What are the common injection sites for trigger point injections in lumbar back pain?

Trigger Point Injection Sites for Lumbar Back Pain

For trigger point injections in the lumbar spine, target the paraspinal muscles (multifidus and erector spinae) at L3-L5 levels bilaterally, the quadratus lumborum muscle, and the gluteal muscles (gluteus maximus and medius), as these are the primary myofascial pain generators in chronic low back pain. 1, 2, 3

Primary Injection Sites

Paraspinal Musculature

• Multifidus muscle at L3 and L5 levels bilaterally is a primary target, as this muscle frequently harbors trigger points contributing to lumbar instability and chronic pain 4
• Erector spinae muscles from L4-S1 should be palpated for trigger points, taut bands, and areas of maximum tenderness 3
• The 2022 American Society of Pain and Neuroscience provides a strong recommendation in favor of trigger point injections, irrespective of medication type, for chronic back pain 1

Quadratus Lumborum Muscle

• The quadratus lumborum is a critical but often overlooked source of lower back and buttock pain that requires specific targeting 2
• Identify five key anatomical landmarks with the patient in lateral decubitus position: the 12th rib, iliac crest, transverse processes of L1-L4, and the posterior superior iliac spine 2
• Target three fiber groups: iliolumbar fibers (from iliac crest to L1-L4 transverse processes), lumbocostal fibers (from L1-L4 to 12th rib), and iliocostal fibers (superficial layer from iliac crest to 12th rib) 2
• Advance a 60-90mm, 28-gauge needle until it contacts the transverse process for deep trigger points in iliolumbar and lumbocostal fibers 2

Gluteal Musculature

• Gluteus maximus and gluteus medius muscles frequently contain trigger points that refer pain to the lower back and hip region 4
• These muscles should be examined with deep palpation for trigger points, particularly on the symptomatic side 5, 4

Posterior Superior Iliac Spine (PSIS) Region

• Intraosseous injections at the PSIS demonstrate superior efficacy compared to other lumbar sites, with 84.7% pain reduction after treatment and sustained 72.2% reduction at 2-month follow-up 3
• PSIS injections are 28.6% more effective than L4-S1 injections for residual pain after spinal surgery 3

Injection Technique Considerations

Depth and Approach

• Intramuscular injections target muscle belly trigger points at depths of 20-40mm depending on body habitus 2, 3
• Intraosseous injections at L5-S1 and PSIS are significantly more effective (92% more effective than intramuscular) but require specialized technique 3
• For quadratus lumborum, advance the needle until it contacts bone (transverse process) to ensure adequate depth for treating deep trigger points 2

Medication Selection

• Local anesthetic alone (0.5% lidocaine) is as effective as local anesthetic plus steroid for trigger point injections 6
• The 2021 American College of Occupational and Environmental Medicine recommends trigger point injections with local anesthetic but specifically recommends against glucocorticosteroids 1
• A mixture of 0.5% lidocaine with 12.5-15% dextrose (prolotherapy) can be used for enthesopathy at tendon insertion sites 2

Clinical Algorithm for Site Selection

Step 1: Identify Pain Pattern

• Axial low back pain without radiculopathy: Target paraspinal muscles (multifidus, erector spinae) at L3-L5 1, 4
• Lower back with buttock/hip radiation: Include quadratus lumborum and gluteal muscles 2, 5
• Residual pain after spinal surgery: Prioritize intraosseous PSIS injections over intramuscular approaches 3

Step 2: Physical Examination Findings

• Palpate for trigger points: Identify taut bands, local twitch response, and referred pain patterns 2, 5
• Positive straight leg raise with trigger points present: Target lower extremity and gluteal trigger points, as this combination responds well to injection therapy 5
• Pain with posterior-to-anterior pressure at specific levels: Target paraspinal muscles at those exact vertebral levels 7

Step 3: Number and Distribution

• Limit to 6 total injection sites per session (up to 3 levels bilaterally) to avoid excessive medication exposure and allow assessment of response 8
• Bilateral treatment is often necessary as trigger points frequently occur symmetrically in paraspinal muscles 3, 4

Important Clinical Caveats

When NOT to Perform Trigger Point Injections

• Do not perform trigger point injections in patients with untreated radiculopathy, as epidural steroid injections are more appropriate for radicular symptoms 1, 8
• Avoid repeated injections without documented quantifiable improvement (≥50% pain reduction for ≥2 months) 9
• Do not repeat injections more frequently than every 2 months if therapeutic effect is achieved 9

Diagnostic Confusion

• Active trigger points with radiating pain can mimic radiculopathy, leading to misdiagnosis 5
• In patients with lumbosacral radiculopathy AND trigger points, treating the trigger points first can significantly improve outcomes (pain scores improved from 7.12 to 2.4 vs 6.7 to 4.06 without trigger point treatment) 5
• Only 7.7% of patients selected for facet injection based on clinical criteria achieve complete relief, highlighting that myofascial pain is often the true pain generator 6

Expected Outcomes

• Immediate to 7-day response: Pain reduction of 40-85% depending on technique and site 3
• Sustained benefit: Effects persist for 2-4 months with proper technique, particularly with intraosseous approaches 3
• Functional improvements: Expect regression of sensory deficits (67.4%), improved gait (48.6%), and increased daily step activity (68.3%) with intraosseous techniques 3