DYNAMICS OF MORPHOLOGICAL CHANGES IN FRACTURE SITES IN VICTIMS WITH THORACIC TRAUMA AND FLAIL CHEST

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Treatment of patients with a severe solitary and concomitant chest injury remains one of the most difficult surgery tasks. The rib cage destruction has the worst course compared to other types of injures. [1, 2, 3, 4]. Thoracic trauma diagnosis and treatment methods are thoroughly defined, but taking into consideration the advantages of new technologies and tools for the flail chest stabilization, it is necessary to continue the study of pathomorphological changes in unstable rib fracture site [5, 6, 7, 8, 9]. Development of effective treatment methods for patients with flail chest is impossible without a profound analysis of varieties of its clinical course, wrong treatment at different stages, and the causes of lethal outcomes. ■ OBJECTIVES Treatment results improvement in patients with a closed chest injury complicated by the flail chest through the evaluation of the pathomorphological changes in fracture sites on the background of their stabilization. 1 ■ MATERIAL AND METHODS The study is based on the autopsy protocols of 402 victims, whose primary cause of death was a closed chest injury with multiple rib fractures. The average age of patients was 50.6±0.41 years. There were 312 (77.6%) men, and 90 (22.4%) women. The causes of injury were motor vehicle accidents - 249 (61.8%) cases, falls from height - 98 (24.5%), other - 55 (13.7%) cases. In all cases the dominant injury was closed thoracic trauma with flail chest. In 289 (71.9%) cases the victims died on the scene of an accident because of the fatal injuries. 113 (29.1%) patients were admitted to the hospitals of Samara and Samara region in different time since the trauma. In the analysis group the patients with flail chest received the syndrome treatment, combined with mechanical ventilation during 4.58 days in average. Only in 5 (4.4%) cases thoracotomy was used, the skeletal traction in the patients with flail chest was applied in 2 (1.8%) cases. Time of lethal outcome is presented in table 1. Medicolegal autopsy procedure was a standard one. During the post-mortem examination the attention was given to the rib fractures number and placement, the direction of the fracture fragments shift, the periosteum and parietal pleura damage, lung injury, the existence and severity of hemorrhages. Tissue fragments from the flail chest zone were studied and it was the basis for definition of 5 groups of material according to the time passed since trauma: less than 1 day, 1-2 days, 3-5 days, 6-14 days, and more than 14 days. Fragments of tissue were fixed in 10% formalin, immersed in spirits, embedded in paraffin, then cut into thin sections of 5-7 pm with the following hematoxylin-eosin and Van Gieson's staining. Histological samples were observed and visualized with a light microscope "Biolam I" with MFN-11 block and digital photo-camera Canon 450D. In total 289 histological specimens were studied, including 82 samples taken from the rib fractures zones of the persons with a flail chest died in different periods after the injury. ■ RESULTS AND DISCUSSION During the 1st day of a trauma, in the fracture site there were grossly noted the hematoma between fragments, edema and blood imbibition in the surrounding tissues. Microscopically revealed there were multiple lymphoid and histiocytic cellular elements supported by a small amount of unformed intercellular substance. On the 2nd day the hematoma changed its quality. Instead of a clot of blood a soft dark-red shapeless mass appeared. The specific changes in rib fracture fragments Time of lethal outcome Number of patients absolute 1 % 1 1 day 29 26.1 2 day 14 12.3 3-5 days 26 23.3 6-14 days 31 27.4 More than 21 day 13 10.9 In total 113 100 Table 1. Time of lethal outcome in patients with thoracic trauma conditioned by the preserved breathing were defined. The changes namely were "hacks" and 2-4 mm detachment of a periosteum on both edges, the formed subperiosteal hematoma which lead to the cancellous bone shift and compression up to 4-6 mm, generally on the vertebral extremity. The microscopy presented the plural poorly differentiated cells of connective tissue, forming fiber bandlike structures of irregular shape. Periosteal apposition was noted in combination with disorganized periosteum structure and expressed capillary stasis and venous congestion in the places of its detachment. In 5 days after a trauma the fracture site got the distinctive plastic strain area on the costal friction surfaces [9, 10]. It was the so-called, "rubbing". Histologically "rubbing" - is the area of the condensed bone tissue, which acquires a light blue color with hematoxylin-eosin staining, -the hematoxylinsensitive platform. The hematoma between fragments was substituted by granulation tissue with single fibroblastic cells. In the hematoma demarcation there appeared a leucio-lymphocytic order and lacunae resorption in the damaged compact bone near the "rubbing" and the endosteum. On the 14th day the bone resorption was progressing with the formation of a distinct "resorption sulcus" in the proximity of the condensing zone ("rubbing") on the compact bone surface at the rib fragment end. This fact revealed the "rubbing" detachment and future partial dispersion as the basis for primary callus formation. In group I the analysis results proved the primary death cause in 29 patients with chest injury as massive blood loss in 22 (75.2%) cases, irreversible traumatic shock in 7 (24.8%) cases. In group II of 14 patients the death cause variations were acute respiratory failure in 9 (64.1%) patients, traumatic shock in 4 (27,4%) and pulmonary thromboembolism in 1 (8,5%) case. These complications are conditionally nonfatal. In groups III, IV and V totally comprising 70 patients the lethal outcome causes were divided into 57(82.5%) pneumonias, 9 (11.8%) sepses, and 4 (5,7%) myocardial contusions with respiratory distress syndrome. We would like to stress the fact that the patients died from the complications which could be prevented by early qualified treatment lowering the death rate. In patients who died in 21 days the morphological study of the rib fracture zone clearly revealed the trabeculae of bone partially filling the fragments splitting. We found out that on the 1st, 2nd, 5th day there were no morphologically significant changes in the fracture zone, aimed at its stabilization. With breathing preserved for more than 5 days, which indirectly proofed the lack of rib cage stabilization treatment, there was a delay in the primary callus formation and enhanced bone resorption in the fracture site. Furthermore, the thoracic cage instability induced "hacks" and 4-6 mm detachment of a periosteum combined with a subperiosteal hematoma, leading to the microcirculatory disorders in the fracture zone. As a result, in the fracture edge area there was poor bone nutrition. The preliminary fracture edge contact resulted in bone condensing and necrosis followed by active lacunae resorption. While comparing the tissue fragments of the solitary and multiple fracture zones we found out that Наука и инновации в медицине 4(12)/2018 the osteoblasts activation, which manifests the proliferation of cellular elements, in fragmentary rib fractures occurred 7-9 days later than in a single fracture. It was conditioned by the persistent "floating" of the rib fragments which impacted the newly formed trabeculae of bone and forced them to rearrange twice during the bony callus formation. The increased time of the rib fracture repair in patients with thoracic trauma is an adverse factor aggravating the lung injury, contributing to the development of pneumonia and purulent-septic complications which, in their turn, are the primary cause of deaths in a long term period. Thus, the conducted study allowed us to identify the group of patients whose death is conditionally preventable. However, it demands the active surgery tactics in thoracic cage instability elimination. Besides mechanical ventilation for internal pneumatic stabilization, the effective technique is skeletal traction, when the traction is applied to the ribs with bullet forceps, clamps and a thread under the ribs with applied weight of one or two kilograms. The analysis of the material in this study revealed the insufficiency of the mechanical ventilation in this group of patients. Extension and stabilization of the flail chest contributes to the rib bone tissue reparation and regeneration. In case the skeletal traction is not implemented, or ribs are fixed with metal devices, the regeneration tends to a pathological pattern, long-term period and complications. The time of traction applied to ribs depends on the time passed since the trauma. If the traction was started within the first day of the injury, the traction period should be 10 days or more. In spite of the absence of the callus, the fracture is aligned by the surrounding tissues. The late traction (3 days since the injury) requires at least 15 days due to the secondary trauma of the damaged tissues. Also the study forced the idea of special training for the personnel responsible for the thoracic injury treatment. The new approaches are necessary; this fact is supported by the study statistics. In the 402 patients with lethal outcome the skeletal traction was done in 2 (0.5%), a thoracotomy - in 5 (1.2%) cases. ■ CONCLUSION In 17.4% of patients with severe chest injury and flail chest the death is conditionally preventable. If the skeletal traction was applied within the first day of the injury, the traction period should be at least 10 days; if the operation was done later than 3 days - the application period is 15 days or more. The essential condition of the effective treatment of patients with the thoracic trauma and flail chest is the usage of various methods of the thoracic cage stabilization. W

About the authors

V I Belokonev

Samara State Medical University

Email: belokonev63@yandex.ru
PhD, professor, head of the Chair of surgical diseases №2 of Samara State Medical University.

S Yu Pushkin

Samara Regional Clinical Hospital named after V.D. Seredavin

Email: serpuschkin@mail.ru
PhD, associate professor of the Chair of surgical diseases №2 of Samara State Medical University, deputy of head physician on surgery of Samara Regional Clinical Hospital named after V.D. Seredavin.

A P Ardashkin

Samara State Medical University

Email: samard@mail.ru
PhD, professor, head of the department of forensic medicine of Samara State Medical University.

N G Ushakov

Samara State Medical University

Email: ushacov-doctor@bk.ru
traumatologist-orthopedist of orthopedic department of Clinics of Samara State Medical University.

I R Kameev

Samara Regional Clinical Hospital named after V.D. Seredavin

Email: kameev@mail.ru
the thoracic surgeon of surgical thoracic department of Samara Regional Clinical Hospital named after V.D. Seredavin.

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