indication | Technique / Details | Expected Outcome |
|---|---|---|---|
| Conservative management | Sural contusion from ankle sprain; mild entrapment without structural compression; early postoperative neuropraxia | Padding and shoe modification to offload nerve at lateral ankle; desensitization therapy; gabapentin or amitriptyline for neuropathic pain; activity modification; topical lidocaine or compounded NSAID cream over nerve course | Most neuropraxia (nerve bruising without structural damage) resolves over 6-12 weeks with conservative care; entrapment from footwear usually resolves with shoe modification |
| Corticosteroid injection | Confirmed sural nerve entrapment; perineural scarring without complete neuroma; focal compression syndrome | Ultrasound-guided injection of 1-2 mL of corticosteroid + local anesthetic perineural (NOT intraneural) at site of entrapment; fluoroscopy acceptable but ultrasound preferred for nerve visualization | 60-70% significant pain relief with perineural injection; repeat injection appropriate if initial response good; persistent entrapment after 2-3 injections → surgical decompression |
| Surgical neurolysis / decompression | Persistent sural entrapment after failed conservative treatment; ganglion cyst compressing nerve; external compressive lesion | Surgical release of fibrous adhesions; ganglion cyst excision; retinacular decompression; external neurolysis with dissection of nerve from scar tissue; care to avoid nerve injury during release | 70-85% improvement in pain and sensory symptoms after neurolysis; best results when nerve continuity intact; poor results if intraneural fibrosis (internal scar) |
| Neuroma excision or burial | Painful traumatic or surgical neuroma with positive Tinel, allodynia, failure of conservative care and injection | Surgical excision of neuroma bulb; proximal nerve stump buried into adjacent muscle (flexor hallucis longus or peroneus) or bone under tension to prevent recurrence; RPNI (regenerative peripheral nerve interface) emerging technique | 60-75% significant pain reduction with neuroma excision and burial; recurrent neuroma possible if stump not adequately managed; best outcomes with muscle burial technique |
At Balance Foot & Ankle in Howell and Bloomfield Hills, lateral foot burning or numbness after ankle surgery or a significant ankle sprain prompts clinical assessment for sural nerve injury — distinguishing nerve contusion (which typically resolves) from traumatic neuroma or entrapment (which requires targeted intervention) by using Tinel testing, sensory mapping, and ultrasound-guided nerve evaluation. Call (810) 206-1402.
PubMed: Sural Nerve Entrapment
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For a complete clinical overview: Ankle Pain Conditions Guide — location-by-location ankle pain diagnosis and treatment
What causes pain on the outside of the ankle?
Lateral ankle pain commonly results from peroneal tendinopathy, ankle sprains, sinus tarsi syndrome, or stress fractures of the fibula. A physical exam combined with ultrasound or MRI pinpoints the exact structure involved and guides treatment.
When is ankle surgery necessary?
Ankle surgery is considered after conservative care—rest, physical therapy, bracing, and injections—has failed over several months. Procedures range from arthroscopic debridement for mild arthritis to total ankle replacement or fusion for advanced joint destruction.
Doctor Answer
What is the sural nerve and how can it be injured at the ankle?
The sural nerve provides sensation to the outer lower leg and lateral heel and is the most commonly used nerve graft donor site in foot surgery. It can be injured during ankle fracture fixation, peroneal tendon surgery, or by direct trauma, causing lateral foot numbness or painful neuroma formation. Dr. Tom Biernacki at Balance Foot & Ankle takes careful intraoperative measures to protect the sural nerve and manages post-injury neuroma pain with injections or surgical neurolysis.
