Osteolysis Complicating Total Knee Arthroplasty

Femoral neck fracture patients with ischaemic stroke choose hemiarthroplasty or constrained liner total hip arthroplasty? A retrospective comparative study of 199 cases

Background

The objective of this study was to assess the long-term survival rate, complications, as well as the clinical and radiological outcomes of hemiarthroplasty and total hip arthroplasty using constrained polyethylene liners in patients with ischemic stroke.

Methods

This study was a retrospective cohort study that included patients with ischemic stroke who underwent hip arthroplasty from March 2010 to September 2017. In the Constrained Acetabular Liners (CAL) group, patients received an uncemented acetabular shell with a constrained polyethylene liner. The Dual Mobility (DM) group underwent hemiarthroplasty (HA). Additionally, hip function, range of motion, quality of life, the incidence of clinical complications, and prosthesis stability were investigated.

Results

96 patients with unilateral femoral neck fractures who underwent hip replacement with CAL were included in the CAL group, while 103 patients who underwent hip replacement with a dual mobility head were included in the DM group. VAS, and SF-36 data were available for both CAL and DM groups. At the 1-year postoperative follow-up, the HHS in the CAL group was significantly lower than that in the DM group (80.83 ± 3.91 vs. 83.17 ± 4.15, P < 0.05). The VAS score in the CAL group peaked at the 1-year follow-up (2.07 ± 0.91 vs. 1.49 ± 0.85, P < 0.05). However, there were no significant differences between the two groups in terms of HSS, VAS, and SF-36 at the last follow-up after surgery. Operative time and the amount of bleeding in the DM group were significantly lower than those in the CAL group (105.30 ± 29.68 vs. 94.85 ± 31.07; 355.11 ± 123.95 vs. 302.22 ± 107.68, P < 0.05). Additionally, there was no significant difference in the mean leg length discrepancy between the two groups.

Conclusion

The clinical, imaging, and postoperative complications of the CAL and DM groups were analyzed. The prognosis for DM appears to be more beneficial for early patient recovery, but a higher likelihood of recurrent dislocation is observed. CAL offers excellent stability for primary THA in high-risk patients; however, attention should be given to preventing aseptic loosening.

Ultra-High-Molecular-Weight Polyethylene in Hip and Knee Arthroplasties

Ultra-high-molecular-weight polyethylene (UHMWPE) wear and particle-induced osteolysis contribute to the failure of total hip arthroplasty (THA) and total knee arthroplasty (TKA). Highly crosslinked polyethylene (HXLPE) was developed in the late 1990s to reduce wear and has shown lower wear rates and loosening than conventional UHMWPE in THA. The irradiation dose for crosslinking is up to 100 kGy. However, during crosslinking, free radical formation induces oxidation. Using HXLPE in THA, the cumulative revision rate was determined to be significantly lower (6.2%) than that with conventional UHMWPE (11.7%) at a mean follow-up of 16 years, according to the Australian Orthopaedic Association National Joint Replacement Registry. However, HXLPE does not confer to TKA the same advantages it confers to THA. Several alternatives have been developed to prevent the release of free radicals and improve polymer mechanical properties, such as thermal treatment, phospholipid polymer 2-methacryloyloxyethyl phosphorylcholine grafting, remelting, and vitamin E addition. Among these options, vitamin E addition has reported good clinical results and wear resistance similar to that of HXLPE without vitamin E, as shown by short-term clinical studies of THA and TKA. This review aims to provide a comprehensive overview of the development and performance of UHMWPE in THA and TKA.

Sclerostin-Mediated Impaired Osteogenesis by Fibroblast-Like Synoviocytes in the Particle-Induced Osteolysis Model

