PUNCTURE WOUNDS OF THE FOOT

A 7-year-old boy was playing in the yard and stepped on a nail two days ago.  He comes in the office now because the bottom of the foot hurts.  There is a small scabbed area around the puncture wound and minimal erythema and no drainage. The child is afebrile and able to bare weight.  How would you further evaluate and treat this patient?

History
1.When did it occur?
2. Was initial wound care given
3. Indoors or outdoors?
4. Object? Did the entire object come out or did it break off?
5. How deep?
6. What was the patient wearing?
7. What part of the foot is involved?
8. What are the symptoms now?
9. Is the tetanus up to date?
10. Any other medical conditions?

The majority of plantar puncture wounds are due to nails (>90%).  An estimated 10% of pedal puncture wounds result in complications including soft tissue infection, abscess, osteomyelitis, tendon laceration/dysfunction or nerve injury.

The depth of the puncture wound is important as well as the location.  The forefoot is associated with more problems compared to the arch and hindfoot because there is less tissue overlying the area and it is more weight bearing.  Also, the retention of a foreign body and wearing of tennis shoes is associated with an increased risk of complications. Tennis shoes have been shown to predispose to infection with Pseudomonas.

Physical Exam:

Visually inspect the wound for jagged edges, evidence of retained foreign body and signs of infection such as edema and erythma. Palpate the edges of the wound to investigate for foreign body retention. Additionally pay attention to any drainage, crepitus (possible sign of a deeper infection) or malodor. Evaluate sensation and mobility of digits to look for nerve or tendon damage.

Common Infecting Organisms: 
-S.aureus (most common pathogen isolated from soft tissue infections)

-Pseudomonas aeruginosa (most common pathogen isolated from osteomyelitis)

-Group A hemolytic streptococcus

-Anaerobes

Management of puncture wound

1. Clean the area thoroughly and remove as much debris as possible
2. Check on the tetanus status of the patient
3. If the puncture wound is clean, superficial, and no foreign body suspected, patient may be sent home and told to return if there is pain, swelling, or redness. They may bear weight as tolerated.  Prophylactic antibiotics are not indicated.
4. If you suspect a foreign body, a radiograph should be taken to look for the object.  A plain film may not demonstrate all foreign objects so further studies such as ultrasound and CT may be needed. Ultrasound has been shown to be a better imaging modality for retained foreign bodies.  
5. If there is a foreign body in the bony structures or joint, refer to orthopedics. Don't attempt blind probes looking for retained foreign bodies
6. Children presenting after 24 hours usually have an infection.  Rule out a foreign body. Start on anti Staph oral antibiotic.
7. If symptoms persist after 5-7 days, suspect osteomyelitis.  Patients frequently have pain on the dorsum of the foot as well as around puncture site. Weight bearing may be refused. Usually the patient isn't ill appearing and there is no drainage around the puncture site. Plain x-ray may not demonstrate bony lesion and you may need to do a 3-phase bone scan or WBC-labeled bone scan.  ESR and WBC are often normal. If there is bone infection, start an anti-Pseudomonas drug such as tobramycin, ticarcillin or piperacillin. May need surgical debridement to hasten recovery.

References
1. Inaba, Alson.  The rusty nail-and other puncture wounds of the foot.  Contemporary Pediatrics March 1993

2. Haverstock, Brent D. Puncture Wounds of the Foot. Clinics in Podiatric Medicine and Surgery April 2012.