Clin Orthop Surg. 2023 Apr;15(2):300-307. English.
Published online Jan 25, 2023.
https://doi.org/10.4055/cios22117
Copyright © 2023 by The Korean Orthopaedic Association
Original Article
Su Cheol Kim, MD,Jae Chul Yoo, MD,Jong Hun Park, MD,Hashem Bukhary, MD,Yang Seon Choi, MD,*Kyu Tae Kang, MD,* and Chul-Ho Kim, MD*
Author information
Author notes
Copyright and License
- Department of Orthopaedic Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
- *Department of Orthopaedic Surgery, Chung-Ang University Hospital, Chung-Ang University College of Medicine, Seoul, Korea.
- Department of Orthopaedic Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
Correspondence to: Chul-Ho Kim, MD. Department of Orthopaedic Surgery, Chung-Ang University Hospital, Chung-Ang University College of Medicine, 102 Heukseok-ro, Dongjak-gu, Seoul 06973, Korea. Tel: +82-2-6299-2571, Fax: +82-2-6299-2064, Email: oschulhokim@cau.ac.kr
Received April 06, 2022; Revised August 01, 2022; Accepted September 02, 2022.
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-
Go to:
Abstract
Background
This study aimed to investigate the changes in the incidence of shoulder trauma and surgery 1 year after the outbreak of coronavirus disease 2019 (COVID-19) with social restriction compared with 1 year before the pandemic.
Methods
Patients managed in our orthopedic trauma center between February 18, 2020, and February 17, 2021 (COVID-19 period) for shoulder trauma were compared with patients managed for the same duration a year ago (non–COVID-19 period; February 18, 2019, to February 17, 2020). The incidence of shoulder trauma, surgery, and mechanism of injury were compared between these periods.
Results
The total number of shoulder trauma cases was lower in the COVID-19 period than in the non–COVID-19 period, although the difference was not significant (160 vs. 180 cases, p = 0.278). In addition, traumatic shoulder surgeries decreased during the COVID-19 period (57 vs. 69 cases, p = 0.285). The incidence of shoulder trauma according to four diagnostic classifications (contusion, sprain/subluxation, fracture, and dislocation) and fracture/dislocation types did not differ between the periods. During the COVID-19 period, accidental falls outdoors (45 vs. 67, p = 0.038) and sports-related injuries (15 vs. 29, p = 0.035) significantly decreased, but accidental falls at home (52 vs. 37, p = 0.112) increased compared with those during the non–COVID-19 period, although the difference was not significant. The monthly incidence of shoulder trauma decreased 2 months after the first outbreak (significant in March, p = 0.019), then steadily increased and significantly decreased during the second outbreak (August, p = 0.012). However, the third outbreak (December, p = 0.077) had little effect on the incidence of shoulder trauma. The number of monthly traumatic shoulder surgeries showed a similar pattern to the monthly incidence of shoulder trauma.
Conclusions
During the COVID-19 pandemic, annual shoulder trauma cases and surgeries decreased compared to those in the non–COVID-19 period, even though the difference was insignificant. The incidence of shoulder trauma and surgery was significantly reduced in the early COVID-19 period; however, the effect of the pandemic on orthopedic trauma practice was minimal after approximately half a year. Decreases in falls outdoors and sports-related injuries, but an increase in falls at home, were observed during the COVID-19 pandemic.
