Quantifying postoperative bone loss in children
Elizabeth A Szalay1, Debra Harriman, Brittany Eastlund
1University of New Mexico Health Sciences Center, 1127 University Blvd NE, Albuquerque, NM 87102, USA. ESzalay@salud.unm.edu
Insights
Children can experience significant bone density loss after lower extremity surgery, losing up to 34% of bone mineral density (BMD) in just 4-6 weeks. This highlights the need for preventative strategies and treatments to mitigate fracture risk in pediatric patients.
Area of Science:
- Pediatric Orthopedics
- Bone Metabolism
- Radiology
Background:
- Postoperative bone density loss in children is a recognized issue.
- Objective quantification of this bone loss has been lacking.
- Dual-energy x-ray absorptiometry (DXA) is used to assess bone mineral density (BMD).
Purpose of the Study:
- To objectively quantify bone density loss in children following lower extremity surgery.
- To compare preoperative and postoperative BMD and Z-scores.
- To evaluate changes in operated versus non-operated limbs.
Main Methods:
- Prospective diagnostic study (Level I evidence).
- Recruited children undergoing lower extremity surgery requiring immobilization (≥4 weeks).
- Performed preoperative and postoperative DXA scans of the lumbar spine and distal femora; analyzed BMD and Z-scores.
Main Results:
- Children lost up to 34% BMD in the cancellous region (average 16.5%) of the operated leg.
- Significant BMD loss observed in transitional (average 11.5%) and cortical (average 4.8%) bone regions (P < 0.05).
- Z-scores decreased by 1.0 SD (cancellous), 0.75 SD (transitional), and 0.45 SD (cortical).
Conclusions:
- Pediatric bone density loss of up to 34% can occur within 4-6 weeks post-surgery.
- A 1 SD drop in Z-score may significantly increase fracture risk, especially in chronically ill children.
- Proactive prevention and treatment strategies are crucial to address this bone loss.
Background:
Postoperative bone density loss is an accepted phenomenon that has not been objectively quantified. The extent of this bone loss is documented using preoperative and postoperative dual energy x-ray absorptiometry scans to demonstrate the magnitude of the problem and to underline the need for prevention and treatment.
Methods:
Children undergoing lower extremity surgery who required a minimum of 4 weeks of either non-weight bearing or cast immobilization postoperatively were recruited to undergo preoperative and postoperative dual energy x-ray absorptiometry scans of lumbar spine and both distal femora. Percent change in bone mineral density (BMD) as well as Z-scores in preoperative and postoperative scans were compared, as were operated and nonoperated limbs, using paired t tests.
Results:
Fifteen of 18 subjects completed the second scan. Children lost up to 34% BMD in the cancellous region of the operated leg (average, 16.5%), up to 28% in transitional bone (average, 11.5%), and up to 16% (average, 4.8%) in the cortical region (P < 0.05). The Z-scores fell 1.0 SD for cancellous, 0.75 transitional, and 0.45 cortical.
Conclusions:
That children can lose up to 34% of BMD in 4 to 6 weeks is sobering. A 1 SD drop in T score, in adults, can infer a 2-fold increase in fracture risk. This may be insignificant in a healthy child with good BMD, but to a chronically ill child, a doubling of fracture risk may lead to insufficiency fracture. Avoiding the problem and proactive treatment are the goals.
Level Of Evidence:
Level I, prospective diagnostic study.
