The Sacroiliac Joint
The sacroiliac (SI) joint connects the ilium, the wing-shaped top of the pelvis, to the sacrum at the base of the spine. Strong ligaments keep these joints stable, but various factors can cause SI joint pain. Common causes include congenital spinal abnormalities, trauma from accidents or falls, stress after spine surgeries, postpartum looseness, inflammatory conditions, and infections. Sometimes the cause is unknown (idiopathic).
CMS Coverage for Sacroiliac Joint Arthrodesis: What You Need to Know
The sacroiliac (SI) joint connects the base of your spine (sacrum) to the pelvis. When this joint becomes unstable or degenerates, it can cause significant low back, buttock, or leg pain. For many patients, conservative treatments like physical therapy, injections, or medications may help. But when these fail, surgery may be an option specifically, minimally invasive (MI) arthrodesis of the SI joint.
Medicare’s Local Coverage Determination (LCD) policies provide criteria as to when minimally invasive (MI) arthrodesis of the sacroiliac joint (SIJ) is considered medically reasonable and necessary. These policies ensure consistency in coverage decisions and establish criteria that providers must follow before the procedure can be reimbursed. Under Title XVIII of the Social Security Act (SSA) §1862(a)(1)(A), Medicare excludes payment for items or services that are not reasonable and necessary for diagnosis, treatment, or improving the function of a malformed body part. The LCD reinforces this standard with specific requirements. It is critical to remember that the presence of a diagnosis code alone does not assure coverage. The procedure must still meet all medical necessity criteria outlined within the LCD policy.
Covered vs. Non-Covered CPT® Codes
When reporting minimally invasive sacroiliac joint (SIJ) arthrodesis, it is important to distinguish between procedures that meet Medicare’s criteria for medical necessity and those that do not. The CPT® codes below represent the covered and non-covered services under LCD guidance:
- 27279 – Arthrodesis, sacroiliac joint, percutaneous or minimally invasive (indirect visualization), with image guidance, includes obtaining bone graft when performed, and placement of a transfixation device → Covered (Group 1) when medical necessity criteria are met.
- 27278 – Arthrodesis, sacroiliac joint, percutaneous, with image guidance, including placement of intra-articular implant(s) without transfixation device → Non-covered (Group 2) as not considered medically reasonable and necessary.
Case Study
✅ Case Study 1: Medical Necessity Proven
Patient: 62-year-old female with chronic low back and pelvic pain localized to the sacroiliac joint.
History: Pain has persisted for 2 years, worsening with weight-bearing. Conservative measures (physical therapy, NSAIDs, and bracing) have failed.
Workup:
- Diagnostic SIJ block provided 80% pain relief.
- Therapeutic intra-articular injection produced sustained 60% pain relief for 4 weeks.
- MRI ruled out lumbar pathology, fractures, or inflammatory arthropathy.
Diagnosis (ICD-10-CM):
- M46.1 – Sacroiliitis, not elsewhere classified
Procedure (CPT®):
- 27279 – Arthrodesis, sacroiliac joint, percutaneous or minimally invasive, with transfixation device
Medical Necessity Met:
- All LCD criteria satisfied (diagnostic block, therapeutic injection, imaging confirmation).
- Procedure is covered since CPT® 27279 uses a transfixation device.
❌ Case Study 2: Medical Necessity Not Proven
Patient: 55-year-old male with generalized low back pain and intermittent leg pain.
History: Reports diffuse pain without clear localization. No structured rehab or home exercise program attempted.
Workup:
- No diagnostic SIJ block performed.
- No therapeutic injection performed.
- Imaging shows only mild degenerative changes.
Diagnosis (ICD-10-CM):
- M54.18 – Radiculopathy, sacral and sacrococcygeal region
Procedure (CPT®):
- 27278 – Arthrodesis, sacroiliac joint, percutaneous, with intra-articular implant(s), without transfixation device
Medical Necessity Not Met:
- LCD requirements (diagnostic block, therapeutic injection, imaging confirmation) not satisfied.
- Procedure is non-covered because CPT® 27278 does not involve a transfixation device.
Conclusion
Sacroiliac joint arthrodesis requires more than simply assigning an ICD-10-CM or CPT® code. Coverage is determined by whether the procedure meets all medical necessity criteria, including diagnostic confirmation, therapeutic response, and appropriate imaging. As shown in the case studies, a patient with documented lumbosacral instability (M53.2X7) undergoing arthrodesis with a transfixation device (CPT® 27279) meets Medicare’s standards for coverage, while a patient lacking diagnostic proof and treated with a non-transfixation procedure (CPT® 27278) does not. Ultimately, accurate coding combined with thorough clinical documentation ensures compliance, supports medical necessity, and protects providers and patients alike.
References
- Centers for Medicare & Medicaid Services. Article: Billing and Coding: Minimally Invasive Arthrodesis of the Sacroiliac Joint (A59697). CMS, 2025, https://www.cms.gov/medicare-coverage-database/view/article.aspx?articleid=59697&ver=5.
- ICD-10-CM Coding Expert for Physicians: Professional and Facility Services, 2025. AAPC, 2025.
- Current Procedural Terminology (CPT®) 2025 Professional Edition. American Medical Association, 2025.
- Centers for Medicare & Medicaid Services. Local Coverage Determination (LCD): Minimally Invasive Arthrodesis of the Sacroiliac Joint (L39812). CMS, 2025, https://www.cms.gov/medicare-coverage-database/view/lcd.aspx?lcdid=39812&ver=8&contractorName=all&contractorNumber=all&updatePeriod=1135&sortBy=updated&bc=13.