Researchers looked at thousands of patients who had surgery to fix curved spines to understand whether low vitamin D levels caused problems after surgery. They found that while low vitamin D seemed connected to some complications, the real culprit might actually be weak bones (osteoporosis) instead. When doctors accounted for bone weakness in their analysis, the vitamin D connection mostly disappeared for long-term outcomes. This suggests that if you’re having spine surgery, your bone health might be more important to focus on than vitamin D alone.

The Quick Take

  • What they studied: Whether low vitamin D levels cause worse outcomes and need for repeat surgery in adults who have surgery to straighten their spine
  • Who participated: Adults who had spine deformity surgery between 2010 and early 2022, tracked through a national medical database. Patients were grouped by whether they had low vitamin D, and researchers matched them by age, sex, and overall health status
  • Key finding: Low vitamin D appeared to increase complications and repeat surgeries at first, but when researchers accounted for weak bones (osteoporosis), the vitamin D connection for repeat surgeries disappeared. This suggests weak bones, not low vitamin D, may be the real problem
  • What it means for you: If you’re planning spine surgery, getting your bone health checked and treated may be more important than focusing only on vitamin D levels. However, this finding needs confirmation from other studies before changing medical practice

The Research Details

Researchers used a large national database of medical records from 2010 to early 2022 to find patients who had surgery for curved spines. They split patients into two groups: those with low vitamin D and those without. To make fair comparisons, they matched patients in both groups by age, sex, and overall health using a special matching technique (4 patients without low vitamin D for every 1 with low vitamin D). They then used statistical methods to look for connections between low vitamin D and problems after surgery, first without considering bone health, then again while accounting for bone weakness. They also tracked how many patients needed repeat surgery within 5 years.

This approach is important because it helps separate which factor—low vitamin D or weak bones—actually causes the problems. Many conditions are connected to each other, so researchers need to carefully untangle which one is the real cause. By doing the analysis twice (with and without considering bone health), they could see if bone weakness was hiding the true relationship

This study used a large, real-world database which is good for finding patterns, but it has limitations. The researchers couldn’t randomly assign people to groups (which would be stronger evidence), and they relied on diagnosis codes in medical records which might not catch everyone with low vitamin D or weak bones. The study is observational, meaning it shows connections but not definite cause-and-effect

What the Results Show

When looking at the initial analysis without considering bone health, patients with low vitamin D had a 34% higher chance of experiencing any complication after surgery and a 39% higher chance of minor complications. They also had nearly twice the risk of wound opening (a serious complication where the surgical cut reopens). Most importantly, patients with low vitamin D had a higher rate of needing repeat surgery within 5 years (39.3% versus 31.7%).

However, when researchers repeated the analysis while accounting for bone weakness, the picture changed. The connection between low vitamin D and needing repeat surgery disappeared completely—both groups had similar rates of repeat surgery. This is the key finding: bone weakness, not low vitamin D itself, appeared to be driving the need for repeat surgeries.

Some complications remained slightly higher in the low vitamin D group even after accounting for bone weakness, including a 35% higher chance of any complication and a 56% higher chance of urinary tract infections. These smaller differences suggest that low vitamin D might have some independent effect on certain complications, but not on the major outcome of repeat surgery.

The study found that patients with low vitamin D were much more likely to also have weak bones (osteoporosis). This connection is important because it suggests the two conditions often occur together. When researchers looked at wound infections and other minor complications, some differences remained between groups even after accounting for bone health, suggesting low vitamin D might independently affect these outcomes. However, the most important long-term outcome—whether patients needed repeat surgery—was fully explained by bone weakness

Previous research had suggested that low vitamin D causes worse outcomes after spine surgery. This study suggests that earlier findings might have been incomplete because researchers weren’t fully accounting for bone weakness. Since low vitamin D and weak bones often occur together, earlier studies may have blamed vitamin D when bone health was the actual problem. This finding aligns with what we know about bone health being critical for surgical recovery and healing

This study used medical records and diagnosis codes, which means some patients with low vitamin D or weak bones might not have been diagnosed or recorded. The researchers couldn’t randomly assign people to have low vitamin D or not (which would provide stronger evidence), so they could only observe what happened naturally. The study looked backward at existing records rather than following patients forward, which can miss important details. Additionally, the study couldn’t measure actual vitamin D blood levels—it only used whether doctors had documented a diagnosis of deficiency. Finally, other factors that affect surgery outcomes (like exercise, diet quality, or smoking) weren’t fully accounted for

The Bottom Line

If you’re planning spine surgery for a curved spine, ask your doctor to check your bone health and vitamin D levels. Focus especially on bone strength, as this appears more directly connected to needing repeat surgery. If you have weak bones, work with your doctor on treatment options. While vitamin D is still important for overall health, this study suggests it may be less critical than bone health for surgical outcomes. Confidence level: Moderate—this finding is helpful but should be confirmed by other studies

Adults considering or recovering from spine deformity surgery should care about this research. People with osteoporosis or low bone density should especially pay attention. However, this doesn’t mean vitamin D doesn’t matter—it’s still important for overall health. People without spine surgery plans can use this as a reminder that bone health is important. This research is less relevant for children or people having spine surgery for other reasons (like injury or cancer)

The study tracked patients for 5 years after surgery. Most complications appeared within 90 days after surgery, while the need for repeat surgery developed over the full 5-year period. If you’re having this surgery, you should expect to see how well you’re healing within the first 3 months, with the full picture becoming clear over several years

Want to Apply This Research?

  • If you’re preparing for or recovering from spine surgery, track your bone health markers (if available from your doctor) and any vitamin D supplementation you’re taking. Record any complications or symptoms that develop, especially wound issues or infections, and note when/if you need follow-up procedures
  • Work with your healthcare team to optimize bone health before surgery through appropriate treatment if you have osteoporosis, adequate calcium and vitamin D intake, weight-bearing exercise (as approved by your doctor), and avoiding smoking. Use the app to set reminders for bone health medications and track compliance
  • Set up long-term tracking for the first 5 years after surgery, monitoring for any complications, repeat surgeries, or ongoing symptoms. Track adherence to bone health treatments and any changes in mobility or pain levels. Share this data with your surgical team at follow-up appointments to help them assess your recovery

This research provides important information about spine surgery outcomes but should not replace personalized medical advice from your doctor. The findings suggest bone health may be more important than vitamin D alone for preventing repeat spine surgery, but every patient is different. Before any spine surgery, discuss your individual vitamin D and bone health status with your surgical team. If you have low vitamin D or weak bones, work with your healthcare provider on appropriate treatment. This study shows associations but cannot prove that one factor directly causes another. Always consult with qualified medical professionals before making decisions about surgery or treatment