Introduction: The “medio-latero-superior trajectory (MLST)”, also known as “cortical bone trajectory”, technique is a novel minimally invasive alternative for lumbar spine fixation. We report here our preliminary clinical experience.
Methods: Medical records of patients who underwent spinal instrumentation with “MLST” screw fixation technique from August 2013-February 2014 were retrospectively reviewed. The study was approved by the Institutional Review Board of SUNY Upstate Medical University.
Results: Eleven patients were identified who underwent instrumented fusion using the MLST technique. Four patients underwent instrumented fusion from T11-L3 for unstable fractures of L1 vertebra. The average length of surgery was 207 minutes (range 201-213 minutes) with an average estimated blood loss of 280 cc (range 200-400 cc). Average postoperative hospital stay was 3 days (range 3-4 days). The average postoperative follow-up is 12.5 weeks.
Seven patients who underwent instrumented fusion for degenerative spine disease. The average length of surgery was 310 minutes (range 232-408) with an estimated average blood loss of 400 cc (range 150-700 cc). The average hospital stay was 3 days (range 1-6 days). The average postoperative follow-up is 10 weeks.
No perioperative or postoperative complications were encountered. Follow- up radiological studies reveal stable placement of the surgical hardware in both groups. Preoperative pain scores averaged 6/10 (range 3-10) and postoperative pain at time of most recent follow-up (range 4-16 weeks) averaged 2/10 (range 0-7) with four patients reporting to be pain free.
Conclusions: The MLST technique of cortical screw insertion is a viable alternative to the ‘standard’ pedicle screws placement. It does offer the advantages of less invasive procedures such as smaller incision, less muscle dissection and retraction, lower peri-operative blood loss, improved postoperative recovery and shorter hospital stay. Biomechanical studies comparing the cortical screws with the ‘standard’ pedicle screws suggest equivalent stability and possible better pull out resistance.
Patient Care: Provide the less invasive alternative option for spinal instrumentation
Learning Objectives: Sharing the clinical experience with the less invasive technique of pedicle screw trajectory.
Technical nuances with the surgical technique will be discussed.
References: 1. Grossbach AJ, Dahdaleh NS, Abel TJ, Woods GD, Dlouhy BJ, Hitchon PW: Flexion-distraction injuries of the thoracolumbar spine: open fusion versus percutaneous pedicle screw fixation. Neurosurg Focus 35:E2, 2013
2. Inceoglu S, Montgomery WH Jr, St Clair S, McLain RF: Pedicle screw insertion angle and pullout strength: comparison of 2 proposed strategies. J Neurosurg Spine 14:670–676, 2011
3. Matsukawa K, Yato Y, Kato T, Imabayashi H, Asazuma T, Nemoto K: In vivo analysis of insertional torque during pedicle screwing using cortical bone trajectory technique. Spine 39:E240–245, 2014
4. Mobbs RJ: The “medio-latero-superior trajectory technique”: an alternative cortical trajectory for pedicle fixation. Orthop Surg 5:56–59, 2013
5. Perez-Orribo L, Kalb S, Reyes PM, Chang SW, Crawford NR: Biomechanics of lumbar cortical screw-rod fixation versus pedicle screw-rod fixation with and without interbody support. Spine 38:635–641, 2013
6. Santoni BG, Hynes RA, McGilvray KC, Rodriguez-Canessa G, Lyons AS, Henson MAW, et al.: Cortical bone trajectory for lumbar pedicle screws. Spine J Off J North Am Spine Soc 9:366–373, 2009
7. Wang H, Li C, Zhou Y, Zhang Z, Wang J, Chu T: Percutaneous pedicle screw fixation through the pedicle of fractured vertebra in the treatment of type A thoracolumbar fractures using Sextant system: an analysis of 38 cases. Chin J Traumatol Zhonghua Chuang Shang Za Zhi Chin Med Assoc 13:137–145, 2010