Trends in Upper Extremity Saw Injuries From 2003 to 2022

Abstract

Background:

Saws are a common source of upper extremity injury. There have been several commercial and government-mandated safety mechanisms designed to reduce the number of saw injuries. We aim to assess the trends in the incidence and impact of saw-related upper extremity injuries over the last 2 decades.

Methods:

The National Electronic Injury Surveillance System database was queried from January 2003 to December 2022 for upper extremity injuries caused by saws. Summary statistics for primary body part injured and diagnosis were calculated. Linear regression was performed to evaluate trends in the number of injuries over time.

Results:

An estimated 1.38 million injuries (weighted) presenting to emergency departments were reported from January 2003 to December 2022. Patients had a mean age of 50.5 ± 18.1. Digits (82.2%) accounted for most injuries, followed by hands (11.9%). The lower arm (3.4%), wrist (1.66%), shoulder (0.3%), elbow (0.2%), and upper arm (0.2%) accounted for fewer injuries. There was a downtrend in number of saw injuries over the study period (R = 0.83, R2 = 0.69, p < .001). Subgroup analysis showed decreases in number of injuries to fingers (R = −0.82, R2 = 0.67, p < .001) and wrists (R = −0.61, R2 = 0.37, p = .004). The most common diagnoses were lacerations (69.7%), fractures (12.6%), and amputations (9.9%).

Conclusions:

Upper extremity saw injuries have significantly decreased over the last 20 years. The fingers and hands account for the vast majority of saw injuries, resulting most commonly in lacerations, fractures, and amputations.

Level of Evidence:

IV.

Introduction

Numerous types of saws are currently available for use in both private and commercial settings. The design of most saws requires manipulation of either the saw itself or the material being cut, placing the user’s hands in close proximity to the sharp blades. The rapidly spinning blades of power saws can either directly injure the user, or loose-fitting clothing or accessories can become entrapped in the blade, pulling the user’s arm into the blade. Saw injuries are therefore a common cause of upper extremity traumatic injury and are frequently treated by hand surgeons.

Saw injuries to the upper extremity are associated with significant morbidity, healthcare costs, and costs to society. Smith et al ¹ found that 43% of saw injuries were characterized as “severe,” indicating partial or complete amputation. Another study examining the economic impact of saw injuries found that patients missed a mean of 64 days of work and incurred $30 754 in medical expenses. ² The Consumer Product Safety Commission (CPSC) estimates that the total cost associated with all saw injuries in the United States is $4.2 billion, with an estimated $3.3 billion (79%) due to addressable causes. ³

Governmental regulations and product safety mechanisms have therefore been introduced in an effort to reduce saw injuries. While these safety mechanisms have been efficacious, ⁴ saw injuries continue to be a common source of upper extremity injury. A nuanced understanding of the continued causes of saw injuries despite current safety mechanisms is critical in directing future safety initiatives. There is currently a paucity of literature comprehensively describing trends in upper extremity injuries caused by various types of saws. The authors therefore aim to assess detailed trends in saw-related upper extremity injuries over the last 2 decades.

Methods and Materials

The United States CPSC (US CPSC)’s National Electronic Injury Surveillance System (NEISS) database was used for the study. This database has previously been used for similar population-level investigations.^5,6 Data related to injuries were completely deidentified and was thus exempt from the institution’s IRB approval requirement. The CPSC randomly samples 100 hospitals each year from a pool of more than 5000 U.S. facilities that operate 24/7 emergency departments (EDs) to report on injuries related to consumer products.

The NEISS database was queried from January 2003 to December 2022 for all upper extremity injuries caused by all workshop saws. Specific product codes used are illustrated in Table 1. Patient demographics, injury date, the corresponding diagnosis, injury location, and disposition data were collected. In addition, weights provided by NEISS were obtained to estimate the approximate number of cases across the United States. Only injuries that occurred to the upper extremity (shoulders, elbow, lower arm, wrist, upper arm, hand, and finger) were included.

Table 1.

Product Codes Queried.

Code	Product name
809	Other portable or stationary power tools
832	Portable circular power saws
841	Bench or table saws
842	Band saws
843	Radial arm saws
844	Power hack saws
845	Saws, not specified
863	Other power saws
864	Sabre saws
875	Jigsaws
894	Hacksaws
895	Power saws, not specific

Statistical Analysis

All analyses were performed with Python using JupyterLab, version 3.12.1 (Project Jupyter, New York, New York). To convert the number of reported cases from NEISS to a national estimate, each case was multiplied by its respective weight factor. To determine the 95% confidence interval, the coefficient of variation for each year, provided by NEISS, was used. Descriptive, summary statistics were utilized for analyses. Linear regression was performed to evaluate trends in weighted number of injuries over time. Shapiro–Wilk’s test was used to evaluate the normality of patient’s age ranges.

