Which Design and Biomaterial Factors Affect Clinical Wear Performance of Total Disc Replacements? A Systematic Review

Background Total disc replacement was clinically introduced to reduce pain and preserve segmental motion of the lumbar and cervical spine. Previous case studies have reported on the wear and adverse local tissue reactions around artificial prostheses, but it is unclear how design and biomaterials affect clinical outcomes. Questions/purposes Which design and material factors are associated with differences in clinical wear performance (implant wear and periprosthetic tissue response) of (1) lumbar and (2) cervical total disc replacements? Methods We performed a systematic review on the topics of implant wear and periprosthetic tissue response using an advanced search in MEDLINE and Scopus electronic databases. Of the 340 references identified, 33 were retrieved for full-text evaluation, from which 16 papers met the inclusion criteria (12 on lumbar disc replacement and five on cervical disc replacement; one of the included studies reported on both lumbar and cervical disc replacement), which involved semiquantitative analysis of wear and adverse local tissue reactions along with a description of the device used. An additional three papers were located by searching bibliographies of key articles. There were seven case reports, three case series, two case-control studies, and seven analytical studies. The Methodological Index for Non-randomized Studies (MINORS) Scale was used to score case series and case-control studies, which yielded mean scores of 10.3 of 16 and 17.5 of 24, respectively. In general, the case series (three) and case-control (two) studies were of good quality. Results In lumbar regions, metal-on-polymer devices with mobile-bearing designs consistently generated small and large polymeric wear debris, triggering periprosthetic tissue activation of macrophages and giant cells, respectively. In the cervical regions, metal-on-polymer devices with fixed-bearing designs had similar outcomes. All metal-on-metal constructs tended to generate small metallic wear debris, which typically triggered an adaptive immune response of predominantly activated lymphocytes. There were no retrieval studies on one-piece prostheses. Conclusions This review provides evidence that design and biomaterials affect the type of wear and inflammation. However, clinical study design, followup, and analytical techniques differ among investigations, preventing us from drawing firm conclusions about the relationship between implant design and wear performance for both cervical and lumbar total disc replacement

Cellular and molecular mediators of bone metastatic lesions

Bone is the preferential site of metastasis for breast and prostate tumor. Cancer cells establish a tight relationship with the host tissue, secreting factors that stimulate or inhibit bone cells, receiving signals generated from the bone remodeling activity, and displaying some features of bone cells. This interplay between tumor and bone cells alters the physiological bone remodeling, leading to the generation of a vicious cycle that promotes bone metastasis growth. To prevent the skeletal-related events (SRE) associated with bone metastasis, approaches to inhibit osteoclast bone resorption are reported. The bisphosphonates and Denosumab are currently used in the treatment of patients affected by bone lesions. They act to prevent or counteract the SRE, including pathologic fractures, spinal cord compression, and pain associated with bone metastasis. However, their primary effects on tumor cells still remain controversial. In this review, a description of the mechanisms leading to the onset of bone metastasis and clinical approaches to treat them are described

Is there evidence for accelerated polyethylene wear in uncemented compared to cemented acetabular components? A systematic review of the literature

Joint arthroplasty registries show an increased rate of aseptic loosening in uncemented acetabular components as compared to cemented acetabular components. Since loosening is associated with particulate wear debris, we postulated that uncemented acetabular components demonstrate a higher polyethylene wear rate than cemented acetabular components in total hip arthroplasty. We performed a systematic review of the peer-reviewed literature, comparing the wear rate in uncemented and cemented acetabular components in total hip arthroplasty. Studies were identified using MEDLINE (PubMed), EMBASE and the Cochrane Central Register of Controlled Trials. Study quality was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach. The search resulted in 425 papers. After excluding duplicates and selection based on title and abstracts, nine studies were found eligible for further analysis: two randomised controlled trials, and seven observational studies. One randomised controlled trial found a higher polyethylene wear rate in uncemented acetabular components, while the other found no differences. Three out of seven observational studies showed a higher polyethylene wear in uncemented acetabular component fixation; the other four studies did not show any differences in wear rates. The available evidence suggests that a higher annual wear rate may be encountered in uncemented acetabular components as compared to cemented components

Total hip replacement for the treatment of end stage arthritis of the hip : a systematic review and meta-analysis

Background: Evolvements in the design, fixation methods, size, and bearing surface of implants for total hip replacement (THR) have led to a variety of options for healthcare professionals to consider. The need to determine the most optimal combinations of THR implant is warranted. This systematic review evaluated the clinical effectiveness of different types of THR used for the treatment of end stage arthritis of the hip. Methods: A comprehensive literature search was undertaken in major health databases. Randomised controlled trials (RCTs) and systematic reviews published from 2008 onwards comparing different types of primary THR in patients with end stage arthritis of the hip were included. Results: Fourteen RCTs and five systematic reviews were included. Patients experienced significant post-THR improvements in Harris Hip scores, but this did not differ between impact types. There was a reduced risk of implant dislocation after receiving a larger femoral head size (36 mm vs. 28 mm; RR = 0.17, 95% CI: 0.04, 0.78) or cemented cup (vs. cementless cup; pooled odds ratio: 0.34, 95% CI: 0.13, 0.89). Recipients of cross-linked vs. conventional polyethylene cup liners experienced reduced femoral head penetration and revision. There was no impact of femoral stem fixation and cup shell design on implant survival rates. Evidence on mortality and complications (aseptic loosening, femoral fracture) was inconclusive. Conclusions: The majority of evidence was inconclusive due to poor reporting, missing data, or uncertainty in treatment estimates. The findings warrant cautious interpretation given the risk of bias (blinding, attrition), methodological limitations (small sample size, low event counts, short follow-up), and poor reporting. Long-term pragmatic RCTs are needed to allow for more definitive conclusions. Authors are encouraged to specify the minimal clinically important difference and power calculation for their primary outcome(s) as well CONSORT, PRISMA and STROBE guidelines to ensure better reporting and more reliable production and assessment of evidence