16/11/2018
Indications for lumbar laminectomy can be divided into two groups. The commonest reason is for lumbar canal stenosis; the other is to gain access to other pathologies: epidural abscess, intradural tumour. The former is invariably in patients with degenerative spine disease; in the later often in younger patients who do not have degenerative spine disease i.e. in them the bony anatomy is normal – as we would have expected from anatomy textbooks.
Lumbar laminectomy for spinal canal stenosis
In spinal canal stenosis often multifactorial: ligamentum flavum hypertrophy, facet joint hypertrophy, osteophyte formation, lateral recess narrowing, foraminal narrowing and disc prolapse. These patients undergo lumbar laminectomy. Though this along with removal of ligamentum flavum ‘de-roof’ the spinal canal and, often surgery for other pathologies i.e. lateral recess narrowing or foraminal narrowing also need to be addressed. However, in this synopsis I will just concentrate on lumbar laminectomy.
An easy operation?
Often residents think that lumbar laminectomy is a ‘dumb’ operation and should be easy and they should be able to do it without any problem. This underestimation, makes the slow progress during the operation and the need for help from the senior surgeon to complete it, doubly disappointing.
Lumbar decompression is for degenerative disease is a more challenging operation than one initially estimates. Many seasoned neurosurgeons will contend that it is more difficult than anterior cervical discectomy. This is primarily because the anatomy in lumbar spine is distorted by the degenerative process that invariably attends the spinal canal stenosis. Moreover, those patients with spinal canal stenosis are also likely to have congenital narrower spine.
However, lumbar laminectomy is a very satisfying and rewarding operation.
Imaging
It is well worth studying the night before the operation, the images of lateral lumbar spine (MRI can and the lumbar x-ray) to understand the osteology. Is there any suggestion lumbarization of sacral vertebra or sacralisation of lumbar vertebra? Is there evidence of movement (flexion/extension x-ray). Familiarity with the lumbar spine x-ray a day prior to the surgery, makes it that bit more easier to interpret intra-op lumbar spine x-ray. Whether you could get pre-op lumbar spine x-ray depends on the practice of your consultant.
Positioning
While positioning can feel cumbersome and boring, this is a crucial step for residents to master. If you do this well, often your mentor will get a good impression of you and likely let you do some operating. However, often the consultants are positioning the patient themselves, so residents do not get a chance to learn to position the patient. Getting the position of the patient correctly is very important for the smooth progress of the rest of the operation. Also, when positioning the patient, the surgeon ‘orientates’ the operation in his/her mind. Different consultants have the own preferences for position. Mastering position is an important skill to learn. Not easy as one assumes. Need to get practice. Before going to the theatre, go through the steps of positioning in your mind. Before the patient arrives in the theatre, get to grip with the controls of the operating table.
If you are using an adjustable (be it electronic or manual) surgical table, then it is very important to know how to adjust it; know it intimately so that you can do this even with your eyes closed. You might have to spend time after work playing with the table. Often the table is not intuitive to adjust (not made by Apple) and the controls often do not work. Moreover, no one knows properly how it works to teach you either. But you have to persevere. Once you have mastered this, you would be slick in adjusting the bed. This would give your consultant great confidence in you. Most people judge a book by its cover.
Types of positioning
There are different types of prone positioning for lumbar laminectomy:i) on the Montreal mattress; knee-chest, Wilson frame, etc.
The essence of any position are: i) let abdomen hang freely to prevent increased abdominal pressure causing venous ooze in the operative site ii) put some kyphosis on the lumbar spine – this opens up the interlaminar space iii) arms usually raised forwards
Incision too short
The commonest mistake that is often done by the beginners is to make the incision too short and then struggle during the operation. While assisting your consultants, check how long are the incisions made by your consultant.
Consultants often boast how short their incisions are. It is human nature to underestimate or overestimate to satisfy our aspirations. ‘Measure’ the incision lengths for yourself to ascertain how long the incision your consultant makes. You can measure the length of the incision against an instrument (forceps), which you can later measure up with a tape.
Your incision has to be at least as long as what your consultant usually makes. It might be worth to make it a bit longer when you are starting. Never make it shorter than what your consultant makes. You need the incision long enough to place your retractors and angle your instruments. As you become more experienced, the incision will naturally start to get shorter.
Making the incision
The incision for lumbar laminectomy is usually relatively long. It is better to hold the scalpel like you are hold the bow of a violin. This grip gives you more stability when you make a long liner incision. Use No.10 blade. Cut the skin with the belly of the blade with just enough pressure to go through the skin. One clean cut leads to nice closure and good wound healing.
——— part 2 to follow soon ———
