Symptoms of Loose Screws After Spinal Fusion
In spinal fusion and other spinal procedures, hardware is essential for stability. Pedicle screws are commonly used to secure the vertebrae and encourage healing. Unfortunately, screw loosening is a prevalent complication of spinal fusion, occurring in up to 60% of patients.
Read on to learn more about loose screws after spinal fusion and how to reduce your risk of back surgery complications, including modern innovations with a lower risk of complications.
Key Takeaways
- Possible symptoms of loose screws after fusion: Persistent back pain, poor mobility, back spasms, nerve symptoms, crepitus
- Timeframe: Loosening usually appears 3 to 6 months after fusion
- Common causes: Poor bone quality/osteoporosis, excess impact, poor healing, wear and tear
How Are Screws Used in Spinal Fusion?
Pedicle screws are often used in spinal fusion to support and stabilize the vertebrae as they heal. Typically, the screws are positioned above and below the fused vertebrae, and a rod links the screws to prevent motion. This helps the vertebrae and bone graft fuse properly.
These screws are called pedicle screws because they’re secured through the pedicles at the back of the vertebrae. The pedicles are cylindrical stubs of hard bone that bridge the vertebral body to the lamina.
Symptoms of Loose Screws After Spinal Fusion
Possible symptoms of loose screws after spinal fusion include persistent or worsening back pain, reduced mobility, back spasms, nerve symptoms, crepitus, visible bulging, sleep disturbances, and signs of infection. If you experience any of these symptoms, contact your spine specialist for guidance.
Persistent or Worsening Back Pain
After spinal fusion, your back pain should improve as your spine heals. But screw loosening can inhibit this process, possibly causing persistent back pain.
Some pain is to be expected during spinal fusion recovery. But if you experience persistent pain that gets worse, not better, or sharply returns after improving, see your doctor for an evaluation.
Reduced Mobility
While the fused segment will always have limited motion, mobility should gradually improve after normal post-op stiffness fades. If you experience persistent stiffness or declining mobility in the months after fusion, you might be dealing with loose screws or another issue.
Back Spasms
You can expect to experience mild back spasms in the early fusion recovery period. But if the spasms become severe and persistent, it might be a warning sign of a hardware issue.
Nerve Symptoms
You might experience mild, occasional tingling and numbness after spinal fusion as nerve irritation gradually heals. But persistent or severe nerve symptoms, like numbness, tingling, and weakness in the extremities, point to a deeper issue. These symptoms require prompt treatment to prevent lasting nerve damage.
Crepitus or Evident Bulging
In some cases, shifting hardware causes a noticeable bulge or crepitus, the term for a grating, grinding, scraping, or popping sound. Crepitus can point to a loose screw or rod, pseudoarthrosis (failed fusion), or hardware-related irritation.
Sleep Disturbances
The discomfort that stems from loose hardware can contribute to chronic pain and sleep disruptions. The link between back pain and sleep issues is well-documented: a European Spine Journal study of 1,941 patients reported a 58.7% prevalence of sleep disturbance in lower back pain patients.
How Common is Screw Loosening?
The prevalence of screw loosening varies greatly, between 1% and 60%, according to a Journal of Orthopaedic Surgery and Research review. Certain factors can increase your risk, including:
- Low bone density and osteoporosis
- A Global Spine Journal study found that screw loosening rates range from 1% to 15% in non-osteoporotic patients and up to 60% in osteoporotic patients.
- Older age
- Infection around the surgical site
What Causes Loose Screws?
The possible causes of screws loosening after spinal fusion include poor bone quality, poor healing, improper screw fixation, and excessive impact on the screws.
Poor Bone Quality/Low Bone Density
Poor bone quality most often causes loose screws after surgery. When the bone tissue isn’t strong and dense enough to support surgical hardware, the screws may gradually loosen and trigger symptoms of failed back surgery syndrome. Additionally, patients with low bone density (whether due to fracture, osteoporosis, rheumatoid arthritis, or other medical conditions) are at an increased risk of loosening screws after spinal fusion.
Osteoporosis is a common cause of diminished bone quality and can contribute to loose screws after surgery. This bone disease occurs when bone mass and mineral density dwindle, leading to weaker, thinner bones.
Prevalence: Research has shown that the rate of screw loosening in non-osteoporotic patients is 1 to 15%, but rises to 10 to 60% in osteoporotic patients, according to a BMC Musculoskeletal Disorders publication.
