Orthopaedic PROSPECT 2021 Moderate–Severe Pain Motor-Sparing Priority

Total Hip Arthroplasty (THA)

Perioperative pain management for primary elective THA — fascia iliaca block, PENG block, LIA, and multimodal systemic analgesia. Based on PROSPECT 2021 (Anger et al., Anaesthesia) and current evidence.

PROSPECT 2021 ↗ ESRA ↗

Moderate–Severe

Pain intensity

FICB / PENG

Regional options

Motor-sparing

Key priority

2021

PROSPECT

Overview

Total hip arthroplasty (THA) is one of the most successful elective surgical procedures, transforming quality of life in patients with debilitating hip osteoarthritis. However, it is associated with moderate-to-severe postoperative pain — particularly in the first 24–48 hours — which if undertreated delays mobilisation and rehabilitation, increases length of stay, and raises complication risk.

Pain after THA arises primarily from the anterior hip capsule (femoral and obturator nerve articular branches), the periosteum, and surrounding soft tissues. The surgical approach (anterior, lateral, posterior) significantly influences which structures are disrupted and which nerve territories are most affected.

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PROSPECT 2021 summary (Anger et al., Anaesthesia 2021;76:1082–1097): Paracetamol + NSAIDs/COX-2 + IV dexamethasone as basic multimodal analgesia. Fascia iliaca block (FICB) or LIA recommended as regional technique, especially when basic analgesics are contraindicated or high pain expected. Femoral nerve block, lumbar plexus block, epidural, and gabapentinoids are not recommended. PENG block was not included in PROSPECT 2021 (insufficient evidence at time of review) but has since accumulated substantial RCT evidence.

Analgesic Pathway — At a Glance

🕐 Pre-operative

Paracetamol 1g PO
COX-2 inhibitor (e.g. celecoxib 200 mg PO)
Fascia iliaca block (FICB) or PENG block pre-op if high pain expected
Routine gabapentinoids — not recommended

🔪 Intra-operative

Spinal or GA (spinal preferred)
Dexamethasone 8–10 mg IV
FICB or PENG block (if not given pre-op)
LIA by surgeon — peri-articular infiltration
Paracetamol 1g IV (if not given pre-op)
Intrathecal morphine 0.1 mg — selected inpatients only
Femoral nerve block — quadriceps weakness
Lumbar plexus block — haematoma risk

💊 Post-operative

Paracetamol 1g QDS regular
COX-2 / NSAID regular (≤5 days)
Opioid PRN rescue (oxycodone 5–10 mg PO)
Cryotherapy
Early physiotherapy — Day 0/1 mobilisation
Regular opioid prescription — avoid

✓ Recommended | ◎ Optional/conditional | ✗ Not recommended. Based on PROSPECT 2021 (Anger et al.).

Systemic Analgesia

✓ Recommended — Grade A — All patients

Paracetamol + COX-2 inhibitors/NSAIDs form the backbone of systemic analgesia for THA, pre-, intra-, and postoperatively. IV dexamethasone 8–10 mg is recommended intraoperatively for both analgesia and PONV prophylaxis. Combined, these agents reduce opioid consumption by 30–50%.

Agent	Dose	Route	Frequency	Duration	Notes
Paracetamol	1 g	IV/PO	QDS	Throughout	Reduce if <50 kg or hepatic impairment
Celecoxib	200 mg	PO	BD	≤5 days	COX-2 preferred; less GI risk
Etoricoxib	60–90 mg	PO	OD	≤5 days	Once daily, good compliance
Ibuprofen	400 mg	PO	TDS	≤5 days	Add PPI; avoid if renal impairment
Dexamethasone	8–10 mg	IV	Single intraop	—	Analgesia + PONV + extends block duration
Oxycodone IR	5–10 mg	PO PRN	4–6h	Rescue only	First-line oral rescue

⚠️

Gabapentinoids: PROSPECT 2021 does not recommend gabapentinoids for THA due to insufficient evidence of benefit and significant adverse effects (sedation, dizziness, falls risk). This is particularly important in the elderly THA population.

Regional Analgesic Strategy

PROSPECT 2021 recommends regional analgesia for THA "especially if there are contraindications to basic analgesics and/or in patients with high expected postoperative pain." The ideal technique provides hip joint capsule analgesia while preserving quadriceps and hip flexor strength for early rehabilitation.

