The use of topical negative pressure is now an established practice among
many surgeons for the treatment of difficult wounds, both as a frontline
therapy and as a salvage procedure. Among difficult wounds, few present more
of a challenge to the reconstructive surgeon than chronic osteomyelitis of the
lower limb. Acutely, persistent sinuses and fistulas typically involve the
whole length of the bone, necessitating extensive débridement that
often results in extensive skin loss. Exposed bone and, frequently, exposed
medullary cavities, leave a surface unsuitable for skin-grafting or
conventional dressings. It is well recognized that the muscle flap is the
optimal treatment following adequate débridement and antibiotic
coverage. Despite an often initially excellent clinical result, some surgeons
remain cautious about the long-term outcomes of treatment with either local or
free flaps because of the recurrent nature of chronic
osteomyelitis1,2.
Treatment options for the lower limb are often further limited by the
difficult anatomical constraints, making amputation always a possibility.
We present a case of chronic osteomyelitis in a thirty-nine-year-old man
who had recurrences, with failed skin grafts, pedicled flaps, and free flaps,
over a period of more than thirty years. Topical negative pressure was used as
a salvage procedure before a planned amputation. Following split-thickness
skin-grafting, the wound healed and the patient had virtually full use of the
limb for the next three years. The patient was informed that data from the
case would be submitted for publication.
We treated a thirty-nine-year-old man in whom acute hematogenous
osteomyelitis of the left tibia had developed in 1963, when he was nine years
old. At that time, he was treated with a cross-leg flap, but the infection
recurred at the age of fourteen. Multiple débridement procedures and
courses of antibiotic therapy were used until he underwent another
reconstruction, with a local myocutaneous gastrocnemius flap. Twenty-two years
later, when the patient was thirty-six, the infection recurred again.
Microvascular reconstruction was performed, but the chance of success was
compromised by severe venous stasis disease for which he had undergone
varicose vein surgery earlier. As a result, two free latissimus dorsi flaps
failed, leaving a residual soft-tissue defect measuring 28 by 10 cm with an
exposed tibial medullary cavity (Fig.
1). There were few options left for further reconstruction.
As a salvage procedure before amputation, a foam pack was placed along the
exposed medullary cavity and suction was applied with use of a topical
negative pressure device (V.A.C. [Vacuum Assisted Closure]; KCI, San Antonio,
Texas) for an initial period of four weeks. At one month, granulation tissue
had formed over the medullary cavity and there was no evidence of active
infection (Fig. 2). The size of
the wound had decreased to 20 by 4 cm. Topical negative pressure was continued
to reduce the size of the wound further, and a split-thickness skin graft was
applied to the wound at six weeks.
At two months, the graft had incorporated well, with no evidence of
recurrent infection. At six months, the wound remained dry and was virtually
healed. Incidentally, the patient was found, during the period of treatment,
to have marked lymphocytosis and was diagnosed with chronic lymphocytic
leukemia.
At the time of writing, the patient had been followed every six months
(Fig. 3) for three years;
although an occasional minor skin infection was seen, there was no evidence of
deep infection, as confirmed by magnetic resonance imaging. He had an active
lifestyle and had virtually full use of the left lower limb.
Chronic osteomyelitis is a persistent and challenging problem. The
relatively avascular nature of bone creates a relatively ischemic interface
between the infection focus and the
host3. Necrotic bone
dies, forming sequestra, and the infection often has multiple foci. The high
rate of recurrence of chronic osteomyelitis is probably related to several
factors, including the low antibiotic concentration achievable in the bone
substance, decreased blood flow with loss of periosteal blood supply as a
result of débridement, dead space, and the appearance of resistant
organisms4.
Thorough débridement and surgical removal of any dead or infected
tissue is unquestionably the first step following a diagnosis of
osteomyelitis. Repeated débridements may be necessary to ensure removal
of all infected foci. Perhaps the most familiar treatment following
débridement is the use of muscle flaps, either free or pedicled. The
well-vascularized muscle can provide the cellular and noncellular elements,
such as oxygen, needed to heal the infection as well as adequate coverage of
the wound, potentially with a single reliable procedure. Mathes et
al.2 studied the
beneficial effects of the use of muscle flaps, compared with random skin
flaps, in the treatment of chronic osteomyelitis in an experimental setting
and found a reduction in the bacteria count and an increase in oxygen tension
with muscle flaps. Some authors, however, have identified reconstructive
difficulties due to the anatomical constraints of the lower
limb1,5
and have also raised concerns over the long-term results of treatment with
muscle
flaps1,4.
Flaps can fail as the result of residual infection, posttraumatic vessel
disease, diabetes, radiation vasculitis, or immunologic
suppression2. In our
patient, the problem was a combination of venous insufficiency and an
underlying lymphocytic blood disorder.
Papineau et al.6
described a more conservative method for the treatment of osteomyelitis with
this technique. With their method, the tissues are initially débrided
in the operating room. This is followed by daily bedside débridements
and dressings with gently packed sponges and compression bandages. Whirlpool
baths for débridement and wet-to-dry dressing changes are performed
until the entire surface of the bone is covered with granulation tissue.
Cancellous grafts are then placed into any residual bone defects. The local
wound-care routine is then carried out again until there is sufficient
granulation tissue for the application of a skin graft. Saleh et
al.7 modified this
technique by adding a circular frame to treat infected tibial nonunions. This
is a time-honored technique that incorporates the principles of radical
excision, continual drainage, immobilization, and space-filling dressings to
discourage secondary infections and promote formation of granulation
tissue.
The topical negative pressure technique is similar in certain aspects to
the Papineau technique and can therefore, in many respects, be considered a
modernization of that method that employs the same principles as described
above. Despite incomplete knowledge regarding the mechanisms by which topical
negative pressure works and a shortage of proper randomized controlled
trials8, the
efficacy of this system has been proven repeatedly in clinical practice. It
accelerates the reduction of the wound surface area, the rate of granulation
tissue formation, and effective wound-cleansing in preparation for subsequent
definitive procedures. Morykwas et
al.9 carried out
several experiments on topical negative pressure in animal models and found
improved microcirculation, reduction in the wound bacterial count, and a
significant increase (p = 0.05) in granulation tissue compared with the
results associated with conventional dressings. The system removes excessive
interstitial fluid, theoretically improving oxygen tension, speeding up the
delivery of growth factors and the removal of inhibitory factors, and
decreasing the number of wound
microorganisms9,10,
all factors that enhance the healing environment of the osteomyelitic wound.
The mechanical forces created by topical negative pressure are also thought to
stimulate
angiogenesis11.
There are some concerns regarding the use of this topical negative pressure
system. Chester and
Waters12 recently
cautioned that it can alter the wound flora, perhaps adversely. They
postulated that the closed air-free environment that is created can result in
a supportive environment for anaerobic infection, and they recommended close
monitoring of wound cultures prior to and during treatment.
Topical negative pressure is a potential addition to the limited arsenal of
wound-care methods that can be utilized by the surgeon in the management of
difficult cases of chronic osteomyelitis. This system can be used as a salvage
procedure, perhaps to avoid amputation, in patients with multiple comorbid
factors that deter successful reconstruction as well as in those for whom
anesthesia poses a high risk. More knowledge gained through basic-science
research regarding the mechanisms of vacuum therapy will guide the future role
of this method in the treatment of chronic osteomyelitis. ?