Distal Radius Fractures (DRF) are anatomically defined as those occurring within 3 cm of the radiocarpal joint, corresponding to one sixth of all fractures treated in emergency units and with great cost to the health system. 1,2 The DRF have significant epidemiological and clinical-surgical importance due to the high prevalence, that is, up to 31%. 3 In addition, the complexity of the lesions varies according to the involvement of adjacent anatomical regions, implying different prognoses whose treatment may be different. conservative or surgical. [4][5][6] Observational Studies (OS) have different degrees of reliability, and can be compared to a photograph of the population (cross-sectional study) or temporal analysis of the sample in question (longitudinal study). 7 Thus, the present scientific dissertation aims to explain the OS of these two methodologies about the epidemiology associated with the trauma of DRF and factors implicating the seasonality of the prevalence and incidence.

The methodology used was the systematic review, in which the research platforms MEDLINE® and LILACS for BIREME, PUBMED and SCIELO were used. In this context, according to the Descriptors in Health Sciences platform and with descriptors in Portuguese, English and Spanish, 2 Volume 23 | Issue 5 | Compilation 1.0 the following descriptors were selected: "Bone fracture" and "Radius fracture"; "Wrist joint"; "radius fracture".

The inclusion criteria corresponded to complete and available articles, from the last five years (October 30, 2016 the same date of the year 2021), only with human beings, OS of the transverse and longitudinal types and that addressed the distal third of the radius as an outcome.

Exclusion criteria were articles that did not address radius fracture, protocol validation studies, case reports and series, systematic reviews, meta-analysis, randomized controlled trials and case-control studies.

Table 1 summarizes the methodology, sample size, study design, primary out-come result, gender and age group included in the studies eligible for this systematic review. elimination of duplicates, 64 articles were selected for reading in full, with 18 being eligible for this systematic review. The flowchart (figure 1)

demonstrates such steps of the methodological process.

Table 2 explains the fracture rate according to the AO 8 classification (types A, B and C) and the frequencies of accidents associated with the trauma mechanism.

When assessing whether obesity increases the severity of DRF, in one study, it was found that there was no correlation based on a sample of 114 patients, although this population is more susceptible to fractures in this region. 9 A study aimed at quantifying the ability of unicortical distal screws to maintain the operative reduction of DRF in adults, in a sample of 75 patients undergoing volar fixation with a locking plate, resulted in data that corresponded to effective fixation and maintained the operative reductions in DRF, whereas it had the potential to decrease the incidence of extensor tendon ruptures in a 12-week post-surgical follow-up. 10 Comparing type B DRF with and without involvement of the semilunar facet treated with a volar blocking plate, we retrospectively analyzed the individuals with involvement of the semilunar facet (n=21) and the others without this involvement (n = 72), it was found that patients with DRF with involvement of the semilunar facet would have slower recovery with regard to wrist flexion, supination, ulnar deviation and greater risk of loss of both reduction and final joint step. 11 Thus, fractures of DRF with involvement of the semilunar facet present clinical factors of severity and longer time for convalescence of the bone material.

When studying patients aged 50 years and over with a total sample of 25,454 fractures, of which 42.1% corresponded to fractures of the radius or ulna, Ogliari et al. 12 verified that most of the injuries in this region occurred in the winter period, in which frosty days were directly associated with fractures of the radius or ulna. In addition, confirmation of the increase in accidents involving DRF in colder seasons can help direct financial resources from health services and increase the number of employees available during this period. Thus, considering the temperate climate of the study site, it can be suggested that other parts of the globe, including the southern region of Brazil, may have a similar rate of involvement, which should be corroborated by future studies and evaluated according to the possibility of greater exposure. to falls from standing height by the general population and higher risk of falls in geriatric individuals on slippery floors.

Another study looked at the profile of DRF in relation to climate, in which a retrospective analysis with 8,380 patients verified wrist joint fractures in all women and men aged ?50 years, and demonstrated an increase in the rate of this type of fracture with the reduction in temperature (milder seasons of the year) and the average rate was 2.9 fractures/day out of a total of 2,922 days analyzed and an increase of 840 in the number of Distal Radius Fracture: A Systematic Review of Observational Studies 6 Volume 23 | Issue 5 | Compilation 1.0 6 procedures during the winter period. 13 Thus, in regions with a cold climate, health services can direct resources to this patient profile. Furthermore, Range of Motion Limitation (RML) after DRF was studied in 88 geriatric patients, in whom daily rehabilitation was applied for 30 minutes for 8 weeks after the fracture, and it was verified that individuals with early stiffness (<3 months after the fracture) had greater RML compared to those with late stiffness (>3 months). 14 A cohort with a sample of 202 children (up to 16 years of age) addressed the complication rate of forearm fractures after treatment with stable intramedullary elastic nails, which correspond to in situ refracture (1.5%), refracture after nail removal (3.5%), vicious junction (1.0%), rupture of the extensor pollicis longus tendon (1.5%), infection 1 (0.5%) and reduced range of motion (1.0%). 15 Wang et al. 16 analyzed, by means of a longitudinal retrospective study, 410 children and adolescents (aged from 6 to 18 years), whose aim was to characterize polytrauma due to sports, in which it was verified that radius fractures were the most common (24.9%) relative to other long bones. In addition, males had a significantly higher rate of fractures and associated nerve injuries, with peaks of incidence in the summer and the most associated sport was basketball (28.9%).

