What is Fusion?

Spinal fusion is a surgery that aims to eliminate painful motion between two (or more) vertebrae by helping them grow into one solid piece of bone. Think of it like bracing a broken branch so the tree can heal—except in your spine, your own bone cells do the healing. Plates, screws, rods, cages, and other hardware aren’t the “fusion” itself; they’re scaffolding that holds things steady so your body can make new bone across the intended bridge.

“Minor” vs “major” surgery—my take

People often label surgeries as “minor” or “major.” Personally, any surgery on someone I care about (my family, friends, or patients) is major, because the stakes are personal. There are real short- and long-term consequences to any operation—especially when we alter spinal mechanics.

Why mechanics matter: long lever arms & adjacent segment stress

By stopping motion at one level, we shift mechanical stress to the levels above and below. Over time, the extra workload can accelerate wear—called adjacent segment degeneration/disease (ASD)—and in some cases lead to symptoms that need additional treatment or even another surgery. Reported rates vary by technique, alignment, and follow-up:

• Radiographic adjacent segment degeneration after lumbar fusion is commonly reported in the 20–40% range over time; the proportion needing revision surgery is lower, 7–20% over two to five+ years, depending on which study you reference.

The #1 complication patients don’t hear enough about: pseudarthrosis

Pseudarthrosis (nonunion) is when the fusion doesn’t fully take—meaning persistent micro-motion remains at the intended fusion site. It’s a leading cause of ongoing pain and one driver of “failed back surgery syndrome,” sometimes requiring revision surgery. Modern studies highlight key risk factors:

• More levels fused → higher risk of nonunion. Number of levels is a consistent predictor.

• Smoking, older age, diabetes, poor metabolic health, osteoporosis, and suboptimal alignment each increase risk.

One level vs. two vs. multi-level: does risk change?

Yes. As you add levels, fusion becomes more biologically and mechanically demanding:

• Reviews and outcomes studies show multilevel fusions have more complications and less pain improvement on average than single-level procedures, and they carry higher nonunion risk.

• In the neck, contemporary cervical fusion data suggest 2-level procedures tend to fuse faster/more reliably than 3-level constructs, reinforcing the “more levels = more challenge” principle.

Bottom line: the biology of bone healing plus the biomechanics of the construct drive success. Hardware helps you hold still so your body can do the fusing—but the fusion is your bone, not the metal.

When do I refer for fusion?

At Osso Health, surgery is never the first step. We build a strong foundation first: precise diagnosis, image review, targeted injections when appropriate, and progressive rehab. When I recommend surgical consultation, it’s typically because:

• Conservative care has been exhausted and the pattern of pain correlates with a surgically correctable problem.

• There is progressive neurologic deficit, worsening weakness, and the goal is to arrest nerve injury and prevent long-term disability.

• The patient is medically optimized and likely to heal - non-smoker, diabetes under control, bone health addressed.

Conversely, isolated axial low back pain without leg symptoms is rarely a good indication for fusion by itself.

Who may not be a good candidate?

Patients with poorly controlled diabetes, active smoking or nicotine use, severe osteoporosis, or significant wound-healing risks have higher complication and nonunion rates. Addressing these before surgery improves outcomes.

What about famous cases?

High-profile athletes, like Tiger Woods, illustrate a real-world pattern: multiple spine surgeries over time, sometimes culminating in fusion and later additonal surgery at adjacent segments. His most recent updates include additional lumbar surgery in October 2025. Every case is unique, but the arc highlights how spinal mechanics and biology play out over years.

How we lower risks at Osso Health

• Precision diagnosis by history, exam, imaging and diagnostic blocks; to fuse only when the pain generator is clear.

• Musculoskeletal and metabolic optimization - bone health, nutrition, diabetes control, nicotine cessation.

• Alignment-aware planning with our surgical partners to minimize undue stress on adjacent levels. Malalignment is a known risk.

• Shared decision-making: realistic expectations about recovery timelines and the possibility of further procedures down the line.

References

• Boonsirikamchai W, et al. Pseudarthrosis risk factors in lumbar fusion. 2024. Identified age, smoking, and number of levels among key predictors.

• Shahzad H, et al. Predictive factors of symptomatic lumbar pseudarthrosis. 2023–2024. ~2.7% symptomatic pseudarthrosis at 10 years; risk rises with more fused vertebrae.

• Steinmetz MP, et al. Adverse impact of diabetes on spine fusion and patient outcomes. Higher nonunion and worse outcomes in diabetes. Spine J 2025.

• Loggia G, et al. Impact of alignment on ASD after lumbar fusion. Estimated ~2.4%/year surgically relevant ASD after L4–S1; alignment matters. Spine J 2025.

• Soh J, et al. Temporal patterns of ASD risk factors. Reported 19.4–40% radiographic degeneration; lower rates for revision surgery. J Clin Med 2025.

• Okuda S, et al. ASD after PLIF. Overall 9% ASD, mean 4.7 years to onset; subsequent ASD episodes possible. 2018.

• Harada GK, et al. Multilevel fusions show more complications and less pain improvement vs single-level. 2021.

• Nouh MR, et al. Instrumentation basics: hardware stabilizes; bone makes the fusion. 2012 (core principle, still valid).

The Osso Health perspective

Spinal fusion can be life-changing for the right problem, in the right patient, with meticulous planning and post-op rehabillitation. It’s not a cure-all for back pain, and it’s not “just hardware.” If you’re considering fusion—or you’ve had fusion and still hurt—get a comprehensive evaluation with someone who lives in the details of spinal mechanics and healing biology.

Questions about whether fusion is right for you? We’ll review your imaging, examine you, and walk through all options—from targeted injections and structured exercise system to surgical second opinions—so you can make an informed decision aligned with your goals.