Experimental studies of the amount of deflection of the plate for the correction of the funnel-shaped deformation of the chest under the influence of bending load

Abstract

One of the leading methods of reconstruction of the funnel-shaped deformity of the chest is nonresection thoracoplasty, or Nuss surgery. For its implementation, implanted systems consisting of one or two corrective plates are used. The technique is minimally invasive, does not require large incisions and resection of ribs. But there are complications related to the insufficient strength of bone tissue, which according to the literature is defined in a very wide range. Purpose - to determine the dependence of the amount of deflection of single and double plates for the correction of sternum deformity on the amount of bending load; to develop a method of determining the corrective load that the plate exerts on bone structures during correction. Materials and methods. Experimental studies of plates for correction of sternum deformities were performed. We used 6 plates. In the first part of the experiment, each plate was tested separately. In the second part, the plates were connected in pairs, and each pair was tested for bending. In total, 3 pairs of plates were tested. The bending force was gradually increased from 0 N in increments of 50 N. At each step, the deflection of the plate was recorded. Results. The results of experimental studies of single plates showed that the deviation of deflection values did not differ statistically significantly (p>0.05) from the calculated values over the entire range of bending loads. The studies of the twin plates for the correction of sternum deformities also did not reveal statistically significant (p>0.05) differences in the deflection values of the samples obtained in the experiment from the calculated values. The results of the study made it possible to develop a methodology for calculating the force with which the plate acts on the sternum when correcting its deformation. Conclusions. A methodology has been developed for determining the force with which the plate acts on the sternum when correcting a deformation of a certain magnitude. It is confirmed that the calculated data on the deflection of the plate under the influence of bending load and the data obtained in the experiment do not differ statistically significantly. The data obtained can be useful for selecting the size of the corrective plate, the method of its attachment to the ribs, as well as for modeling the options for applying plates to correct various sternum deformities. The research was carried out in accordance with the principles of the Helsinki Declaration. The study protocol was approved by the Local Ethics Committee of the institution mentioned in the paper. The informed consent of the patient was obtained for conducting the studies. No conflict of interests was declared by the authors.

Comparative analysis of the stress-deformed state of the chest during the correction of the funnel-shaped deformity with the use of two plates: a comparison of the parallel and crossed methods of placing the fixators

“…За критерієм розподілу напружень у кісткових елементах моделі схрещений метод розташування коригуючих пластин забезпечує трохи нижчий їхній рівень практично у всіх кісткових елементах, але максимальне значення напружень 9,0 МПа на сьомому ребрі за хрестоподібного розташування коригуючих [11]. Однак за останнє десятиліття метод вимушено зазнає модифікацій від провідних хірургічних інститутів світу для поліпшення стабільності та збільшення коригуючого впливу фіксаторів на запалу передню грудну стінку [17]. Так, для поліпшення стабільності металевих загрудинних пластин і результатів хірургічного втручання запропоновано застосовувати більше ніж одну загрудинну пластину [3].…”