Orthopedic injuries due to parachute jumping in soldiers and the effect of trauma scoring systems in determining injury level: A prospective observational study

During parachute jumping in soldiers, minör or life-threatining majör injuries may be occur in various parts of the body. Various trauma scoring systems have been developed to determine the severity of these injuries. The aim of this study is to determine orthopedic injuries and other injuries due to parachute jumping for military training who admitted to ED and the severity of their injuries using by anatomical and physiological trauma scores (AIS and ISS), to examine applied treatment methods, their hospitalization conditions and the length of hospital stay prospectively over a 44-month period between January 2016 and August 2019.


Introduction Background
The idea of jumping from a high place without getting damaged, first appeared in China about 2000 years ago. As a result of human trials throughout history, the first successful parachute jump took place in 1797 by jumping from the balloon and then modern parachuting developed. The word parachute is derived from the Greek word "money", that is, "protection", and the French word from "chute", that is "fall" (1,2).
With the Second World War, parachuting was used and developed for military purposes. In line with the developments in military technology and aviation, some countries still use parachute dropping actively today as part of the air defense system and for the deployment of troops quickly to a narrow area (2,3). Military or hobby parachute jumps are widely used today.

Importance
Parachuting requires high concentration and physical performance. During these jumps, various injuries may occur both in the air and during landing, and in some cases, fatal accidents may occur. In the literature, it has been reported that the rate of injuries as a result of parachute jumping is between 3 to 24 per thousand per person (4,5). In these injuries, it is known that the factors such as the altitude, performing the jump at night, the equipment and technique used, the factors about the plane, the selected parachute type, the weather and environmental factors, the personal factors (age, weight, height, experience, aircraft leaving technique, loss of control, etc.) and the ground are effective (3,(6)(7)(8)(9)(10). Most of the parachuting accidents and fatal injuries are known to occur at low

Goal of This Investigation
Due to its geographical structure, air sports such as paragliding, military training or hobby parachuting and balloon tour are performed intensely in Central Anatolia and its surroundings. Various injuries may occur while performing these sports. Especially for military training purposes, more than 30.000 parachute jumps occur annually and as a result of these jumps, the number of applications to the emergency service increased in recent years. In literature reviews, parachute injuries are usually in the form of case reports or retrospective (10,11). In this study, we aimed to determine orthopedic injuries and other injuries due to parachute jumping for military school training applied by ambulance or outpatient to Kayseri City Education and Resources Hospital Emergency Medicine Clinic Trauma Unit, the severity of their injuries by anatomical and physiological trauma scores (Abbreviated Injury Scale (AIS) and Injury Severity Score (ISS)), to examine applied treatment methods, their hospitalization conditions and the length of hospital stay prospectively over a 44-month period between January 2016 and August 2019.

Study Design and Setting
This study was conducted at a tertiary center, Kayseri City Education and Resources A total of 15 patients who were not recorded to hospital information management system (HIMS), whose trauma scoring system (AIS and ISS) was not calculated, who applied for parachute and balloon injuries, who could not obtain consent and who have missing parts in the patient observation form were excluded. Verbal or written consent of all participants was obtained.

Measurements
For a total of 185 patients, demographic data such as age, gender, ISS trauma region classification, anatomical injury sites, AIS and ISS scores, diagnosis, treatment methods applied, hospitalization status and duration of hospitalization were interviewed prospectively with the patients and information was obtained from HIMS and patient registration forms and processed with consent. The injured were classified according to age and trauma scoring scores. The injury rate was stated as a percentage. The patients were divided into 3 groups according to age groups; 19-23 years group (n = 81), 24-29 years group (n = 58) and 30 years and older (n = 46). Outcomes AIS scores are calculated as 1 point minor, 2 points moderate, 3 points serious, 4 points severe, 5 points critical, 6 points maximal (currently untreatable) maximum 6 points, and the ISS the sum of the squares of the three sites with the most serious injury (ISS = a2 + b2 + c2) with minimum 1 maximum 75 points. ISS trauma exposure site was divided into 6 sites, and anatomically injured sites were divided into 17 different sites and recorded on the patient registration form.

