Evaluation of metal ion levels in the blood of patients with malseated and seated metal backed insert after cementless total hip arthroplasty

Introduction: Today, the incidence of osteoarthritis is increasing with the increase in obesity and the prolongation of human lifespan. Although there are many conservative treatment modalities, these treatments may not fully improve the joint functions of the cases. In this case, total hip replacement surgery is a good treatment alternative. Ceramic-ceramic surface is often preferred in the selection of cementless hip prosthesis surfaces in young cases, due to less wear. In the postoperative follow-up, it is determined that the metal-backed insert is malseated into its socket in some cases. In this study, we aimed to compare the clinical and radiological evaluation results of the patients and metal ion levels in the blood, who underwent total hip arthroplasty, in which malseated metal-backed inserts and seated metal-backed inserts were used. Materials and methods: Our study was planned on patients who underwent cementless total hip arthroplasty with ceramic-ceramic surface selection in our clinic between 2013 and 2020. Postoperatively, x-rays of the hip AP and frog position were examined, and it was evaluated whether the insert was placed or not. Harris hip scores were calculated by performing physical examinations of the cases. Blood was taken from all cases to determine the level of metal ions in their content. Cases with and without metal-backed inserts were grouped (Group 1 and Group 2), and the two groups were compared in terms of clinical, radiological and blood metal ion levels. Results: Of the 40 cases included in the study, 13 were male and 27 were female. The mean age at the time of their participation in the study was 56.42 ± 7.43 (min: 37, max: 69), and the mean BMI of all subjects was 29.34 ± 3.72. Preoperative Harris hip scores were 63.7 ± 4.31, and postoperative mean scores were 91.18 ± 8.79. The mean angle of the malseated inserts was found to be 4.14 ± 0.99 (max: 5.3, min: 2) degrees and it was determined that this did not change over the years. It was determined that as the angle of non-settlement increased, the levels of vanadium ions in the blood increased significantly (p: 0.026). Group 1 and Group 2 metal ion levels were compared. Aluminum levels were found to be significantly higher in Group 2 (p: 0.028) (Group 1 aluminum level 1.78 ± 0.38 µg/L; Group 2 aluminum level 2.26 ± 0.59 µg/L). Conclusions: When we compared the cases with malseated inserts with the cases with implanted inserts in relatively young patients who underwent ceramic-ceramic total hip arthroplasty surgery, no unfavorable situation was found in terms of clinical and laboratory values. No significant difference was observed in Harris hip scores. A significant level of aluminium metal ion was detected in Group 2 compared to Group 1. In addition, it was determined that the increased vanadium levels of the malseated insert significantly as the non-settling angle increased. We suggest that the blood aluminum and vanadium levels of the patients with osteolysis findings on the control radiographs should be checked.