VAC Therapy Direct to the Medullary Cavity for Chronic Tibial Osteomyelitis

Background. Vacuum-assisted wound closure (VAC) is useful for difficult wound beds, although sites where bleeding or infection is expected are usually regarded as problematic for this therapy. This report outlines the treatment of chronic tibial osteomyelitis (Cierny-Mader type III) due to mixed infection with Nocardia spp and Bacteroides fragilis by postoperative VAC therapy direct to the medullary cavity, followed by wound coverage with a gastrocnemius myocutaneous skin flap. Case Report. A 64-year-old man developed chronic left tibial osteomyelitis after a work injury. The nonviable tissues were debrided, including a sequestrum. Nocardia spp and B. fragilis were isolated from surgical bone specimens, and chronic tibial osteomyelitis due to mixed infection was diagnosed. Postoperatively, VAC therapy was performed directly to the open medullary cavity of the tibia and subsequently covered the residual soft tissue defect with a gastrocnemius myocutaneous flap. Discussion. The authors could not find any English literature on VAC therapy direct to the medullary cavity combined with transplantation of a myocutaneous flap for osteomyelitis. Nocardia spp can cause a variety of infections, among which osteomyelitis occupies a relatively small percentage. Conclusion. This case raises the possibility of treating chronic tibial osteomyelitis caused by mixed infection with Nocardia spp and B. fragilis by applying postoperative VAC therapy directly to the medullary cavity and covering the residual wound with a gastrocnemius myocutaneous flap. 

Vacuum-assisted wound closure (VAC) therapy is a sophisticated development of a standard surgical procedure for managing difficult wound beds.¹ While sites where bleeding or infection is expected are usually regarded as problematic for VAC therapy, there are no clear indications.

Vacuum-assisted wound closure therapy was originally used to improve staged management of open fractures with associated soft-tissue defects; there are some reports of VAC therapy for open wounds caused by fractures.^2,3 However, the authors were not able to find any reports in the English literature of applying VAC therapy directly to the medullary cavity combined with a myocutaneous flap for the skin defect after osteomyelitis surgery. Nocardia spp is a very rare cause of osteomyelitis. 

This report focuses on the treatment of chronic tibial osteomyelitis due to mixed infection with Nocardia spp and Bacteroides fragilis by applying postoperative VAC therapy directly to the medullary cavity and covering the residual soft tissue defect with a gastrocnemius myocutaneous flap.

The local ethics committee approved this study, which was conducted in accordance with the Declaration of Helsinki.  All work was performed at Hoshigaoka Medical Center, Osaka, Japan. 

The patient was a 64-year-old man with a history of cardiac surgery.  At age 58, he hit his lower leg on a drum and caused an ulcer. Because the initial injury was merely an abrasion, it was not treated. As a result, he eventually developed a fistula that discharged pus.

He presented on admission with an ulcer on his left leg that was tender and foul-smelling (Figure 1). Imaging showed a sequestrum-like mass, with enhancement of the surrounding bone (Figures 2, 3, and 4). Accordingly, the authors diagnosed chronic tibial osteomyelitis (Cierny-Mader type III) due to direct spread of bacteria from his skin ulcer. Serum C-reactive protein and the erythrocyte sedimentation rate (1 hour) were 6.1 mg/dL and 48 mm/h, respectively.

The patient underwent debridement of nonviable tissues, including removal of a sequestrum. The authors inserted antibiotic-impregnated cement beads (cement 40 g, vancomycin 1 g) into the cavity after removal of the sequestrum (Figure 5). Bone specimens sampled at surgery were sent for histological examination and culture, resulting in isolation of Nocardia spp and B. fragilis. He was treated with trimethoprim-sulfamethoxazole (TMP-SMX) at 6-8 g/d for 6 months, as well as clavulanic acid/amoxicillin (CVA/AMPC) (1000 mg/d) and AMPC (1000 mg/d) for 3 months; and he showed a good clinical response. 

On the third postoperative day, a VAC (V.A.C. ATS Therapy System, KCI, An Acelity Company, San Antonio, TX) dressing was applied directly to the bone marrow to evacuate infected fluid from the medullary cavity (Figure 6A). 

The cement beads were removed on the fourteenth postoperative day, and VAC therapy was then continued for 28 days as granulation tissue gradually formed around the skin defect. On postoperative day 28, the authors decided to stop VAC therapy because no fluid was removed and fresh granulation tissue had not formed. On day 60 of postop, the residual defect was covered with a gastrocnemius myocutaneous flap. At the second surgery, the surgeons confirmed there was no clinical sign of infection. On day 135 after the first operation, he was discharged from the hospital and was walking without assistance. The patient has subsequently been followed up for 2 years and has remained asymptomatic (Figure 6B).

Although wounds where good perfusion is expected are generally regarded as the main indication for VAC therapy, there have also been some reports about VAC therapy for osteomyelitis in recent years. Tan et al¹ treated 35 patients with osteomyelitis (Cierny-Mader types II-IV) by VAC therapy and achieved culture negativity in 29 wounds (82.9%). When their patients were followed for an average of 15 months, only 1 patient (Cierny-Mader type IV) still had an infection after 1 month. However, the authors are not aware of any reports about application of a VAC dressing directly to the bone marrow or its use for a skin defect after osteomyelitis surgery.