Data Analysis
In summarizing of the data obtained from the study, descriptive statistics were given as the mean ± standard deviation, median (width between quarters) and minimum-maximum  (Table 1). Descriptive statistics are given as number (%) for categorical variables and mean ± standard deviation for numerical variables.
When the trauma sites exposed according to ISS are examined; pelvis (75.7%), extremity (67.6), head and neck (13.5) and chest (13.5%) injuries were observed to be the majority.
The patients' Glaskow Coma Scores (GKS) were ≥ 13. The mean ISS of the patients was 5.16 ± 3.92 (minimum: 1, maximum: 25). The exposed ISS trauma region was most frequently extremity and the pelvis was 67.6% (n = 125). This was followed by head and neck 8.6% (n = 16) and chest 7.0% (n = 13), respectively. The least injury was observed in the abdomen (n = 3) with 1.6%. According to the ISS classification, the most common shoulder injury (50%) (n = 9) was observed in the upper extremity group. This was followed by whole upper extremity, arm, elbow, hand and wrist injuries, respectively (n = 18). In the lower extremity group, the most common was foot injury (24.1%) (n = 32). This was followed by ankle (13.5%) (n = 18), leg (7.5%) (n = 10), knee (5.3%) (n = 7), thigh (3.8%) (n = 5), whole lower extremity (31.6%) (n = 42) and pelvis (14.3%) (n = 19) injuries, respectively. Similarly, according to ISS, in the head and neck spinal group, the most common injuries were found to be spine (18.4%) (n = 34), head (13.5%) and cervical (1.1%). Again, according to ISS, the most common injuries in the body group were thoracic (66.7%) (n = 6) injuries. This was followed by abdomen (33.3%) (n = 3) and cutaneoussubcutaneous superficial (11.1%) (n = 1) injuries, respectively (Table 3).  Injury sites rates were compared according to the age groups of the patients admitted to the emergency department. Accordingly, the rate of leg injury in patients 30 years and older was found to be statistically more significantly than patients between the ages of 24-29 (p = 0.043). In addition, in patients between the ages of 19-23, the knee injury rate was statistically more significant than those between the ages of 24-29 and those over 30 years old (p = 0.006). In other comparisons, there was no statistical difference between foot, ankle, thigh, pelvis, spine, abdomen, thorax, shoulder, hand, ankle, forearm, elbow, arm, cervical and head injury rates by age groups (for each p > 0.05) ( Table 6).  There was a statistically significant difference in hospital admission rates according to AIS score levels in patients admitted to the emergency department (p < 0.001). The hospitalization rate of patients with a critical AIS score was significantly higher than those with a severe AIS score. Similarly, the difference between the median scores of ISS was statistically significant according to their hospitalization status (p < 0.001). Accordingly, the median ISS score of the hospitalized patients was significantly higher than those who were not hospitalized (Table 7). Table 7 Comparison of hospitalization rates according to AIS score levels and ISS score medians in terms of hospitalization. While 5.9% (n = 11) of the patients received inpatient treatment, 94.1% (n = 174) were discharged with outpatient treatment. The average length of hospitalization of inpatients was found to be 3.45 ± 2.20 (minimum: 1, maximum: 7). Also, in Table 7.1, the median day of hospitalization of patients with a severe AIS score level was 3 days, while the median day of hospitalization of critical patients was 6 days.

