Keywords SGAP flaps - implant-associatedinfections -
Mycobacterium massiliense
- debridement
Introduction
Nontuberculous mycobacterial (NTM) infections are defined as infections of mycobacterial
species other than Mycobacterium tuberculosis complex and Mycobacterium leprae . Increasing incidence of NTM infections has been reported globally. These infections
are initially thought to be environmentally acquired, but recent studies suggest local
spread potential with fomite and aerosols.[1 ] We presented a case of chronic NTM infection of spinal hardware, which failed the
initial wide local excision (WLE) procedure and eventually underwent successful treatment
with multidisciplinary approaches.
Case
This is the case of a 77-year-old male patient with a history of chronic Mycobacterium abscessus and later Mycobacterium massiliense infection of L2 to L5 posterior spinal fusion and L2 to L3 lateral interbody cage
hardware. The patient's past medical history was significant for coronary artery disease
treated with percutaneous transluminal coronary angioplasty, hyperlipidemia, chronic
renal disease, nephrolithiasis, and hypertension. The initial posterior spinal fusion
and interbody cage procedure were performed outside the United States. The patient
presented 3 months later with pruritus and a draining sinus tract in the posterior
wound ([Fig. 1 ]). This failed to improve with oral cephalexin and ciprofloxacin, and the patient
had a brief course of IV antibiotics which were discontinued due to the development
of drug-induced hepatitis and pancytopenia. The patient underwent WLE and debridement
of the deep tissue. Unable to be closed due to the persistent mycobacterial infection
on deep tissue biopsies, his wound was managed with negative pressure wound therapy.
Fig. 1 Photo of the patient's original wound with chronic, draining sinus and pruritus.
With limited expertise locally, the patient presented to our multidisciplinary mycobacterial
soft tissue team. After extensive discussion, he elected to have his spinal hardware
removed, the wound managed with multiple debridements to obtain source control of
the infection, and definitive closure with a soft tissue flap. Throughout this process,
he was treated with systemic antimycobacterial drugs. The patient underwent a total
of 16 irrigation and debridement procedures with amikacin antibiotic bead placement
and negative pressure wound therapy. Since establishing care at our institution, serial
wound cultures have been intermittently negative. However, due to failure to obtain
consistently negative cultures and having reached the limits of safe debridement,
we elected to reconstruct the wound after a new appliance was placed. The patient
would be maintained on suppressive antibiotics for a year.
The combined procedure was performed by the orthopaedic spine and plastic surgery
teams. The spine team removed the L2 and 3 interbody spacer, judiciously debrided
the area, and performed a lateral fusion of L2 and 3 and L4 and 5, using tricortical
structural allograft and bone morphogenic protein (BMP) via a lateral approach. The
posterior wound was debrided further with revision of the posterior instrumentation
with pedicle screws placed at L1 and S1 and bilateral iliac bolts, and posterior instrument
spinal fusion of L1 to the ilium with BMP, demineralized bone cortical fibers, and
allograft cancellous bone. Antibiotic beads were placed into the wound bed prior to
closure.
We then defined the extent of the defect and evaluated the reconstructive options.
The defect was full thickness down to the level of bone and fascia and measured 196 cm2 . A preoperative CT scan with a specific focus on the area of the gluteal vasculature
was performed. It showed a prominent right-side perforator ([Fig. 2 ]) outside the zone of injury and close enough to serve as the pivot point and nutrient
vessel. The flap was designed long enough to reach after transposition. This would
be a 10 × 35 cm superior gluteal artery perforator (SGAP) flap ([Fig. 3 ]). If the 180-degree transposition compromised the flap, the flap could be harvested
as a free perforator flap and anastomosed to the superior gluteal artery.
Fig. 2 CT angiography demonstrating prominent superior gluteal artery perforator. CT, computed
tomography.
Fig. 3 Immediate postoperative flap photo.
The flap was incised and elevated in the subfascial plane to the perforator identified
on the CT scan and confirmed with Doppler signal. Once the perforator was identified,
the fibers of the gluteus muscle were split to facilitate rotation, but the distal
end of the flap did not reach the defect. The muscle fibers were split further ([Fig. 4 ]), and the perforator was brought closer to the defect. At this point, the flap easily
covered the defect, and the distal end was deepithelialized and inset to fill the
dead space laterally. The perfusion to the flap was confirmed with SPY angiography,
and the flap showed no clinical evidence of venous compromise ([Fig. 5 ]).
