Is Your Lower Back Pain from the Facet Joint or the Sacroiliac Joint? Dr. Moriwaki Maps the Scope of Stem Cell Conditioned Media Joint Injection by Source of Pain2026.07.17

“My lower back hurts” can mean many different things. Pain arising from the facet joints — the paired synovial joints at the back of the lumbar spine — and pain from the sacroiliac joints — the joints at the center of the pelvis — differ in where you feel them, how they relate to movement, and how far a lumbar joint injection can realistically reach. Repeating injections without clarifying this distinction often leads to disappointing results and the familiar comment: “I had the shot, but the ache never quite cleared.” In this article, Dr. Moriwaki of AVAN TOKYO Ginza organizes the scope and limits of stem cell conditioned media joint injection according to the origin of the pain.

Key Points of This Article

・A lumbar joint injection typically targets one of two joints: the facet joint or the sacroiliac joint. The pain location, movement relationship, and therapeutic aim differ between them.

・Facet-joint pain tends to worsen with backward bending and morning stiffness, while sacroiliac pain often presents as a sharp ache deep in one buttock.

・Stem cell conditioned media joint injection aims to calm the intra-articular inflammatory environment and support tissue repair in either joint. Nerve-derived pain and spinal stenosis themselves are outside its indications.

・Combining diagnostic block injections, imaging, and orthopedic examination to pinpoint the pain source before planning injection improves the reproducibility of results.

・Response varies between individuals, and cautious judgment is required in cases with active infection or advanced joint destruction.

Which Joint Does a “Lumbar Joint Injection” Actually Target?

The phrase lumbar joint injection is used broadly, but it primarily refers to two joints: the facet joint and the sacroiliac joint. Facet joints are synovial joints on both sides at the back of the lumbar spine, heavily loaded when the body arches or twists. Sacroiliac joints sit at the center of the pelvis, transferring upper-body weight down to the pelvis and legs, and accumulate stress during single-leg standing, turning in bed, or stair climbing. Both are experienced as pain “around the lower back,” but without distinguishing where the pain originates, you cannot decide which joint to inject.

Facet-Joint Pain: Features and Realistic Scope of Injection

Facet-joint pain typically worsens when leaning backward or twisting behind, and the patient often notices morning stiffness on rising. The ache tends to be felt in the back of the low back and can radiate to the posterior thigh, but generally lacks clear leg numbness or motor weakness — an important distinction from nerve-derived pain. Diagnostic support comes from X-ray findings of facet degeneration, MRI signs of synovitis, and response to a diagnostic facet joint block. Facet-derived pain is clinically recognized as a driver of chronic low back pain, and the Japanese Orthopaedic Association guidelines can also be referenced for joint-disease information.

When stem cell conditioned media is applied to this facet-type pain, the aim is to gently modulate the intra- and peri-articular inflammatory cycle and prepare an environment conducive to repair. Rather than the rapid, potent anti-inflammatory action of steroids, multiple growth factors and cytokines act on the synovial tissue and joint capsule to shift the underlying chronic inflammation over time. In advanced cases where the facet joint itself has undergone marked bony deformation, the scope of what injection can achieve has a clear ceiling.

Sacroiliac-Joint Pain: Features and Realistic Scope of Injection

Sacroiliac joint pain often presents as a sharp ache deep in one buttock, pain the moment one rises after prolonged sitting, or waking at night when turning over. The pain center sits slightly lateral to the midline, and firmly pressing just below the posterior superior iliac spine (the bony bump at the back of the pelvis) can reproduce the symptom. Examination combines multiple loading tests — the Newton, Gaenslen, and FABER tests — and diagnosis is confirmed by response to a diagnostic block.

When stem cell conditioned media is injected into the sacroiliac joint, the aim is to suppress chronic intra-articular inflammation and improve the repair environment at the joint capsule and surrounding ligament attachments. The sacroiliac joint has minimal motion but bears strong load, and chronic inflammation there tends to prolong pain. The stem cell conditioned media approach acts on both inflammation control and tissue repair, but sacroiliitis from systemic inflammatory disease such as ankylosing spondylitis follows a fundamentally different treatment framework, so ruling out rheumatologic disease is a prerequisite.

Distinguishing the Pain Source Through Examination, Imaging, and Diagnostic Blocks

Distinguishing facet-type from sacroiliac-type pain is done by combining history taking, physical examination, imaging, and diagnostic blocks in stages. First, history clarifies “which movements provoke it” and “where pressure reproduces it.” Then X-ray and MRI evaluate facet degeneration, sacroiliac bony changes, and the state of intervertebral discs and nerve roots. When radiculopathy or neurogenic claudication is present, spinal stenosis or disc herniation may be the primary cause, which can place the case outside the indication for a lumbar joint injection.

A diagnostic block delivers short-acting local anesthetic into the target joint to check whether the pain temporarily eases. A joint that responds well to the block is more likely to be the “pain source” worth targeting with stem cell conditioned media. Ultrasound-guided or fluoroscopy-guided injection is important for reproducibility. For more on our treatment framework, please also see our dedicated page: learn more about stem cell conditioned media joint injection here.

Honestly Naming the Pain a Lumbar Joint Injection Cannot Address

A lumbar joint injection is not a universal answer. Leg pain from nerve-root compression, neurogenic claudication from spinal stenosis, disc herniation itself, and back pain from malignancy, infection, fracture, or inflammatory rheumatologic disease are not primary indications for stem cell conditioned media. In those cases, nerve blocks, surgical care, or specialist systemic treatment come first. When a joint component coexists, we address the principal cause first and then consider the injection in a complementary role.

Because stem cell conditioned media works as a biological approach that reshapes both inflammatory and repair environments, effects vary between individuals and require weeks to months to evaluate. Some patients notice a strong change after a single session, while others improve gradually over multiple sessions. Any decision on indication and limits should always be made cautiously, supported by history, imaging, and examination.

Frequently Asked Questions

Q. Between the facet and the sacroiliac joint, which is injected first?

There is no universal order. We consider the joint that responded best to the history, examination, and diagnostic block. When both contribute, we begin with the joint carrying the larger share of pain and reassess whether to add treatment based on the response.

Q. Does a stem cell conditioned media joint injection work after a single session?

Some patients feel a strong change after one session, but because the aim is to reshape the inflammatory and repair environments, evaluation typically spans weeks to months. Response varies between individuals, and a multi-session design that follows the course over time is common.

Q. How does this differ from steroid or hyaluronic acid joint injections?

Steroid injection is centered on strong anti-inflammatory action, while hyaluronic acid supplements the viscoelastic properties of joint fluid. Stem cell conditioned media is a biological approach that acts on the repair environment itself through multiple growth factors and cytokines — a different therapeutic axis.

Q. Will it help leg pain from spinal stenosis?

Nerve-derived symptoms are not a primary indication for a joint injection. Nerve blocks, conservative therapy, or surgical care when needed take priority. If a joint component coexists, injection may be considered only in a complementary role.

Q. What is a typical interval between sessions?

During the induction phase, several sessions every few weeks to one or two months are common. In the maintenance phase, intervals are usually extended as symptoms stabilize. The need for further sessions is judged each time in dialogue with the physician.

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【監修】森脇 進 / Shin Moriwaki（監修医師）

日本美容外科学会(JSAS)会員 / American Academy of Aesthetic Medicine 会員

ECFMG Certificate

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📍AVAN TOKYO 銀座 関節再生医療

AVAN TOKYO Ginza Joint Regenerative Medicine

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