Improved lag screw positioning in the treatment of proximal femur fractures using a novel computer assisted surgery method: a cadaveric studyReportar como inadecuado

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BMC Musculoskeletal Disorders

, 15:189

Orthopedics and biomechanics


BackgroundThe importance of the tip-apex distance TAD to predict the cut-out risk of fixed angle hip implants has been widely discussed in the scientific literature. Intra-operative determination of TAD is difficult and can be hampered by image quality, body habitus, and image projection. The purpose of this paper is to evaluate, through a cadaveric study, a novel computer assisted surgery system ADAPT, which is intended for intraoperative optimisation of lag screw positioning during antegrade femoral nailing. A 3D measure for optimal lag screw position, the tip-to-head-surface distance TSD, is introduced.

Methods45 intra-medullary hip screw procedures were performed by experienced and less experienced surgeons in a cadaveric test series: in 23 surgeries the ADAPT system was used, and in 22 it was not used. The position of the lag screw within the femoral head and neck was evaluated using post-operative CT scans. TAD, TSD, fluoroscopy as well as procedure time and variability were assessed.

ResultsThe use of the ADAPT system increased accuracy in TSD values i.e. smaller variability around the target value for both groups of surgeons interquartile range IQR of experienced surgeons: 4.10 mm Conventional vs. 1.35 mm ADAPT p = 0.004-IQR of less experienced surgeons: 3.60 mm Conventional vs. 0.85 mm ADAPT p = 0.002. The accuracy gain in TAD values did not prove to be significant in the grouped analysis p = 0.269 for experienced surgeons; p = 0.066 for less experienced surgeons; however, the overall analysis showed a significant increase in accuracy IQR: 4.50 mm Conventional vs. 2.00 mm ADAPT p = 0.042. The fluoroscopy time was significantly decreased by the use of the ADAPT system with a median value of 29.00 seconds Conventional vs. 17.00 seconds ADAPT for the less experienced surgeons p = 0.046. There was no statistically significant impact on the procedure time p = 0.739.

ConclusionsThe ADAPT system improved the position of the lag screw within the femoral head, regardless of the surgeon’s level of clinical experience, and at the same time decreased overall fluoroscopy usage. These positive effects are achieved without increasing procedure time.

KeywordsComputer assisted surgery Lag screw placement Proximal femur fractures Hip fractures Cut-out Surgical technique Electronic supplementary materialThe online version of this article doi:10.1186-1471-2474-15-189 contains supplementary material, which is available to authorized users.

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Autor: Matthias Regling - Arno Blau - Robert A Probe - James W Maxey - Brian D Solberg


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