Keywords
Shoulder; Injuries; COVID-19; Coronavirus; Pandemic
The coronavirus disease-2019 (COVID-19) was declared a pandemic in January 2020, and South Korea was one of the first countries affected by COVID-19. In South Korea, the first diagnosis was made on January 20, 2020, and the first outbreak was observed in a religious group in Daegu on February 18, 2020. Subsequently, cases peaked, awareness of the disease among the people rose, and voluntary social distancing behavior and mask wearing were implemented. On March 21, 2020, the South Korean government announced a social distancing policy to control multi-purpose facilities. However, restaurant operating hours and the number of people at meetings were not restricted.1, 2)
The second outbreak occurred in August 21, 2020. More than 400 patients (441 cases) were diagnosed for the first time, and nationwide social distancing was enforced on August 30, 2020. All restaurants were forced to close after 9 PM.1, 2) The third outbreak occurred in December 2020, and more than a thousand diagnoses were made. On December 22, 2020, outdoor winter sports facilities across the country were forcibly closed, and gatherings of more than four people were banned in restaurants.1, 2)
The enforcement of the social distancing policy and the depressed minds of people with COVID-19 also affected orthopedic practice.3, 4, 5, 6, 7, 8, 9, 10, 11) Fewer cases in outpatient clinics and elective surgeries have been reported.12, 13, 14) However, due to the never-ending pandemic and accumulating mental and physical fatigue, people gradually returned to a normal lifestyle similar to that in the non–COVID-19 period, and some countries are experiencing a paradigm shift toward the “with corona” era along with vaccination.15)
However, few studies have investigated changes in shoulder trauma in the long term (≥ 1 year).15) One study involving skeletally immature populations investigated the incidence of shoulder and elbow trauma for 1 month after the COVID-19 pandemic with social restrictions. Other studies have reported changes in orthopedic practice only for less than 3 months during the COVID-19 pandemic.12, 13) Recently, Yu et al.16) reported monthly changes in orthopedic diagnoses in the pre-, peak-, and recovery-COVID-19 periods. However, they evaluated 7 months of the COVID-19 period, analyzed shoulder dislocation and proximal humerus fracture for shoulder trauma, and did not report injury mechanism and fracture/dislocation type.
Regarding the types of injuries during the COVID-19 pandemic, Sherman et al.17) reported an increase in non-accidental penetrating trauma, including gunshot wounds, and a decrease in accidental blunt trauma in the United States. However, general trauma cases were observed during the first 2 months of the COVID-19 pandemic. The long-term effects of pandemics on orthopedic practice should be explored, as it may serve as a reference model for orthopedic surgeons in the future. In addition, analyzing the effect of the current pandemic in various ways can be valuable. Hence, this study aimed to report the changes in the incidence of shoulder trauma, surgery, and mechanism of injury during the COVID-19 pandemic for 1 year and compare it with the non–COVID-19 period at a trauma center in our university hospital from a South Korean perspective. This study hypothesized that there would be a short-term decrease in the number of shoulder trauma cases and surgeries at the start of the COVID-19 pandemic, but it will return to non–COVID-19 levels in 1 year.
Go to:
METHODS
This retrospective chart review study involving human participants was conducted in accordance with the ethical standards of the institutional and national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. The Human Investigation Committee of Chung-Ang University Hospital (No. 2111-066-19395) approved the study. The requirement for informed consent was waived because of the retrospective design and lack of additional harm to the patients. However, patients were informed about the study and gave consent that clinical data without identifiable information could be released to the public or submitted for publication during consultation.
All skeletally mature patients (aged > 18 years) managed in this hospital for shoulder trauma from February 18, 2020, to February 17, 2021 (COVID-19 period), were retrospectively reviewed and compared with patients managed from February 18, 2019, to February 17, 2020 (non–COVID-19 period). Since increased awareness about the COVID-19 pandemic and the changes in people’s behavior appeared to be initiated by the first outbreak in the Daegu religious group, this study performed the analysis according to the presence of the COVID-19 pandemic.
All clinical data were collected from existing electronic charts including information about baseline characteristics (age and sex), mechanism of injury, diagnosis, and surgical management. Four diagnostic categories were distinguished: contusion, fracture, sprain/subluxation, and dislocation. To analyze the difference in injury severity between the periods, the fracture/dislocation types were analyzed. Neer classification was used for proximal humerus fractures.18) The Allman classification was used for clavicle fractures,19) and Cho’s classification was used for distal clavicle fractures.20) The Rockwood classification was used for acromioclavicular joint injury:21) types I and II were regarded as sprain/subluxation, and types III–VI were considered dislocation.21) Glenohumeral dislocation was classified according to directions of instability, and anterior glenohumeral dislocation was recorded as recurrent or first.
Regarding the mechanism of injury, patients were classified into six subgroups: (1) accidental falls at home; (2) accidental falls outdoors; (3) sports-related injuries; (4) high-energy trauma incurred by car, motorcycle, or public transport accidents as occupant or pedestrian involvement; (5) accidents at work; and (6) trauma due to assault or beating. The monthly incidence of shoulder trauma and surgery was analyzed to determine the short-term changes in shoulder trauma. The February incidence in the first year was counted from February 18 to the last day, and the February incidence in the following year was calculated from February 1 to 17.
