Purpose: Delayed infections after spinal instrumentation typically require complete implant removal and extensive wound debridement due to the difficulties in establishing an early diagnosis. We report a case of occult late infection after posterior spinal instrumentation that was detected early using PET/CT and therefore was successfully treated with antibiotics alone.
Methods: A 26-year-old woman who underwent posterior spinal instrumentation and fusion for scoliosis correction had superficial pseudomonal infection that healed with ceftazidime and levofloxacin and was admitted 4 months later with mild back pain. She had no fever and the surgical wound healed well. Laboratory tests were compatible with late infection but radiographs showed no signs of implant infection. The patient was suspected of having ongoing occult late infection and thus, underwent a PET/CT.
Results: PET/CT revealed a significant pathological FDG uptake at the T5 vertebral body and the area surrounding proximal end of the T5 instrumentation. The maximal standardized uptake value (SUV) was 7.9 for the T5 vertebra and only 2.3 for the patient's liver, suggesting an infection pathology. A conclusive diagnosis of delayed onset infection after spinal instrumentation was established and the patient was immediately started on oral anti-pseudomonal treatment. The scoliosis correction was well maintained 10 months after the index surgery and she had no signs of implant infection.
Conclusions: PET/CT provides detailed diagnostic information for occult infections in the absence of morphological changes and thus, is valuable for an early diagnosis of late infection after spinal instrumentation. It is possible to retain the instrumentation in the case of late infection, if early detection and efficacious treatment can be achieved timely.
Keywords: Delayed infection; Diagnosis; PET/CT; Posterior spinal fusion; Scoliosis; Spinal instrumentation.