What is the role of Demineralized Bone Matrix (DBM) in posterior sacroiliac fusion procedures?

Role of Demineralized Bone Matrix (DBM) in Posterior Sacroiliac Fusion Procedures

Overview

Demineralized bone matrix (DBM) serves primarily as a graft extender or enhancer in posterior sacroiliac fusion procedures, but lacks sufficient evidence to support its use as a standalone graft material. While DBM provides osteoconductive and osteoinductive properties that can facilitate bone healing, it should be used in combination with autograft or other bone graft materials to optimize fusion outcomes 1.

Properties and Mechanism of Action

DBM is an acid-extracted organic matrix derived from human bone sources that:

• Retains most of the native proteinaceous components of bone
• Contains growth factors that act as potent osteogenic agents
• Provides a degradable matrix that facilitates endogenous release of compounds to bone wound sites
• Induces new bone formation and accelerates healing 1

Clinical Evidence in Spinal Fusion

The evidence regarding DBM in posterior sacroiliac fusion specifically is limited, but data from lumbar fusion studies can provide relevant insights:

• In instrumented lumbar fusion procedures, DBM demonstrates fusion rates between 60% and 100% 2
• When used as a graft extender in combination with autograft, DBM shows comparable efficacy to autograft alone 3
• No significant differences in fusion rates, complications, surgery duration, or patient-reported outcomes have been observed between DBM-augmented grafts and autologous bone grafts 4

Limitations and Considerations

Several important factors should be considered when using DBM:

• DBM functions best in a healthy tissue bed but has limited impact in anoxic or avascular environments often encountered in traumatic orthopedic conditions 5
• Efficacy may vary based on:
  • Donor variability
  • Manufacturing processes
  • Formulation and carriers used
  • Patient factors (hormonal status, nicotine use) 5
• As an allogeneic material, DBM carries a potential risk for disease transmission 5

Practical Application in Posterior SI Fusion

When considering DBM for posterior sacroiliac fusion:

1. Use as a graft extender/enhancer: Combine DBM with autograft (iliac crest or local bone) to reduce the amount of autologous bone needed while maintaining fusion potential
2. Consider instrumentation: DBM appears to perform better in instrumented versus non-instrumented fusion procedures 2
3. Select appropriate formulation: DBM is commercially available as putty, paste, sheets, and flexible pieces - choose based on the specific surgical approach and defect characteristics 1
4. Evaluate tissue bed quality: Ensure adequate vascularity at the fusion site to maximize DBM effectiveness 5

Monitoring Outcomes

For patients undergoing posterior SI fusion with DBM:

• Follow-up imaging is recommended to assess fusion progress
• DXA or QCT may be considered for monitoring bone mineral density in patients with underlying osteoporosis 6
• Trabecular bone score (TBS) can provide additional information on bone microarchitecture and fracture risk when used as an adjunct to DXA 6

Conclusion

While DBM shows promise as a bone graft extender or enhancer in posterior sacroiliac fusion procedures, high-level evidence specifically addressing its use in this application is lacking. The current evidence suggests it is most effective when combined with autograft material in instrumented fusion procedures rather than as a standalone graft option.