Results

A total of 25 375 injuries (unweighted) were reported from the random sample of NEISS-participating hospitals, which was estimated to be a national total of 1 386 085 injuries (weighted). Nearly all injuries were due to power saws, with hand saws accounting for 5 out of 25 375 unweighted injuries (0.02%) and 132 out of 1 386 085 weighted injuries (0.01%). There was a statistically significant downtrend in number of saw injuries over the study period (R = 0.83, R² = 0.69, p < .001). Linear regression of weighted injuries per year is shown in Figure 1, and weighted estimates are plotted with 95% confidence intervals in Figure 2.

Figure 1.

Linear regression showing the weighted national estimates of upper extremity saw injuries.

Figure 2.

Weighted national estimates of upper extremity saw injuries with 95% confidence interval.

Saw injuries primarily affected men (95.53%). Subgroup analysis showed that males had a statically significant decrease in injuries over the study period (R = −0.85, R² = 0.72, p < .001), but there was no difference observed for females over the interval (R = −0.23, R² = 0.05, p = .32).

Patients had a mean age of 50.5 ± 18.1 years. Shapiro–Wilk’s testing failed to reject the null hypothesis of a normal age distribution (p < .05) (Figure 3); prompting a subgroup analysis of age groups. The majority of injuries were in 3 age groups: 50 to 60 years (19.8%), 60 to 70 (19.2%), and 40 to 50 years (16.8%). Subgroup analysis by age showed statistically significant decreases in saw injuries in the 10 to 20 year (R = −0.93, R² = 0.87, p < .001), 20 to 30 year (R = −0.75, R² = 0.56, p < .001), 30 to 40 year (R = −0.68, R² = 0.47, p < .001), 40 to 50 year (R = −0.93, R² = 0.86, p < .001), and 50 to 60 year (R = −0.83, R² = 0.69, p < .001) age ranges. There were statistically significant increases in saw injuries in the 60 to 70 year (R = 0.76, R² = 0.57, p < .001) and 70 to 80 (R = 0.56, R² = 0.32, p = .01) year age groups. All other ages between 0 and 100 showed statistically nonsignificant trends.

Figure 3.

Upper extremity saw injuries age distribution.

The majority of patients affected were White (65.13%) or African-American (3.42%). Many entries did not include a stated race (30.71%) or were coded as “other” (4.31%). Subgroup analysis showed a statistically significant decrease in injuries in white patients (R = −0.65, R² = 0.42, p = .002) and “other” race patients (R = −0.72, R² = 0.51, p < .001). All other races showed statistically nonsignificant trends.

Digits (82.2%) accounted for the majority of injuries, followed by hands (11.9%). The lower arm (3.4%), wrist (1.66%), shoulder (0.3%), elbow (0.2%), and upper arm (0.2%) accounted for fewer injuries. Subgroup analysis showed statistically significant decreases in number of injuries to fingers (R = −0.82, R² = 0.67, p < .001) and wrists (R = −0.61, R² = 0.37, p = .004). Hands, lower arms, elbows, upper arms, and shoulders exhibited high variability with statistically nonsignificant trends.

The most common diagnoses were lacerations (69.7%), fractures (12.6%), and amputations (9.9%). Subgroup analysis showed statistically significant decreases in lacerations (R = −0.92, R² = 0.84, p < .001) and avulsions (R = −0.74, R² = 0.55, p < .001). There were statistically significant increases in fractures (R = 0.63, R² = 0.40, p = .003) and “other/not stated” injuries (R = 0.70, R² = 0.49, p < .001). There were statistically nonsignificant decreases in contusions/abrasions (R = −0.37, R² = 0.14, p = .11) and amputations (R = −0.16, R² = 0.03, p = .49). Further subgroup analysis examining amputations by saw type showed no significant changes in amputation injuries for any saw type.

Subgroup analysis was performed to stratify injuries by saw type. The majority of injuries were caused by bench or table saws (47.3%), followed by saws that were unspecified (15.7%), power saws that were not specified (14.8%), portable circular power saws (13.6%), band saws (4.1%), hacksaws (1.0%), sabre saws (0.8%), and jigsaws (0.8%). The remaining 1.9% are accounted for by various other products summing to less than 0.5% each. There were statistically significant decreases in injuries due to bench or table saws (R = −0.66, R² = 0.44, p = .001), circular saws (R = −0.69, R² = 0.48, p < .001), band saws (R = −0.58, R² = 0.34, p = .007), hacksaws (R = −0.71, R² = 0.51, p < .001), and unspecified saws (R = −0.70, R² = 0.50, p < .001). Powered milter saws had a statistically nonsignificant decrease in injuries (R = 0.73, R² = 0.01, p = .73).