Discussion
The average age of the patients included in the study is 26.70 ± 6.24. According to A.
Ekeland's study, the average age is 24.5 + 3.6 and has a similar range. Similarly, in our study, the rate of injury increases with increasing age (3,4). Serious and critical patient rates were higher than previous studies (15.1% and 0.5%, respectively) (3,4). We think that the reason for this difference may have been due to the higher average age of the people included in our study.
Jumping with a static parachute from the plane at an altitude of approximately 400 m (1200 feet), it was learned from the participants that the cases included in our study, used 5 points technique with a self-opening mushroom-shaped parachute at 1-2 knots wind speed, 5.9-7.1 km/h landing speed, and landed on the flat ground. In addition, the equipment of all jumpers was complete and suitable for jumping. In literature studies, it was reported that the injury rate increases when wind speed exceeds 9 knots and high altitude jumps (7). In our study, although the wind speed was not high, we think that the rate of injury was high due to inappropriate falling during landing.
Static jump, free fall or HALO (high altitude-low opening) in the American army is specified as a jumping technique used by private forces. However, 141 injuries were detected in 134 parts in the HALO jumping (3,8). In addition, in two different studies conducted in the American and British army, the total injury rate in parachute jumps, the majority of which are minor injuries, is about 2.5% (1,8). The injury rate in the static jump is specified as 8.1/1.000 (3). In our study, the way of jumping is usually self-opening and low-altitude jumping. Since it is not known how many people jumped in total, the injury rate could not be determined.
In our study, the most common injury site was foot 33.5% (n = 62) when we evaluate patients in terms of injury site. This is followed by ankle 29.1% (n = 54), spine 18.3% (n = 34) and head 12.4% (n = 23), respectively. The rate of foot injury is higher than previous studies (4,7,10). In a comprehensive study conducted by A. Ekeland, the injury rate is the most common ankle with 36%. In our study, when the foot and ankle are evaluated together, the injury rate reaches to 62.6%. When the two injuries are evaluated together, similar to this study, the rate of foot and ankle injury is most common. Similarly to a retrospective study examining Ball V. L. et al. examined injuries due to static parachute jump, lower extremity was the most frequently injured body region in our study (19).
In emergency departments, scoring systems such as GCS, AIS, ISS, Trauma and Injury Severity Score (TRISS) and Revized-Trauma Score (RTS) are used to determine the severity of trauma patients (20,21). In our study, the participants' GCS was ≥ 13, and we chose to determine the severity of the patients according to AIS and ISS scoring systems due to the ease of application in a crowded emergency. In addition, we aimed to determine the severity of the injury by dividing the body into 17 different regions anatomically, noting the injury areas, evaluating them together with AIS and ISS.
The purpose of performing trauma scores of patients is to determine the severity of injury in patients; the mean ISS was determined to be 5.16 ± 3.92. According to the study of Sozuer EM et al, the mean ISS was lower than our study (8.15 ± 4.29 to 5.16 ± 3.92) (22).
We think that the reason for this difference is that the number of patients included in our study was more and the more severe patients came to the emergency department.
Compared to the ISS trauma region exposed, in our study, the most frequent was extremity and pelvis with a rate of 67.6% (n = 125). This was followed by head and neck 8.6% (n = 16) and chest 7.0% (n = 13). The least number of injury was observed in the abdomen (n = 3) with 1.6%. In our study, it was determined that trauma region separation rates are higher than ISS (3)(4)(5)7,22).
In terms of diagnosis, it was observed that the patients were most frequently diagnosed with soft tissue trauma (sprain and stretching) (n = 119) and lower extremity fracture dislocation (n = 28). The percentage of these diagnoses is 64.3% and 15.1%, respectively.
These rates are higher compared to the study of Craig et al. (3). We think that this may be due to the landing ground selection and the lack of experience of the soldiers.
In our study, when the fracture rates of the patients were examined, 28 patients had lower extremity fractures, 4 patients had lower extremity fractures and 1 patient had pelvic fractures. In the literature, it is generally in the form of a case report, and extensive studies are generally conducted by scanning and summarizing the literature. In a case reported by A. Bourghli et al., a clavicle fracture was observed (11). In our study, no clavicle fracture was found. Although the fractures of the upper extremity are generally reported in the study of J.G. Bonnin as a humeral surgical neck fracture or stable humerus fracture, in our study, the most common shoulder injury was observed in the upper extremity and fracture was found in 4 people. In the same study, it was observed that the most common foot and ankle injuries were similar to our study (23). In another study, the ankle injury rate was calculated as 4.5/1000 (10 to reverse airflow, loss of vision due to weather, or acrobatic movements), deaths have been reported (6). Similar factors have been reported to be effective in injuries, as well as high rates of injury during nighttime jumps (9). In the literature studies, the wrong landing technique was mentioned as the most common cause of injury (4,19). Similar to these studies, we think that the most common cause of injury is inappropriate landing technique. Since the night jump was not performed in our study, the rate of injury in the night jump could not be calculated. It is pleasing that no fatal case was encountered in our study. This may be due to the preference of jumping when the wind speed is low, the preference of jumping in the open air, and good training before jumping.
Although there is no statistically significant difference in our study, it is interesting to see an increase in ISS score with age. We think that the reason for this is that as the age increases, the attention may decrease due to the increase in self-confidence with the experience of the person and this may cause an increase in injury.

Limitations
We think that our study has some limitations. It was not discriminated that how many of the jumpers were instructors and how many were students. Also, the experience of the jumpers or how many times they had jumped before and how many had been injured in the same day were not questioned. Although it was learned that the vast majority of the

Availability of data and materials
All data presented in this study were retrieved from Kayseri City Hospital's archieve.

Conflict of Interest Disclosure
TS and SB declareted that there is no conflict of interest.

Presentations
We planned to present as an oral presentation at the 7th Intercontinental Emergency Medicine Congress, on 9-12 April 2020 at Antalya, Turkey.

Ethics approval and consent to participate
Ethical approval was obtained fort his study from the Kayseri City Education and Resources Hospital Research Committee by ID 16.11.2016/09 and Erciyes University Ethics Committee by ID 96681246/340 and adhered to Decleration of Helsinki.

Constent for publication
Not applicable.  Frequency of patients according to their diagnosis