Nickel-free implants for TKA may not improve outcomes in patients with nickel allergy
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LAS VEGAS — Results showed little differences in revision rates or patient-reported outcome measures among patients with a nickel allergy who received either nickel-containing or nickel-free implants during total knee arthroplasty.
“The role of hypersensitivity in poor clinical outcomes after total knee remains unclear. The decision to use a nickel-free implant still remains a surgeon preference,” Breana Siljander, MD, said in her presentation at the American Academy of Orthopaedic Surgeons Annual Meeting. “Future studies are needed to identify a better gold standard test to diagnose nickel sensitivity at the level of the total knee, as well as consensus for using these implants.”
Nickel-free vs. cobalt chrome implants
Siljander and colleagues collected preoperative, 6-week and 1-year patient-reported outcome measures, including VAS, Knee Osteoarthritis Outcome Score Joint Replacement, Lower Extremity Activity Scale, Patient-Reported Outcomes Measurement Information System (PROMIS) and Veterans Rands-12 score, among patents who reported a nickel allergy prior to undergoing TKA. Researchers also collected revision rate and postoperative hypersensitivity. They performed a Kaplan-Meier analysis to assess survivorship free from all-cause revision.
Among the 20,000 TKAs identified, Siljander noted about 1.4% of patients had a nickel allergy.
“Most [patients] received nickel-free implants, [and] 14% received a cobalt chrome implant,” Siljander said.
Siljander noted patients who received a nickel-free implant were slightly younger, had a sightly higher BMI and that male patients with a nickel allergy received a nickel-free implant.
“Interestingly, patients who received the nickel-free implant had slightly significantly higher rates of dermatitis postoperatively,” she said.
The two groups had no differences in depression, anxiety, pain syndromes or clinical findings of hypersensitivity, as well as no differences in revision rate or clinical outcome scores, according to Siljander.
Subgroup analysis
“The decision to use nickel-free implants is mainly based on surgeon preference,” Siljander said. “To account for this, we eliminated surgeons that only used nickel-free implants or only used cobalt chrome implants.”
In the subgroup analysis, Siljander noted patients with a nickel-free implant were younger, had a slightly higher BMI and a proportionately lower American Society of Anesthesiologists grade 3 score. She added the two groups had no differences in depression, anxiety or pain diagnoses and no differences in revision rate or clinical manifestation of hypersensitivity.
“However, when you look at the clinical outcome scores, preoperatively, patients who received a cobalt chrome implant had slightly higher VAS scores,” Siljander said.
Although the two groups had no differences in outcome measures at 6 weeks, Siljander said patients who received a nickel-free implant had significantly lower KOOS JR and PROMIS-10 scores, as well as higher VAS pain scores at 1 year.
“Overall, looking at the individual cohorts, patients had significant longitudinal improvement in their outcome scores, so they did benefit from this procedure,” Siljander said.
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Henson M, et al. Paper 77. Presented at: American Academy of Orthopaedic Surgeons Annual Meeting; March 7-11, 2023; Las Vegas.
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