The Measurement of the Oxidative Index of Polyethylene Obtained during Revision Hip Arthroplasty and Assessment of Its Variability Depending on the Degree of Osteolysis, Implantation Time, as Well as the Size and Material of the Utilized Head.

Background/Objectives: Aseptic loosening is the leading cause of late revision in total hip arthroplasty, primarily due to degenerative oxidation of polyethylene components, leading to wear particle formation and periacetabular osteolysis. This study aimed to analyze the oxidation levels in polyethylene liners and cemented cups retrieved from revision surgeries using Fourier-transform infrared spectroscopy (FTIR) and to explore the correlation between oxidation levels and factors such as head size, head material, fixation method, and implant survival time. Methods: Polyethylene liners and cups were analyzed post-revision surgery to assess oxidation levels, which were then compared to periacetabular bone loss measured by the Paprosky classification. This study evaluated the impact of head size (28 mm vs. 32 mm), head material (ceramic vs. metal), and fixation methods on oxidation. The relationship between the mean oxidation index (OI) and implant survival time was also investigated. Results: There was a significant positive correlation between the mean oxidation index of the polyethylene components and the severity of periacetabular osteolysis according to the Paprosky scale. While the mean OI for samples articulating with ceramic heads was lower than for those with metal heads, and the mean OI for samples with a 32 mm head size was lower than for those with a 28 mm size, these differences were not statistically significant. Furthermore, the fixation method did not affect the oxidation index, and no correlation was found between OI and the survival time of the implants. Conclusions: This study confirms a direct correlation between polyethylene oxidation and periacetabular osteolysis in hip replacements, highlighting the importance of material choice and design in potentially reducing the risk of aseptic loosening. Despite the lack of significant differences in oxidation levels based on head material and size, these factors may still play a role in the long-term outcome of hip arthroplasty, warranting further investigation.

Chronic, Neglected Medial Subtalar Dislocation with Associated Talar and Calcaneal Fractures. A Case Report.

Subtalar dislocation is a very rare injury that accounts for just approximately 1% of traumatic dislocations. Stan-dard treatment in acute subtalar dislocations is immediate closed reduction and cast immobilization. Early reduction is of key importance and allows avoiding further damage to soft tissues, nerves and blood vessels. Neglected, chronic subtalar dislocations are seen extremely rarely and only a few cases have been reported in the literature to date. Considering the lack of guidelines and very few literature reports relating to the treatment of such injuries, we have decided to present the case of a male patient with a chronic, neglected, closed medial subtalar dislocation of the right foot with associated fractures of the talar and calcaneal bones. The patient was admitted 4 months post trauma to his right ankle joint caused by a fall from a ladder. An open subtalar reduction was performed with arthrodesis of the talocalcaneal joint and the talonavicular joint of the right foot. The treatment was effective and recreated the me-chanical axis of the limb. One year after the surgery, the patient reported no pain and no limitations in everyday functioning, work and activities. At the one-year follow-up, his AOFAS score was 88/100.