The incidence of lumbar infectious spondylitis is increasing. Clinically, the elderly and people with diabetes, poor nutrition, and autoimmune diseases are prone to infectious spondylitis. Most infections are blood borne. Pathogenic bacteria spread from the endplate to the intervertebral disc and then invade the adjacent vertebral body, causing severe low back pain and lumbar muscle spasm as a result of increased disc pressure. Nerve root compression by large abscesses may lead to severe radiating lower limb pain[8, 9].In this study, five (20%) patients had recently undergone lumbar acupotomology release and other aggressive manipulations, and the infection might have been related to the invasive lumbar procedure.
Delayed diagnosis and treatment of spondylitis are common because the early clinical findings are non-specific. Routine laboratory tests (WBC count, ESR, CRP, and PCT), although very sensitive to infection, have poor diagnostic specificity. MRI can detect signs of infection early; however, the false-positive rate is very high. Percutaneous disc biopsy can be used to culture microorganisms and select appropriate antibiotics, but its detection rate is low. Negative microbial cultures do not rule out infection if the patient has been treated with antibiotics before sampling[10].A positive intervertebral space tissue specimen culture is the gold standard for diagnosing pathogenic microorganisms. However, the positive rate of microbial culture after a needle biopsy varies greatly among researchers[11, 12].CT-guided percutaneous biopsy, debridement, and drainage are safe and effective in spondylodiscitis[13].The diagnosis of lumbar infectious spondylitis is based on the patient’s symptoms, imaging examination, serologic testing, pathology, bacteriology, and molecular biology. Preoperative blood cultures serve as a basis for diagnosis. In our series, five patients were febrile preoperatively, and two had positive blood cultures, providing a reliable basis for diagnosis.
The treatment of lumbar intervertebral space infection can be conservative or surgical. Conservative treatment mainly involves bedrest and appropriate antibiotics, and can cure most cases of lumbar infectious spondylitis[14].However, the intervertebral disc blood supply is poor, and it is difficult to maintain effective antibiotic concentrations in the lesions. Vancomycin, clindamycin, and quinolone can achieve effective concentrations in bone, but the treatment is long and the effect is slow. Good patient compliance is needed to achieve a therapeutic effect. Therefore, some scholars suggest that early surgical treatment is needed to avoid long-term bed rest and improve the quality of life of these patients[15].In the elderly, the effects of conservative treatment are worse than in young people. We suggest early surgical treatment for debridement, rapid symptom relief, and restoration of spinal stability, and to avoid the complications associated with prolonged bed rest.
In patients undergoing surgery, postoperative antibiotics are important. All our patients received intravenous antibiotics for 2–3 weeks postoperatively, followed by oral antibiotics for 6–8 weeks. The antibiotics can be discontinued when the WBC count, ESR, CRP, and PCT return to normal. Open surgery is recommended if low back pain recurs, the serological indexes rise, there is progressive bone tissue destruction on CT, or MRI indicates that the lesion continues to spread.
Surgical approaches included anterior, posterior, and combined approaches[16].The anterior approach alone can completely remove lesions from the anterior middle column and retain the posterior ligament complex, but cannot remove spinal canal lesions; its disadvantages include unstable internal fixation, a prolonged bedridden period, and more surgical complications[17, 18].Posterior open surgery has disadvantages such as incomplete clearance of anterior lesions, easy diffusion of infection to the spinal canal and posterior healthy tissue, and destruction of the normal posterior ligament complex[4, 19].With either open approach, the infection readily spreads to the internal fixation surface, and it is difficult to kill all bacteria this may lead to internal fixation failure. All of our patients underwent minimally invasive percutaneous pedicle screw internal fixation via the vertebrae and healthy muscle, avoiding contact of the internal fixation with infected areas. Patients with lumbar infectious spondylitis often have many comorbidities and low immune function, and cannot tolerate traditional open surgery[20, 21].Minimally invasive debridement can achieve good clinical results, with less trauma and rapid recovery[22, 23]. Percutaneous endoscopy allows a bacteriological diagnosis, the identification of suitable antibiotics, and symptom relief[24].Minimally invasive endoscopic treatment is effective in lumbar pyogenic spondylodiscitis, with less trauma and lower risk than traditional open surgery; moreover, it does not affect lumbar stability[5, 25].
Early debridement and drainage is preferred for treating lumbar intervertebral infection[26].Continuous irrigation dilutes and removes pathogens, inflammatory factors, and necrotic tissue. Combined with antibiotics, it kills pathogenic bacteria, inhibits inflammation, and relieves symptoms. Continuous perfusion is used to prevent blockage of the drainage tube. We performed continuous daily postoperative perfusion and irrigation with 0.9% normal saline (1,000 mL) and 6 × 106 U gentamicin. The drainage tube was removed after 7–10 days when the drainage was clear and there were two consecutive negative bacterial cultures. However, the lack of strong internal fixation can lead to vertebral collapse and spinal deformity, which can cause low back pain and poor infection control[27];percutaneous endoscopic debridement with PPSF for lumbar pyogenic spondylodiscitis can relieve the symptoms and restore spinal stability[28].In our series, all patients had posterior internal fixation to restore spinal stability and the physiological curvature of the spine, providing a good mechanical environment for spinal fusion and focal immobility. In the long term, CT showed obvious bone bridge formation around the debrided disc space, indicating satisfactory stability.