Use of the Microvascular Free Fibula Transfer as a Salvage Reconstruction for Failed Anterior Spine Surgery due to Chronic Osteomyelitis

E et al. are to be lauded for their successful treatment of four patients with spinal osteomyelitis using a combination of débridement, stabilization, and free fibula transfer. Not all types of osteomyelitis are created equal. Distinctions drawn among the types and causes of osteomyelitis lead to a better understanding of management options. The two mechanisms by which spinal osteomyelitis may develop are hematogenous spread and local inoculation. Hematogenous spinal osteomyelitis is increasing in incidence with the aging of our population and is generally treated with long-term antibiotics and bracing. Surgery is reserved for failures of medical management that include persistent fevers and spinal collapse.1 Spine osteomyelitis from local inoculation is a separate entity. The zone of infection is typically larger, scar rather than normal soft-tissue planes surround the inflamed area, and foreign bodies in the form of hardware are now present, making eradication of the infection more difficult. Early ( 3 months) postsurgical bone and hardware infections can be treated with débridement and improved soft-tissue coverage without removal of hardware, so long as the hardware is well fixed.2 A major concept of surgical infections is that the reduced motion significantly aids in treatment, so maintenance of effective hardware helps to solve the infection problem. Chronic infections, defined as infections occurring more than 3 months after surgery, act quite differently from acute infections. The patients have often already undergone rounds of antimicrobial therapy. The soft-tissue bed is fibrotic and heavily scarred. Finally, more often than not, the hardware is loose, does not stabilize the tissues, and needs to be removed. In this series, the first patient had hematogenous osteomyelitis that failed conservative treatment. The last three patients had osteomyelitis as a result of direct surgical inoculations. All of the infections were in a chronic phase, and the two patients with hardware had the implants removed as part of their definitive treatment. After débridement and removal of any loose hardware, the spine team must decide whether or not to further stabilize the anterior column of the spine. Patient management is complex when the anterior spinal elements are not judged to be stable. The posterior column normally only carries 20 percent of the spinal load; therefore, a posterior spinal fusion alone would not be expected to compensate long term for the loss of anterior column support. Management is simplified if the residual spine is deemed stable. If so, the patient is treated with antibiotics and the infective process is allowed to calm down before new instrumentation is placed (if necessary). The spine team must have many techniques available by which to solve the dual problem of an infected dead space with a loss of anterior column support. Titanium cages for support along with autografting have been a standard treatment of this problem, with published good results.3 To better fill the dead space, at Northwestern Memorial Hospital vascularized pedicled rib flaps have been placed inside titanium cages through a slot cut into the cage. The flaps provide structural support and speed osteogenesis in cases of thoracic osteomyelitis.4 The advantage of using flaps is that immediate anterior column load support is provided until ankylosis is accomplished. Titanium mesh cages do not significantly stress shield bone from healing. We have also added biologic modifiers, such as bone morphogenic protein, to speed the fusion process and promote small vessel ingrowth in cases such as these. When the soft tissues are fibrotic around the anterior spine, pedicled omental flaps based on the right gastroepiploic vessels have been used to cover the titanium cages from the LS spine to the upper thoracic spine. In the cervical spine, the fibula is commonly used for structural support. In cases of expected problematic healing, I, too, have used a vascularized fibula flap for the same reasons documented by the authors, including in two cases of Received for publication June 1, 2005. Copyright ©2006 by the American Society of Plastic Surgeons