Micro-Lumbar Diskectomy (MLD)
Neurosurgeons have used a binocular microscope for brain surgery since the 1960’s. In 1978 I began to use it for disk surgery after hearing about successful use of microsurgery by a colleague in Las Vegas. He had to operate on showgirls who wanted to avoid a large incision so he adapted some small instruments and successfully treated their HNPs using the microscope. When I adopted this technique, patients were leaving the hospital in one or two days. Several of them awoke from surgery with less pain than before going to sleep.
MLD is made safer by the better visibility, but use of the microscope increases the risk of infection slightly, despite it being covered with sterile clear plastic drape. After we learned to be more careful handling the “scope” and began to give an antibiotic before beginning, the infection rate fell to almost nothing. We also now inject a long-acting local anesthetic (Marcaine with epinephrine) before closing to reduce post-operative pain. The technique and outcomes are described in detail in my publications (refs. 38, 6, 9). In the last years of my practice HNP patients got MLD operations as outpatients in a surgery center.
Minimal Exposure Tubular Retractor (METRx)
Minimally invasive exposure here is through a tube inserted around a series of dilators put through the paraspinal muscles, down to the lamina. The operation is otherwise the same as the MLD described above. I have found this device to have no advantage over MLD and several drawbacks. The muscle is disrupted, not retracted and allowed to fall back into place as in MLD. That results in more postoperative back pain compared to MLD, according to a Cochrane Database Syst Review in 2014. The tube also limits exposure and visibility in locating all the fragments of HNP, probably the reason the above review found more leg pain after surgery compared to MLD.