Excessive Impact on Pedicle Screws
Excess impact on the screws after spinal fusion can result from high-impact physical activity, poor posture, and a sedentary lifestyle. Patients who frequently partake in high-impact activities (like heavy lifting) or activities that involve intensely bending or twisting the spine may experience fusion hardware failure as a result. Your surgeon will advise you on the activities to avoid after the fusion procedure.
Poor Healing
Poor healing or failed fusion can cause the pedicle screws and other hardware to loosen. Failed fusion occurs when the bone graft doesn’t successfully merge the vertebrae into a single bone.
Certain factors can increase your risk of pedicle screw loosening after spinal fusion, including:
- Diabetes: Pedicle screw loosening is more common in patients with diabetes.
- Older age: The older a patient is, the higher the risk of pedicle screw loosening.
Normal Wear and Tear
Screws can also simply loosen after spinal fusion with time. Over the years, the screws undergo normal wear and tear, which can lead to loosening or damage. Older patients may pass naturally before experiencing the effects of wear and tear on the screws, but younger patients will likely develop symptoms at some point.
When Do Pedicle Screws Typically Loosen?
Pedicle screws typically loosen in the first three to six months after spinal fusion.
In a study from the London Spine Unit evaluating 212 patients who underwent single-level lumbar fusion with pedicle screw fixation, roughly half of the cases were observed within 90 days post-op, and close to two-thirds within 180 days. The study reported that while most cases occurred in the early post-op stage, some appeared up to a year after surgery.
How Loose Screws Are Diagnosed
Loose screws after fusion are usually diagnosed with a physical exam and imaging tests. In some cases, your doctor may order a bone scan or nerve studies to exclude other possible causes of pain.
- Physical exam: Your doctor will start with an exam to check for pain, tenderness, and abnormalities that could point to hardware issues.
- Imaging tests allow your doctor to see the inside of the body, including the hardware. Options include:
- An X-ray is usually sufficient to view the spinal bones and check for loose screws.
- A CT scan or MRI may be necessary if the X-ray isn’t clear enough for a definitive diagnosis. CT scans provide 3D, cross-sectional X-ray images, while MRIs use magnets and radio waves to produce detailed images of the body, including soft tissue.
- A bone scan is a nuclear medicine scan. It uses tiny amounts of radioactive material to diagnose bone issues. It may be required if imaging tests are inconclusive to help diagnose hardware issues, failed fusion, or other issues (like a bone infection).
- A nerve study, like an EMG study, assesses nerve and muscle function to help diagnose neurological symptoms like tingling, weakness, and numbness.
What Happens When Spinal Fusion Screws Loosen?
When spinal fusion screws loosen, they can irritate the neighboring nerves and tissue. This can cause pain, neurological symptoms, and crepitus (a grating noise or sensation).
New or recurrent back pain after spinal fusion as a result of pedicle screw loosening can indicate failed spinal fusion (also known as failed back surgery syndrome). Many patients who develop this syndrome after undergoing spinal fusion require re-operation for pain management.
Symptoms of failed spinal fusion include:
- Limited spinal mobility
- Spasms in the back
- Insomnia
- Numbness, tingling, or weakness in the extremities
- Persistent back pain
What Should You Do If You Suspect Loose Screws?
If you experience new, persistent, or worsening back pain, reduced mobility, severe spasms, or persistent nerve symptoms after spinal fusion, don’t wait to contact your healthcare provider. Acting quickly will keep the problem from progressing, which could lead to lasting damage. Your doctor will likely start with a physical exam, followed by imaging tests if required to diagnose your symptoms.
If you experience any of the following red flag symptoms, go to the nearest ER. These symptoms may point to a medical emergency, like cauda equina syndrome or an infection:
- Changes in bowel or bladder function
- Sudden, severe back pain
- Numbness in the inner thighs, buttocks, groin, and genitals
- Fever and chills
- Warmth and swelling at the incision site
Can Failed Spinal Fusion Be Fixed?
Failed spinal fusion can often be fixed with revision surgery. Before the operation, your spinal surgeon can evaluate what went wrong and consider other surgical methods to address your symptoms, including alternatives to spinal fusion. A review published in the Asian Journal of Neurosurgery involving 95 spinal surgeries found that among patients with failed back surgery syndrome, 60% underwent further surgery.