Fig. 4 Flap elevation and muscle fibers separation to facilitate rotation and inset.
Fig. 5 Intraoperative photo showing lumbosacral defect and flap marking.
The patient's postoperative recovery was uneventful, and the patient was discharged
on postoperative day 19. Initial intraoperative cultures were positive for M. abscessus . However, multiple subsequent isolates were positive for subspecies M. massiliense , with phenotypic susceptibility to macrolides. The patient was, therefore, started
on imipenem, amikacin, bedaquiline, and clofazimine. Amikacin was discontinued, and
the patient was started on azithromycin. Eravacycline was prescribed later but discontinued
secondary to drug-induced hepatitis, edema, and nausea. This was replaced with a course
of ceftaroline.
Before discharge, the patient was extensively counseled regarding the range of motion
limitations, including off-loading, turning frequently, no direct pressure on the
flap, laying on his left side, and maintaining 45 degrees of flexion when sitting
or in bed. He began physical therapy, focusing on upper back strengthening, core strengthening,
and overall reconditioning at 3-month postoperation.
Twenty-four months after his reconstructive surgery, the patient is doing well. He
has been off antibiotics for at least 1 year and shows no signs of infection. Recently,
the patient had painful iliac bolts removed, and cultures obtained in the operating
room showed no infection. His SGAP flap continues to provide well-vascularized, durable,
and aesthetic coverage ([Fig. 6 ]). Most importantly, the patient has returned to his preoperative level of activities
of daily living without significant debility.
Fig. 6 Postoperative photos 2 years later.
Discussion
Defects in the lumbosacral region are common but challenging conditions that are frequently
treated with local muscle flaps like the paraspinous or gluteal flaps by reconstructive
surgeons. In this case, these flaps were not options due to the invasive nature of
the infection and the need for aggressive debridement, which compromised these local
muscle flaps. Recently, perforator flaps have been used for pressure ulcers, pseudomeningoceles,
and exposed hardware.[2 ] The SGAP flap is considered an ideal option, as it preserves muscle function in
the gluteal region while maintaining adequate perfusion via a single perforator.[3 ] This permits a greater arc of rotation in comparison to other local flap options.
Nontuberculous mycobacterial infections involving hardware have been reported in the
literature, and they pose a significant treatment challenge. To treat these infections
adequately, patients often require prolonged antibiotics with risks of adverse reaction,
prolonged hospitalization, periods of debility, multiple operative interventions,
and need for rehabilitation. In most cases, patients ultimately require hardware removal
for successful treatment of their infection.[4 ] NTM infections have been reported to affect both immunocompetent and immunocompromised
patients. They should be considered when patients present with prolonged infections,
chronic wounds or draining sinuses, hardware failure, and persistent systemic symptoms
of infection.[5 ]
[6 ]
Chronic hardware infection is a challenging condition to treat. Successful treatment
often requires a multidisciplinary approach with multiple surgical specialties or
subspecialties, along with infectious disease, radiology, and physical and occupational
therapy. In cases such as ours, biofilms inherent in implant-associated infections
result in the persistence of bacteria, despite aggressive serial debridements. Therefore,
the infected hardware is ideally explanted and replaced in order to facilitate successful
extirpative surgery and antibiotic penetrance.[7 ]
Obtaining antimicrobial drug sensitivity is also crucial in the treatment of mycobacterial
infections. Different combination therapies for NTM infection have been described,
with a median duration of 14 months.[4 ] In our case, 3 months of continued combination antibiotic therapy after flap coverage
and a year total of suppressive antibiotics proved successful.
Flap coverage can be instrumental in infection control and promoting chronic wounds
to heal. Flap coverage has long been viewed as critical in open fracture treatment
and deep wound infection treatment, as they can eliminate dead space and provide vascularization
to poorly perfused areas.[8 ]
[9 ] In the case presented above, SGAP flap coverage provided definitive, durable vascularized
tissue to a deep, large wound in an anatomically challenging region, while allowing
for antibiotic penetration and eradication of long-standing NTM hardware infection.
Chronic mycobacterial infections of spinal hardware can be challenging to treat and
often require a multidisciplinary approach, with long-term antibiotics, extirpative
surgery, hardware removal and/or replacement, and flap coverage for definitive treatment.
In this case, the patient underwent all of the above. This patient has now been NTM
infection free for more than 2 years without sacrificing mobility or function.
