A rare case of delayed hypersensitivity reaction to metal ions secondary to a remnant pedicle screw fragment after spinal arthrodesis

A Rapid and Safe Minimally Invasive Procedure for Percutaneous Pedicle Screw Removal: A Case-Control Study and Technical Description

Purpose

Percutaneous pedicle screw fixation is a common minimally invasive treatment for traumatic thoracolumbar and lumbar fractures; however, research on hardware removal after successful healing is limited. We aimed to introduce a rapid, safe, minimally invasive, and cost-effective method for percutaneous pedicle screw removal.

Patients and Methods

We conducted a retrospective analysis of demographic (age, sex, body mass index, alcohol use, and current smoking), clinical (hypertension and diabetes mellitus), surgical (affected levels, number of screws, time of surgery, and blood loss), and treatment cost characteristics of 92 patients who had undergone percutaneous pedicle screw removal between May 2016 and February 2023. The first 57 patients underwent the conventional method, and the remaining 35 underwent the modified method. Independent-sample t-tests and chi-square tests were used to compare continuous and categorical variables, respectively, between the two groups.

Results

No significant differences were observed in the demographic parameters, complications, or affected levels between the groups. However, the average surgical time (P=0.000) was significantly shorter, and the average blood loss volume (P=0.002) and total cost (P=0.000) were significantly lower in the modified group than in the conventional group.

Conclusion

Compared with the conventional method, our modified method can shorten the surgical time, reduce blood loss, and reduce the total cost of treatment. It is a quick and safe minimally invasive method that does not require additional surgical instruments and is suitable for implementation in primary hospitals.

Hypersensitivity reactions to metals in spine surgery

Hypersensitivity to orthopedic devices is a rare condition with an underestimated incidence due to the lack of diagnostic guideline and ambiguous clinical manifestations. Although hypersensitivity to metal is common, a few cases of hypersensitivity reactions have been reported after spinal instrumentation. Spinal fusion and stabilization require a wide range of devices such as screws, wires, bands, and artificial disk replacement devices. Spinal instrumented surgeries are different from total joint arthroplasty in several aspects such as degree and pattern of motion, loading environment, and adjacent tissues with distinct characteristics. The interval for hypersensitivity reactions to occur after spinal metallic implantation is usually weeks to months. The present review covers the topic of hypersensitivity reactions that have been reported after spinal surgeries with the focus on cutaneous presentations.

Neurological emergency from rare spinal metalloma: Case report and literature review

Metallosis is a rare and poorly understood long-term complication of instrumented surgery that can result in an inflammatory pseudotumor termed metalloma. We describe a particularly unique case and compare it to 6 analogous cases identified by PubMed and/or Medline search through July 2020. A 79-year-old male with multiple prior spinal lumbar fusion procedures presented with progressive weakness and pain. Imaging revealed a large mass surrounding the right-sided paraspinal rod with extension into the spinal canal, neural foramina, extraforaminal spaces, psoas muscle, marrow spaces, and right sided pedicles. The case presented is a unique example of a unilateral metalloma with mixed-metal instrumentation that created a progressive neurologic deficit without infection, pseudoarthrosis, or hardware failure. This case highlights the lack of understanding regarding the pathophysiology of metallosis and metalloma in spinal instrumentation. We highlight the imaging findings of metalloma to encourage early identification for removal and decompression.

Emerging Issues Questioning the Current Treatment Strategies for Lumbar Disc Herniation

Lumbar disc herniation is among the common phenotypes of degenerative lumbar spine diseases, significantly affecting patients' quality of life. The practice pattern is diverse. Choosing conservative measures or surgical treatments is still controversial in some areas. For those who have failed conservative treatment, surgery with or without instrumentation is recommended, causing significant expenditures and frustrating complications, that should not be ignored. In the article, we performed a literature review and summarized the evidence by subheadings to unravel the cons of surgical intervention for lumbar disc herniation. There are tetrad critical issues about surgical treatment of lumbar disc herniation, i.e., favorable natural history, insufficient evidence in a recommendation of fusion surgery for patients, metallosis, and implant removal. Firstly, accumulating evidence reveals immune privilege and auto-immunity hallmarks of human lumbar discs within the closed niche. Progenitor cells within human discs further expand the capacity with the endogenous repair. Clinical watchful follow-up studies with repeated diagnostic imaging reveal spontaneous resolution for lumbar disc herniation, even calcified tissues. Secondly, emerging evidence indicates long-term complications of lumbar fusion, such as adjacent segment disease, pseudarthrosis, implant failure, and sagittal spinal imbalance, which get increasing attention. Thirdly, systemic and local reactions (metallosis) for metal instrumentation have been noted with long-term health concerns and toxicity. Fourthly, the indications and timing for spinal implant removal have not reached a consensus. Other challenging issues include postoperative lumbar stiffness. The review provided evidence from a negative perspective for surgeons and patients who attempt to choose surgical treatment. Collectively, the emerging underlying evidence questions the benefits of traditional surgery for patients with lumbar disc herniation. Therefore, the long-term effects of surgery should be closely observed. Surgical decisions should be made prudently for each patient.

Metal allergy hypersensitivity after posterior thoracic spinal fusion: A case report and review of the literature

Background:

Spine surgeons rarely consider metal allergies when placing hardware, as implants are thought to be inert.

Case Description:

A 32-year-old male presented with a skin rash attributed to the trace metal in his spinal fusion instrumentation. Patch testing revealed sensitivities to cobalt, manganese, and chromium. He underwent hardware removal and replacement with constructs of commercially pure titanium. His skin findings resolved at 2 weeks after surgery and were stable at 6 weeks.

Conclusion:

Hypersensitivity to metal (i.e., metal allergy) should be considered before performing instrumented spinal fusions.