Do Antibiotic-Impregnated Calcium Sulfate Beads Improve the Healing of Neuropathic Foot Ulcers With Osteomyelitis Undergoing Surgical Debridement?

Andrew Peter Dekker, BMBS, BMedSci(Hons), FRCS; Chukwudi Uzoho, MRCS; Brigitte Scammell, DM, FRCS(Orth)

Disclosures

Wounds. 2019;31(6):145-150. 

In This Article

Abstract and Introduction

Abstract

Background: Neuropathic foot ulcers are common and difficult to treat. Calcium sulfate (CAS) has been used for antibiotic delivery in the treatment of osteomyelitis with success. Recent case series suggest success in treating osteomyelitis of the foot with CAS in a mean time to healing of 4 months; however, few studies with a control group for comparison exist.

Objective: This study aims to determine if antibiotic-impregnated CAS beads improved the healing of neuropathic foot ulcers with proven osteomyelitis undergoing surgical debridement.

Materials and Methods: A consecutive retrospective cohort study of 50 patients undergoing surgical debridement of neuropathic foot ulcers for osteomyelitis from December 2015 to May 2016 was performed. Exclusion criteria consisted of amputations and microbiology findings inconsistent with osteomyelitis. Patients were divided into 2 groups: the surgical debridement (SD) group was treated with SD alone and the other (CAS) was treated with debridement and implantation of vancomycin- and gentamicin-impregnated CAS beads.

Results: After exclusion criteria, 42 patients were included: 13 in the SD group and 29 in the CAS group. In the SD group, the mean time to healing was 5.8 months (range, 2–9 months), and in the CAS group, it was 5.5 months (range, 2–13 months). There was no significant difference in ulcer healing (P = .81), time to healing (P = .79), reoperation rate (P = .51), length of stay (P = .74), or mortality (P = .13) between the 2 groups.

Conclusions: Ulcer healing in patients treated with antibiotic-impregnated CAS beads did not show statistical significance. Healing rates in both groups were similar to those in recent literature. Surgical debridement alone may be as effective as supplementation with local antibiotics in a bioabsorbable carrier.

Introduction

As of November 2017, the prevalence of diabetes in the United Kingdom was 3.7 million;[1] diabetic foot ulcers (DFUs) are a common problem with a global prevalence of 6.3%.[2] This is partly due to about 50% of patients with diabetes being diagnosed with peripheral neuropathy with loss of protective sensation due to microvascular damage.[3] The lifetime risk of a foot ulcer is estimated at 10% in this patient population, with a 5-year risk of amputation estimated at 70% and a 5-year risk of death at 50%.[4] Foot ulcers are difficult to heal and carry a high recurrence rate.[5]

The use of antibiotics within a bioabsorbable carrier has demonstrated a reduction of dead space, improvement of local antibiotic delivery to tissues delivering higher concentrations to the wound,[6] and eradication and prevention of bacterial biofilms.[6,7] Historically, polymethyl methacrylate (PMMA) cement beads have been used, but they carry the disadvantage of needing a second procedure to remove them.[8]

STIMULAN (Biocomposites Ltd, Keele, UK) is a bioabsorbable calcium sulfate (CAS) product prepared at the time of surgery and can be mixed with chosen antibiotics. In vitro studies[9,10] have demonstrated antibiotic elution is effective for more than 40 days. A recent study[8] found local concentrations above the minimum inhibitory concentration for staphylococci (4 mg/L) 4 weeks after treatment for hip joint infection. Researchers have reported[9–11] success in treating tibial and femoral osteomyelitis.

There are few published studies on the outcomes of the use of bioabsorbable antibiotic-impregnated CAS beads in the neuropathic foot. A case report[12] of incision and drainage for forefoot osteomyelitis with packing of the wound with vancomycin- and gentamicin-impregnated CAS beads found the ulcer healed in 4 months. A 12-patient case series[13] concluded CAS beads to be effective in the treatment of calcaneal osteomyelitis when combined with hydroxyapatite, with a mean time to healing of 4 months. In addition, a large case series[14] of 337 patients with lower extremity osteomyelitis treated over a 5-year period found success with CAS beads in treating osteomyelitis in which 86% of patients ultimately healed; however, the time to healing was not reported. A study[15] of 20 patients with forefoot ulcers undergoing treatment with vancomycin- and gentamicin-impregnated CAS beads reported a median healing time of 5 weeks.

In a comparative case series[16] of 60 patients with transmetatarsal amputation for diabetic forefoot ulcers that failed nonoperative management, the use of tobramycin-impregnated CAS beads showed no difference in length of stay, time to a dry wound, or time to healing when compared with amputation alone. Further, a study[17] of 46 patients illustrated an improved average healing time for CAS beads (4 months) when compared with gentamicin-impregnated PMMA beads (6 months).

A literature search revealed no study directly comparing the outcomes of the use of CAS in osteomyelitis of the foot in neuropathic ulcers when compared with surgical debridement (SD; excluding amputation); antibiotic-impregnated CAS beads have not been proven more effective than surgical debridement. A local audit within the Trauma and Orthopaedic Surgery Division of Nottingham University Hospitals NHS Trust (Nottingham, UK) demonstrated that patients treated with amputation for foot ulcers all healed within 2 weeks and had amputations through healthy tissue far from the ulcer that grew no organism on microbiological culture. Surgical wounds unable to close surgically by definition take longer to heal as they must do so by granulation; thus, they were the subject of the present study.

This study aims to determine if antibiotic-impregnated CAS beads improved the healing of neuropathic foot ulcers with proven osteomyelitis undergoing concurrent SD when compared with SD alone.

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