Quadratus Lumborum Injection

The quadratus lumborum muscle is a muscle of the posterior abdominal wall lying deep inside the abdomen and dorsal to the iliopsoas. The quadratus lumborum muscle can be palpated above the posterior iliac crest. The muscle runs craniomedially from the iliac crest and attaches to the 12th rib and the transverse processes of the 1st to 4th lumbar vertebrae. The fibers together give the muscle a rectangular appearance. It is innervated by the subcostal nerves and the branches of the lumbar plexus.

The quadratus lumborum muscle contributes to the stabilization and movement of the spine and the pelvis. Bilateral contraction leads to extension of the lumbar spine. Unilateral contraction of the muscle leads to ipsilateral flexion, so the trunk is bent towards the same direction. In addition, the muscle fixes the 12th rib during movements of the thoracic cage and thus supports expiration (accessory muscle of expiration).

Overuse and strain of the quadratus lumborum is one of the major causes for chronic pain in the lower back. Typical cause includes the habit of sitting at the desk using a reclining seat, which relaxes the intrinsic back muscles and weakens them in the long term. The weak back muscles are compensated by the quadratus lumborum, leading to painful tension and stiffening of the muscle. Other causes can be direct damage or any type of imbalance of the pelvis or spine, which forces the quadratus lumborum to stabilize them.

• Quadratus lumborum pain is described as an intense, deep ache in the lower back. Pain is exacerbated with standing and sitting down.
• Patients may attempt to support and stabilize their body with their hands. This bracing with hands occurs during walking and sitting, and is the hallmark sign of active quadratus lumborum trigger points.
• Pain may be exacerbated with coughing and sneezing.
• Patients may find difficulty in standing upright on getting out of bed and may be forced to crawl on their hands and knees.
• Pain can radiate to the iliac crest, hips, buttocks and less commonly to the groin area. It can mimic hip pain or trochanteric bursitis.

The trigger points in quadratus lumborum muscle can be accurately targeted under ultrasound guidance. The procedure is usually done on an outpatient basis. Patients need to be aware that the outcome of the procedure is variable and they may not receive the desired benefits. Similarly, they must be aware of the transient nature of the therapeutic benefits and that there may need repeated injections.

Generally a mixture of local anaesthetic and steroid is injected. The local anaesthetic agent within the injectate may act on the nociceptive fibres in the muscle, whereas corticosteroids may reduce inflammation. The anaesthetic is probably responsible for immediate pain relief, whereas steroids are believed to be responsible for pain relief 2–6 days after their administration.

Botox may be injected in to the quadratus lumborum muscle to help with the myofascial pain. It is recommended for patients who get short-term benefit from local anaesthetic and steroid injection.

Injections are generally avoided in patients with systemic infection or skin infection over puncture site, bleeding disorders or coagulopathy, allergy to local anaesthetics or any of the medications to be administered.

Complications are rare, particularly if injections are performed using a precise needle-positioning technique and imaging guidance. Severe allergic reactions to local anaesthetics are uncommon. Steroid injections may produce local reactions, occurring most often immediately after injection. These local reactions last for 24 to 48 hours, and are relieved by application of ice packs. Post-procedural pain flare-up may occasionally occur, and may be treated with painkillers. Infection can occur but can be avoided with aseptic technique.