The Effect of Subluxation of Articulating Antibiotic Spacers on Bone Defects and Degree of Constraint in Revision Knee Arthroplasty

© 2016 Elsevier Inc. This study investigated whether subluxation of articulating antibiotic spacers is associated with the bone defects found and constraint required when re-implanting the knee arthroplasty components. Staged revisions for infections of primary total knee arthroplasties between 2004 and 2012 were examined. Radiographic sagittal and coronal subluxations of 72 knees were measured prior to second stage revision. Coronal subluxation was found to be associated with increased requirement for constrained knee systems (P\u3c. 0.035). Sagittal subluxation was associated with greater tibia bone defects (P\u3c. 0.037). Careful surgical technique and monitoring of articulating spacers should be done to avoid subluxation after stage 1 revision. If subluxation of the articulating spacer is present, constrained revision knee systems as well as augments should be available at time of re-implantation

Tribocorrosion: Ceramic and Oxidized Zirconium vs Cobalt-Chromium Heads in Total Hip Arthroplasty

© 2016 Elsevier Inc. Background This matched-cohort study aims to compare tribocorrosion between matched ceramic and cobalt-chromium femoral head trunnions and between matched Oxinium and cobalt-chromium femoral head trunnions. Secondary objectives were to investigate whether taper design, depth of trunnion, implantation time, age, body mass index, and gender have an effect on fretting and corrosion. Methods All hip prostheses retrieved between 1999 and 2015 at one center were reviewed, giving a total of 52 ceramic heads. These were matched to a cobalt-chromium cohort according to taper design, head size, neck length, and implantation time. The trunnions were examined by 2 observers using a 4-point scoring technique and scored in 3 zones: apex, middle, and base. The observers were blinded to clinical and manufacturing data where possible. A separate matched-cohort analysis was performed between 8 Oxinium heads and 8 cobalt-chromium heads, which were similarly scored. Results Ceramic head trunnions demonstrated a lower median fretting and corrosion score at the base zone (P \u3c.001), middle zone (P \u3c.001), and in the combined score (P \u3c.001). Taper design had a significant effect on fretting and corrosion in the apex zone (P =.04) of the ceramic group, as well as the cobalt-chromium group (P =.03). Between Oxinium heads and cobalt-chromium heads, there was no significant difference in the fretting and corrosion score across all 3 zones (base: P =.22; middle: P =.92; and apex: P =.71) and for the combined score (P =.67). Conclusion This study shows that ceramic head confers an advantage in trunnion fretting and corrosion. Taper design and implantation time were also significant factors for fretting and corrosion