Fascia Iliaca Block (FICB)

PROSPECT ✓

Supra-inguinal approach recommended. Blocks femoral nerve + LFCN ± obturator branches. Established evidence base for THA. May cause some quadriceps weakness.

NervesFemoral + LFCN ± obturator

Motor sparingPartial — some quad weakness

Volume30–40 mL

AgentRopivacaine 0.2–0.25%

PENG Block

Emerging ◎

Pericapsular Nerve Group — targets articular branches of femoral, obturator, and accessory obturator nerves at the hip capsule. Motor-sparing. Growing RCT evidence. Not in PROSPECT 2021 but increasingly adopted.

NervesFemoral art. + obturator art.

Motor sparing✓ Excellent

Volume20–30 mL

AgentRopivacaine 0.25–0.375%

Local Infiltration Analgesia (LIA)

PROSPECT ✓

Peri-articular infiltration by surgeon — circumferential coverage of capsule, periosteum, and soft tissues. Motor-sparing. Can be combined with nerve block or used alone.

Who performsSurgeon (intraoperative)

Motor sparing✓ Yes

Volume100–150 mL

AgentRopivacaine 0.2%

💡

FICB vs PENG for THA: PROSPECT 2021 recommends FICB based on the evidence available at the time. Multiple subsequent RCTs (2022–2024) show PENG block provides superior motor-sparing and comparable or better analgesia vs FICB for THA. A 2024 RCT found PENG + LFCN outperformed FICB in quadriceps strength, hip flexion, pain scores, and opioid use. PENG + LFCN also resulted in significantly earlier first postoperative walking time (19.6h vs 26.5h) compared to supra-inguinal FICB. Either technique is acceptable — choose based on experience and local practice.

Fascia Iliaca Compartment Block (FICB)

✓ PROSPECT 2021 Recommended — supra-inguinal approach preferred

Single-shot supra-inguinal FICB provides broader spread (femoral nerve + LFCN ± obturator nerve) than the infra-inguinal approach, giving better hip coverage. No catheter recommended — evidence does not support added benefit over single-shot for THA.

Technique — Supra-inguinal, Ultrasound-Guided

Probe placement
Patient supine. Place linear probe just below the ASIS (anterior superior iliac spine) parallel to the inguinal ligament. Identify the iliac crest, iliopsoas muscle, and the fascia iliaca (hyperechoic line overlying iliopsoas).
Identify the target plane
The target is the plane deep to the fascia iliaca and superficial to the iliopsoas muscle, medial to the ASIS. This is more proximal than the infra-inguinal approach, allowing spread to reach femoral and obturator nerve branches at the level of the hip.
In-plane needle insertion — lateral to medial
Insert the needle lateral to the probe. Advance in-plane until the tip is beneath the fascia iliaca. Confirm correct plane with 1–2 mL saline — LA should spread between fascia iliaca and iliopsoas (not above fascia).
Injection
Inject 30–40 mL of ropivacaine 0.2% in incremental aliquots with aspiration. Observe spread medially beneath the fascia. Adequate spread medially is key to blocking the femoral nerve territory.

Dosing

Agent	Concentration	Volume	Duration	Notes
Ropivacaine	0.2%	30–40 mL	10–16 h	Standard for THA — motor-sparing concentration
Ropivacaine	0.25%	30 mL	12–18 h	Slightly denser; more quadriceps effect
Levobupivacaine	0.25%	30–35 mL	12–18 h	Preferred in frail/elderly — safer cardiac profile

⚠ High volumes — always calculate max safe dose (ropivacaine 3 mg/kg). 40 mL × 2 mg/mL = 80 mg for 0.2% — well within limits for most adults.

PENG Block — Pericapsular Nerve Group

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Emerging technique — not in PROSPECT 2021 but rapidly accumulating evidence. An RCT (BJA 2023) showed PENG block significantly improved 24h quality of recovery (QoR-15) scores in THA compared to sham block. A 2024 systematic review and meta-analysis (Pai et al., Clin J Pain) evaluated PENG for THA and found evolving but promising evidence for opioid-sparing and motor preservation. PENG is increasingly adopted as first-line or adjunct to LIA for THA.