Engineered biomaterials are envisioned to replace, augment, or interact with living tissues for improving the functional deformities associated with end-stage joint pathologies. Unfortunately, wear debris from implant interfaces is the major factor leading to periprosthetic osteolysis. Fibroblast-like synoviocytes (FLSs) populate the intimal lining of the synovium and are in direct contact with wear debris. This study aimed to elucidate the effect of Ti particles as wear debris on human FLSs and the mechanism by which they might participate in the bone remodeling process during periprosthetic osteolysis. FLSs were isolated from synovial tissue from patients, and the condition medium (CM) was collected after treating FLSs with sterilized Ti particles. The effect of CM was analyzed for the induction of osteoclastogenesis or any effect on osteogenesis and signaling pathways. The results demonstrated that Ti particles could induce activation of the NFκB signaling pathway and induction of COX-2 and inflammatory cytokines in FLSs. The amount of Rankl in the conditioned medium collected from Ti particle–stimulated FLSs (Ti CM) showed the ability to stimulate osteoclast formation. The Ti CM also suppressed the osteogenic initial and terminal differentiation markers for osteoprogenitors, such as alkaline phosphate activity, matrix mineralization, collagen synthesis, and expression levels of Osterix, Runx2, collagen 1α, and bone sialoprotein. Inhibition of the WNT and BMP signaling pathways was observed in osteoprogenitors after the treatment with the Ti CM. In the presence of the Ti CM, exogenous stimulation by WNT and BMP signaling pathways failed to stimulate osteogenic activity in osteoprogenitors. Induced expression of sclerostin (SOST: an antagonist of WNT and BMP signaling) in Ti particle–treated FLSs and secretion of SOST in the Ti CM were detected. Neutralization of SOST in the Ti CM partially restored the suppressed WNT and BMP signaling activity as well as the osteogenic activity in osteoprogenitors. Our results reveal that wear debris–stimulated FLSs might affect bone loss by not only stimulating osteoclastogenesis but also suppressing the bone-forming ability of osteoprogenitors. In the clinical setting, targeting FLSs for the secretion of antagonists like SOST might be a novel therapeutic approach for preventing bone loss during inflammatory osteolysis.

Cementless Fixation for Total Knee Arthroplasty in Various Patient Populations: A Literature Review

The number of total knee arthroplasties (TKAs) performed in the United States has increased considerably in recent years, with a major contribution from younger patients. Maximizing survivorship of these implants has always been a point of emphasis. Early TKA designs with cementless fixation were associated with high rates of complications and implant failures. However, recent advances in cementless designs have shown excellent results. The decision to use cemented or cementless fixation for patients undergoing TKA is typically based on the surgeon's experience and preference. However, several patient characteristics must also be taken into account. The purpose of this review was to describe the clinical outcomes of studies in which a cementless TKA system was utilized for patients who (1) were less than 60 years of age, (2) were greater than 75 years of age, (3) were obese, (4) had rheumatoid arthritis, and (5) had osteonecrosis of the knee. Based on the studies included in this review, it appears that cementless fixation is a viable option for patients who have all of the above demographics.

Fibroblast-Like-Synoviocytes Mediate Secretion of Pro-Inflammatory Cytokines via ERK and JNK MAPKs in Ti-Particle-Induced Osteolysis

Biomaterials are designed to replace and augment living tissues in order to provide functional support to skeletal deformities. However, wear debris produced from the interfaces of metal implants initiates inflammatory bone loss, causing periprosthetic osteolysis. Lately, fibroblast-like synoviocytes (FLS) have been shown to play a role in wear-debris-induced osteolysis. Thus, here we have tried to understand the underlying mechanism of FLS involvement in wear-debris-induced osteolysis. Our results demonstrate that the effects of Ti particle (1:100 cell-to-Ti particle ratio) on FLS can induce Cox-2 expression and activate NFkB signaling. Moreover, the mRNA expression of pro-inflammatory cytokines such as IL-6, IL-8, IL-11, IL-1β, and TNFα was found to be elevated. However, among these pro-inflammatory cytokines, the mRNA and protein levels of only IL-6, IL-1β, and TNFα were found to be significantly higher. Ti particles activated extracellular signal-regulated kinase (ERK) and c-Jun N-terminal kinase (JNK) mitogen-activated protein kinases (MAPKs) as an early response in FLS. Co-inhibition of ERK and JNK signaling pathways by their specific inhibitors (PD9805 and SP600125, respectively) resulted in the suppression of mRNA and protein levels of IL-6, IL-1β, and TNFα in FLS. Taken together, targeting ERK and JNK MAPKs in FLS might provide a therapeutic option for reducing the secretion of bone-resorbing pro-inflammatory cytokines, thus preventing periprosthetic osteolysis.