Orthopedics

Review Article 

Understanding Nail Gun Injuries in Orthopedics: Mechanisms and Treatment

Jonathon M. Spanyer, MD; Harrison M. Lands, BA; Sean C. Kelly, MD; Paul S. Page, MD; Madhusudhan R. Yakkanti, MD

Abstract

Nail gun injuries are common among users, and most frequently involve the hands and lower extremities. A wide variation in costs and time are missed from work due to these injuries, and training on the proper use of nail guns has been shown to decrease workplace-related injuries. Minimal long-term disability can be expected, and orthopedic evaluations provide an opportunity to inform patients on proper use of these devices. In this article, management of nail gun injuries is discussed, including the necessity for a high suspicion for wound contamination because foreign material is often deposited with the nail, as well as treatment with debridement and antibiotics. [Orthopedics. 201x; xx(x):xx–xx.]

Abstract

Nail gun injuries are common among users, and most frequently involve the hands and lower extremities. A wide variation in costs and time are missed from work due to these injuries, and training on the proper use of nail guns has been shown to decrease workplace-related injuries. Minimal long-term disability can be expected, and orthopedic evaluations provide an opportunity to inform patients on proper use of these devices. In this article, management of nail gun injuries is discussed, including the necessity for a high suspicion for wound contamination because foreign material is often deposited with the nail, as well as treatment with debridement and antibiotics. [Orthopedics. 201x; xx(x):xx–xx.]

Nail guns have been used in a variety of commercial construction applications since their advent in the 1950s and have evolved into a common tool for residential projects.1 The extremities remain the most commonly affected area of injury due to nail gun use.2–9 Often, injuries are associated with local tissue damage and contamination, necessitating operative debridement, which is frequently performed by an orthopedic surgeon.10 The authors present an overview of appropriate nail gun operation, mechanisms of injury, treatment options, and safety considerations in an effort to provide recommendations for the management of nail gun injuries among orthopedic surgeons.

Nail Gun Operation

Nail gun manufacturers use a variety of mechanisms to generate the force necessary to project nails into target objects. The most common mechanisms include a spring-loaded electric actuator (simple electric) and compressed air (pneumatic), and less common mechanisms are solenoids and combustion chambers. The simple electric nail gun is less expensive and ideal for residential use but may lack the power necessary for commercial use. The pneumatic nail gun (Figure 1) is the most popular type in the commercial setting because firing and reloading are quickly accomplished (Figure 2).3,11

Photograph of commercially available pneumatic nail gun (compressed air hose not shown).

Figure 1:

Photograph of commercially available pneumatic nail gun (compressed air hose not shown).

Pneumatic nail gun mechanism. Compressed air from an external source (A) travels through the handle/grip of the gun and may be discharged when the safety latch is depressed and the trigger (B) is pulled. The pressure gradient propels the plunger (C) and actuating arm (D), driving it toward the projectile (nail), which remains stationary in the cartridge/magazine. The return air chambers (E) conserve this kinetic energy by acting as a reservoir for compressed air as the piston is being driven forward, eventually allowing this energy to drive the piston back into place for the next cycle. The air pressure is released via the exhaust behind the mechanism.

Figure 2:

Pneumatic nail gun mechanism. Compressed air from an external source (A) travels through the handle/grip of the gun and may be discharged when the safety latch is depressed and the trigger (B) is pulled. The pressure gradient propels the plunger (C) and actuating arm (D), driving it toward the projectile (nail), which remains stationary in the cartridge/magazine. The return air chambers (E) conserve this kinetic energy by acting as a reservoir for compressed air as the piston is being driven forward, eventually allowing this energy to drive the piston back into place for the next cycle. The air pressure is released via the exhaust behind the mechanism.

The American National Standards Institute classifies nail guns based on the projectile velocity, with pneumatic guns classified as low velocity (<99 m/s, or approximately 325 ft/s), and combustion chamber guns reaching projectile speeds of up to 454 m/s (approximately 1500 ft/s).3,11–13 The amount of energy required to cause serious injury is relatively low, with penetration of the skin occurring at projective speeds of 150 ft/s and fractures occurring at speeds of 195 ft/s.14,15

It is important to understand the structure of these tools so that the extent of the damage can be appropriately evaluated. Nearly all nail guns share a few common features, including handle/grip, cartridge/magazine, actuating arm, and trigger/safety feature(s). The cartridges hold the nails together and allow for easy loading of the projectiles into nail guns. Many nails come glued to each other, coiled by metal wire, or bonded with long metallic strips/barbs, plastics, or tape. These binding resins and wires may be found in wounds at the time of injury, and often do not manifest on radiographic evaluation.

