High-pressure injection hand injuries are often overlooked, with severe complications owing to the acute inflammatory response. Prognosis for depends on the type of material injected, location of injection, involved pressure, and timing to surgical decompression and debridement. Acute management involves broad-spectrum antibiotics, tetanus prophylaxis, emergent decompression within 6 hours, and complete removal of the injected material. Most patients have residual sequelae of stiffness, pain, sensation loss, and difficulties in returning to work. The hand surgeon’s role is prompt surgical intervention, early postoperative motion, and education of patient and staff regarding short- and long-term expectations.
Key points
- •
High-pressure injection injuries of the hand are often overlooked injuries with potentially devastating consequences and high rates of amputation.
- •
High-pressure injection injuries require broad-spectrum antibiotics, tetanus prophylaxis, and emergent surgical debridement and decompression within 6 hours of injury.
- •
Prognosis depends on the type of material involved, location, pressure, and time to surgical intervention.
- •
Frequent residual sequelae include stiffness, pain, sensation loss, and difficulties in returning to work.
Introduction
Injection injuries to the hand are uncommon and may have devastating consequences owing to the associated high pressure and serious risks. Initial presentation of high-pressure injection injuries to the hand may be deceptively benign. Small skin wounds with minimal discomfort or loss of function may suggest an innocuous injury; however, progressive swelling and pressure leads to severe pain, increasing pressure, and ultimately an ischemic digit with high amputation rates. Failure to recognize and emergently treat high-pressure injection injuries to the hand leads to permanent and ultimately high rates of amputation.
Historically, injection injuries have been noted to cause severe soft tissue injury with increased rates of amputation. Rees in 1937 noted gangrene owing to injection of oil under high pressure that required ultimately amputation. In 1938, Dial supported the severe nature of oil-based injection injuries to the hand. High-pressure injuries to the hand have continued to increase in numbers owing to the progressive industrialization of the economy.
Introduction
Injection injuries to the hand are uncommon and may have devastating consequences owing to the associated high pressure and serious risks. Initial presentation of high-pressure injection injuries to the hand may be deceptively benign. Small skin wounds with minimal discomfort or loss of function may suggest an innocuous injury; however, progressive swelling and pressure leads to severe pain, increasing pressure, and ultimately an ischemic digit with high amputation rates. Failure to recognize and emergently treat high-pressure injection injuries to the hand leads to permanent and ultimately high rates of amputation.
Historically, injection injuries have been noted to cause severe soft tissue injury with increased rates of amputation. Rees in 1937 noted gangrene owing to injection of oil under high pressure that required ultimately amputation. In 1938, Dial supported the severe nature of oil-based injection injuries to the hand. High-pressure injuries to the hand have continued to increase in numbers owing to the progressive industrialization of the economy.
Epidemiology
On average, 1 in 600 traumatic hand injuries involve a high-pressure injection injury, and large surgical centers average 1 to 4 injection injuries annually. High-pressure injection injuries to the hand typically occur on the dominant hand, particularly the index finger. The majority of patients are male, manual laborers with a large percentage involving worker’s compensation claims ( Table 1 ). Hogan and Ruland found the nondominant extremity to be injured 78% of the time, and the index finger as the most common site of injury, followed by the middle finger and palm ( Table 2 ). The most common scenario occurs at the workplace as the patient is an industrial worker who typically is accidentally injured from attempting to clean a nozzle with their nondominant hand. Often, many of these injuries involve an employee of a new job or handling unfamiliar equipment. The majority of these injuries are first regarded as benign but quickly escalate to emergencies owing to intense pain from progressing pressure and edema formation.
| Risk Factors | n | % |
|---|---|---|
| Gender | ||
| Male | 99 | 70.7 |
| Female | 41 | 29.3 |
| Marital status | ||
| Unmarried | 50 | 35.7 |
| Married | 85 | 60.7 |
| Other a | 5 | 3.6 |
| Salary level (NTD b ) c | ||
| <20,000 | 35 | 30.4 |
| 20,000–30,000 | 37 | 32.2 |
| ≥30,001 | 43 | 37.4 |
| Education level (y) | ||
| <10 | 48 | 34.3 |
| 10–12 | 54 | 38.6 |
| ≥13 | 38 | 27.1 |
| Occupation | ||
| White collar | 45 | 32.1 |
| Blue collar | 95 | 67.9 |
| Workers’ compensation | ||
| No | 38 | 27.1 |
| Yes | 102 | 72.9 |
| Age (y) | Mean ± SD | |
| 140 | 42.6 ± 12.9 | |
a Other marital status includes separation and divorce.
b 33 NTD (New Taiwan Dollar) = 1 USD.
c Numbers of subjects do not add up to total n because of missing data.
| Location | n |
|---|---|
| Index | 172 |
| Long | 64 |
| Ring | 20 |
| Small | 6 |
| Thumb | 41 |
| Palm | 62 |
| “Hand” or “finger” | 16 |
| Forearm | 7 |
Pathophysiology
After high-pressure injections injuries, rapid development of tissue necrosis occurs from the inciting pressure. Injected materials themselves may be caustic and directly injure the surrounding soft tissue to further produce additional necrosis and significant damage to the surrounding tissues. An acute inflammatory reaction follows, causing elevated fluid pressures within confined compartment volumes. The increased compartmental pressures then cause vasospasm, leading to further swelling, local ischemia, and thrombosis. The result of this ever-increasing inflammatory response is a vicious cycle of swelling, ischemia, and ultimately compartment syndrome. Without acute and emergent operative intervention, ischemia ensues and the loss of the digit may be inevitable.
