The use of intramedullary nails to treat trochanteric fractures of the femur has increased with the increasing size of the elderly population. The third generation Gamma nail is currently one of the most popular devices for the treatment of trochanteric fractures. Nail breakage is a rare complication, possibly resulting from fatigue fracture of the implant. We present the first reported case of breakage of a third generation Gamma nail that was not used to treat a pathological fracture. An 83‐year‐old woman with an unstable trochanteric fracture of the femur was treated using a third generation Gamma nail. She was referred to our hospital 14 months postoperatively with nail breakage at the opening for the lag screw. The breakage was secondary to nonunion, which was thought to be mainly due to insufficient reduction of the fracture. The broken nail was removed, and the patient underwent cemented bipolar hemiarthroplasty. At followup 18 months later, she was mobile with a walker and asymptomatic with no complications. This case shows that inadequate operation such as insufficient reduction of the trochanteric fracture may result in nonunion and implant breakage, even when using a high‐strength, well‐designed implant.

Atypical femoral fractures have emerged as one of the potential complications of bisphosphonates during the past decade. The American Society for Bone and Mineral Research published a Task Force report on atypical femoral fractures in 2010 and a second report in 2014. Although the current definition of atypical femoral fractures in these reports excludes periprosthetic fractures, each of three published case reports describe a bisphosphonate-associated atypical femoral fracture that occurred around the stem of a total hip arthroplasty. We report a rare case of an atypical femoral fracture that occurred at the stem tip of a total hip arthroplasty that fulfills the major criteria defined by the second American Society for Bone and Mineral Research Task Force report for an atypical femoral fracture and that was associated with prolonged use of bisphosphonate. A 69-year-old Japanese woman with a right cementless total hip arthroplasty undertaken 44 months previously had a right femoral shaft fracture that occurred without trauma. She related that the bone fractured while she was standing, after which she fell down. Radiographs showed a noncomminuted transverse fracture located at the tip of the stem with localized periosteal thickening of the lateral cortex. The fracture was complete, extending through both cortices, and was associated with a medial spike. Her history revealed that she had been taking prednisolone to treat dermatomyositis and interstitial pneumonia for approximately 15 years. Alendronate was administered for more than 7 years. We performed open reduction and internal fixation using a locking plate with cable grip. The latest follow-up was performed 2 years after the fracture surgery. Bony union was successful. She regained the ability to walk, although her activity was limited by her comorbidities. Although the current definition of an atypical femoral fracture excludes periprosthetic fractures, there may be a periprosthetic fracture with the same or similar pathology as that of an atypical femoral fracture. We must be vigilant and aware of this type of fracture, especially in patients with prolonged bisphosphonate use.

Objective: To elucidate the roles of interleukin-6 (IL-6) and tumour necrosis factor-α (TNF-α) in cell cycle regulation and proliferation of rheumatoid arthritis fibroblast-like synovial cells (RA-FLSs). Methods: Under stimulation with IL-6/soluble interleukin-6 receptor (sIL-6R) and TNF-α, we examined the expression of cell cycle regulators [p16^INK4a, p21^Cip1, p27^Kip1, cyclin-dependent kinase-4 (CDK4), CDK6, Cyclin D, Cyclin E, and retinoblastoma protein (pRB)] by quantitative polymerase chain reaction, Western blotting, and immunofluorescence staining. The expression of pRB, with or without 10% foetal bovine serum, was examined by Western blotting. DNA synthesis and cell viability were examined by the BrdU assay and WST-8 assay, respectively. After transfection with siRNA/p16^INK4a, siRNA/p21^Cip1, siRNA/p27^Kip1, siRNA/CDK4, or siRNA/CDK6, RA-FLSs were successively stimulated with or without IL-6/sIL-6R or TNF-α to determine cell viability. Results: IL-6/sIL-6R significantly decreased the expression of p16^INK4a, and increased p21^Cip1, Cyclin E1, CYCLIN D, and pRB. TNF-α decreased the expression of CDK4, and significantly increased p27^Kip1, CDK6, Cyclin E1/E2, CYCLIN D, CYCLIN E, pRB, and phosphorylated pRB (phospho-pRB). By immunofluorescence staining, CYCLIN D and phospho-pRB were simultaneously stained in the single cell. In serum-free culture, the expression of pRB was apparently decreased. DNA synthesis and cell viability were significantly increased by IL-6/sIL-6R and TNF-α. Silencing of CDK6 attenuated the cell viability induced by IL-6 and TNF-α. Conclusion: The results indicate that IL-6 and TNF-α interact with each other in regulating the cell cycle and accelerate the proliferation of RA-FLSs.

Bone defects may occur because of severe trauma, nonunion, infection, or tumor resection. However, treatments for bone defects are often difficult and have not been fully established yet. We previously designed an efficient system of topical cutaneous application of carbon dioxide (CO2) using a novel hydrogel, which facilitates CO2 absorption through the skin into the deep area within a limb. In this study, the effect of topical cutaneous application of CO2 on bone healing was investigated using a rat femoral defect model. In this basic research study, an in vivo bone defect model, fixed with an external fixator, was created using a rat femur. The affected limb was shaved, and CO2 was applied for 20 min/day, 5 days/week. In the control animals, CO2 gas was replaced with air. Radiographic, histological, biomechanical, and genetic assessments were performed to evaluate bone healing. Radiographically, bone healing rate was significantly higher in the CO2 group than in the control group at 4 weeks (18.2% vs. 72.7%). The degree of bone healing scored using the histopathological Allen grading system was significantly higher in the CO2 group than in the control group at 2 weeks (1.389 ± 0.334 vs. 1.944 ± 0.375). The ultimate stress, extrinsic stiffness, and failure energy were significantly greater in the CO2 group than in the control group at 4 weeks (3.2 ± 0.8% vs. 38.1 ± 4.8%, 0.6 ± 0.3% vs. 41.5 ± 12.2%, 2.6 ± 0.8% vs. 24.7 ± 5.9%, respectively.). The volumetric bone mineral density of the callus in micro-computed tomography analysis was significantly higher in the CO2 group than in the control group at 4 weeks (180.9 ± 43.0 mg/cm3 vs. 247.9 ± 49.9 mg/cm3). Gene expression of vascular endothelial growth factor in the CO2 group was significantly greater than that in the control group at 3 weeks (0.617 ± 0.240 vs. 2.213 ± 0.387). Topical cutaneous application of CO2 accelerated bone healing in a rat femoral defect model. CO2 application can be a novel and useful therapy for accelerating bone healing in bone defects; further research on its efficacy in humans is warranted.