Anatomy & Target

The PENG block deposits LA in the musculofascial plane between the iliopsoas tendon and the superior pubic ramus / iliopubic eminence, targeting articular branches supplying the anterior hip capsule:

Articular branches of the femoral nerve (primary target)
Accessory obturator nerve (~25% of patients)
Obturator nerve articular branches (variable)

Unlike FICB, PENG targets only the articular (sensory) branches — the main femoral nerve motor branch to quadriceps is not blocked, making it highly motor-sparing. For lateral skin coverage, a supplementary lateral femoral cutaneous nerve (LFCN) block is commonly added (10 mL ropivacaine 0.25% subfascially just medial to ASIS).

Technique — Ultrasound-Guided

Position & probe placement
Patient supine. Place linear or curvilinear probe in the inguinal region parallel to the inguinal ligament. Identify the AIIS (anterior inferior iliac spine) and iliopubic eminence (IPE) of the superior pubic ramus. The femoral artery and nerve should be visible medially.
Identify target plane
Target plane: between the iliopsoas tendon (anteriorly) and the superior pubic ramus/AIIS (posteriorly), medial to the AIIS. Femoral artery and nerve are medial — visualise and avoid.
In-plane needle — lateral to medial
Insert needle lateral, in-plane. Advance to the target plane. Aspirate. Confirm correct plane with 1–2 mL — LA should spread between psoas tendon and ilium (not beneath periosteum, not above tendon).
Injection
Inject 20 mL in incremental aliquots. Observe hydrodissection in the correct plane. For complete lateral coverage, add LFCN block: 10 mL ropivacaine 0.25% subfascially below ASIS.

Dosing

Agent	Concentration	Volume (PENG)	+ LFCN	Duration
Ropivacaine	0.25–0.375%	20 mL	10 mL 0.25%	12–18 h
Bupivacaine	0.25%	20 mL	10 mL 0.25%	14–20 h
Levobupivacaine	0.25%	20 mL	10 mL 0.25%	14–20 h

Local Infiltration Analgesia (LIA)

✓ PROSPECT 2021 Recommended

Peri-articular LIA provides circumferential coverage of the hip joint capsule, periosteum, and surrounding soft tissues. Motor-sparing. Can be used alone or combined with FICB/PENG. Performed by the surgeon intraoperatively.

Agent	Concentration	Volume	Total Dose	Notes
Ropivacaine	0.2%	100–150 mL	200–300 mg	Check total dose when combined with nerve block
Levobupivacaine	0.25%	60–80 mL	150–200 mg	Lower volume; safer cardiac profile

Some centres add adrenaline 1:200,000 to reduce absorption and prolong duration. Ketorolac in LIA cocktail is off-label in most countries. Always calculate total LA dose when combining with nerve block — ropivacaine max 3 mg/kg.

Anaesthetic Technique

Technique	PROSPECT	Notes
Spinal anaesthesia	Preferred	Lower opioid use, less PONV, earlier mobilisation in meta-analyses. Hyperbaric bupivacaine 0.5% 2–3 mL standard.
General anaesthesia	Acceptable	When spinal contraindicated. Regional blocks remain important adjuncts.
Intrathecal morphine 0.1 mg	Conditional	Effective 12–18h analgesia. PROSPECT 2021 acknowledges efficacy but emphasises PONV, pruritus, and respiratory depression risk. Hospitalised patients only — not day-case THA.

Surgical Approach & Analgesic Implications

The surgical approach affects which structures are disrupted and therefore which regional techniques are most appropriate. PROSPECT 2021 notes that surgical technique has a minor impact on postoperative pain overall — choice should be guided by surgical preference, not analgesic considerations.

🔱 Anterior (DAA)

Anterior capsule disrupted — PENG block most targeted. Less posterior pain. Faster early recovery reported in some studies.

🔱 Lateral (Hardinge)

Lateral and anterior capsule disruption. FICB or PENG appropriate. Moderate posterior pain. Standard approach in many centres.

🔱 Posterior

Posterior capsule disrupted — more posterior pain component. LIA especially important for posterior coverage. PENG covers anterior; LIA covers posterior.