In addition, most nail guns have 1 or more manufacturer-introduced safety mechanisms to prevent injuries. Safety locks require the user to flip a small switch before the trigger can be depressed. Another common safety feature requires the muzzle of the nail gun to be placed on the target object and the tip depressed prior to discharge. With this type of trigger, a contact actuation trigger (CAT), the user must concomitantly depress the muzzle of the nail gun against the target object and squeeze the trigger to deploy the nail. However, the nail gun will still deploy a projectile if the trigger is pulled first and the muzzle is subsequently depressed against the target. Alternatively, the sequential actuation trigger (SAT) requires the depression of the muzzle into the target object, followed by depression of the trigger before deploying a nail.16,17

Orthopedic Injuries

Nail gun injuries most often occur in men, with a median age of 27 years for commercial workers and 35 years for residential users.6 An analysis released by the Centers for Disease Control and Prevention showed that the injuries occur most frequently among those in an occupational setting (28,600 documented injuries in 2005), followed by consumers in the residential setting (13,400 injuries).6 Of these injuries, the most common locations were the nondominant hand and fingers (58%), likely from stabilizing the target object, followed by the knee and distal lower extremity (24%).3,9,18

Similar to other projectiles, nails cause injury to soft tissue through direct trauma and cavitation.3,11 Importantly, shock waves produced in tissues compress adjacent structures and cause damage.13 In a retrospective study of 87 nail gun injuries to extremities, Ling et al3 reported a 16% incidence of neurovascular injury, a 24% incidence of bone involvement, and a 37% incidence of tendon injury. In another review of 88 nail gun injuries over a 4-year period, Horne et al9 found no vascular or neurological injuries that required repair,19 suggesting that surgical repair is not often indicated for neurovascular injuries, but that simple extraction is sufficient.

Contamination of the soft tissue was commonly identified among operatively treated patients. Ling et al3 reported a 20% incidence of retained foreign material, many of which were not radiographically identifiable prior to surgery.11 Horne et al9 showed that infections associated with nail gun injuries were uncommon (3.4%) and that infections were limited to those patients who presented 1 or more days after the injury.

Hand Injuries

Because hand-related injuries are the most common type of injury with nail guns, they deserve a more detailed focus, especially because hand injuries in general represent a significant cause of morbidity.10 Injuries to the hands can be classified as (1) direct bony; (2) articular, tendinous, neurovascular, and other structures; and (3) isolated soft tissue injuries, with the majority being the latter. The poorest prognosis is associated with second type.2,20

As with any other nail gun–related injury, evaluation begins with detailed history and physical examination especially time elapsed since the injury.10 It is important to examine the patient neurovascularly and pay attention to the mechanism because even if the patient is neurovascularly intact, the nail can be in close proximity to a neurovascular structure that could lead to iatrogenic injury during treatment.8,18 Radiographs in a minimum of 2 views should be obtained to look for bony and articular injuries, as well as the presence of barbs, which may or may not be visible.10

If there is a suspicion of more severe injury, then the wound must be explored intraoperatively and the surgeon must be cautious to avoid damaging other structures during debridement and nail removal.8 It has been reported that approximately 25% of injuries result in structural damage, including damage to bones, ten-dons, joints, or nerves, requiring surgical exploration.18,21

Treatment Considerations

Debridement

Treatment relies on standard wound management principles, including use of antibiotics and thorough irrigation with isotonic sodium chloride solution with the potential to add antimicrobial agents to the irrigation solution.10 Particularly when there is limited contamination and soft tissue injury, most authors agree that emergency department removal of the nail with local debridement and a short course of antibiotics is all that is necessary, without the need for surgical debridement in an operating room.9,19 In a study of 88 nail gun injuries to the extremities, Horne et al9 found that nonsurgical nail removal leads to low rates of infection with rapid return of function, suggesting that the majority of cases can be managed with simple extraction and debridement, as well as a short course of antibiotics.