Statistical Analysis
Continuous variables were expressed as mean ± standard deviation and analyzed using Student t-test. Categorical variables were expressed as numbers (%) and were analyzed using the chi-square or Fisher’s exact test. Statistical analyses were performed using R software version 4.0.2 (R Foundation for Statistical Computing). All statistical analyses were two-tailed, and significance was set at p < 0.05.
Go to:
RESULTS
A total of 160 and 180 patients were managed during the COVID-19 and non–COVID-19 periods, respectively (p = 0.278), indicating an 11.1% reduction in patients during the COVID-19 period. During both periods, sex and mean age of the patients were not different between the COVID-19 group and non–COVID-19 group (male patients, 89 and 92, respectively, p = 0.405; 53.6 ± 20.1 years and 52.8 ± 20.6 years, respectively, p = 0.710). Traumatic shoulder surgeries were performed in 57 and 69 patients during the COVID-19 and non–COVID-19 periods, respectively (p = 0.285).
Table 1 shows the diagnoses and traumatic mechanisms during the two examined periods. No difference was found in the incidence of shoulder trauma according to the four diagnostic classifications between the two periods. Shoulder fractures or dislocations were observed in 144 and 166 patients during the COVID-19 and non–COVID-19 periods, respectively, which were not significantly different (p = 0.212). Accidental falls outdoors and sports-related injuries were observed significantly less frequently during the COVID-19 period than during the non–COVID-19 period. In addition, more accidental falls at home than outdoors (52 vs. 45, p = 0.477) were observed during the COVID-19 period. The incidence of high-energy trauma and accidents at work did not differ between the two periods.
Table 1
Diagnosis and Mechanism of Injury
- Click for larger image
- Click for full table
- Download as Excel file
The incidences of fracture/dislocation types are presented in Table 2, and no differences were observed between the periods. In addition, 5 scapular body fractures (2 in the COVID-19 period and 3 in the non–COVID-19 period), 2 acromion fractures (each period), 1 coracoid fracture (non–COVID-19 period), 1 glenoid fracture (non–COVID-19 period), and 1 glenoid and scapula neck fracture (COVID-19 period) were observed. Multiple fractures were observed in 4 patients: 2 coracoid base and acromion fractures (1 for each period), 1 scapula body and clavicle fracture (non–COVID-19 period), and 1 scapula body and coracoid base fracture (non–COVID-19 period).
Table 2
Type of Fracture or Dislocation
- Click for larger image
- Click for full table
- Download as Excel file
Fig. 1 shows the age plot of the four diagnoses or injury mechanisms between the two periods; accidents at work and assault/beating are not presented (unable to compare this because of the small number of cases). Age was not different between the periods for each diagnosis and injury mechanism. Furthermore, age difference was not observed in proximal humerus fractures (COVID-19 group vs. non–COVID-19 group, 65.5 ± 17.0 vs. 64.2 ± 18.4 years, p = 0.671) and clavicle fractures (COVID-19 group vs. non–COVID-19, 48.3 ± 19.1 vs. 47.4 ± 17.7 years, p = 0.793) between the periods.
Fig. 1
(A) Age plot of the four diagnoses in the two periods. 1, contusion; 2: sprain/subluxation; 3, fracture; 4, dislocation. (B) Age plot of the injury mechanisms in the two periods. 1, accidental fall at home; 2, accidental fall outdoors; 3, sports-related injuries; 4, high-energy trauma. Dots mean outliers. COVID-19: coronavirus disease 2019.
- Click for larger image
- Download as PowerPoint slide
The monthly incidence of shoulder trauma is shown in Fig. 2. During the early COVID-19 period from February to March 2020, the number of shoulder trauma cases was lower than that in the same months of the non–COVID-19 period (significant in March, p = 0.019). After March, the incidence of shoulder trauma gradually recovered and slightly reversed in April, and similar values were observed from May to July. However, the second outbreak occurred in August and the number of shoulder trauma cases during the COVID-19 period decreased sharply in August (p = 0.012). The third outbreak occurred in December, but the incidence did not differ by period. In January, the incidence of shoulder trauma was higher in the COVID-19 period than in the non–COVID-19 period; however, the difference was not significant (p = 0.077).
