Overview
Foot and ankle surgery — particularly hallux valgus (bunion) repair — is associated with moderate-to-severe postoperative pain, often disproportionate to the apparent size of the procedure. This reflects the high density of sensory innervation in the foot. Effective analgesia is essential for early mobilisation and patient satisfaction in what is predominantly day-case surgery.
The foot is innervated by five separate nerves — four terminal branches of the sciatic nerve (tibial, deep peroneal, superficial peroneal, sural) plus the saphenous nerve (terminal branch of the femoral nerve). An ankle block targeting these five nerves provides dense, motor-sparing analgesia and is the cornerstone of regional technique for foot surgery.
PROSPECT 2025 summary (Wust et al., updated hallux valgus guideline, Eur J Anaesthesiol): Paracetamol + NSAIDs/COX-2 inhibitors + systemic dexamethasone as basic multimodal analgesia. Ankle block recommended as first-choice regional technique, with local anaesthetic wound infiltration as an alternative. Minimally invasive/percutaneous osteotomy now preferred over open osteotomy — an important update from the 2020 guideline. Opioids reserved for rescue analgesia.
Analgesic Pathway
- Paracetamol 1g PO
- COX-2 inhibitor or NSAID PO
- Ankle block — performed pre-op or intra-op
- Popliteal sciatic block — extensive hindfoot/ankle surgery
- Dexamethasone 8 mg IV
- Paracetamol 1g IV (if not given pre-op)
- Minimally invasive / percutaneous technique where appropriate
- Local anaesthetic wound infiltration — alternative to ankle block
- Liposomal bupivacaine — insufficient evidence
- Extended-release bupivacaine infiltration — insufficient evidence
- Paracetamol 1g QDS regular
- COX-2 / NSAID regular (≤5 days)
- Opioid PRN rescue (oxycodone 5–10 mg PO)
- Elevation, ice, compression
- Weight-bearing per surgical instruction
- Continuous popliteal catheter — limited routine evidence
✓ Recommended | ◎ Optional/conditional | ✗ Not recommended/insufficient evidence. Based on PROSPECT 2025 (hallux valgus).
Systemic Analgesia
Paracetamol + NSAID or COX-2 inhibitor, administered pre- or intraoperatively and continued postoperatively, forms the basic multimodal regimen. Systemic dexamethasone is recommended as an additional analgesic adjuvant — both 2020 and 2025 PROSPECT updates confirm benefit.
| Agent | Dose | Route | Frequency | Notes |
|---|---|---|---|---|
| Paracetamol | 1 g | IV/PO | QDS | Regular throughout — not PRN |
| Celecoxib | 200 mg | PO | BD | COX-2 preferred — ≤5 days |
| Ibuprofen | 400 mg | PO | TDS | Non-selective; add PPI if prolonged use |
| Dexamethasone | 8 mg | IV | Single intraop | Analgesia + PONV prophylaxis; PROSPECT-supported |
| Oxycodone IR | 5–10 mg | PO PRN | 4–6h | Rescue only |
Insufficient evidence: Gabapentinoids, liposomal bupivacaine, perineural magnesium, and extended-release local anaesthetic wound infiltration all lack sufficient evidence per PROSPECT 2025 to be recommended for hallux valgus/foot surgery.
Foot Innervation — The Five Nerves
The foot, defined as distal to the malleoli, is supplied by five nerves. Four are terminal branches of the sciatic nerve (tibial, deep peroneal, superficial peroneal, sural); the fifth — the saphenous nerve — is a terminal sensory branch of the femoral nerve, the only one not derived from the sciatic nerve.
Posterior Tibial Nerve Deep
Largest of the five. Enters tarsal tunnel posterior to medial malleolus, alongside posterior tibial artery. Supplies heel and sole of foot via medial/lateral plantar branches. Most clinically important for plantar surgery.
Deep Peroneal (Fibular) Nerve Deep
Runs with anterior tibial artery, lateral to EHL tendon at the ankle. Supplies first web space and small area between 1st/2nd toes. Easily blocked alongside the artery.