On the contrary, in the setting of significant tissue damage or the presence of foreign materials, most authors have advocated for surgical debridement.18,20 Surgical exploration is particularly warranted in cases involving devitalized tissue, neurovascular deficits, a high level of contamination, tendon injury, unstable fractures, intraarticular involvement, or deep penetration of the nail head precluding safe removal without surgical exploration.2,8,22,23 However, surgeons should be cautioned that surgical exploration may reveal more contamination than initially anticipated from radiographs.2,8 During surgery, materials from construction sites and nail coils may be debrided.2,8 These wounds may be left open depending on the relative contamination of the wound.8 If the injury is uncomplicated, patients can be followed up 48 to 72 hours postoperatively but should remain as inpatients if the extent of the damage requires greater observation.10 With surgical debridement of contaminated wounds after nail gun injury, uneventful recovery without subsequent infection or disability can be anticipated.3,11

Antimicrobials

Along with debridement of the damaged tissues, tetanus prophylaxis, early intravenous antibiotics (usually a single dose of a first-generation cephalosporin), and a subsequent course of oral antibiotics have been shown to reduce the risk of infection the and development of septic arthritis, particularly for intra-articular injuries.3,7,9 Although infection after nail gun injury remains uncommon, the most typical offending species include Streptococcus, Staphylococcus, Enterobacter, and diphtheroids.9 Antipseudomonal antibiotics should also be considered because infections with Pseudomonas aeruginosa have been frequently documented at the foot and ankle.3,9 Infectious disease consultation may be beneficial in select cases. Compartment syndrome and complex regional pain syndrome have been reported with nail gun injuries to the extremities,24 but these complications represent the minority of cases.3

Surgical Technique

Techniques for removing the nail remain specific to the clinical scenario, as well as to the site of injury. Standard surgical equipment will be sufficient to remove most nails. Rhee et al23 summarized the recommended methods of nail removal from the hand, suggesting that careful radiographic evaluation for the presence of nail barbs (used to improve nail strength by gripping onto surrounding materials) should dictate the direction of nail extraction, as retrograde removal of the nail could result in barbs causing further soft tissue damage.19,22 If the retained nail has both an entrance and exit wound, 1 proposed technique involves cutting the nail head flush with the entrance wound and removing the nail antegrade through the exit wound.25,26 Alternatively, open exploration and removal of the nail under direct supervision is another technique to avoid damage to surrounding structures during extraction.10

In addition, if the nails are held together by glue, then the adhesive can make removal difficult because it melts from the friction created on penetration, subsequently hardens in the wounds, and is transparent, and thus hard to identify.14,27 The tract should be formally explored22 to ensure complete removal of all adhesives, clothing, or skin dragged into the wound.9,14,17

Discussion

Nail guns have gained popularity as a residential tool since their inception as useful commercial tools in the late 1950s.1 Residential projects have been associated with an increasing percentage of injuries, including those to the head, neck, chest, abdomen, and extremities, with orthopedic injuries accounting for more than 80% of all nail gun–related injuries.6,28,29 Injury to the radial aspect of the nondominant hand is most common, presumably from a self-inflicted injury while stabilizing the target object.22,23 Consistent with these reports, in a survey of 464 carpenter trainees, the majority of injuries reported were self-inflicted, with only 12% of reported injuries being caused by another worker.30,31

Lipscomb et al5 executed a large scale, active surveillance study involving 5137 union residential carpenters and drywallers, who accrued more than 9,346,603 total hours. Nail guns led to more than 20% of “struck-by” injuries and 14% of all injuries. Notably, the more experienced and older journeymen had a 0.6 per 100,000 hours rate of injury compared with a larger rate in less experienced apprentices (1.9 to 5.2 per 100,000 hours), of which nearly 25% had no safety training on nail gun use and 6% had no formal training at all.5,32 In addition, they found that 25% of apprentices reported a nail gun injury within 1 year of the study, with 88% of injuries self-inflicted.32 The potential danger of this lack of training in apprentices may be magnified because apprentices conducted more than 50% of the nailing done.5 Formal instruction of trainees in a controlled study revealed that injuries occurred in 38% of untrained apprentices compared with only 17% in those who were trained by hands-on instruction, lectures, videos, and periodic proficiency and safety tests.32

The economic impact associated with lost work hours, medical fees, and decreased productivity remains burdensome. Baggs et al11 studied Washington State workers' compensation data during a 9-year period, showing an average total cost of $692,548 per year spent on nail gun injuries amounting to an average cost of $1723 per claim. The authors found that 79.8% of all nail gun injuries (3616 total) resulted in medical-only claims and approximately 20% of claims resulted in indemnity payments. Although the majority of claims resulted in a brief period off work, 20% of claims resulted in more than 3 days away from work, averaging nearly 60 days away from the job.5

