Cluneal nerve block: superior and middle cluneal nerves

Basic to intermediate. The injections are superficial, but the nerves are small and often hard to see, so the drug is placed by landmarks on the bone and in the right fascial plane.

The superior cluneal nerves are the lateral branches of the dorsal rami of about L1–L3. They run down through the back muscles, pierce the thoracolumbar fascia and cross the iliac crest about 7–8 cm from the midline, often through a tight fibrous tunnel where they can be trapped. They supply the skin of the upper buttock.

In a cadaver study the branches pierced the fascia about 6–7 cm lateral to the posterior superior iliac spine (PSIS) along the crest, in a zone about 3 cm wide.

The middle cluneal nerves are the lateral branches of the dorsal rami of S1–S3. They come out of the dorsal sacral foramina and pass through or under the long posterior sacroiliac ligament between the PSIS and the side of the sacrum, then pierce gluteus maximus to supply the skin of the inner buttock.

The inferior cluneal nerves (from the posterior femoral cutaneous nerve) supply the lower buttock and are not blocked here.

• Iliac crest and its highest point.
• Posterior superior iliac spine (the dimple above the buttock).
• Median sacral crest.
• Tender spot with a positive Tinel sign over the crest, in entrapment.

• Diagnosis and treatment of superior or middle cluneal nerve entrapment (low back, sacroiliac and buttock pain with normal imaging).
• Total hip arthroplasty: superior cluneal block added to a fascia iliaca or PENG block for the upper buttock skin.
• Iliac crest bone graft harvest and posterior pelvic incisions.
• Pain after falls or bruising of the buttock and iliac crest.

• Superior cluneal nerves (L1–L3 dorsal rami)
• Middle cluneal nerves (S1–S3 dorsal rami)

Surface anatomy, relevant structures and landmarks

Superior: the point of most tenderness on the crest, or about 7 cm from the midline. Middle: just medial and below the PSIS, over the edge of the sacrum.

Positioning

Prone with a pillow under the abdomen, or lateral.

Block technique

• Superior: insert the needle onto the top of the iliac crest at the marked point and inject 3–5 mL as the needle is withdrawn slightly, fanning along the crest.
• Middle: insert the needle onto the back of the sacrum just medial to the PSIS and inject 3–5 mL on the long posterior sacroiliac ligament.

Needle choice

22–25 G, 50 mm.

Neurostimulation technique

Not used.

Choice of local anaesthetic (including volume)

• Diagnostic block: 2–3 mL of 1% lidocaine or 0.25% bupivacaine per site.
• Treatment: local anaesthetic with or without steroid, 3–5 mL per site.
• Surgery: 5–10 mL of 0.25% levobupivacaine or 0.2% ropivacaine for the superior cluneal nerves.

Positioning

Prone. Operator on the side of the block.

Scanning technique

• Superior: place the probe across the iliac crest (along the line of the spine) about 7 cm from the midline. Find the bright curve of the crest with the back muscles above it and gluteus medius below.
• Look for small dark dots in the fat just superficial to the thoracolumbar fascia where it crosses the crest. Inject 3–5 mL in this plane over the crest, in plane from below.
• Middle: place the probe across the buttock at S1–S2, between the median sacral crest and the PSIS. Find the sacrum medially, the ilium (PSIS) laterally and the long posterior sacroiliac ligament bridging the gap.
• Inject 3–5 mL on the ligament, deep to gluteus maximus, in plane from lateral.

Structures to identify

• Iliac crest
• Thoracolumbar fascia
• Superior cluneal nerves (small dots, not always seen)
• Gluteus medius and gluteus maximus
• Sacrum and posterior superior iliac spine
• Long posterior sacroiliac ligament
• Middle cluneal nerves

Position / ergonomics

Stand on the side of the block, screen opposite.

Probe

Linear high-frequency.

Settings

Musculoskeletal preset, depth 3–4 cm.

Depth

1–3 cm.

Needle size

22–25 G, 50 mm.

Needling technique

In plane.

Optimal needle-tip position

Superior: superficial to the thoracolumbar fascia over the crest. Middle: on the long posterior sacroiliac ligament, deep to gluteus maximus.

Drug choice

See above.

Volume

3–5 mL per site (5–10 mL for surgery).

Optimal current if nerve stimulation is used

Not used.

Muscle responses acceptable

Not applicable.

Testing block success

• Numb skin over the upper or inner buttock
• In entrapment, 70% or more pain relief after a diagnostic block supports the diagnosis

Not used. Radiofrequency ablation, nerve stimulation and surgical release are options for lasting entrapment pain.

• Think of cluneal entrapment when back or buttock pain has a tender, Tinel-positive spot on the iliac crest and the imaging is normal.
• Press on the crest to find the tender point, then scan there.
• Use a small volume for a diagnostic block so the answer is clear.
• For hip surgery, the superior cluneal block covers the upper buttock skin that a fascia iliaca block misses.

• Kiral and colleagues (2024) studied 200 patients with chronic low back pain: superior cluneal entrapment, confirmed by an ultrasound-guided diagnostic block, was the cause in 12%.
• Ismailoglu and Sac (2026) mapped the superior cluneal branches in cadavers and defined a target zone over the lateral part of the line from the PSIS to the highest point of the crest.
• Zheng and colleagues (2026) randomised 82 patients having hip replacement: adding a superior cluneal block to a fascia iliaca block reduced opioid use and early pain, though by less than the clinically important difference.
• Fujihara and colleagues (2024) found superior or middle cluneal entrapment in about one in five adults over 80 with low back pain, confirmed by nerve blocks.

• Kiral BS, Misirlioglu TO, Terlemez R, et al. The frequency of superior cluneal nerve entrapment diagnosed with ultrasound-guided nerve block in patients with low back pain: a prospective, cross-sectional study. Pain Pract 2024;24:989–996. PubMed
• Ismailoglu AV, Sac A. Defining a bony landmark-based target zone for superior cluneal nerve blockade: a cadaveric mapping study. Reg Anesth Pain Med 2026. PubMed
• Zheng Z, Gong H, Shi Z, et al. The analgesic effect of fascia iliaca compartment block combined with superior cluneal nerve block after total hip arthroplasty: a prospective, triple-blind, randomized controlled trial. BMC Anesthesiol 2026;26:58. PubMed
• Fujihara F, Kim K, Isu T, et al. Paralumbar spine disease as a cause of low back pain in older adults. Cureus 2024;16:e53983. PubMed