Fig. 2
The number of shoulder trauma cases during the coronavirus disease 2019 (COVID-19) and non–COVID-19 periods. *Counted from February 18 to the last day. †Counted from February 1 to 17. ‡Statistically significant.
- Click for larger image
- Download as PowerPoint slide
The number of monthly traumatic shoulder surgeries performed is shown in Fig. 3. During the first 2 months of the COVID-19 period, the number of shoulder surgeries was significantly lower than that of the non–COVID-19 period (February p = 0.025, March p = 0.004), but gradually increased until July. However, a significant decrease (p = 0.020) was observed in August (second outbreak), followed by steady recovery, and a high incidence of surgery was observed in January 2021 (third outbreak) (p = 0.007).
Fig. 3
The monthly number of shoulder trauma surgeries during the coronavirus disease 2019 (COVID-19) and non–COVID-19 periods. *Counted from February 18 to the last day. †Counted from February 1 to 17. ‡Statistically significant.
- Click for larger image
- Download as PowerPoint slide
Go to:
DISCUSSION
The main findings of this study are that the incidence of shoulder trauma and surgery during the early COVID-19 period seemed to decrease due to the outbreak of the disease and changes in people’s behavior. However, approximately half a year after the pandemic, the effect of the pandemic on shoulder trauma decreased. The injury mechanism during the COVID-19 pandemic showed a decrease in falls outdoors and sports-related injuries but an increase in falls at home. However, there was no change in the incidence of high-energy trauma during the pandemic compared with the normal period.
Since the COVID-19 outbreak, decreased orthopedic practices have been reported. Knebel et al.12) described the cancellation of elective orthopedic surgery during the early COVID-19 period and an increase in pain level and analgesia usage. Regarding orthopedic trauma, the national shutdown following the COVID-19 outbreak in Italy induced a 65% decrease in orthopedic health services, especially low-energy trauma cases, sports-related injuries, and traffic accident-related injuries causing shoulder and elbow trauma for 1 month.13) Dillon et al.22) reported decreased shoulder arthroplasty surgeries due to proximal humerus fractures 2 months after the outbreak of COVID-19, which was attributable to the shelter-in-place policy.
In this study, the number of shoulder trauma cases and surgeries during the early 2 months of the COVID-19 period was lower than that in the non–COVID-19 period as in previous studies.13) Various factors may have affected this phenomenon, possibly the decreased accessibility to hospitals for patients with orthopedic trauma because of COVID-19 restrictions. Some hospitals in South Korea converted the inpatient beds into COVID-19 special care units. However, our hospital did not reduce the orthopedic inpatient rooms and outpatient capability to cover COVID-19 cases. Moreover, there has never been a shoulder trauma case that was not allowed to be cared for during the COVID-19 pandemic.
Social restrictions and distancing policies in Italy and South Korea for the pandemic were not the same, but the decreased shoulder trauma during the initial COVID-19 period looked similar. Italy started strong restrictions on society 1 month after the spread of COVID-19.13) The South Korean government implemented voluntary social distancing and mask wearing, which were less intense than those in Italy.1) However, the phobia and awareness of COVID-19 might have protected people during the first outbreak in Korea. Many social gatherings were voluntarily postponed, and people were restrained from going out, as in Italy.
Although many similar studies have been conducted regarding orthopedic practice changes during the COVID-19 pandemic in different nations, they analyzed a short duration (1–3 months after the COVID-19 outbreak).9, 12, 13, 22) They focused on the effect of strong social restrictions, called shelter-in-place order. However, the current study analyzed changes in orthopedic practice over a year and focused on changes in practice with repeated outbreaks. The incidence of shoulder trauma gradually returned to the previous level 2 months after the first COVID-19 outbreak, which lasted before the second outbreak. Previously, Gumina et al.13) and Knebel et al.12) analyzed data for 1 and 2 months of the early COVID-19 period, respectively; therefore, restoration of orthopedic practice after the first outbreak was not addressed.
The second outbreak in August significantly reduced the number of shoulder traumas and surgeries performed in the current study. However, it recovered rapidly just 1 month after the first outbreak. Interestingly, the third large-scale outbreak in December 2020 seemed to have little effect on shoulder trauma. It might be because people were tired of quarantine for almost a year, and the awareness of the disease decreased. The COVID-19 pandemic may have affected shoulder trauma initially; however, its effect seemed to decline after about half a year.