The majority of patients (91.8%) were released (with or without treatment). A minority of patients were treated and admitted for hospitalization within the same facility (4.5%) or treated and transferred to another hospital (2.8%). Less than 1% of patients were held for observation or left without being seen. There were no reported fatalities in the dataset.

Discussion

Saw use places the fingers and hands in high-risk positions for injury. Safety regulations and device safety mechanisms have been associated with a decreased number of injuries in the last decade, yet saws still account for a significant number of upper extremity injuries and ED visits each year. ⁴ Accurate estimates of national trends are important in guiding future safety initiatives. This study evaluated epidemiological trends in upper extremity saw injuries from 2003 to 2022.

There was a statistically significant decrease in upper extremity saw injuries between 2003 and 2022. This downtrend was driven by relatively larger decreases in males more than females, fingers more than more proximal anatomic locations, lacerations more than other injury types, and White patients more than other races.

These findings are consistent with and expand on prior literature examining trends in saw injuries.^4,7,8 In their examination of saw injuries at a single institution, Hoffa ⁹ found that table saws accounted for the largest proportion of injuries at 48%, which is nearly identical to our national estimate of 47.3%. They identified fingers as the most commonly injured body part, accounting for 92.2% of injuries compared to our national estimate of 82.2%. Amputations accounted for 19.4% of their series, compared to the national estimate of 9.9%. Their overrepresentation of amputations may be due to their investigation being performed at a Level 1 trauma center which may preferentially receive the most severe injuries.

The reasons for these decreases are multifactorial. Several passive and active saw safety mechanisms have been developed. Additionally, new safety regulations were adopted which appear to have been successful in decreasing the rate of saw injuries. ⁴ Based on recommendations from the CPSC, Underwriters Laboratories began requiring the use of riving knives on newly designed table saws in 2008 and their incorporation into all table saws by 2014. Riving knives are thin blades which sit immediately behind a table saw blade opposite the user. These function to prevent kickback of the wood by preventing binding of the wood segments on the blade. This likely accounts for some of the decrease in table saw injuries but would not be relevant to other types of saws.

Modular blade guards are a passive table saw safety mechanism which involves a plastic shield which sits over the saw blade. It opens only enough to allow the material being cut to contact the saw. It improves the safety of table saws via several mechanisms. First, it covers all portions of the blade not involved in cutting the material, significantly limiting the area where the user’s fingers can contact the blade. Second, it covers the top of the blade which prevents accidentally dropped pieces of material from being projected at high speed toward the user. Third, it limits the scatter of debris toward the user while cutting. While effective at limiting injuries, blade guards are commonly removed by users for a variety of reasons including improved visualization, incompatibility with certain types of cuts and instruments, and personal preference.

Table saws with Active Injury Mitigation (AIM) systems were first developed by SawStop (Tualatin, OR, USA) as an active safety feature to decrease table saw user injuries, and similar technology has since been adapted by other manufacturers. By running a low-voltage electric current through the saw blade, these devices can differentiate between flesh and wood. Upon contact with flesh, a high-speed braking system is activated, causing the blade to stop spinning and retract into the table. While these AIM systems are highly effective, widespread adoption appears to be limited.

Amputations are the most severe saw-related injuries. They did not significantly decrease over the study period, neither overall nor when stratifying by individual saw types. The reasons for this are not clear. Resistance to adoption of safety standards and inadequacy of current safety mechanisms are hypothesized to be the largest contributors. ¹

The limitations of this study are those inherent to large database studies. Data are dependent on accurate reporting. NEISS data are sourced from hospitals and EDs, so this dataset would not include injuries treated in the office of hand surgeons or other physicians. Injuries self-managed by patients at home would similarly not be included in this dataset. Patients with less severe injuries may preferentially not seek care or present directly to the clinic, which would bias these data by overrepresenting more severe injuries. In addition, the study period included the years of the COVID-19 pandemic, which could potentially affect the injury rates. This is consistent with prior studies which found that overall visits to the ED related to nonfatal accidents as well as upper extremity injuries decreased when comparing the prepandemic period to the pandemic period.^10,11

However, these limitations would be expected to affect the entire dataset equally, so the demonstrated trends are expected to be accurate.

Conclusions

While saw injuries have steadily declined over the prior 2 decades, upper extremity saw injuries are still a regular occurrence and cause of disability. This study provides preliminary evidence that national trends have demonstrated a decrease in these injuries over the interval studied using a validated, nationwide injury tracking system. Further development of safety innovations, government regulations, and user education are needed to continue to decrease saw injuries.