Infected bone defects of the limb are an extremely serious complication that is difficult to treat, takes a long time to treat, and is not always treated successfully. Infection of bone remains a serious challenge for orthopaedic surgeons. Most bacterial infections can be treated with a high success rate with antibiotics, but the physiological and anatomical peculiarities of the bone make antibiotic therapy ineffective in the treatment of bone infections that gradually develop into infected bone defects.
Etiology.
Infected bone defects do not always have a clear etiology, but are all associated with the severity of the injury and early treatment, usually as a result of two conditions.
1, severe open fractures, incomplete debridement, early inappropriate internal fixation, wound dehiscence or non-healing, and other factors, secondary to infection, leading to infected bone defects in the limb;
2. Infection of soft tissue defects of the limb caused by trauma or chronic diseases, which in turn causes bone destruction, bone resorption or dead bone discharge to form infected bone defects of the limb. The literature reports that 30% of bone defects are due to infection, and 70% of bone defects are due to open fractures. The tibia is the most common, accounting for approximately 60% of cases, and Staphylococcus aureus can be isolated in 75% of cases.
Diagnosis.
Diagnosis of infected bone defects in the limb is relatively easy, as evidenced by localized erythema and pain on physical signs, and signs of infection on laboratory tests, as well as obvious bone defects and signs of infection on radiographs and CT. Identification of whether the infection is still active, the type of pathogen, whether the osteonecrosis is atrophic or hypertrophic, and whether there is dead bone formation due to infection is important for the development of the surgical plan. Specifically, this includes.
1. Medical history.
A thorough and detailed review of the initial history of injury, the entire course of treatment, radiographs, microbiological cultures, and the course of antibiotic therapy is extremely important to clarify the etiology and the type of microorganism responsible for the infection, as well as other relevant medical histories and smoking habits.
2. Physical examination.
An assessment of local conditions is required, taking into account location at the time of injury, soft tissue viability, blood supply, sinus tract conditions, scar and pin tract locations, nerve function, and adjacent joint viability. The whole body assessment includes age, whether other chronic diseases are combined, treatment conditions, nutritional status and functional status of other limbs, etc.
3. Laboratory tests.
Erythrocyte sedimentation rate (ESR), CRP, albumin, blood culture (in case of hyperthermia) may be abnormal, and bacterial culture of wound secretions may have positive findings or may be contaminated.
4. Imaging examination.
X-ray plain film examination is routinely performed, CT, MRI and radionuclide examination are feasible if necessary. MRI and intraoperative use of methylene chloride examination can help to precisely locate the infected tissue and dead bone and clarify their scope.
Treatment principles.
Systemic application of sensitive antibiotics, thorough local removal of lesions, removal of dead bone and inflammatory granulation tissue, elimination of residual cavities and sinus tracts, temporary coverage of the trauma with negative pressure closed drainage (VSD) can be used to smooth drainage, control infection, timely and effective coverage of the trauma and repair of the bone defect.
1.Treatment plan selection.
The choice needs to be made according to the specific injury and the patient’s condition. For those who have the conditions, limb reconstruction is used, and bone defects can be treated with autologous or allogeneic bone graft repair or bone handling to restore the integrity of the bone anatomy; for elderly patients and those who cannot tolerate long-term surgical reconstruction and recovery process, amputation and postoperative prosthesis installation are better choices.
2.Reconstruction principles.
Removal of necrotic tissue; eradication of infection; establishment of a healthy vascular bed with soft tissue; bone reconstruction to keep it stable and enable fracture healing.
3.Treatment methods.
Bone infection requires a combination of antibiotic therapy and surgical treatment. For closed infected bone defects, the combination of effective antibiotic treatment and surgical debridement treatment can control and eliminate the infection, and after the infection is completely eliminated, traditional bone grafting and bone grafting with blood vessels can be performed according to the bone defect. For infected bone defects with soft tissue defects, microsurgical methods need to be applied for soft tissue coverage and one-stage or two-stage bone grafting treatment; or the entire section of diseased bone can be amputated and directly bone ported or shortened and then bone ported to repair the bone defect.
Surgical treatment should be staged, and in the absence of active infection within 3 months, it can be treated as an aseptic osseous discontinuity with phase I bone grafting and internal or external fixation. In the case of active infection, a comprehensive analysis is required depending on the location of the lesion, the soft tissue condition, and the bone defect, but the infection needs to be controlled or eliminated first.
Surgery usually requires staging.
1. Phase I: debridement, removal of the infected foci and stabilization of the fracture. First of all, all necrotic tissues and dead bones should be completely removed, and the internal fixation materials should be removed in case of heavy infection. For milder infections, slow-release calcium phosphate cement beads or gel containing antibiotics can be used to increase the local drug concentration. For infected bone exposures, negative pressure closed drainage (VSD) can be used to cover the wound, and its own irrigation tube containing antibiotic solution such as gentamicin can be used to continuously irrigate the wound for 2 to 3 weeks, while systemic application of sensitive antibiotics can be used for more than 2 to 6 weeks. Sometimes repeated debridement is required.
2. Phase II: After the soft tissue and bone reconstruction is thoroughly debrided and the infection is initially controlled, soft tissue coverage and elimination of potential dead space should be performed. Bone grafting, wound closure and irrigation can be performed. Depending on the trauma, stamped implants, local flaps, free flaps, myocutaneous flaps or anastomotic vascular bone flaps are used for repair of small traumatic areas. The skin flap can be used to reconstruct soft tissue, while the myocutaneous flap fills the dead cavity and improves the blood supply to the infected area.
Small bone defects smaller than 6 cm can be fixed with muscle flaps and cancellous bone grafts, and depending on the site, they can be fixed with internal and external fixation frames. For large bone defects, free fibula or iliac flap graft with anastomotic tip is preferable, and can also be treated with bone transfer technique and fixed with external fixation frame.
3, Phase III: Functional rehabilitation period, pay attention to regular postoperative follow-up, strengthen rehabilitation therapy, prevent complications of long-term treatment, physical therapy is very important to control contracture and joint stiffness.