Abstract
Objectives:
Tendon ruptures affect quality of life, participation in competitive athletics and increase healthcare costs. Previous literature has focused on diagnostic evaluation and management of tendon ruptures and there is scarce epidemiological data on this topic. The epidemiological literature that does exist regarding this topic is often limited to the achilles and patellar tendons. Furthermore, to our knowledge these studies are largely based out of Europe or Canada and prior to 2010. The purpose of this study was to provide a U.S population-based study using the NEISS database, on the incidence of tendon ruptures and describe whether racial differences exist in the incidence of tendon ruptures.
Methods:
The NEISS, a nationally representative sample of US hospital emergency departments, was used to ascertain the incidence rates of various types of tendon ruptures in the United States. All cases from 2001-2020 were reviewed for case narratives to select only those cases with a clear diagnosis of an acute primary tendon rupture. After exclusions, a total of n=5,765 unweighted cases were identified, representing a national estimate of N=235,189 tendon ruptures (95% CI=186,833-283,546). The NEISS database contains patient demographic information including age, sex, and race. Race categories were regrouped as follows: American Indian/Alaska Native (AI/AN) individuals were added to the category “Other,” and Native Hawaiian(NH)/Pacific Islander (PI) individuals were added to the category “Asian” due to the small number of cases involving these groups. Thus, the race categories for final analysis included (1) White, (2) Black/African American, (3) Other (including “Other” and “AI/AN”), and (4) Asian/Pacific Islander (“Asian,” including “Asian” and “NH/PI”). Statistical analysis was performed using the survey data commands in Stata/IC, version 17.0 (StataCorp, College Station, TX, US), accounting for sample weights and the complex survey designs. The incidence rate (IR) of tendon ruptures and mechanism were calculated and chi-square tests were used to compare estimated IRs between groups. Incidence rate ratios (IRRs) are reported and represent unitless expressions of risk used for the comparison of IRs between two distinct subgroups, with the IR of an identified referent subgroup serving as the denominator. IRRs among race, sex, and age groups are reported. Student t-test/analysis of variance and design-adjusted Rao-Scott chi-square analysis was used for direct comparisons of means for continuous variables and proportions for categorical variables, respectively. Temporal trends and annual percentage changes were assessed via regression analysis.
Results:
Race was specified in 71.4% of cases. Race data was unavailable for the remaining 28.6% of cases. Unweighted case numbers (n) and national estimates (N) for each racial category, prior to regrouping, are displayed in Table 1. Due to the small number of cases involving AI/AN and NH/PI individuals, these were regrouped for further analysis, as described in the Methods. The largest total number of injuries occurred in White patients, with an estimated N=115,905 tendon ruptures (95% CI=83,461-148,348) in this group for an overall IR of 24.0 PYR (95% CI=17.3-30.7). As seen in Table 2, Black patients had the highest overall IR, with an estimated N=38,679 ruptures (95% CI=21,552-55,807) occurring in this group for an overall IR of 47.8 PYR (95% CI=26.6-68.9). An estimated N=9,186 ruptures (95% CI=5,881-12,491) occurred in patients of Other race for an overall IR of 43.5 PYR (95% CI=27.8- 59.1). Finally, N=4,151 ruptures (95% CI=777-7,524) occurred in Asian patients for an overall IR of 12.9 PYR (95% CI=2.4-23.2). When compared with White patients, the overall injury rate was significantly higher among Black patients (IRR=1.99, 95% CI=1.06-3.76; p<0.05) and Other patients (IRR=1.81, 95% CI=1.09-3.03; p<0.05), and was similar in Asian patients (IRR=0.53, 95% CI=0.27-1.06; p>0.05). There was no statistically significant difference in overall incidence among Black and Other patients (with Other race as the referent, IRR=1.10, 95% CI=0.62-1.95; p>0.05). Figure 1 illustrates the rising annual incidence of tendon ruptures overall and the differences between racial groups between 2001-2020.
Conclusions:
To our knowledge, no other study analyzes racial differences in tendon injuries in the general US population. Our study showed that patients who identified within the "Black" race had a significantly higher IR of tendon rupture than “White” and “Asian” patients but no statistically significant difference compared to “Other” races. Higher incidence rate of tendon rupture seen in Black individuals is likely multifaceted and further studies would be required to ascertain specific differences. Tendon injuries are often due to acute sudden contractile forces that overcome the ultimate strength of the specific tendon. Therefore, differences seen in our study most likely arise from differences in recreational activity/ sports participation. However, overuse, age-related degeneration, genetics, corticosteroids have all been described as risk factors for tendon injury. The purpose of this study was to identify that there is indeed a difference in incidence rate of tendon rupture between racial groups in the US.
The limitation of our study is that the NEISS database is composed entirely of ED encounters and the accuracy of the IR reported in this study are also highly reliant upon accuracy of the case narrative descriptions, which are prone to reporter bias. Despite these limitations, the NEISS database is an established model for epidemiological surveillance of musculoskeletal injuries. Its strengths include its large scale, heterogeneous patient population, and substantial external validity.
