The Second Opinion Nobody Orders

Before a spinal fusion. Before a series of epidural injections. Before a long term pain management plan. There is a question most patients are not asked and most providers do not think to offer.

Has anyone assessed how this spine is actually moving?

Imaging tells a structural story. It shows what has degenerated, where compression exists, what the bones are doing. For surgical and procedural planning, that information is essential. But imaging does not show load patterns, segmental motion, or the mechanical environment that has been driving the breakdown. That part of the picture is available. It just requires a different kind of assessment to capture it.

What a Biomechanical Evaluation Adds

A full biomechanical evaluation starts with the whole spine, not the region of complaint. Every spine has fixed structural reference points in the pelvis and the base of the neck that define what the ideal curves should look like for that individual. Those do not change. What does change is how far the spine has drifted from that architecture, and how the body has compensated around that drift.

Full-spine X-rays with specific measurements map that drift. They show not just where the problem is visible but how forces are distributed across the entire system. The segment that hurts is not always the segment driving the most stress. Often the mechanical load originates elsewhere in the chain and transfers to the area that eventually breaks down.

Motion X-rays add the dynamic layer. Taken as the patient bends forward and backward or captured as real time video, they show which segments are moving correctly, which have lost motion, and which are moving too much. They evaluate the ligaments under load in a way that static imaging cannot.

That information changes the picture.

The Case for Getting This Before Irreversible Steps

Surgery is sometimes the right answer. Pain management procedures are sometimes the right answer. The goal is not to avoid those options but to make sure the decision to pursue them is based on the most complete information available.

When the mechanical driver of a problem is identified before a procedure, the procedure can be aimed precisely. When it is not, procedures address what imaging shows without accounting for what imaging misses. Sometimes they still work. Sometimes they do not, and the reason they do not is that the mechanical forces driving the problem were never identified or addressed.

In cases like that, the missing piece was not a better technique. It was knowing where to look. A biomechanical evaluation done earlier in the process could have provided that direction before multiple procedures had already been attempted.

Who Should Consider This

If you are being told surgery is the next step, a biomechanical evaluation before that decision is reasonable and worth requesting.

If you have had procedures that provided partial or temporary relief, a full mechanical assessment of what is still driving the problem is a logical step before another round of the same approach.

If you have imaging findings and a diagnosis but treatment has not produced the results it should, the mechanical picture deserves attention.

Spine care works best when the team has the most complete information available. A biomechanical assessment is part of that information. Getting it before major decisions are made is not a delay in your care. It is how you make sure your care is aimed at the right target.

What the Evidence Says About Pre-Surgical Biomechanical Assessment

The decision to perform spinal fusion is irreversible. Unlike most medical interventions, it cannot be undone if it fails to produce the expected outcome. Despite this, the pre-surgical evaluation for most fusion candidates focuses on the structural abnormality identified on imaging — the herniated disc, the stenotic level, the degenerative segment — without a systematic assessment of whether the mechanical drivers of the patient’s symptoms have been identified and addressed. This is a gap in the standard of care that the literature has been documenting for decades.

Glassman and colleagues (2005) published outcome data from the Spinal Deformity Study Group demonstrating that positive sagittal balance — the forward shift of the spine’s center of gravity relative to the pelvis — is the single strongest predictor of poor outcomes following spinal surgery in adult patients. Patients with uncorrected positive sagittal imbalance at the time of surgery had significantly higher pain scores and worse functional outcomes at two years than those with neutral or negative balance.¹ This means that a patient whose surgery corrects the structural lesion but leaves the sagittal alignment uncorrected is being set up for a poor outcome before they leave the operating table.

Schwab and colleagues (2012) established specific radiographic thresholds for sagittal alignment parameters — pelvic incidence minus lumbar lordosis mismatch, pelvic tilt, and sagittal vertical axis — that correlate with disability scores and health-related quality of life measures. Their work, published in Spine, provides surgeons with quantitative targets for alignment correction, but it also implies that any pre-surgical evaluation that does not include these measurements is incomplete.² A chiropractor with fellowship training in spinal biomechanics can perform this evaluation, identify the mechanical drivers, and either resolve them through conservative care or provide the surgical team with the specific alignment data they need to plan the operation correctly.

References

1. Glassman SD, Bridwell K, Dimar JR, Horton W, Berven S, Schwab F. The impact of positive sagittal balance in adult spinal deformity. Spine. 2005;30(18):2024-2029.
2. Schwab F, Ungar B, Blondel B, et al. Scoliosis Research Society-Schwab adult spinal deformity classification: a validation study. Spine. 2012;37(12):1077-1082.
3. Hilibrand AS, Robbins M. Adjacent segment degeneration and adjacent segment disease: the consequences of spinal fusion? Spine J. 2004;4(6 Suppl):190S-194S.
4. Mummaneni PV, Shaffrey CI, Lenke LG, et al. The minimally invasive spinal deformity surgery algorithm: a reproducible rational framework for decision making in minimally invasive spinal deformity surgery. Neurosurg Focus. 2014;36(5):E6.