Two Years Experiences with a New Titanium-Coated Radiolucent TLIF Carbon-PEEK Cage

Abstract

Introduction PLIF and TLIF are standard treatment methods for many degenerative spinal diseases that result in spinal stenosis or segmental instability. The cage-bone surface has a role in facilitating osteointegration. A significant quality and quantity increase of bone on growth was achieved with the titanium (Ti) coating by vacuum plasma spraying (VPS). This study aimed to evaluate the short-term radiological and clinical results of the carbon fiber-reinforced PEEK (carbon/PEEK) interbody fusion cage, coated with VPS-Ti. Patients and Methods A total of 42 Patients (47 levels), mean age 59.6, receiving cage treatment were scanned retrospectively. Pre-, postoperative, and final follow-up graphs, and clinical information were obtained. Primary diagnoses were degenerative spinal diseases. Pedicle screws were used in all cases. TLIF and PLIF technique was applied in 28 and 72% of patients. Around 51% were L4–5, 23% L5–S1, 17% L3–4, and 9% L2–3. Local graft was used in 39 patients, DBM in 2 patients, and BCT in 1 patient. The following were measured/evaluated: (1) Segmental lumbar lordosis; (2) Radiological fusion according to the IBF grading system of Bridwell; (3) Early degeneration in neighboring disks; (4) Foraminal and segmental height and loss of disc height using the Mochida index; (5) Pedicle screws' loosening. Results A mean change of 1.38 degrees was observed in the angle of neighboring segment lordosis, and an increase of 0.59 degrees was obtained in the global lumbar lordosis. Grade 1 fusion (according to the four-point Bridwell classification) was achieved in 94% of all patients 18 months after the operation (6% grade 2, 0% grades 3 and 4). Two (4.3%) patients underwent operation due to neighboring segment degeneration during the follow-up period. Progression of degeneration in the neighboring segment discs increased by 10.95% between preoperative and final follow-up graphs. In two patients, a pedicle screw loosening angle of 2 degrees and/or above was observed, no reintervention was needed. In the final follow-up at 24 months, the segmental height and foraminal height Mochida index were 5.8 and 3.82, as compared with the early postoperative graph. Around 87% of the patients had good or perfect results. Discussion Solid fusion was achieved in all but one patient after 2 years, the complication rate was low. Limitations of the study include its predominantly radiological structure, the lack of control group, and the relatively short follow-up of 2 years that may explain the relatively low number of patients who underwent a secondary operation due to neighboring segment degeneration. PEEK and carbon/PEEK increases the formation of surrounding fibrous tissue because of the hydrophobic surface structure. Therefore, carbon/PEEK was coated with VPS Ti, facilitating osteointegration while remaining its radiolucent properties. The first VPS Ti-coated cage proved to be clinically successful and is commonly accepted as a suitable geometrical shape. These findings must be supported with long-term results.