A monthly evaluation of shoulder trauma could help identify the population’s reaction to the pandemic. Yu et al.16) reported monthly changes in orthopedic diagnoses before and after the COVID-19 pandemic. They showed a significant decrease in cases including shoulder dislocation and proximal humerus fracture during the peak of the COVID-19 period and the number of cases recovered during the recovery period of the COVID-19 pandemic, which were similar to our results.
In our study, a strangely high incidence of trauma and related shoulder surgery in December and January during the COVID-19 period was observed. The reason for this, whether it was a random effect in our analysis because of the small number of monthly cases, was unclear. Regarding injury mechanisms, Gumina et al.13) reported that sports-related injuries were reduced, and low-energy falls (domestic) remained during the COVID-19 period, even though they analyzed 1 month of data for each period. In this study, the number of falls at home was higher than that outdoors during the COVID-19 period. In addition, sports-related injuries were less frequently observed during the COVID-19 period, which is similar to the results of a previous study.13) This seems reasonable considering the COVID-19 pandemic induced a decrease in outdoors and sports activities.
Gumina et al.13) investigated shoulder and elbow fracture types during the COVID-19 and non–COVID-19 periods; however, the number of cases was insufficient. Only proximal humerus fracture types were sufficient for comparison, and there was no difference between periods. Although the injury mechanisms differed between the two periods in this study, the fracture/dislocation types did not. Because many factors, including sex, age, bone quality, injury energy, and direction of force causing injury (direct blowing, compression, bending, and twisting), could be attributed to fracture/dislocation types, the pandemic does not seem to be a single factor affecting disease severity.
Since the 20th century, COVID-19 has been the only pandemic that has hit the world, and the national and humanitarian response to this pandemic seems almost unprecedented. As the pandemic has persisted for a long time, there have been many changes in our daily lives. However, we are adapting to an endless COVID-19 pandemic. This study is significant as it can reveal how the pandemic has affected orthopedic practice, especially shoulder trauma, for a year. The results of this study can serve as a model for orthopedic surgeons during future pandemics.
This study has several limitations. First, this study is a single-institution survey; therefore, it cannot generalize all cases of shoulder trauma during the COVID-19 period. In addition, because this study analyzed the trauma center of a university hospital that cares for COVID-19 patients, the situation may be different from that of a private clinic. Second, this single-country study could not be applied to other countries. Government policies and civic behaviors differ from one country to another, and these may affect the spread of COVID-19. Third, only a small number of shoulder trauma cases were analyzed. At the trauma center of a university hospital, it was not easy to register patients with a simple contusion, which could have induced selection bias. Although the annual number of shoulder trauma cases and surgeries showed no difference between the two periods, a larger case analysis is necessary. Fourth, the accessibility of patients to university hospitals during the COVID-19 period changed. During the COVID-19 period, the emergency room required negative COVID-19 testing results before registration, thus the accessibility of the patients may have been affected. However, there is no way to verify this hypothesis.
During the COVID-19 pandemic, annual shoulder trauma cases and surgeries decreased compared to those in the non–COVID-19 period, even though the difference was insignificant. The incidence of shoulder trauma and surgery was significantly reduced in the early COVID-19 period; however, the effect of the pandemic on orthopedic trauma practice was minimal after approximately half a year. Decreases in falls outdoors and sports-related injuries, but an increase in falls at home, were observed during the COVID-19 pandemic.
Go to:
Notes
CONFLICT OF INTEREST:No potential conflict of interest relevant to this article was reported.
Go to:
References
Dighe A, Cattarino L, Cuomo-Dannenburg G, et al. Response to COVID-19 in South Korea and implications for lifting stringent interventions. BMC Med 2020;18(1):321
Korean National Statistical Office. COVID-19 dashboard in Republic of Korea [Internet]. Korean National Statistical Office; 2022 [cited 2022 Sep 2].
Available from: https://kosis.kr/covid_
eng/covid_ index.do.
Sahu D, Gupta A, Bansal SS. A surge in neglected shoulder dislocations and delayed surgical management due to the coronavirus disease 2019 lockdown in India. Clin Shoulder Elb 2021;24(4):265–271.
