Puncture wounds caused by foreign bodies can be deceptive in appearance. This is because many show little or no signs of external damage, yet they may have caused a serious internal injury. Some of the more common objects that cause these injuries include nails, pins or tacks, wood, glass and thorns. There is usually little bleeding from puncture wounds and these wounds seem to close almost immediately. However, this does not mean treatment is not necessary. Puncture wounds do have a risk of becoming infected. The object that caused the wound may carry spores of tetanus or other bacteria, especially if the object was exposed to the soil. Always ask the patients if they can recall when they received their last tetanus shot. The patient will need a tetanus shot if it has been more than 10 years since the last shot or if the last tetanus shot was more than five years ago and the wound has been contaminated by dirt. You should obtain a detailed medical history and try to determine what caused the puncture wound and the relative cleanliness of the penetrating object. Additionally, you should discuss the type of footwear the patient was wearing at the time of the injury. Any pieces of shoe or clothing can be forced into the wound and increase the potential for a retained foreign body. When you examine the patient, cleanse the surrounding skin and carefully inspect the wound with good light and adequate time. Examine the lower extremity for signs of a deep infection such as swelling and pain with motion of the toes. You should also test for loss of sensory or motor function, although this is unlikely to have been caused by a foreign body-related puncture wound. Key Pointers On Diagnostic Modalities If there is a question as to whether the object may have broken off in the tissues, obtain a radiograph. This is usually the first diagnostic option one would use to identify a foreign body. Radiopaque objects such as glass, metal and stone will be detectable via an X-ray. However, be aware that the size of the glass may be a limiting factor for detection. If the objects are plastic, aluminum or wood, these can be radiolucent and would require an ultrasound, computed tomography (CT) or MRI. Obtaining a CT gives you the ability to identify radiolucent objects and locate the three dimensional position. CT seems to be the modality of choice when it comes to identifying wood although xeroradiography is reportedly an excellent modality for identifying wooden foreign bodies. However, keep in mind that the longer the wood is surrounded in the tissue, the more difficult it may be to detect. Essential Treatment Considerations The pathophysiology and management of a foreign body wound is dependent upon the material that has punctured the foot, the location, depth and time of presentation, footwear and underlying medical conditions of the patient. When splinters penetrate the skin, the patient will usually feel an immediate sensation of pain and can often see the splinter in or right under the skin. Usually, there is only a small amount of bleeding or no bleeding at all. In some cases, though, the patient may not even notice the splinter until an infection develops. Also keep in mind that some splinter injuries can occur not only when someone steps on the splinter but slides his or her foot forward as well. Doing so may allow the foreign body to become deeply lodged into the tissues. Large splinters that interfere with sensation or movement may have the potential for creating deep puncture wounds that may impact nerves and tendons. Splinters are full of germs. If the splinter is not removed, an infection or an allergic response may occur. Needles can become embedded under any skin surface, but these injuries generally occur when a patient has stepped on one while he or she was walking or running barefoot on a carpeted floor. These patients will typically complain of pain upon weightbearing. When you do your clinical examination, you may see a small puncture wound at the point of entry and a portion of the needle may be palpable as well. If the puncture was created by a slender object like a needle or a tack and the patient is positive that it was removed intact, no further treatment may be necessary. However, you should have the patient return in a few days so you can ensure there are no clinical signs of infection or ischemia. Overall, when treating foreign body puncture wounds, you should convert a contaminated wound into a clean wound as quickly as possible and safeguard against tetanus. What About Patients Who Have Diabetic Neuropathy And A Foreign Body Injury? Patients who have diabetes may not even be aware they stepped on anything and present because they “smell something awful” emanating from their foot. These patients may have diabetic neuropathy. Symptoms of neuropathy include numbness and sometimes pain in the hands, feet and legs. Patients with diabetes can develop nerve problems at any time, but significant clinical symptoms develop within the first 10 years after diagnosis. It appears that diabetic neuropathy is more common among smokers, people over the age of 40 and those who struggle to control their blood glucose levels. Patients who have diabetic neuropathy may not feel the puncture of a foreign object and often will present with an infection. (Patients who have diabetic neuropathy should be strongly advised to never walk barefoot in order to prevent such injuries.) Aggressive medical management of these patients is critical to prevent an amputation. A thorough debridement, antibiotics, radiographs and local wound care are all essential. Detecting And Treating Infection In general, small, clean and superficial wounds from foreign bodies usually do well. They may resolve on their own or one can apply basic first aid, cleaning the wound with a topical antiseptic and applying a topical antibiotic. However, be aware that patients who present 24 hours after the injury may have the beginnings of an early subclincial infection. Clinical signs of an infection include redness, pain, swelling and induration. Additionally, the patient may present with systemic signs as well as fever, chills and shakes. Unsuspected fragments of sock or rubber soles are a major source of potential infection. Osteomyelitis caused by Pseudomonas aeruginosa remains the most devastating sequela. P. aeruginosa is the most common organism responsible for the development of osteomyelitis after a puncture wound. One can diagnose osteomyelitis via plain radiographs, but be aware that bony changes may not show up on radiographs for up to 14 days after the foreign body injury has occurred. If osteomyelitis is not clearly evident on plain film and you remain suspicious of the condition, order a bone scan. Another option is obtaining a MRI exam as it is highly sensitive for detecting osteomyelitis and is capable of detecting the condition within one to two