On the Discipline of Smaller Incisions

A patient's first question on the day after surgery is rarely about the angled instrument that reached behind the lamina, or the precise plane of dissection that spared the descending nerve root. It is, more often, about the bandage—whether the incision is small, whether the recovery will be quick. That question is reasonable, and over the years it has reshaped the way we operate. Yet I think it is worth asking, as someone who works in this field daily, what we are really claiming when we say “minimally invasive.”

The phrase has become so familiar that it threatens to lose its meaning. In the spine surgery literature of the past two decades, “minimally invasive” has been applied to procedures as different as a percutaneous discectomy and a tubular-retractor interbody fusion; it has covered approaches that share little but a common marketing instinct. Patients hear the term and infer a quieter recovery, a smaller scar, a procedure of unambiguous benefit. The truth, as is usually the case in surgery, is more careful.

I trained, as most of my generation did, in the era when the microscope was the standard tool for spinal decompression. The view through the operating microscope is excellent: depth of field, magnification, illumination—all of these conspire to give the surgeon a sense of confident control. When I began working with the biportal endoscopic technique, the optics were different. The image is bright and magnified, but it arrives on a screen rather than through eyepieces, and the working corridor is narrower. The first cases ask more of the operator's hands, and more of the surgeon's tolerance for the discomfort of new motor patterns. There is, in the early phase, a real possibility of operating worse than one did before. This is rarely emphasized in the marketing of the technique, but it is the central honest fact of its adoption.

In our recent comparative study of uniportal and biportal endoscopic transforaminal lumbar interbody fusion in the early learning stage (Kim JY, Hong HJ, et al. JMISST. January 2024), my colleagues and I documented something that practicing surgeons already know but that the comparative literature has been slow to acknowledge: technical refinement during the learning curve is neither linear nor symmetric across approaches. Outcomes that are stable in experienced hands behave differently when the same procedures are performed by surgeons in transition. This has implications for how new techniques should be evaluated and for how they should be taught.

Our systematic review of biportal endoscopic decompressive surgery for lumbar stenosis (Heo DH, Park DY, Hong HJ, et al. World Neurosurgery. 2022) attempted to organize what is known about the indications, contraindications, and complications of the approach. The review is clarifying not because it announces a uniformly favorable verdict, but because it confines the technique to those situations in which the evidence supports its use. Central, lateral recess, and foraminal stenoses fall within its current indications. High-grade spondylolisthesis, severe scoliosis, infection, and tumor do not. The discipline of smaller incisions is, in part, the discipline of not overreaching.

I find it useful, in clinical practice, to separate two questions that the phrase “minimally invasive” tends to conflate. The first is whether the incision is small. The second is whether the operation is biologically and mechanically conservative—whether it preserves muscle, ligament, and bone that the patient will continue to need. These questions are related but not identical. An open midline laminectomy can be performed with restraint; a tubular procedure can be performed aggressively. The relevant measure is not the length of the skin closure but the integrity of what lies beneath it.

The biportal endoscopic approach has, in my experience, given me a useful tool for preserving the posterior musculoligamentous complex while still permitting wide visualization of the dural sac and exiting nerve roots. It is not a substitute for clinical judgment, and it is not a procedure I would offer in every case. The patients in whom I think it serves them best are those whose pathology fits its corridor: discrete decompressive needs without significant deformity, anatomy that is not severely altered by prior surgery, and a clinical situation in which faster recovery genuinely matters.

The cases that I think serve them less well are those in which the temptation to apply a familiar tool obscures the more difficult question of whether an alternative would be more appropriate. A reconstructive problem requires reconstructive thinking, whatever the corridor. An advanced deformity is not a candidate for a procedure designed for a different anatomical situation. These are obvious points when stated plainly, but they are not always observed in practice.

It seems to me, then, that the conversation about minimally invasive spine surgery would be improved by a shift in vocabulary. The relevant virtue is not size but discipline: the discipline of patient selection, the discipline of honest reckoning with the learning curve, the discipline of acknowledging that an approach is a tool rather than an identity. Smaller incisions are valuable insofar as they reflect this discipline. They are misleading insofar as they substitute for it.

I do not think the question my patients ask the day after surgery is the wrong question. They are right to ask about recovery, and the trend toward less invasive technique has, on balance, served them. But I think we owe them a more careful answer than the one the phrase has come to permit. The bandage is small. The work behind it should be the more interesting subject of conversation.