Conventionally, the Papineau technique is widely used for intractable defects of the skin and bone due to chronic osteomyelitis.^4,5 This technique involves thorough debridement of the infected site followed by irrigation, drainage, and implantation of a cancellous bone graft. As part of the process, washing the wound, debridement, and dressing with gauze need to be done on a daily basis. Using the VAC system can simplify management, reducing both cost and manpower requirements.

Vacuum-assisted wound closure therapy involves the application of controlled negative pressure with a special wound dressing to promote or assist wound healing. It was introduced by Fleischmann et al² in 1993 and has become a popular modality for the management of both acute and chronic wounds.

It was originally employed to improve staged management of open fractures with associated soft-tissue defects and was subsequently used for several additional indications associated with orthopaedic trauma, including surgical incisions with an increased risk of breakdown or infection and skin grafts.^2,3,6-8 In general, the presence of untreated osteomyelitis, necrotic tissue with eschar, malignancy, and exposed vasculature, nerves, or organs are contraindications to VAC therapy.^6,9 Conditions that require careful consideration prior to initiating VAC therapy are treated osteomyelitis, wound infection, wounds located near nerves, exposed tendons or ligaments, and a high risk of bleeding (especially in patients on anticoagulants or platelet aggregation inhibitors).^6,9 An extensive systematic review of the literature on VAC therapy identified the following points that require attention when a VAC system is used for the management of an infected surgical wound⁶:

1. Serial debridement of the wound is necessary to increase blood flow and enhance granulation;

2. Dressings must be applied to the incision to obtain complete occlusion of the wound and an airtight seal that allows effective generation of a vacuum, while avoiding overlap of the intact wound edges; and

3. Intermittent negative pressure of 125 mm Hg is recommended.

In the present patient, owing to considerable pain and the position of the wound, the VAC system was initially changed 3 times per week along with debridement and irrigation. The average amount of fluid was below 100 mL/d during the immediate postoperative period, and its character was bloody. The authors used a sterile mesh sheet to cover the medullary cavity so as not to evacuate an excessive amount of fluid. Then a polyurethane ether sponge was placed carefully to avoid overlapping the intact wound edges. The authors set the system at -75 mm Hg for application to the medullary cavity because increased local wound perfusion and persistent drainage were observed when it was set at -100 mm Hg or -125 mm Hg.

In this patient, multiple bone specimens removed during surgery were sent for histological examination and culture, and Nocardia spp and B. fragilis were identified. Detection of gram-positive beaded and branched filaments that were partially acid-fast suggested Nocardia spp, however the authors were not able to perform identification at the species level by culture because there was no growth of Nocardia colonies. The patient had injured the anterior surface of his left leg on a drum at work and an ulcer developed at the site of injury, so the authors made a diagnosis of chronic left tibial osteomyelitis due to direct spread from cutaneous nocardiosis. Only 19 cases of primary Nocardia osteomyelitis with mixed infection have been reported in the English literature,^10,11-22 and some of the reported patients were immunocompetent like the patient in this case. 

Nocardia was first isolated from cattle in 1888. Two years later, Eppinger reported the first human infection, which was a brain abscess.^11,14,21Nocardia is an opportunistic pathogen and has become more prevalent recently because of a significant increase in immunocompromised patients with a variety of underlying diseases, including malignancy, pulmonary disease, diabetes, and alcoholism, as well as patients receiving immunosuppressive therapy for autoimmune diseases or organ transplantation.²¹Nocardia can infect the upper or lower respiratory tract and hematogenous dissemination can lead to involvement of the central nervous system and heart valves, making cutaneous nocardiosis important in the differential diagnosis of intractable skin ulcers. Most patients recover after receiving prolonged antimicrobial therapy (for at least 3 months), usually with TMP-SMX.^11,14 Considering these features of Nocardia, in this case it was reasonable to think that the abrasion at the initial injury was the entry point of Nocardia and that the chronic evolution following direct inoculation of the microorganism accounted for the infection of the medullary cavity of the bone. This patient responded well to treatment with TMP-SMX at 6-8 g/d for Nocardia spp and with CVA/AMPC (1000 mg/d) and AMPC (1000 mg/d) for B. fragilis.

To the best of the authors’ knowledge, this is the first report on the treatment of chronic tibial osteomyelitis (Cierny-Mader type III) due to mixed infection with Nocardia spp. and B. fragilis with postoperative VAC therapy directly to the medullary cavity and a gastrocnemius myocutaneous flap. Because using a VAC system simplifies the process of wound closure, it seems possible to treat chronic tibial osteomyelitis with postoperative VAC therapy direct to the medullary cavity and a myocutaneous flap to cover the wound.

The authors are extremely grateful for the help provided by the late Takanobu Nakase, MD, PhD, Department of Orthopaedic Surgery, Hoshigaoka Medical Center, Osaka, Japan.

From the Department of Orthopaedic Surgery, Osaka University, Graduate School of Medicine, Osaka, Japan; Department of Orthopaedic Surgery, National Hospital Organization, Osaka Minami Medical Center, Osaka, Japan; Department of Orthopaedic Surgery, Iwai Hospital, Fukui, Japan; and Department of Orthopaedic Surgery, Japan Community Health Care Organization, Hoshigaoka Medical Center, Osaka, Japan

Address correspondence to:
Shigeyoshi Tsuji, MD, PhD 
Department of Orthopaedic Surgery
National Hospital Organization
Osaka Minami Medical Center
Osaka, Japan
shige-tt@nike.eonet.ne.jp 

Disclosure: The authors disclose no financial or other conflicts of interest.