The Use of Silver-Impregnated Packing Strips in the Treatment of Osteomyelitis: A Case Report

The incidence of neurotropic ulcers is reported to affect between 4% and 6% of the diabetic population and is associated with significant morbidity.¹ It has been reported that 85% of lower leg amputations initially present as a foot ulceration.¹ Complicating the initial clinical presentation of the ulcer is the extent and degree of pathology involved. The sensory deprivation and lack of pain associated with these ulcers causes the initial clinical presentation to include significant tissue necrosis requiring extensive surgical intervention. Deep-seated abscesses with extensive undermining and osteomyelitis often accompany the small ulceration that initially brings the patient to seek medical attention. The diminished immune response found in the diabetic population also factors into the degree of pathology associated with these ulcers.
The diagnosis of osteomyelitis is problematic with these ulcers. Though it is suspected clinically when probing to bone is present, the classical radiographic findings often lag behind the clinical picture. Additionally, the use of systemic antimicrobials can be ineffectual in achieving suitable levels at the ulcer site.² The polymicrobial flora that is often present in the chronic wound may limit the use of topical antimicrobial agents because of the lack of sensitivity, potential toxicity to the host cellular components, and the potential for the development of resistant strains.³
The use of topical silver dressings has expanded in the chronic wound care setting due to the broad antimicrobial spectrum, low toxicity, and resistance profile of silver.⁴ The recent introduction of silver-impregnated wound packing strips (SilverSeal® packing strips with X-Static®, Noble Biomaterials, Scranton, Pa) affords the clinician the ability to deliver the antimicrobial effect of silver using recommended treatment protocols.⁵ Silver-impregnated packing strips are similar to existing packing products on the market in that they come in varying widths (Figure 1) to accommodate diverse clinical presentations. Unlike standard gauze, the strips are manufactured using nylon fiber that has been metalized with pure silver (Figures 2 and 3). The nylon resists absorption of wound fluid, enhancing the wicking effect and allowing the metalized silver fiber greater surface area to interact in the wound environment. The hydrophobic effect of the nylon fiber prevents saturation of the dressing, allowing it to function over longer periods of time, thereby decreasing dressing changes. The following case presentation represents the clinical use of this modality, resulting in resolution of the patient’s ulcer in a shorter period of time than the usual 6 weeks stipulated for such treatment.

Case Report

History. An 84-year-old man with type II adult onset diabetes and sensory and motor neuropathy presented with a malperforans ulcer of the right first metatarsal head in September 2005. According to the patient, a small, draining ulcer developed on the plantar surface of the first metatarsal head. The patient denied any change in shoe apparel and direct trauma to the foot but did admit to increased walking activity prior to the onset of his symptoms. Conservative treatment with antimicrobial ointments and gauze bandages was ineffectual. His primary care physician referred him to the wound center for further evaluation and treatment (Figure 4). Past medical history included essential hypertension, atrial fibrillation, macular degeneration, gait disturbance secondary to sensory neuropathy, bilateral internal fixation of both tibia and fibula following a motor vehicle accident, and bilateral carotid endarterectomies.
Evaluation at the time of presentation revealed mild arterial restrictive disease by duplex scan with an ankle brachial index of 0.9, normal chemical profile, normal HgbA1C, normal complete blood count and differential, normal venous duplex exam, atrial fibrillation, and no evidence of osteomyelitis on x-ray (Figure 5).
Positive findings of the physical examination were macular degenerative changes, well healed carotid incisions, irregular heart rate, healed lower leg incisions, and a malperforans ulcer involving the plantar surface of the base of the first metatarsal head, which extended down into and included the plantar fascia but did not extend into the metatarsal head on examination.
Hospital course. The patient underwent exploration and operative debridement of the ulcer, and negative pressure wound therapy (NPWT) was initiated. Operative findings and pathology revealed chronic ulceration with inflammatory changes and granulation tissue. The patient was seen on a weekly basis during which progressive decrease in the size of the ulcer occurred (Figure 6).
Eight weeks after initial presentation, the NPWT was discontinued, and the use of oxycellulose (Promogran®, Johnson & Johnson Wound Management, Somerville, NJ) was initiated.
Concomitant with the cessation of NPWT at Week 8 was the onset of tenderness and erythema of the metatarsophalangeal joint along the medial aspect. Laboratory testing revealed a normal uric acid level. Aspiration of the metatarsophalangeal joint revealed blood that grew Enterococcus sensitive to ciprofloxacin on culture. The patient was placed on ciprofloxacin and was continued on oxycellulose dressings to the plantar malperforans ulcer. Twelve weeks after initial presentation, the plantar wound healed; however, tenderness of the metatarsophalangeal joint persisted, and an ulcer developed (Figure 7). Radiographic examination of the joint confirmed osteomyelitis. Surgical exploration and debridement of the new area of ulceration revealed necrosis of the underlying subcutaneous tissue and bone. Operative cultures and pathologic examination confirmed acute osteomyelitis with Enterococcus isolated form bone cultures (Figure 8).
Cultures again revealed Enterococcus sensitive to ciprofloxacin. The patient was continued on the same regime of ciprofloxacin, and the wound was packed open with cotton gauze. The patient continued on this therapy to Week 2 with no decrease in wound size. At Week 2, the patient’s packing was changed to silver-impregnated wound packing strips. Four weeks after the initiation of packing with the silver-impregnated strips, the patient presented with both wounds completely healed (Figures 9–12).
A 22-week follow-up exam showed no evidence of recurrence, and 26-week follow-up x-ray examination showed healing bone.

Conclusion

The treatment of osteomyelitis requires adequate drainage and debridement of infected bone and the use of systemic antimicrobials. The underlying disease process in chronic osteomyelitis, as in many chronic wounds, may prevent systemic antimicrobials from reaching adequate levels. The use of local antimicrobials, however, has been shown to be bactericidal on the flora of such wounds. In the case discussed here, adequate levels of systemic antimicrobials were administered throughout the clinical course, but clinical symptoms persisted. The use of a silver-impregnated packing strip when added to the regime was effective in facilitating closure of the wound, thus supporting the need for effective local antimicrobial treatment in this patient population. The use of a silver-impregnated packing strip affords a unique advantage because of its clinical profile and warrants further evaluation and study as an adjunct to the treatment protocol in clinical osteomyelitis.

Acknowledgements

The authors would like to thank Jeffrey B. Keane and William McNally for their support in facilitating this study.