Chang DG, Park JB, Baek GH, et al. The impact of COVID-19 pandemic on orthopaedic resident education: a nationwide survey study in South Korea. Int Orthop 2020;44(11):2203–2210.
Um SH, Kim DH, Youn MY, et al. Protection of surgical team from COVID-19 during bipolar hemiarthroplasty in an infected elderly patient. Clin Orthop Surg 2020;12(3):286–290.
Oputa TJ, Dupley L, Bourne JT. North West COVID NOF Study Group. One hundred twenty-day mortality rates for hip fracture patients with COVID-19 infection. Clin Orthop Surg 2021;13(2):135–143.
Sahu D, Rathod V, Phadnis A, Bansal SS. Telehealth for consultation and shoulder rehabilitation: a preliminary study on the perspectives of 30 patients during the COVID-19 lockdown. Clin Shoulder Elb 2021;24(3):156–165.
Simon MJ, Regan WD. COVID-19 pandemic effects on orthopaedic surgeons in British Columbia. J Orthop Surg Res 2021;16(1):161
Best J, Stoker S, McDaniel D, et al. Effects of easing shelter-in-place restrictions and the lingering COVID-19 pandemic on orthopaedic trauma at a community level 2 trauma center. OTA Int 2021;4(2):e123
Scarlat MM, Sun J, Fucs PM, et al. Maintaining education, research and innovation in orthopaedic surgery during the COVID-19 pandemic: the role of virtual platforms: from presential to virtual, front and side effects of the pandemic. Int Orthop 2020;44(11):2197–2202.
Mavrogenis AF, Quaile A, Scarlat MM. The virus crisis affects orthopaedic surgery and scientific activities worldwide. Int Orthop 2020;44(5):813–817.
Knebel C, Ertl M, Lenze U, et al. COVID-19-related cancellation of elective orthopaedic surgery caused increased pain and psychosocial distress levels. Knee Surg Sports Traumatol Arthrosc 2021;29(8):2379–2385.
Gumina S, Proietti R, Polizzotti G, Carbone S, Candela V. The impact of COVID-19 on shoulder and elbow trauma: an Italian survey. J Shoulder Elbow Surg 2020;29(9):1737–1742.
Oussedik S, MacIntyre S, Gray J, McMeekin P, Clement ND, Deehan DJ. Elective orthopaedic cancellations due to the COVID-19 pandemic: where are we now, and where are we heading? Bone Jt Open 2021;2(2):103–110.
Graichen H. What is the difference between the first and the second/third wave of COVID-19? German perspective. J Orthop 2021;24:A1–A3.
Yu JS, Rodrigues AJ, Bovonratwet P, et al. Changes in Orthopaedic diagnoses during the COVID-19 pandemic. J Clin Orthop Trauma 2021;22:101603
Sherman WF, Khadra HS, Kale NN, Wu VJ, Gladden PB, Lee OC. How did the number and type of injuries in patients presenting to a regional level I trauma center change during the COVID-19 pandemic with a stay-at-home order? Clin Orthop Relat Res 2021;479(2):266–275.
Neer CS 2nd. Displaced proximal humeral fractures. I. Classification and evaluation. J Bone Joint Surg Am 1970;52(6):1077–1089.
Neer CS 2nd. Fracture of the distal clavicle with detachment of the coracoclavicular ligaments in adults. J Trauma 1963;3:99–110.
Cho CH, Kim BS, Kim DH, Choi CH, Dan J, Lee H. Distal clavicle fractures: a new classification system. Orthop Traumatol Surg Res 2018;104(8):1231–1235.
Rockwood CA, Green DP. In: Rockwood and Green’s fractures in adults. Lippincott; 1984. pp. 860-910.
Dillon MT, Chan PH, Prentice HA, et al. The effect of a statewide COVID-19 shelter-in-place order on shoulder arthroplasty for proximal humerus fracture volume and length of stay. Semin Arthroplasty 2021;31(2):339–345.
- Cite
- Article
Cited by
Publication Types
Original Article
MeSH Terms
Since 2023/04/01
Metrics
Page Views 132
PDF Downloads 28
Figures
Show all...
1 / 3
Tables
Show all...
1 / 2