Suspected Metal Allergy and Femoral Loosening After Total Knee Arthroplasty: A Diagnostic Dilemma

Nickel allergy does not correlate with function after total knee arthroplasty

PURPOSE

The purpose of this study is to determine if there is a relationship between clinical outcomes and nickel allergy by evaluating asymptomatic total knee arthroplasty (TKA) patients with well-functioning implants through quantitative metal allergy (MA) testing.

METHODS

A prospective case series was performed on 50 patients with well-functioning TKA of various implant types. Inclusion criteria included primary TKA with a minimum 12-month follow-up and Oxford knee score (OKS) ≥ 40. A commercially available Lymphocyte Transformation Test measured the amount of a hypersensitivity lymphocyte immune response after exposure to a particular antigen. MA results were stratified based on the stimulation index (SI). The Cochran-Mantel-Haenzel test was used to test the homogeneity of metal reactivities. The Wilcoxon-Mann-Whitney test was used to compare individual metal SI by gender and the association of OKS and metal SI was ascertained with the Spearman correlation.

RESULTS

Nickel, cobalt, and chromium do not have the same reactivity scores (p < 0.001), and only nickel showed reactive/highly reactive scores. Females were found to have 3.41 times the odds of males for higher Ni reactivity (p = 0.0295, odds ratio [OR], 95% confidence interval [CI] = 3.41 [1.13-10.3]) only. Clinically, there was no correlation between metal SI and OKS score by metal (Ni rho = -0.1779; Co rho = -0.0036; Cr rho = -0.1748).

CONCLUSION

This is the first study looking at MA in well-functioning TKA. There is no correlation between clinical results and nickel reactivity. Surgeons should exercise caution when revising a painful or poorly functioning TKA based solely on a 'positive' Nickel Allergy test and look for other possible reasons for failure.

LEVEL OF EVIDENCE

Level II.

Establishing clinically meaningful ranges of metal hypersensitivity in orthopaedic patients using COVID-19 vaccine-induced adaptive immune responses from fully vaccinated adults

Background

This study aimed to assess metal sensitization ranges among orthopaedic patients by comparing adaptive immune responses in all-comer pre- and post-operative orthopaedic adults who were COVID-19 unvaccinated or vaccinated vs patients with a painful aseptic implant by lymphocyte transformation test (LTT) to SARS-CoV-2-Spike-Protein (SP) and implant metal(s), respectively.

Methods

Data were retrospectively reviewed from three independent groups: unvaccinated COVID-19 adults (n = 23); fully COVID-19 vaccinated adults (n = 35); unvaccinated, painful aseptic implant patients with history of metal allergy (n = 98). Standard in vitro LTT for SP and implant metal(s) (nickel, cobalt) were performed and rated as negative (stimulation index [SI]<2), mild (SI ≥ 2), positive (SI ≥ 4-15), and high sensitization (SI > 15) adaptive immune responses to tested antigen.

Results

Overall, 17/23 (74%) of unvaccinated adults showed negative to mild LTT ranges, and 35/35 (100%) of vaccinated showed mild to positive LTT ranges to SP. Vaccinated individuals showed significantly higher median SI (16.1) to SP than unvaccinated (median SI, 1.7; P < 0.0001). Most vaccinated adults (94%) showed a lymphocyte SI > 4 to SP, establishing LTT SI ≥ 4 with >90% sensitivity for diagnosing effective COVID-19 adaptive immune responses. Significantly fewer painful orthopaedic patients (41%) showed comparable elevated levels of lymphocyte metal sensitivity at SI ≥ 4 compared to vaccinated group (P < 0.0001).

Conclusions

Vaccinated adults showed significantly higher lymphocyte SI to SP than unvaccinated indicating that SI ranges ≥4 should be set as unequivocally diagnostic of LTT-positive adaptive immune responses to tested antigen. This analysis supports using higher LTT SI ranges (SI ≥ 4) in diagnosing clinical orthopaedic-related Type IV metal-hypersensitivity responses among orthopaedic patients.

Uncemented Tibial Fixation Has Comparable Prognostic Outcomes and Safety Versus Cemented Fixation in Cruciate-Retaining Total Knee Arthroplasty: A Meta-Analysis of Randomized Controlled Trials

BACKGROUND

Cemented and uncemented fixation are the primary methods of tibial prosthesis fixation in total knee arthroplasty. However, the optimal fixation method remains controversial. This article explored whether uncemented tibial fixation has better clinical and radiological outcomes, fewer complications, and revision rates compared to cemented tibial fixation.

METHODS

We searched the PubMed, Embase, Cochrane Library, and Web of Science databases up to September 2022 to identify randomized controlled trials (RCTs) that compared uncemented total knee arthroplasty (TKA) and cemented TKA. The outcome assessment consisted of clinical and radiological outcomes, complications (aseptic loosening, infection, and thrombosis), and revision rate. Subgroup analysis was used to explore the effects of different fixation methods on knee scores in younger patients.

RESULTS

Nine RCTs were finally analyzed with 686 uncemented knees and 678 cemented knees. The mean follow-up time was 12.6 years. The pooled data revealed significant advantages of uncemented fixations over cemented fixations in terms of the Knee Society Knee Score (KSKS) (p = 0.01) and the Knee Society Score-Pain (KSS-Pain) (p = 0.02). Cemented fixations showed significant advantages in maximum total point motion (MTPM) (p < 0.0001). There was no significant difference between uncemented fixation and cemented fixation regarding functional outcomes, range of motion, complications, and revision rates. When comparing among young people (<65 years), the differences in KSKS became statistically insignificant. No significant difference was shown in aseptic loosening and the revision rate among young patients.

CONCLUSIONS

The current evidence shows better knee score, less pain, comparable complications and revision rates for uncemented tibial prosthesis fixation, compared to cemented, in cruciate-retaining total knee arthroplasty.

A Brief Insight to the Electrophoretic Deposition of PEEK-, Chitosan-, Gelatin-, and Zein-Based Composite Coatings for Biomedical Applications: Recent Developments and Challenges

Electrophoretic deposition (EPD) is a powerful technique to assemble metals, polymer, ceramics, and composite materials into 2D, 3D, and intricately shaped implants. Polymers, proteins, and peptides can be deposited via EPD at room temperature without affecting their chemical structures. Furthermore, EPD is being used to deposit multifunctional coatings (i.e., bioactive, antibacterial, and biocompatible coatings). Recently, EPD was used to architect multi-structured coatings to improve mechanical and biological properties along with the controlled release of drugs/metallic ions. The key characteristics of EPD coatings in terms of inorganic bioactivity and their angiogenic potential coupled with antibacterial properties are the key elements enabling advanced applications of EPD in orthopedic applications. In the emerging field of EPD coatings for hard tissue and soft tissue engineering, an overview of such applications will be presented. The progress in the development of EPD-based polymeric or composite coatings, including their application in orthopedic and targeted drug delivery approaches, will be discussed, with a focus on the effect of different biologically active ions/drugs released from EPD deposits. The literature under discussion involves EPD coatings consisting of chitosan (Chi), zein, polyetheretherketone (PEEK), and their composites. Moreover, in vitro and in vivo investigations of EPD coatings will be discussed in relation to the current main challenge of orthopedic implants, namely that the biomaterial must provide good bone-binding ability and mechanical compatibility.