Can Rib Fractures Directly Alter DEXA Scores?
Rib fractures do not directly affect DEXA bone mineral density (BMD) scores because ribs are not standard measurement sites for diagnostic DEXA scanning. DEXA measurements are performed at the lumbar spine (L1-L4), hip (total hip and femoral neck), and distal forearm—not the ribs 1.
Standard DEXA Measurement Sites
The established regions of interest (ROI) for DEXA scanning specifically exclude the ribs 1:
- Lumbar spine (L1-L4): Primary site for trabecular bone assessment
- Hip (femoral neck and total hip): Reference site for epidemiological studies
- Distal forearm (33% radius): Alternative site when spine/hip cannot be measured
The ribs are not included in any standard DEXA protocol for osteoporosis diagnosis or monitoring 1.
Why This Question Matters Clinically
While rib fractures don't affect DEXA scores directly, the presence of rib fractures has important implications for osteoporosis diagnosis and fracture risk assessment 1:
Rib Fractures as Osteoporotic Fractures
- Recent guidelines recognize rib fractures as major osteoporotic fractures, alongside hip, spine, forearm, humerus, and pelvis fractures 1
- A diagnosis of osteoporosis may be presumed in the presence of a prior low-trauma rib fracture, even with normal BMD according to EANM, ASBMR, and CSEM societies 1
- Rib fracture history after age 45 is associated with a 5.4-fold increased risk of future rib fractures and 2.4-fold increased risk of any new clinical fracture 2
Clinical Implications
If a patient presents with low-trauma rib fractures, you should:
- Obtain DEXA scanning of standard sites (lumbar spine and hip) to assess BMD 1
- Consider the patient osteoporotic regardless of DEXA results if the rib fracture was low-trauma 1
- Evaluate for appropriate osteoporosis management and fracture prevention interventions 2
Important Caveats
Artifacts That DO Affect DEXA Scores
While rib fractures themselves don't interfere with measurements, vertebral fractures at the thoracolumbar junction (T12-L2) can spuriously increase lumbar spine BMD 1:
- Fractured vertebrae show increased BMD due to trabecular impaction and condensation, with mean increases of 0.070 g/cm² 1
- Vertebrae with fractures should be excluded from analysis if they differ by more than 1.0 T-score from adjacent vertebrae 1
When Rib Fractures Suggest Underlying Bone Disease
Low bone mineral density may be a risk factor for exercise-induced rib stress fractures, as demonstrated in elite rowers with significantly lower L2-L4 BMD (1.22 vs 1.40 g/cm², P=0.028) 3. Spontaneous rib fractures in the absence of significant trauma should prompt evaluation for metabolic bone disease and osteoporosis 4.
Bottom Line for Clinical Practice
Rib fractures don't change DEXA scores because ribs aren't measured, but their presence should trigger osteoporosis evaluation and may justify treatment even if DEXA shows normal BMD 1, 2. The fracture itself is the clinical endpoint that matters for morbidity and mortality, not just the bone density number.