Abstract

IntroductionOpen transforaminal lumbar interbody fusion (TLIF) has been performed for many years with good results. However, one of the drawbacks of Open TLIF is the extensive soft tissue dissection that is necessary to expose the anatomic landmarks for pedicle screw insertion, to achieve a proper lateral-to-medial screw trajectory and for resection of the facet complex. The significant iatrogenic muscle and soft tissue injury that occurs during the surgical approach can result in increased postoperative pain, lengthened recovery time, and impaired spinal function. Minimally invasive techniques for transforaminal lumbar interbody fusion (MISTLIF) have recently been introduced with the aim of smaller wounds, less tissue trauma and faster recovery. TechniqueFluoroscopy is used to determine the operative level. A parasagittal incision is made lateral to the midline and sequential soft-tissue dilators are then inserted through the incision to dilate the muscles and expose the spine. Using the tubular retractor, lumbar decompression, discectomy and interbody graft placement is performed. The pedicle screws are inserted percutaneously. Under fluoroscopic guidance, a needle is inserted into the pedicle percutaneously. A K-wire is then passed through the needle to serve as a guide for the screw placement. The needle is then removed and using cannulated instruments, the pedicle screw is passed over the K-wire into the pedicle. As the screws are placed percutaneously, the wound is smaller than open surgery. Indications/ContraindicationsIndications for surgery include spondylolisthesis and degenerate discs presenting with mechanical low back pain and radicular symptoms. Relative contraindications for MIS include patients with severely collapsed disc space which does not move on flexion/extension and revision/repeat surgery. ComplicationsComplications of MIS are similar to Open TLIF and include bleeding, infection, nerve root injury, cerebrospinal fluid leak, deep vein thrombosis, pseudoarthrosis and implant failure. However, MISTLIF is more technically challenging as most of the surgery requires working in a limited space. Clinical outcomesClinical and Radiological Outcomes Of Minimally Invasive Versus Open Transforaminal Lumbar Interbody Fusion: 29 MIS TLIF were matched paired with 29 Open TLIF at our institution (Singapore General Hospital). Intra-operatively, MIS has less blood loss but longer duration of operation and fluoroscopic time. Postoperatively, MIS has faster recovery, shorter hospitalization and less analgesia use. There was significant improvement in NASS, ODI, SF-36 and VAS scores at 6 months and 2 years postoperatively for both. However, there was no significant difference in clinical outcomes for MIS vs Open TLIF at 6 months and 2 years. 80% of MIS and 86.7% of Open TLIF levels achieved Bridwell Grade 1 fusion. ConclusionMIS TLIF is a safe and efficacious technique. It is associated with less tissue trauma, smaller wounds, less initial postoperative pain, faster recovery and shorter hospitalization. It has similar long term clinical outcomes and fusion rates as OPEN TLIF.