Patients who don’t want to undergo another surgery, or who can’t due to an underlying medical condition, can try non-surgical treatment methods. Epidural steroid injections, physical therapy, and radiofrequency ablation, among other techniques, are non-surgical options for failed spinal fusion.
How Loose Pedicle Screws Are Treated: Revision Surgery
Revision surgery for loose screws after fusion involves removing the loose hardware, cleaning the area, and replacing them with larger or cement-augmented screws. To improve stability and prevent further loosening, your surgeon may use:
- A longer or larger screw
- Cement augmentation, a revision strategy that involves injecting bone cement (like polymethylmethacrylate, PMMA) into fenestrated screws for reinforcement. Fenestrated screws are hollow, allowing cement to be injected into the empty space.
- Bone grafting with a synthetic bone graft or autograft to help anchor the screw
How to Reduce Your Risk of Loose Screws
For a proactive approach to post-fusion hardware issues, consider:
- A bone density screening to check for weak bone tissue in advance
- Adhering to all recommended post-op activity modifications, like avoiding bending, lifting, and twisting (BLT modifications), limits excess stress on the hardware
- Quitting smoking protects your bone health: a PLOS ONE meta-analysis found that smokers are approximately 57% more likely to develop fusion failure than non-smokers.
- Good nutrition supports your body’s ability to recover after fusion. For bone growth, focus on protein, calcium, and vitamins D3 and K2.
Spinal Fusion Alternatives
Spinal fusion alternatives include dynamic stabilization systems, IDET, and stem cell therapy. These advanced treatments promote healing without limiting the motion of the spine.
Stem Cell Therapy
Stem cell therapy is rapidly gaining traction as a non-surgical treatment option for musculoskeletal conditions. With the potential to regenerate damaged tissue, stem cell therapy may offer benefits for degenerative spinal conditions.
During stem cell therapy, stem cells derived from the patient’s blood or a donor are administered directly into the damaged area via injection. Stem cells have the unique ability to self-renew and develop into just about any specialized cell. As a result, stem cells can gradually repair injured tissue in the spine, leading to lasting pain relief in some patients.
Given that stem cell therapy for back pain is a relatively new treatment option, research is still in its early stages. Not all patients have access to an experienced stem cell specialist in their area. However, the initial experiments with rats produced positive results, indicating that stem cells may help heal damaged intervertebral discs.
Intradiscal Electrothermal Coagulation (IDET)
IDET involves inserting a needle into the affected disc area. The physician then threads a catheter through the needle and applies gentle heat to the exterior of the intervertebral disc. This process helps strengthen and thicken the collagen fibers in the disc exterior, potentially offering relief from chronic back pain.
Dynamic Stabilization Systems
Dynamic stabilization systems can replace spinal fusion after spinal decompression surgery. This type of surgical implant stabilizes the spine without permanently limiting its motion. One dynamic stabilization system is the TOPS System for the L3 to L5 vertebrae.
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The TOPS System offers immediate pain relief with the ability to move the spine in all directions. It also reduces the stress on adjacent spinal levels when compared to spinal fusion. As an alternative to lumbar spinal fusion for spinal stenosis and spondylolisthesis, the TOPS System provides motion preservation, ideal decompression, and stability.
Spinal fusion alternatives like the TOPS System may help you avoid re-operation after back surgery. Schedule an appointment with a spine specialist in your area to learn more.
FAQs
How do I know if my spinal fusion screws are loose?
Your screws might be loose if you experience persistent back pain (that doesn’t improve in the weeks or months after surgery), poor mobility, back spasms, nerve symptoms, or crepitus.
Can loose screws be fixed without surgery?
No, loose screws can’t be tightened without surgery. But conservative methods might be sufficient for mild or asymptomatic cases, especially if the patient isn’t a candidate for revision surgery.
How long after spinal fusion can screws loosen?
Screws typically loosen 3 to 6 months after spinal fusion, but can loosen at any point (even years down the line).
Is a loose screw an emergency?
Not usually, unless it occurs with severe nerve symptoms, changes in bowel or bladder control, or infection symptoms. But you should still contact your doctor at the earliest sign of a loose screw, as early intervention leads to better outcomes.
What’s the difference between normal post-surgery pain and loose-screw pain?
Normal post-op pain improves over time and often feels like stiffness or soreness. Loose-screw pain doesn’t improve (or gets worse) over time, often feels sharp, and may occur with other symptoms, like crepitus, tingling, and numbness.