The "shadow sign": a radiographic differentiation of stainless steel versus titanium spinal instrumentation in spine surgery

The Use of Carbon Fiber-Reinforced Instrumentation in Patients with Spinal Oncologic Tumors: A Systematic Review of Literature and Future Directions

INTRODUCTION

Metastatic spine tumors affect over 30% of patients who have been diagnosed with cancer. While techniques in surgical intervention have undoubtedly evolved, there are some pitfalls when spinal instrumentation is required for stabilization following tumor resection. However, the use of carbon fiber-reinforced polyetheretherketone (CFR-PEEK) implants has become increasingly popular due to improved radiolucency and positive osteobiologic properties. Here, we present a systematic review describing the use of CFR-PEEK-coated instrumentation in the oncologic population while identifying advantages and potential shortcomings of these devices.

METHODS

In accordance with PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, a systematic review was conducted in March 2022 to identify articles detailing the use of CFR-PEEK implants for spinal instrumentation in patients with primary and secondary spine tumors. The search was performed using the PubMed, Scopus, and Embase databases.

RESULTS

An initial search returned a total of 85 articles among the three databases used. After the exclusion of duplicates and screening of abstracts, 21 full-text articles were examined for eligibility. Eleven articles were excluded due to not fitting our inclusion and exclusion criteria. Ten articles were subsequently eligible for full-text review.

CONCLUSIONS

CFR-PEEK possesses a similar safety and efficacy profile to titanium implants but has distinct advantages. It limits artifact, increases early detection of local tumor recurrence, increases radiotherapy dose accuracy, and is associated with low complication rates (9.96%)-making it a promising alternative for the demands unique to the treatment/outcome of spinal oncologic patients.

Prevalence and Risk Factors Associated With Pelvic Rod/Screw Radiographic Lucency Following Scoliosis Surgery in Spastic Cerebral Palsy: A Longitudinal Study

BACKGROUND

Radiographic lucency around a smooth pelvic rod (Galveston/unit rod technique) or sacroiliac/iliac screw following spinal fusion in children with nonambulatory spastic cerebral palsy (CP) has been described as a "windshield wiper" phenomenon. We evaluated demographics, radiographs, and complications in 101 cases from a single center to determine prevalence, risk factors, and complications associated with persistent radiographic lucency from 1 to 5 years following spinal fusion.

METHODS

Inclusion criteria were diagnosis of nonambulatory spastic quadriplegic CP [Gross Motor Function Classification System (GMFCS) IV-V], under 18 years of age, scoliosis treated by posterior fusion from upper thoracic to sacrum with pelvic fixation (Galveston rod, iliac screw, or sacroiliac screw), adequate radiographs (preoperative, immediate postoperative, first-year, and second-year), and minimum 5-year follow-up. We evaluated demographics, radiographic parameters, comorbidities, scoliosis curve type, type of pelvic screw/rod, use of off-set connector, screw width, associated with posterior column osteotomy and/or additional anterior spinal release concurrent with posterior spine fusion, and infection over the follow-up period. Specific attention was given to the area and shape of the radiographic lucency. The logistic regression analysis was performed for continuous and categorical variables to define risk factors ( P =0.05).

RESULTS

In 101 patients, data were collected at mean intervals of 1-year, 2-year, and >5-year follow-up and were 12.9±1.5, 25.8±2.5, and 81.5±23.0 months, respectively. Prevalence of pelvic rod/screw radiographic lucency was unchanged at 33%, 35%, and 24% at 1-year, 2-year, and >5-year follow-up, respectively, and radiographic parameters did not change ( P >0.05). Furthermore, no risk factors or complications were associated with radiographic lucency around pelvic rods/screws ( P >0.05).

CONCLUSION

In patients with spastic nonambulatory CP who had scoliosis treated with posterior spinal fusion from upper thorax to pelvis, the prevalence of pelvic rod/screw lucency is high. Persistent lucency >2 mm around pelvic implants is not clinically significant, does not warrant advanced imaging, or indicate a complication if stable over time and wider distally than proximally.

LEVEL OF EVIDENCE

Level III.