Oxinium is an alternative bearing surface designed to emulate the superior wear and scratch properties of ceramic femoral heads in total hip arthroplasty while minimizing the risk for brittle fracturing. However, recent studies have indicated that hip dislocation following total hip arthroplasty may be a risk factor for catastrophic failure of the femoral head. Here, we report on a novel case of a catastrophic Oxinium head and polyethylene liner failure in the absence of previous hip dislocation or trauma and review the probable failure mechanism. This report underscores the need to be vigilant about proper acetabular cup and liner seating, particularly in the setting of Oxinium femoral head use. In the event of Oxinium head failure, metallosis may compromise stabilizing soft tissues including the abductors. Dual-mobility articulation, which was successful in this case, is one option to consider when the risk for chronic redislocation is elevated.

Study Design: Single-center retrospective review. Objectives: The cervicothoracic junction (CTJ) is typically difficult to visualize using traditional radiographs. Whole-body stereoradiography (EOS) allows for imaging of the entire axial skeleton in a weightbearing position without parallax error and with lower radiation doses. In this study we sought to compare the visibility of the vertebra of the CTJ on lateral EOS images to that of conventional cervical lateral radiographs. Methods: Two fellowship-trained spine surgeons evaluated the images of 50 patients who had both lateral cervical radiographs and EOS images acquired within a 12-month period. The number of visible cortices of the vertebral bodies of C6-T2 were scored 0-4. Patient body mass index and the presence of spondylolisthesis >2 mm at each level was recorded. The incidence of insufficient visibility to detect spondylolisthesis at each level was also calculated for both modalities. Results: On average, there were more visible cortices with EOS versus XR at T1 and T2, whereas visible cortices were equal at C6 and C7. Patient body mass index was inversely correlated with cortical visibility on XR at T2 and on EOS at T1 and T2. There was a significant difference in the incidence of insufficient visibility to detect spondylolisthesis on EOS versus XR at C7-T1 and T1-2, but not at C6-7. Conclusions: EOS imaging is superior at imaging the vertebra of the CTJ. EOS imaging deserves further consideration as a diagnostic tool in the evaluation of patients with cervical deformity given its ability to produce high-quality images of the CTJ with less radiation exposure.

Oxidized zirconium (OxZr) femoral heads were developed to emulate the superior wear and scratch properties of ceramics while eliminating their unwanted tendency for brittle fracturing. Studies using OxZr have demonstrated reduced linear and volumetric wear of polyethylene (PE) liners when compared with cobalt chrome, ceramic, and steel femoral heads. The purpose of this systematic review was to determine the difference in revision rates, radiologically determined linear wear rates, and patient-reported outcomes among OxZr and alternative bearing materials. Following the Preferred Reporting Items for Systematic Review and Meta-Analysis protocols, a systematic review of published literature through April 24, 2018 was conducted. Among the 862 cases included at a mean weighted follow-up of 4.78 years, the revision THA rate and patient-reported outcomes were similar among OxZr and alternative bearing materials. One of the five studies demonstrated significantly lower linear wear rates in the OxZr group when paired with ultrahigh molecular-weight PE (OxZr 0.03 mm/y vs. stainless-steel 0.11 mm/y; p < 0.001) and when paired with highly-crosslinked PE (OxZr 0.02 mm/y vs. stainless-steel 0.04 mm/y; p < 0.001). The remaining four studies found no difference in linear wear rates. OxZr demonstrated similar outcome to that of modern-day ceramic and metal femoral heads for short- and mid-term revision surgery rates and patient-reported outcomes. Longer term studies are needed to evaluate if any long-term wear advantages are seen with the use of OxZr femoral heads and if the use of OxZr is cost effective compared with ceramic or metal alternatives. The level of evidence of the study is level II, systematic review.