Treating puncture wounds in the lower extremity can be challenging, especially given the potential for retained foreign bodies. In the first part of a discussion, our expert panelists discuss appropriate workup and diagnostic studies for such wounds, offer their perspectives on imaging modalities, and impart a few helpful surgical pearls.
Q: What are your general workup/diagnostic studies for a plantar foot puncture wound?
A: Molly Judge, DPM emphasizes obtaining a thorough medical history as well as a very concise account of the history of the puncture wound. All of the panelists recommend radiographs to rule out a retained foreign body. Depending on the clinical picture, Dr. Judge says one might use other, more detailed imaging studies but she notes these are not always necessary.
If the puncture occurred recently, Michael Keller, DPM, suggests obtaining radiographs and ultrasound views. If the puncture occurred several days prior to the appointment, Dr. Keller says an MRI might be relevant to rule out the possibility of osteomyelitis, especially if an infection is present. In the event of a retained foreign body, he says MRI or ultrasound views are relevant. If a metallic object has punctured the foot, Dr. Keller says plain films or fluoroscopy can provide “significant benefit.”
Dr. Judge adds that plain radiographs can also rule out soft tissue emphysema in these cases. Lawrence Karlock, DPM, points out that puncture wounds “notoriously have more soft tissue damage than what is noted superficially.”
With puncture wounds, blood work (including CBC, CMP, ESR and CRP) is indicated, according to Dr. Keller. Dr. Judge concurs, noting that CBC, CRP and creatinine are “the bare minimum for a healthy individual.” When it comes to patients with a chronic disease, Dr. Judge suggests checking electrolytes and disease specific chemistries. She says one should also check the patient’s HgbA1C if he or she has diabetes and the potential for poor disease control.
If there is any question of a retained foreign body or shoe/sock material within the wound, Dr. Karlock says one should explore the majority of these wounds. After she discusses possible medication allergies with patients, Dr. Judge performs an in-office incision and drainage as appropriate for the clinical picture. After a sterile prep, draping and nerve block, she debrides the wound, widens the portal of entry and explores for the foreign body.
After copious irrigation, Dr. Judge says there is now a reasonable setting for obtaining a deep wound culture. As she notes, a simple wound packing of plain 1/4-inch gauze strips and a sterile compressive dressing with surgical shoe is often sufficient to keep the region clean and dry.
Dr. Judge closely monitors puncture wounds and has patients return to the office in three days so she can review culture reports, modify antibiotics if necessary and consider timing for a delayed primary closure if indicated.
Q: How often do you utilize diagnostic ultrasound or MRI or bone scans in these cases?
A: As Dr. Keller notes, one can use diagnostic ultrasound to detect any loose foreign bodies deep in the soft tissues, particularly in early presentation. He stresses that ultrasound is highly dependent on the technician “and, for that reason, is often underutilized.”
For puncture wounds, Dr. Judge often uses ancillary imaging based upon the clinical presentation. For example, if she wants to retrieve a retained foreign body that is deeply seated, she uses ultrasound for guidance in the OR.
“It is often pretty simple to triangulate the location of the object using this modality and it obviates the need to use other more expensive techniques,” points out Dr. Judge.
She says ultrasound is “very helpful” when one is dealing with a wooden foreign body. If a retained foreign body is aligned with other fibrous structures like the intrinsic muscles of the plantar foot, Dr. Judge cautions that MRI may not be able to distinguish between normal tendon and a wooden foreign body.
Dr. Keller often uses MRI to rule out osteomyelitis in the presence of a deep space abscess, saying MRI is “very sensitive and specific in these cases.” Dr. Karlock says he occasionally uses bone scans to detect potential osteomyelitis. Concurring with a previous point from Dr. Keller about the duration of puncture wounds, Dr. Karlock says he will utilize MRI or bone scan to rule out osteomyelitis for puncture wounds that are a couple of weeks old and have chronic swelling. However, he cautions clinicians to be aware of a false positive rate with these.
“A negative bone scan in a well vascularized limb can usually rule out any osseous infectious process,” adds Dr. Karlock.
If a joint space is involved or if an osseous structure has sustained concomitant insult, Dr. Judge will use nuclear medicine imaging to rule out infection. She adds that a radio-labeled leukocyte scan can identify the location and extent of any existing infection. Dr. Judge claims she has never experienced a false negative nuclear medicine WBC scan in the face of a foreign body with infection.
Q: Do you have any surgical pearls or techniques for these wounds?
A: Dr. Karlock teaches residents to extend the incision to allow full visualization of the deep structures including the flexor tendons.
Podiatrists should excise any necrotic tissue to healthy tissue, and adequately decompress any deep pockets of purulence, according to Dr. Keller. He says one should follow the path the foreign body took to see if any bone was inoculated during the initial injury. If one suspects osteomyelitis, Dr. Keller recommends a bone biopsy at the time of incision and drainage.
Dr. Karlock normally recommends copious amounts of high pressure irrigation to flush puncture wounds. For irrigations performed in the office or in the hospital, Dr. Judge advises using a 1-liter bottle of saline or sterile water. She says one should leave the whole lid intact and pierce it with an 18-gauge needle to make three very small holes that are close together. Doing so permits sterile irrigation with a moderate amount of pressure for enhanced debridement and wound irrigation, according to Dr. Judge.
Dr. Judge suggests using the metal center from a sanding disc to mark the portal of entry, noting that when taking X-rays, this is helpful in precisely marking the location of the retained foreign body. “I have never used those discs for anything else as a matter of fact,” she comments.
When taking X-rays with markers in place, Dr. Judge notes the importance of multiple projections. Since one is using planar imaging to identify the location of an object in three dimensions, she says multiple orthogonal planes can help determine the foreign body’s location, which provides a better perception of depth from the portal of entry.
Dr. Karlock will sometimes utilize intraoperative fluoroscopy to remove any retained foreign body and to utilize triangulation techniques.
Dr. Judge is a Fellow of the American College of Foot and Ankle Surgeons. She completed a three-year surgical residency program in major reconstructive surgery for the leg, foot and ankle. She is board-certified in reconstructive rearfoot and ankle surgery. She has offices in Port Clinton, Ohio and Lambertville, Mich. Dr. Judge is the Official Foot and Ankle Physician for The Jamie Farr Owens Corning LPGA Classic.
Dr. Keller is a Fellow of the American College of Foot and Ankle Surgeons. He is the Residency Director of the Benedictine Podiatric Residency Program (PM&S-36) in Kingston, N.Y. He practices at Hudson Valley Foot Associates in Kingston, N.Y.
Dr. Karlock is a Fellow of the American College of Foot and Ankle Surgeons, and practices in Austintown, Ohio. He is the Clinical Instructor of the Western Reserve Podiatric Residency Program in Youngstown, Ohio. Dr. Karlock is a member of the Editorial Advisory Board for WOUNDS, a Compendium of Clinical Research and Practice.