LAUSR

STUDY DESIGN Case-report and literature review. OBJECTIVE To depict main features of a potentially deleterious postoperative spinal fixation complication. SUMMARY OF BACKGROUND DATA Tisular deposit of metal particles from prosthetic systems -metallosis- is an uncommon complication of spinal fixation surgery. Manifestations as chronic post-operative pain, instrumentation failure, infection or neurological impairment can be developed, but metallosis often appears as an unexpected intraoperative finding. METHODS A 70 y.o. female underwent several spinal fixation procedures due to progressive degenerative adult scoliosis, who developed instrumentation failure. Unexpected metallosis was evidenced extensively surrounding the dislodged construct due to vertebral osteolysis. Instrumentation replacement and debridement of metallotic tissue was performed. We also conduct a literature review for the terms "spinal metallosis" and "spinal corrosion" on the PubMed/MEDLINE database. Previous publications depicting black/dark staining, discoloration and/or fibrotic tissue, as well as histopathological metal particle deposits, or merely metallosis, were reviewed. Articles reporting individual cases or case-series/cohorts with patient-discriminated findings were included. RESULTS The histopathological analysis of our patient revealed dense fibroconnective tissue with black metallic pigment associated. She evolved with great pain relief in the immediately postoperative period. The patient achieved pain-free standing with significant pharmacotherapy reduction and independent ambulation. The literature search retrieved 26 articles for "spinal metallosis" and 116 for "spinal corrosion"; 16 articles met selection criteria. Approximately 60% of the reported cases accounted for patients younger than 30 y.o., mainly related to expandable fixation system (65%) for idiopathic scoliosis. Usually, the symptoms were correlated with abnormal radiological findings: instrumentation breakage, dislodgement, loosening, expandable systems fracture. All the reviewed patients evolved free of pain and neurologically recovered. CONCLUSION Instrumentation removal and metallosis debridement seems to be useful for symptomatic patients, but remains controversial on fixed asymptomatic patients. If solid fusion has not been achieved, extension and reinforcement of the failed fixation could be required. LEVEL OF EVIDENCE 4.