Nail guns may cause injuries similar to other low velocity projectiles, such as gunshot wounds.9,14,20 To prevent accidental discharge of a nail, most pneumatic nail guns require some combination of trigger activation and muzzle depression.32 One factor that may increase the risk of nail gun injury is the CAT, which allows a nail to be fired anytime the nose element and trigger are depressed simultaneously. The majority of nail gun injuries were caused due to bypassed or inoperable safety mechanisms.33 Holding down the trigger between firing (the bouncing method) is particularly dangerous for the operator, who can catch the knee or loose clothing on the way to the next target location, thus leading to injury to the distal femur/proximal tibia. These CAT nail guns are also susceptible to double firing, usually by an inexperienced operator overcompensating for recoil.29 When the energy of the gun lifts the nosepiece after firing and the employee's downward directed force pushes the nose back down and makes contact, the gun may unexpectedly re-fire.5,32,33 These often-preventable injuries have been the target of safety education initiatives.5,29

Because injuries may occur after the operator bypasses the safety mechanisms of CATs to improve efficiency, the implementation of SATs has been recommended by the federal department of Occupational Safety and Health Administration.29,32 Sequential actuation triggers help reduce these injuries by requiring the muzzle contact to be depressed and then the trigger squeezed prior to the nail being fired. The trigger cannot be locked into “fire mode,” so the gun cannot accidentally discharge if its nose bumps a surface or worker. Lispcomb et al5 showed that sequential triggers would have prevented 65% of injuries from tools with contact triggers. Overall, the use of sequential rather than contact triggers cuts the risk of injury in half, even after adjusting for training and experience.5,31,33 Critics of such SAT safety mechanisms cite decreased productivity as a reason to avoid implementation, but recent reports identify both the skill and working speed of the carpenter as greater factors in productivity than the type of trigger used.4

The hands and fingers accounted for the majority (up to 66%) of nail gun injuries,5,9,17,18,27,33 followed by the feet, knees, toes, eyes, thighs, and wrists.11,33 In addition, paralyzing spinal cord injuries, organ perforations, eye injuries causing blindness, fractures, brain damage, severe heart and lung injuries, and even death have been reported.5,9,14,18,27,32,33

Concerns remain that injuries may be underreported and therefore underestimated, especially in residential settings.31 Job site norms may cause employees to refrain from seeking medical treatment for nail gun injuries or from following up after the initial visit, thus limiting effective treatment and accurate estimates of injury prevalence.

Clinical Care

Health care providers must educate patients on preventative measures in addition to simply treating the injuries that present. To reduce job site injuries, providers may encourage nail gun users to avoid bypassing the CAT safety mechanisms, as well as the adoption of the safer SAT mechanism. Appropriate personal protective equipment should always be worn on the job site because, in the event of an unintentional discharge of a nail, safety glasses and steel toe boots or work shoes will help protect employees from serious injury. The Occupational Safety and Health Administration also recommends detaching the compressed air hose when passing the tool, using scaffolding instead of ladders, and having the nailer only use his or her dominant hand.29 Having a medical kit on site is encouraged to preliminarily treat injuries at the scene by keeping them relatively clean until proper medical attention can be obtained.29

Orthopedic surgeons should debride the wound thoroughly and be prepared for more contamination than originally thought. If barbs are present, the head of the nail can be cut and the nail removed anterograde or the tract can be explored. The use of radiographs and other imaging techniques can help determine whether barbs are present and the extent of the injury; however, barbs are not always visible on radiographs. If adhesives have been used to hold the nails together in the cartridge, then the tract should be explored because the adhesive can harden within the tract.

Nail gun injuries do not differ from the typical management of orthopedic wounds because early intravenous antibiotics, usually a first-generation cephalosporin, followed by a short course of oral antibiotics can help prevent infection. Infectious disease consultation may be necessary in some cases.

Conclusion

The use of nail guns has increased since their inception, along with associated injuries. Orthopedic injuries account for more than 80% of these injuries, and surgical debridement with antimicrobial therapy is recognized as the mainstay of treatment. Familiarity with safety recommendations for nail gun use and the nature of nail gun injuries remains paramount for treatment by the orthopedic surgeon.

References

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Authors

The authors are from Commonwealth Orthopaedic Centers (JMS), Edgewood, Kentucky; the University of Virginia (HML), School of Medicine, Charlottesville, Virginia; the University of Arizona (SCK), Tucson, Arizona; the University of Wisconsin Hospitals and Clinics (PSP), Madison, Wisconsin; and the University of Louisville (MRY), Louisville, Kentucky.

The authors have no relevant financial relationships to disclose.

Correspondence should be addressed to: Harrison M. Lands, BA, University of Virginia, School of Medicine, 860 Estes St, Charlottesville, VA 22903 ( hml5we@virginia.edu).

Received: June 23, 2018
Accepted: October 25, 2018
Posted Online: August 13, 2019

10.3928/01477447-20190812-03

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