The interface between bone tissue and metal implants undergoes various types of mechanical loading, such as strain, compression, fluid pressure, and shear stress, from daily activities. Such mechanical perturbations create suboptimal environments at the host bone-implant junction, causing an accumulation of wear particles and debilitating osseous integration, potentially leading to implant failure. While many studies have focused on the effect of particles on macrophages or osteoprogenitor cells, differential and combined effects of mechanical perturbations and particles on such cell types have not been extensively studied. In this study, macrophages and osteoprogenitor cells were subjected to physiological and superphysiological mechanical stimuli in the presence and absence of Ti particles with the aim of simulating various microenvironments of the host bone-implant junction. Macrophages and osteoprogenitor cells were capable of engulfing Ti particles through actin remodeling and also exhibited changes in mRNA levels of proinflammatory cytokines under certain conditions. In osteoprogenitor cells, superphysiological strain increased proinflammatory gene expression; in macrophages, such mechanical perturbations did not affect gene expression. We confirmed that this phenomenon in osteoprogenitor cells occurred via activation of the ERK1/2 signaling pathway as a result of damage to the cytoplasmic membrane. Furthermore, AZD6244, a clinically relevant inhibitor of the ERK1/2 pathway, mitigated particle-induced inflammatory gene expression in osteoprogenitor cells and macrophages. This study provides evidence of more inflammatory responses under mechanical strains in osteoprogenitor cells than macrophages. Phagocytosis of particles and mechanical perturbation costimulate the ERK1/2 pathway, leading to expression of proinflammatory genes.

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PurposeA basicervical femoral fracture is defined as a fracture of base of neck of femur that occurs medially from intertrochanteric line above lesser trochanter. In this study, we intended to evaluate radiological and clinical results of basicervical femoral fractures treated by intramedullary nailing.Materials and MethodsFifteen patients, who underwent intramedullary nailing among 50 patients, out of 50 who were diagnosed with basicervical femoral fractures from July 2012 to May 2015 were studied. All of 15 patients' fracture were two-part basicervical fractures. Using radiography, we characterized the: i) state of reduction, ii) location of the lag screw, iii) tip apex distance (TAD), and iv) sliding distance of lag screw and bone union. Additionally, we performed clinical assessment before injury and at final follow-up.ResultsIn radiological assessment, we achieved acceptable reduction state in all patients. All lag screws were fixated on appropriate locations. Mean TAD was 17.3 mm (11.0–21.1 mm), which showed insertion point of <25 mm in all cases. The mean sliding distance of the lag screw was 5.1 mm (0.1–16.0 mm) at the final follow-up. The mean bone union period was 4.8 months (3–10 months) with achieving in all cases. In clinical assessment, Harris hip score, visual analogue scale score and Western Ontario and McMaster Universities Arthritis Index score, all of them significantly improved postoperatively compared with preoperative scores (P<0.05).ConclusionIn elderly patients with basicervical femoral fractures, treatment with intramedullary nailing showed satisfactory results, considered to be a useful method if performed with skilled technique.

Retrospective Cohort Design, Treatment Study, level III.

Arthroscopic release of the ECRB is an effective method of treatment in patients with recalcitrant lateral epicondylitis. Decortication of the lateral epicondyle leads to increased pain postoperatively and did not improve clinical results.