Superficial Peroneal Nerve Superficial
Subcutaneous, anterolateral ankle. Supplies dorsum of foot (most of it) except first web space. Easily blocked by subcutaneous infiltration.
Sural Nerve Superficial
Purely sensory. Runs near lesser saphenous vein, between lateral malleolus and Achilles tendon. Supplies lateral foot and 5th toe. Should always be included — provides deep sensory coverage.
Saphenous Nerve Superficial
Only non-sciatic branch. Runs with great saphenous vein, anterior to medial malleolus. Supplies medial midfoot. Can often be omitted for forefoot/toe surgery — innervation rarely extends past midfoot (~97% of patients).
Ankle Block
Ankle block is recommended as the first-choice regional analgesic technique for hallux valgus and forefoot surgery, with local anaesthetic wound infiltration as an effective alternative. The block is motor-sparing above the ankle, allowing safe ambulation with appropriate footwear.
Technique — Combined Landmark + Ultrasound
Ultrasound guidance is most beneficial for the two deep nerves (posterior tibial, deep peroneal) — improving accuracy and reducing volume required. The three superficial nerves (saphenous, superficial peroneal, sural) can be reliably blocked with simple subcutaneous infiltration, with or without ultrasound.
-
Posterior tibial nerve — ultrasound-guided
Patient supine or lateral, ankle in slight dorsiflexion. Place linear probe posterior to the medial malleolus. Identify the posterior tibial artery — the nerve lies adjacent (usually posterior). In-plane or out-of-plane needle approach; inject 3–5 mL around the nerve. This is the most clinically important nerve — supplies the sole of the foot.
-
Deep peroneal nerve — ultrasound-guided
Probe anteriorly at the ankle, identify the anterior tibial artery between extensor hallucis longus and extensor digitorum longus tendons. The nerve lies adjacent to the artery, deep to the extensor retinaculum. Inject 3–5 mL around the artery/nerve.
-
Superficial peroneal nerve — subcutaneous
Subcutaneous infiltration anterolaterally, from the anterior tibial artery laterally toward the lateral malleolus. 5 mL subcutaneous "ring" injection — no need to visualise the nerve directly.
-
Saphenous nerve — subcutaneous
Subcutaneous infiltration anterior to the medial malleolus, around the great saphenous vein. 3–5 mL. Can be omitted for isolated forefoot/toe surgery (saphenous territory rarely extends past midfoot).
-
Sural nerve — subcutaneous or perivascular
Infiltrate subcutaneously between the lateral malleolus and the Achilles tendon, around the lesser saphenous vein. 4–5 mL. Always include — provides important deep sensory coverage of the lateral foot.
Dosing
| Nerve | Volume | Agent | Approach |
|---|---|---|---|
| Posterior tibial | 3–5 mL | Ropivacaine 0.5% or Lidocaine 1–2% | US-guided (preferred) |
| Deep peroneal | 3–5 mL | Ropivacaine 0.5% or Lidocaine 1–2% | US-guided (preferred) |
| Superficial peroneal | 5 mL | Ropivacaine 0.5% or Lidocaine 1% | Subcutaneous infiltration |
| Saphenous | 3–5 mL | Ropivacaine 0.5% or Lidocaine 1% | Subcutaneous infiltration |
| Sural | 4–5 mL | Ropivacaine 0.5% or Lidocaine 1% | Subcutaneous / perivascular |
Total volume typically 18–25 mL. Avoid adrenaline-containing solutions at the ankle/toe — historical concern re: end-artery ischaemia, though modern evidence is reassuring with dilute concentrations in healthy patients without peripheral vascular disease. Most practitioners avoid it regardless given alternatives exist.
Forefoot/toe surgery shortcut: For isolated hallux valgus or toe surgery, the saphenous nerve block can often be omitted — its innervation rarely extends past the midfoot. A 4-nerve block (tibial, deep peroneal, superficial peroneal, sural) is usually sufficient, simplifying the procedure.
