2023, Number 2
Analysis and electronic monitoring of the stability of the lumbar spine, after surgery with and without transpedicular instrumentation. Experimental model
Jiménez ÁJM, Salcido RMV, Méndez LF, Muleiro EP, Granados PI
Full text
10.35366/111628
Language: Spanish
References: 24
Page: 69-75
PDF size: 307.61 Kb.
ABSTRACT
Introduction: the spine must reconcile two imperative mechanisms, to a certain extent contradictory, which are "rigidity and flexibility", in order to maintain balance and equilibrium, based on a principle of "stability", any mechanism that alters this process, can generate a pathological entity characterized by "instability", which is defined as the loss of the spine's capacity (under physiological loads) to maintain relations between the vertebrae in such a way that there is no damage, no irritation of the spinal cord or nerve roots, and no painful deformity. Objective: to describe the biomechanical behavior of the lumbar spine after spinal surgery with and without transpedicular instrumentation in an experimental electronic model. Material and methods: LabView SignalExpress software system, strain gauge sensors, conditioner card, central processing unit (CPU), model for experimentation and specimen placement, porcine column segments T6-L5, transpedicular instrumentation system, surgical equipment and material. After preparation of the sensors (strain gauge) on a rigid mica (7 × 30 mm) with application of cyanoacrylate glue, anatomical dissection is performed in the lumbar segments of the porcine spine (fresh, segment T6-L5), placing in the L1-L2 segment, sensors in the anterior longitudinal ligament (ALL), interspinous ligament (IEL), supraspinous ligament (SEL), which in turn is placed in the model for experimentation, subjecting an axial load of 10 kg. Measurements are performed as basal origin without any surgical procedure, starting measurements with movement sessions, which have the same range and amplitude, 0° for resting position with 10 kg load, 30° flexion, 20° in extension of the lumbar area, maximum axial compression before fatigue at 0°. Once the data had been stored, the same procedures were performed, always adding the following procedure (foraminectomy, discoidectomy, hemilaminectomy, laminectomy and transpedicular instrumentation at the first level in the same segment). Results: baseline measurements showed an amplitude of 0.3 volts, with the left-sided foramen the level of instability manifested with sensor voltage amplitude at 0.8 volts with positive voltage variations. When proceeding with discectomy, an amplitude variation of 2.0 volts is found, with negative voltage variations. Hemilaminectomy increases to an amplitude of 3.0 volts. With laminectomy it increases further to 3.8 volts, in addition to a marked clinical instability during the experiments. When transpedicular instrumentation is applied, the sensor shows a correction of the instability by switching to a signal pattern with an amplitude of 0.5 positive volts which shows a correction of the instability, but at the same time the voltage value of the sensors shows a shift in the voltage level indicating that the joint is in a rigid, forced position and different from those obtained in the basal measurements. Conclusions: the results obtained are translated into a biomechanical map, which allows an objective analysis of how the spine behaves in different decompressive situations that generate instability. In the experimental model, each decompressive surgical procedure can destabilize 15 to 20% and even with rigid instrumentation in a segment through the posterior approach, complete stability cannot be recovered, since 5% is lost due to the bone and ligament material removed.REFERENCES