Article
First clinical results of Minimally Invasive Vector Lumbar Interbody Fusion (MIS-VLIF) in spondylodiscitis and concomitant osteoporosis. Development of the K-template to facilitate the use of MIS-VLIF in degenerative lithesis: implants and biomechanical behavior
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Authors
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Witold Polanski
- Universitätsklinik Dresden, Carl-Gustav-Carus Universitätsklinikum an der Technischen Universität Dresden, Dresden, Deutschland
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Hongzhen Jiang
- Dresden, Deutschland
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Daniel Ruess
- Köln, Deutschland
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Clemens Reinshagen
- Boston, United States
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Marek Molcanyi
- Köln, Deutschland
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Jozef Zivcak
- Kosice, Slovakia
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Huaiyu Tong
- Beijing, China
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Gabriele Schackert
- Klinikum Carl Gustav Carus, Klinik und Poliklinik für Neurochirurgie, Carl-Gustav-Carus Universitätsklinikum an der Technischen Universität Dresden, Dresden, Deutschland
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Bernhard Rieger
- Universitätsklinikum Carl Gustav Carus der TU Dresden, Klinik und Poliklinik für Neurochirurgie, Dresden, Deutschland
| Published: | June 9, 2017 |
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Outline
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Objective: Dorsal stabilization is used worldwide since 1970. Although there were advancements in detail, the basic principle of the fixateur interne together with transpedicular screw connection is still in exclusive use, but minimal access spinal technologies promoted a diversification of surgical procedures according the pathology. To benefit seriously ill patients by minimizing the surgical approach, MIS-VLIF was introduced. This technical requirement of combining screws from different directions within a small unilateral approach was solved by the development of a K-shaped template together with screws of special designed multi-axial heads and special thread.
Methods: After informed consent, 11 patients suffering from lumbar spondylodiscitis underwent a single level MIS-VLIF. Pre- and postoperative clinical status was documented using numeric rating scale (NRS) for leg and back pain. In all cases, the optimal height for the cage was preoperatively determined using software-based range of motion and sagittal balance analysis. CT scans were obtained to evaluate correct placement of the construct and to verify fusion after six months. Observing good outcome in weak bony conditions the method should be able to be used in degenerative listhesis, also, therefore a special stabilization system was built and its biomechanical behavior was studied.
Results: Since 2013, 11 seriously ill patients with spondylodiscitis - eight of them with concomitant osteoporosis - underwent MIS-VLIF. Mean surgery time was 159min and average blood loss was less than 400ml. Postoperative CT scans showed correct placement of the implants. Six months follow-up CT-scan showed remaining sagittal balance. All patients had postoperative improvement in clinical scores (NRS back<0.001; NRS leg<0.004). For surgical treatment of listhesis a K-shaped template together with specially designed screws was created with excellent biomechanical behavior.
Conclusion: The load-bearing trajectories (vectors) of MIS-VLIF are different from those of conventional pedicle screw implantation. The dorsally converging construct combines the heads of dorsoventral pedicle screws with laminar pedicle screws following cortical bone structures within a small approach. MIS-VLIF relies on cortical bony structures for all screw vectors and the construct does not depend on conventional coaxial pedicle screws in the presence of inflamed, weak, cancellous or osteoporotic bone. MIS-VLIF allows full 360° lumbar fusion including cage implantation via a small, unilateral dorsal midline approach. At present, MIS VLIF is not suggested in degenerative listhesis, because after required repositioning in listhesis, it is a challenge to combine the screws with only one rod. All efforts must be made to improve this promising surgical procedure and make it fit for common clinical use.