days of its initial onset. Once you have established a diagnosis of osteomyelitis, you should proceed with aggressive treatment consisting of IV antibiotics and debridement of all soft tissue and bone that is infected. What You Should Know About Bullet Wounds Bullet wounds are marked by three known mechanisms of tissue damage: laceration and crushing, shock waves and cavitation. The bullet causes laceration and crushing when it displaces the tissue in its track. The degree and amount of tissue laceration are dependent on the bullet velocity, shape and angle of impact. Shock waves are generated by high velocity bullets that cause compression of tissues that are ahead of the bullet. A bullet’s ability to produce a temporary cavity is an important component in the wound production and the amount of tissue destruction. When a bullet enters the body, it produces kinetic energy on the surrounding tissue that forces the tissues forward and produces a temporary cavity or a temporary dislodgment of the tissues. This temporary cavity may be larger than the diameter of the bullet and rarely lasts longer than a few milliseconds before it collapses into the permanent cavity or wound track. This permanent cavity or wound track is produced by the defect that is generated when the tissues in the projectile’s pathway are expelled from the body. Any damage resulting from the cavitation is due to the stretching of the tissues. This cavitation phenomenon is used to explain why fractures of bone occur that are not in the direct pathway of the projectile. Any resulting bone fragments often act as secondary projectiles that make tissue destruction worse. This temporary cavity phenomenon is very significant because it has been found to be the most important factor in determining the extent of the wound injury. Low velocity bullets, such as pistol bullets, produce a direct path of destruction with very little lateral expansion within the surrounding tissues. As a result, they only cause a small temporary cavity. When a high velocity bullet enters the body, there is a “tail splash” or the backward hurling of injured tissue. The bullet passes through the target and creates a large temporary cavity that can be up to 30 times the diameter of the original bullet. In injuries involving high velocity fire rifles, the expanding walls of the temporary cavity are very capable of sustaining severe damage. This type of pressure may produce injuries to blood vessels, nerves or even organs that are a distance from the path of the bullet. Fractures may occur even without direct contact with the bullet. An array of complications ranging from nerve and tendon injuries to non-unions can occur. The wounding capacity of a bullet striking bone is greater than it is on soft tissue, because bone acts as a retardant force that is much more effective at decelerating a projectile. Cancellous bone (spongy bone) will experience less damage than cortical bone, because the kinetic energy can more readily dissipate within the honey comb structures of the cancellous bone. Detecting The Impact Of A Gunshot Wound Detection of a gunshot’s impact on the long bones and the irregular bones is difficult. The smaller bones, cancellous bones and bones that have degenerative diseases can shatter upon impact, bearing very little similarity to the typical trauma area. If damage from a bullet is suspected, one can obtain a radiograph to confirm the existence of radiopaque particles that are left by the slug’s path. If the bullet enters the distal ends of the bones, the defects are smooth and clean and have a “drill-hole” appearance. If the bullet enters the shafts, the appearance is often comminuted. In the first few hours after an extremity is exposed to the temporary cavity stretch, a marked vasoconstriction of these tissues will reveal a blanching of the skin of about 6 to 8 cm from the skin edges. In about four hours after the injury, you’ll notice a marked hyperemia. Keep in mind that blood flow in the muscle around the projectile’s path is constantly changing and it is very difficult to be certain if you are excising only non-viable tissue. Dr. Fishman is Chairman of the Wound Care Institute in North Miami Beach, Fla. Editor’s Note: For a related article, see “Essential Treatment Tips For Foreign Bodies” in the December 2000 issue of Podiatry Today. CE Exam #109 Choose the single best response to each question listed below: 1. Which of the following can cause a foreign body puncture wound? a) nail b) pin c) wood d) thorn e) all of the above 2. Patients with a foreign body injury will need a tetanus shot if … a) it has been more than three years since the last shot b) the last tetanus shot was more than five years ago and the wound is contaminated by dirt c) it has been more than 10 years since the last shot d) the last tetanus shot was less than two years ago and the wound is contaminated by dirt e) b or c 3. What is usually the first diagnostic option for identifying a foreign body? a) MRI b) Radiograph c) Computed tomography d) Ultrasound e) None of the above 4. Which of the following is a clinical sign of infection from a foreign body wound? a) pain b) redness c) swelling d) induration e) all of the above 5. Which diagnostic modality is particularly useful for identifying wooden foreign bodies? a) ultrasound b) xeroradiography c) computed tomography d) b and c e) a and c 6. Which modality is highly sensitive for osteomyelitis and detects the condition within one or two days of its initial onset? a) radiograph b) computed tomography c) MRI d) xeroradiography e) b or d 7. The most devastating sequela caused by a puncture wound is: a) osteomyelitis caused by Pseudomonas aeurginosa b) Staph epidermis c) erythema d) edema e) c and d 8. The known mechanisms of tissue damage from bullet wounds are: a) laceration and crushing b) shock waves c) cavitation d) a, b and c e) a and b 9. A bullet creates a large temporary cavity that can be up to __ times the diameter of the original bullet. a) 10 b) 5 c) 20 d) 30 e) none of the above Instructions for Submitting Exams Fill out the postage-paid card that appears on the following page or log on to www.podiatrytoday.com and respond electronically. Within 60 days, you will be advised that you have passed or failed the exam. A score of 70 percent or above will comprise a passing grade. A certificate will be awarded to participants who successfully complete the exam. Responses will be accepted up to 12 months from the publication date.
References 1. Kaplan EN, Hentz VR: Emergency Management of Skin and Soft Tissue Wounds: Lippincott Williams and Wilkins; 1984. 2. Yale’s Podiatric Medicine 3rd Edition, Jeffrey F. Yale, Williams and Wilkins; 1987. 3. Coe JI. External beveling of entrance wounds by handguns. The American Journal of Forensic Medicine and Pathology 3:215-219. 1982. 4. Belkin, M. Wound Ballistics. Progress in Surgery 16:7-24 1978.