Not Recommended — PROSPECT 2021

✗ Not Recommended — Femoral Nerve Block

Causes significant quadriceps motor blockade, delaying mobilisation and increasing falls risk. Adverse effects outweigh analgesic benefits when effective alternatives (FICB, PENG, LIA) are available.

✗ Not Recommended — Lumbar Plexus Block

Risk of retroperitoneal haematoma, deep technique, and no evidence of superiority over FICB or LIA. Adverse effects outweigh benefits for routine THA.

✗ Not Recommended — Epidural Analgesia

Bilateral lower limb effects, urinary catheter requirement, hypotension, and impaired mobilisation. No superiority over combined nerve block + LIA. Not recommended for routine THA.

✗ Not Recommended — Gabapentinoids

Insufficient evidence of clinically meaningful benefit in THA. Sedation, dizziness, and falls risk — particularly problematic in the elderly THA population. PROSPECT 2021 does not recommend routine use.

Practical Analgesic Protocol

Suggested protocol for a typical adult (70 kg, eGFR >60, no NSAID contraindication) undergoing primary elective THA under spinal anaesthesia:

Suggested Protocol — Primary THA (Spinal Anaesthesia)

PRE-OP

Paracetamol 1g PO · Celecoxib 200 mg PO

REGIONAL

PENG block: Ropivacaine 0.375% 20 mL (75 mg) + LFCN: Ropivacaine 0.25% 10 mL (25 mg) — or — Supra-inguinal FICB: Ropivacaine 0.2% 35 mL (70 mg)

INTRA-OP

Spinal: Hyperbaric bupivacaine 0.5% 2.5 mL ± ITM 0.1 mg (inpatients only) · Dexamethasone 8 mg IV · LIA by surgeon: Ropivacaine 0.2% 100 mL (200 mg) — check total ropivacaine ≤3 mg/kg

POST-OP

Paracetamol 1g QDS regular · Celecoxib 200 mg BD (≤5 days) · Oxycodone 5–10 mg PO PRN 4–6h (rescue) · Cryotherapy · Physiotherapy Day 0 · DVT prophylaxis per protocol

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Always verify total LA dose: PENG 20 mL × 3.75 mg/mL = 75 mg + LFCN 10 mL × 2.5 mg/mL = 25 mg + LIA 100 mL × 2 mg/mL = 200 mg = 300 mg total ropivacaine — within 3 mg/kg for ≥100 kg patients. Reduce LIA volume for lighter patients. Use the Drug Calculator ↗

Clinical Disclaimer Information on this page is for educational reference only and does not constitute medical advice. All doses and techniques must be verified against local formulary and adapted to individual patients by a qualified practitioner. The site owner accepts no liability for clinical outcomes.

References

Anger M, Valovska T, Beloeil H, et al. PROSPECT guideline for total hip arthroplasty: a systematic review and procedure-specific postoperative pain management recommendations. Anaesthesia. 2021;76:1082–1097. PMID 34015859 ↗
ESRA PROSPECT. Total Hip Arthroplasty 2019 (published 2021). esraeurope.org ↗
Girón-Arango L, Peng PWH, Chin KJ, et al. Pericapsular Nerve Group (PENG) Block for Hip Fracture. Reg Anesth Pain Med. 2018;43(8):859–863.
Lin DY, Morrison C, Brown B, et al. PENG block for THA: quality of recovery RCT. Br J Anaesth. 2023. BJA ↗
Liang L, Zhang C, Dai W, He K. PENG + LFCN vs supra-inguinal FICB for THA: RCT. J Anesth. 2023;37(4):503–510. PMC ↗
Pai P, Amor D, Lai YH, Echevarria GC. PENG block in THA: systematic review and meta-analysis. Clin J Pain. 2024;40(5):320–332. PubMed ↗
Zhang XY, Ma JB. Fascia iliaca compartment block for THA: meta-analysis. J Orthop Surg Res. 2019;14(1):33.
Hussain N, Brull R, et al. Motor-sparing nerve blocks for hip arthroplasty: network meta-analysis. Anesthesiology. 2023;139:444–461.
Abdallah FW, McCartney CJL. PROSPECT guidelines for THA: reply. Anaesthesia. 2022;77:1306.