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Pedicle screws and bone mineral density
K Kumano1, S Hirabayashi, Y Ogawa
1Department of Orthopedic Surgery, Kantoh Rosai Hospital, Kawasaki, Japan.
Spine
|May 15, 1994
Summary
Spinal fusion surgery using pedicle screws can be safe for patients with low bone mineral density, but those with severe osteoporosis (Grade III) should be excluded. Bone mineral density is a more reliable measure than X-rays for assessing osteoporosis risk.
Area of Science:
- Orthopedic Surgery
- Spinal Surgery
- Radiology
Background:
- Degenerative lumbar disorders often require surgical intervention, including decompression and spinal fusion.
- Pedicle screws are commonly used in spinal fusion procedures, but their success can be influenced by bone quality.
- Assessing bone mineral density (BMD) preoperatively is crucial for predicting surgical outcomes in spinal fusion.
Purpose of the Study:
- To investigate the relationship between lumbar spine bone mineral density (BMD) and the success rates of one-level spinal fusions using pedicle screws.
- To evaluate the incidence of screw-related complications in relation to BMD in patients undergoing surgery for spinal canal stenosis.
- To compare the reliability of quantitative computed tomography (QCT) for BMD measurement versus radiographic grading of osteoporosis.
Main Methods:
- A cohort of 35 patients undergoing decompression and one-level fusion with Cotrel-Dubousset pedicle screws for spinal canal stenosis was studied.
- Preoperative BMD of the third lumbar vertebral body was measured using quantitative computed tomography (QCT).
- Patients were divided into two groups based on BMD (<100 mg/mL and >100 mg/mL) to compare fusion success and screw complication rates.
Main Results:
- No statistically significant difference in successful fusion or screw complication rates (loosening, breakage) was found between the low and high BMD groups.
- Non-union and screw problems occurred in patients across all BMD and osteoporosis grading levels.
- Radiographic grading of osteoporosis did not correlate with BMD measurements, with frequent discrepancies observed.
Conclusions:
- One-level spinal fusion with pedicle screws for degenerative lumbar disorders can be safely performed in patients with decreased bone mineral density, provided Grade III osteoporosis is excluded.
- Bone mineral density measurement via QCT is a more reliable indicator of osteoporosis than radiographic grading for preoperative evaluation.
- Preoperative assessment of BMD should be incorporated into the surgical planning for spinal fusion to mitigate risks.