Abstract
Evaluation of the initial stability of implants is essential to reduce the number of implant failures of pedicle screws after orthopedic surgeries. Laser resonance frequency analysis (L-RFA) has been recently proposed as a viable diagnostic scheme in this regard. In a previous study, L-RFA was used to demonstrate the diagnosis of implant stability of monoaxial screws with a fixed head. However, polyaxial screws with movable heads are also frequently used in practice. In this paper, we clarify the characteristics of the laser-induced vibrational spectra of polyaxial screws which are required for making L-RFA diagnoses of implant stability. In addition, a novel analysis scheme of a vibrational spectrum using L-RFA based on machine learning is demonstrated and proposed. The proposed machine learning-based diagnosis method demonstrates a highly accurate prediction of implant stability (peak torque) for polyaxial pedicle screws. This achievement will contribute an important analytical method for implant stability diagnosis using L-RFA for implants with moving parts and shapes used in various clinical situations.
Highlights
With an aging population, the surgical use of orthopedic implants, such as pedicle screws [1,2] and acetabular cups, has increased
Effecthead on of thethe spectrum can be attributed to three skew tilt.the. These results show that theThis movable polyaxial pedicle screwpedicle affects factors: first, tilt direction influences the center of gravity of the polyaxial screw factors: first, the tilt direction influences center ofspectrum gravity of the the laser-induced vibration spectrum
We evaluated a polyaxial pedicle screw using Laser resonance frequency analysis (L-RFA) to reveal the influence of the movable head part on the vibration spectrum
Summary
The surgical use of orthopedic implants, such as pedicle screws [1,2] and acetabular cups, has increased. 12% [3] and a reported reoperation rate of 40% [4]. In this regard, evaluation of the initial fixation of the implant (implant stability) as a factor that contributes to loosening of screws is essential to prevent implant failure [5,6]. Evaluation of the initial fixation of the implant (implant stability) as a factor that contributes to loosening of screws is essential to prevent implant failure [5,6] Parameters such as the pull-out force [7] and insertion torque [5,8] are used to evaluate implant stability. Insertion torque can be measured clinically, but only once at the time of insertion, and is affected by subjective factors attributable to each surgeon, such as the speed of insertion and the amount of force applied in the direction of insertion
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