Osteoporosis Surveillance Crucial Before Long Spinal Fusion for Adult Spinal Deformity
Key findings
- This retrospective study involved 399 adults, including 131 with osteoporosis, who underwent spinal fusion surgery spanning at least seven levels for spinal deformity
- Osteoporosis correlated with the likelihood of revision surgery (OR = 1.75), but gender and age did not
- The timing of revision surgeries was not significantly different between the osteoporotic and non-osteoporotic groups
- Bone quality should be assessed in all adults undergoing long spinal fusion for spinal deformity, regardless of age and gender
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Osteoporosis often co-occurs with symptomatic adult spinal deformity (ASD). When patients undergo surgery, osteoporotic bone exhibits decreased pullout strength and reduced insertional torque, which can result in loosening hardware, pseudoarthrosis or vertebral fracture.
In recent years, orthopedic surgeons have developed strategies to minimize the risk of construct failure in patients with osteoporosis, such as using large-diameter pedicle screws at multiple fixation points, under tapping of screws, cement augmentation, pelvic fixation and avoidance of soft tissue destruction.
However, Stuart Hershman, MD, surgeon in the Orthopaedic Spine Center at Massachusetts General Hospital, and colleagues have found that, despite advanced surgical techniques, revision of ASD surgery is still more common in osteoporotic patients than in those without osteoporosis. Their report appears in The Spine Journal.
Study Details
In this retrospective study, records were reviewed on 399 patients, age ≥40, who had ASD surgery at one of two large academic medical centers between January 1, 2010, and May 1, 2018, and had at least two years of follow-up. The spinal fusion had to span at least seven vertebrae, and patients whose deformity was due to a tumor were excluded.
131 of the patients (33%) had received a diagnosis of osteoporosis prior to the index surgery.
Incidence of Revision
The researchers found:
- Overall, 32% of patients required unplanned revision surgery for a spine-related complication within two years of their index procedure
- The rate was 41% for osteoporotic patients and 28% for non-osteoporotic patients (P = .01)
- The incidence of multiple revision surgeries was similar in the two groups (8.4% vs. 8.6%)
- Complications included the failure of hardware, pseudoarthrosis, proximal junction failure and infection, among other problems
Effect of Medication
34% of osteoporotic patients were using at least one medication for the treatment of low bone mineral density at the time of the index surgery. Their rate of revision surgery was similar to that of osteoporotic patients who were not medically treating their condition. The overwhelming majority of patients taking medicine for osteoporosis were taking a bisphosphonate.
Predictive Factors
Osteoporosis correlated with the likelihood of revision surgery (OR = 1.75; P = .01), but gender and age did not.
Time of Revision
The time of revision surgery did not differ significantly between the osteoporotic and non-osteoporotic groups:
- Within 30 days: 21% and 28%
- 1–3 months: 9% and 8%
- 3–24 months: 70% and 64%
Applying the Results to Practice
It appears that osteoporosis doesn't affect how quickly complications of ASD surgery arise but does increase the risk that they will occur. The importance of assessing bone quality in all ASD patients undergoing long spinal fusion, regardless of age and gender, cannot be overstated. More attention should be given to optimizing patients before surgery to try and minimize the risks associated with poor bone density.
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