Prognosis
Injected Material
The composition of the injected material is important as many of the components amplify the inflammatory response from direct toxicity causing further tissue necrosis. Grease, diesel fuel, and paint are some of the most common injected substances, and paint is associated with a particularly poor outcome.
In a study of 127 patients with high-pressure injections, Schoo and colleagues determined an average amputation rate of 48% ( Table 3 ). The highest incidence of amputation from high-pressure injections was at 80% owing to paint thinner, followed by 67% from diesel fuel injections and 58% from paint injections. Grease injections are less inflammatory and had much lower amputation rates. Grease has a tendency to produce chronic granulomas rather than direct chemical irritation.
| Material | No. of Patients | No. of Patients with Amputations | Percentage |
|---|---|---|---|
| Paint thinner | 5 | 4 | 80 |
| Diesel fuel | 6 | 4 | 67 |
| Paint | 36 | 21 | 58 |
| Grease | 40 | 9 | 23 |
| Hydraulic fluid | 7 | 1 | 14 |
Hogan and colleagues later reported from a study of 435 patients that organic solvents are the agents with the highest rates of amputation ( Fig. 1 ). The worst outcomes from high-pressure injections involved diesel, followed by paint thinner and oil. High-pressure injections of air or water had the most favorable outcomes and did not result in amputation, likely owing to the innocuous nature of these materials. Paint is composed of multiple components, each classified into 1 of 4 main categories: a binder, solvent, pigment, and additive. Oil-based paints have a much greater risk for amputation (58%) compared with latex-based paints (6%). Each of these categories injure the soft tissues directly and create a higher inflammatory response owing to their cytotoxic nature.
Other materials have also been described in the literature, such as cement, hydrochloric acid, dry cleaning solvents, insecticides, natural gas, silicone, and vaccinations.
As a chemical irritant promoting further necrosis and inflammation, materials from the majority of high-pressure injections of the hand must be completely removed to stop the inflammatory response, ultimately leading to ischemia of the digit. Rare high-pressure injections of water, air, and small volume vaccinations may be treated initially with observation, and successful results have been reported without operative intervention.
Location
The location of high-pressure injections impacts the prognosis and rate of amputation. Owing to limited space and volume, injections toward the fingertips typically involve higher rates of amputations than more proximal locations, such as the palm or thumb. The injected material tends to spread by following the paths of least resistance, typically the neurovascular bundles and flexor tendon sheaths. Injections within the thumb and small finger may spread proximally via the radial and ulnar bursa, respectively, to the forearm and even more proximal locations, whereas injections within the index, middle, and long fingers tend not to spread proximally and may be associated with higher amputation rates owing to higher accumulation of pressure. Hogan and Ruland have shown a 69% amputation rate with injections of caustic materials to the fingers, an amputation rate 3 times greater than that of caustic material injected to the thumb and small finger. Remote spread after injections has been reported, with 1 case citing pneumomediastinum from an air gun injury to the hypothenar space that traveled along the ulnar artery.
Pressure
Pressures as low as 100 psi are sufficient to penetrate the skin, and working pressures may be as high as 10,000 psi. The higher the pressure and greater the volume of injected material, the greater the damage and extent of injury will be for the patient. Many injections occur from placing the finger or thumb over the nozzle, causing even high amounts of pressure to be injected to the hand. Injections of greater than 1000 psi resulted in amputation 43% of the time, and injections of less than 1000 psi had amputation rates at 19% of the time.
Timing
Perhaps the most important factor for physicians treating high-pressure injections is time of injury to surgical intervention, because time to operation is the 1 factor within the surgeon’s control for treatment of these devastating injuries. Emergent operative intervention is warranted for high-pressure injuries other than potentially air and water to decompress the progressing pressure as well as to prevent and remove the toxicity to the surrounding tissues caused by the offending agent.
The timing of thorough decompression and debridement has been directly associated with lowering the risk of amputation for organic high-pressure injections of organic solvents (paint, paint thinner, gasoline, oil, or jet fuel). Debridement within 6 hours of high-pressure organic solvent injections has significantly lowered the amputation rate to 40% of the time, compared with an amputation rate of 57% if debridement was delayed for longer than 6 hours. Amputation rates of 88% are found if debridement is delayed for longer than 1 week. Likely owing to the less toxic nature and lower amputation rates of materials not classified as organic solvents, Hogan and Ruland did not find time to debridement to be a significant factor for treatment of more benign injected materials.
Patient Evaluation Overview
The course of high-pressure injection injuries usually begins with a small, innocuous-appearing entry wound that many times is overlooked ( Fig. 2 A ). The initial clinical appearance is typical underestimated; however, within hours, pain progressively intensifies and parallels marked swelling and edema of the affected extremity ( Fig. 2 B). The digit may quickly become cold, pale, and erythematous with associated paresthesia. Without prompt treatment, gangrene and sepsis may quickly follow. Radiographs may be helpful to not only determine the location of the radiopaque foreign body and air, but also to reveal the dispersal of injected material proximally. Emergent surgical decompression and debridement is the mainstay for most high-pressure injections.