A prospective longitudinal study followed patients with DRF for 12 months in order to verify the future risk of fracture in two groups, that is, young versus elderly men (65 years or older), whose result associated that the second group was more prone to having a disability in working with hands, arms and shoulder ipsilateral to the injury, regardless of the macroscopic radiographic finding. Furthermore, the decreased bone strength of these patients was associated with an increased risk of fracture at 10 years. 17 Furthermore, another population-based retrospective longitudinal analysis sought to determine the proportion of DRF treated without adequate medical follow-up after initial care, as well as the type of medical care provided by different hospitals and physicians. And, from the analysis of 70,801 fractures, it was found that 20.8% (n=14,742) of fractures were treated without continuous medical follow-up after initial care and treatment by a small hospital emergency department, pediatric specialty or subspecialty in a pediatric emergency, were more likely to result in no follow-up. In addition, small hospitals and living in a rural area were significantly associated with non-monitoring after the injury. 18 A retrospective observational cohort with the aim of determining the incidence of DRF, in which 90,970 DRF were identified between the years 2005 to 2012, whose incidence rate during the entire period analyzed was 52.9/10,000 people/year, with the distribution between genders equal in the age group from 0 to 10 years old, however, higher in males from 11 to 17 years old. Furthermore, there was a significant variation in incidence throughout the year, with higher peaks in May (68.7/10,000 person-years) and September (73.2/10,000 person-years). 19 Thus, considering that the period ob-served of higher incidences corresponds to milder temperatures, it can be suggested that such incidence may be related to sports activities or activities of greater impact.

A prospective cross-sectional study compared pediatric patients (<18 years) and adults (? 18 years) in two moments, before and during the covid-19 pandemic, with the aim of characterizing variation in epidemiological data on hospitalization and the need for a surgical approach. The first group showed a decrease in hospitalizations (3.8%), hospitalizations with surgical treatment (11.5%) and patients undergoing conservative treatment (7.2%). The adult population showed a decrease in the rate of hospitalizations treated surgically (12.7%) and in the number of individuals undergoing conservative treatment (30.3%), while those who underwent surgical treatment with fixation by volar plate increased substantially (275%). 20 Rundgren et al. 21 with the aim of determining Surgical Site Infections (SSI) after DRF surgery using different techniques (plate fixation, percutaneous pinning and external fixation), as well as factors associated with SSI in a sample of 31,807 patients, found that the rate of SSI corresponded to rates of 5%, 12% and 28%, respectively. Furthermore, it was found that the type of open fracture and being male were associated with SSI. Nagai et al. 22 evaluated the relationship between Potentially Inappropriate Medications (PIM), activities of daily living and subsequent falls in elderly patients with DRF, aged 65 years and over and divided into two groups (a group using PIM and a group not using PIM). The prevalence of prescriptions for PIM was 42.3% and their use hindered the improvement in activities of daily living and was associated with an increase in subsequent falls.

A retrospective cohort study included 304 adults aged 60 years or older who had isolated DRF and divided into two groups: group I with 187 participants (volar locking plate, percutaneous pinning or external fixation) and group II with 117 individ-uals (treated with a cast) and classified into highly and less active based on the degree of physical activity prior to the injury. The results suggested that more physical activity practiced before the injury was associated with better functional results and patient-reported self-improvement. Thus, supervised physical activity, due to the risk of falls, should be encouraged in these patients. 23 Another research, when evaluating Parkinson's Disease (PD) in two groups with (n=23) and without (n=65) the disease regarding the best outcome in patients with DRF, in which both groups underwent open reduction followed by of internal fixation, with the aim of verifying whether the PD group would have a lower result after surgery compared to non-PD patients, it was found that there was a shorter time and a significant rate of treatment failure, these being 39.1% and 4.6%, respectively. 24 A retrospective longitudinal study with the objective of investigating the asso-ciation between nutritional status and functional prognosis in elderly patients with DRF in elderly individuals, found that a positive association between malnutrition and the ability to resume activities of daily living after DRF and low levels of albumin serum levels may increase the risk of subsequent falls, and a rate of 13.5% of patients with DRF had malnutrition. 25 When assessing the frequency with which children younger than 10 years old undergo a potentially unnecessary closed reduction associated with sedation for the DRF procedure and the cost implications, Orland et al. 24 found that among 258 participants, 142 (55%) underwent this procedure and 38 children (27%) were considered potentially unnecessary with a cost increase of about 8 times the amount and the fractures could have been treated with in situ immobilization. 26

It is verified that there is seasonality in the DRF regarding the seasons. The reduced bone strength of these patients was associated with an increased risk of frac-ture in 10 years, and individuals from a rural environment have less hospital support and a greater chance of not having adequate post-fracture follow-up. In addition, obe-sity was not a serious factor for DRF recovery.