Popliteal Sciatic Block — Alternative/Adjunct
For more extensive ankle or hindfoot surgery (ankle ORIF, ankle fusion, major reconstruction), a popliteal sciatic nerve block provides more proximal and complete coverage than an ankle block alone, blocking the sciatic nerve before it divides into tibial and common peroneal branches.
| Ankle Block | Popliteal Sciatic Block | |
|---|---|---|
| Best for | Forefoot, toes, hallux valgus | Ankle, hindfoot, major reconstruction |
| Coverage | Distal to malleoli | Entire foot + ankle joint |
| Saphenous coverage | Included separately | Requires separate saphenous/ACB block for medial coverage |
| Motor block | None above ankle | Foot drop until block resolves |
| Duration | 6–14 h | 10–18 h (single-shot) |
Dosing — Popliteal Sciatic Block
| Agent | Concentration | Volume | Duration |
|---|---|---|---|
| Ropivacaine | 0.5% | 15–20 mL | 10–16 h |
| Bupivacaine | 0.5% | 15–20 mL | 14–20 h |
| Levobupivacaine | 0.5% | 15–20 mL | 14–20 h |
PROSPECT 2025 found no evidence to support continuous popliteal sciatic catheter for routine hallux valgus surgery — single-shot is standard for ambulatory cases.
Surgical Technique & Analgesia
Key PROSPECT 2025 update: Minimally invasive surgery or percutaneous osteotomy is now recommended over open osteotomy for hallux valgus repair — an important change from the 2020 guideline. This reflects accumulating evidence of reduced postoperative pain with minimally invasive approaches, independent of the analgesic regimen used.
Where surgically appropriate and within the surgeon's expertise, percutaneous/minimally invasive techniques should be considered as part of the overall strategy to minimise postoperative pain — alongside (not instead of) the multimodal analgesic regimen described above.
Not Recommended / Insufficient Evidence
PROSPECT 2025 found insufficient evidence to recommend gabapentinoids for hallux valgus/foot surgery. Sedation and dizziness risk without clear benefit.
No clear benefit demonstrated over standard local anaesthetic infiltration despite higher cost. Not recommended as routine.
No studies meeting PROSPECT methodology support routine continuous catheter techniques for hallux valgus surgery. Single-shot block is standard.
Insufficient or no evidence to support these techniques as part of routine analgesic regimen for foot surgery.
Practical Analgesic Protocol
Suggested protocol for ambulatory hallux valgus repair (minimally invasive technique):
Discharge advice: Warn patients of possible rebound pain as the ankle block wears off (typically 10–14h). Ensure adequate rescue analgesia is dispensed before discharge, and regular paracetamol/NSAID is started before the block resolves.
References
- Wust M, Desai N, Joshi GP, Rawal N, Van de Velde M, Moka E, Elmers J, Albrecht E; PROSPECT Working Group. Pain management after hallux valgus repair surgery: an updated systematic review and PROSPECT recommendations. Eur J Anaesthesiol. 2025. PMID 41122054 ↗
- Mauchet B, Lirola A, Marbaix P, et al. PROSPECT guideline for hallux valgus repair surgery (2020). Anaesthesia. 2020. PMID 32595141 ↗
- NYSORA. Ankle Block — Landmarks and Nerve Stimulator Technique. nysora.com ↗
- NYSORA. Ultrasound-Guided Ankle Nerve Block. nysora.com ↗
- Purushothaman L. Ultrasound-guided ankle block. BJA Education. 2013;13(5):174–178. BJA Education ↗
- ASRA. How I Do It: Ultrasound-Guided Ankle Block. asra.com ↗
- StatPearls. Sural Nerve Block. NCBI Bookshelf ↗
- Pascarella G, et al. Motor-sparing ultrasound-guided regional techniques for ambulatory foot and ankle surgery: updated review. J Clin Med. 2025.