Minimally Invasive Spine Surgery

"Minimally invasive spine surgery", or MIS, is not a single operation but an umbrella term for a whole spectrum of techniques that aim to achieve the same goal as traditional open surgery while disturbing far less of the body to get there. The unifying idea is to reach the spine through the smallest reasonable opening, splitting and preserving muscle rather than cutting and stripping it, so that people recover faster and more comfortably.

An important point that surprises many patients is that minimally invasive does not automatically mean endoscopic. Endoscopy — operating through a tube with a camera passed to the spine — sits at the "ultra-minimally invasive" end of the spectrum. But much minimally invasive surgery uses no endoscope at all. A very common approach uses tubular retractors: a set of tubes (dilators) of increasing size is passed through the muscle to gently split it apart, and a final working tube — often around 18, 22 or 26 millimetres across — holds that channel open while the surgeon operates through it, usually with a microscope or loupes and standard instruments. No muscle is cut; the fibres are simply parted. Other minimally invasive methods include microscope-assisted "mini-open" surgery and percutaneous (through-the-skin) screw placement for fusions.

So MIS is best thought of as a ladder. At one end is traditional open surgery. Then mini-open and microsurgery. Then tubular, muscle-splitting approaches. Then microendoscopic and biportal endoscopic techniques. And at the far, least invasive end, full single-portal endoscopy through a tube the width of a pen. The right rung of the ladder is chosen to match the problem, its complexity and location, and the individual patient.

• People who need surgery for a disc problem, stenosis or a fusion and want the least disruptive approach appropriate to their problem
• People in whom preserving muscle and reducing blood loss and recovery time is particularly valuable
• People for whom a specific technique on the MIS spectrum — tubular, microendoscopic, biportal or full endoscopic — best fits the exact problem
• The choice of where on the spectrum to operate is always made individually by the specialist

• The common principle across all minimally invasive techniques is muscle preservation. Rather than a long incision and stripping muscle off the bone, the surgeon uses sequential dilators to split the muscle fibres and create a narrow corridor to the spine. In a tubular approach, a working tube of a chosen diameter is then locked in place and the surgeon operates down it with a microscope and standard instruments. In endoscopic approaches, a camera is passed down the tube (one portal in full endoscopy, or two portals in biportal endoscopy) so the surgeon works from a screen. Percutaneous techniques place screws for a fusion through tiny stab incisions using X-ray or navigation guidance, again sparing the muscle. In every case the aim is the same: do the necessary work on the nerves, disc or bone while disturbing as little else as possible.

• Muscle split and preserved rather than cut, protecting the spine's natural support
• Smaller incisions, less blood loss and less post-operative pain than equivalent open surgery
• Shorter hospital stays and faster return to normal activity
• Lower infection and wound-healing problems given the smaller wounds
• A flexible spectrum, so the least invasive technique that will safely do the job can be selected
• Often possible as day-case or short-stay surgery, depending on the procedure

• Standard surgical risks still apply — infection, bleeding, dural tear, nerve irritation, and a small risk of nerve injury
• "Minimally invasive" describes the access, not a guarantee of a smaller problem — the underlying procedure and its risks still matter
• Working through a narrow corridor is technically demanding and each technique has a learning curve
• Not every problem is suited to the least invasive end of the spectrum; complex or unstable problems may need a more open approach
• The best results come from matching the technique to the problem rather than using the smallest possible approach in every case

• Non-surgical care where appropriate — physiotherapy, injections, time
• Traditional open surgery, where the problem requires it
• Any specific point on the MIS spectrum: tubular decompression, microdiscectomy, biportal endoscopy or full endoscopy

Recovery depends on both the technique and the underlying procedure, but across the board minimally invasive approaches tend to mean less pain, less blood loss, shorter stays and a quicker return to normal life than the open equivalent. The further towards the endoscopic end of the spectrum, the gentler the access tends to be. The important thing is that the outcome for the underlying problem is not compromised — the goal is to achieve the same surgical result through a smaller, kinder route. Your specialist will explain which approach suits your problem and what recovery to expect.

• —NICE — Low Back Pain and Sciatica in Over 16s (NG59)
• —British Association of Spine Surgeons (BASS)
• —Royal College of Radiologists — iRefer: Making the Best Use of Clinical Radiology

This information is for general patient education and is not a substitute for an individual consultation. Always seek personalised advice from a qualified spinal specialist.