Long-term clinical and radiological outcomes after total lumbar disc replacement at the lumbosacral junction

The study objective is to analyze long-term clinical and radiological outcomes in patients after performing total lumbar disc replacement at the level of the lumbosacral junction.Materials and methods. A multicenter retrospective observational cohort study was performed. The study included medical records of patients who underwent total lumbar disc replacement at the level of the lumbosacral junction. Both clinical and instrumental parameters were assessed. According to the eligibility criteria, 93 patients were included in the study (38 men, 55 women, mean age 39.9 ± 7.5 years). The average postoperative observation period for the respondents was 33.4 ± 9.5 months.Results. The severity of pain in the lumbar spine on a visual analogue scale significantly decreased (from 7.3 ± 2.5 to 1.9 ± 2.2 cm, p <0.001). The indicators of the quality of life according to the Oswestry Disability Index and according to the Short Form-36 scale (including the mental and physical components) of the studied group of respondents significantly improved (from 43.4 ± 17.6 to 18.9 ± 16.0 %, р <0.001 and from 30.8 ± 8.5 to 52.3 ± 12.4 %, p <0.001, respectively). From the 12th month of observation of the respondents, a significant decrease in the values of the range of motions of the operated segment was noted from 5.3 ± 3.2° to 4.1 ± 3.6° (p <0.009). Also, from the 12th month of postoperative observation, a slight decrease in the values of the range of motions of the adjacent segment from 8.6 ± 4.1° to 7.8 ± 3.8° (p >0.05) was verified. The value of global lumbar lordosis after the installation of a lumbar intervertebral disc prosthesis at the level of the lumbosacral junction significantly increased from 49.1 ± 4.8° to 55.6 ± 5.5° (p <0.001). Intervertebral disc prostheses with a lordotic angle of 10° reliably positively correlate with an increase in the values of segmental lordosis, in contrast to implants with an angle of 6° (rS = 0.86, p = 0.04). The severity of pain in the lumbar spine according to visual analogue scale and the range of motion of the operated segment has a significant negative correlation in the late periods of postoperative follow-up (24 and 36 months, rS = -0.74, p = 0.015).Conclusion. The total lumbar disc replacement technique is an effective method of surgical treatment of patients with degenerative diseases of the intervertebral discs of the lumbosacral spine, including at the level of the lumbosacral junction.

Design, Fabrication, and Testing of Prototype of Total Lumbar Disc Replacement

Total Disc Replacement (TDR) implant is part of the prosthesis to treat degenerative disease by retaining the maneuverability of the disk itself. The TDR implant allows to repair the movement of the spines, absorbs the friction of intervertebral discs, and restore the height of the vertebrae. In this study, we constructed a new model of TDR implant, which is feasible to be mass-produced in Indonesia and performed static test to examine the mechanical properties of the new model. Before starting the prototype production, the finite element simulation is necessary. Simulation using Abaqus 6.14 software show that our design is safe from mechanical failure. The simulation test was performed using the static general model, non linear by considering the plasticity of UHMWPE material. Manufactured using CNC 3 Axis and the prototype was tested with ASTM 2077 standards, using two calibration model on horizontal position and tilted position of 27° to measure the compressive strength and shear strength respectively.