Evaluation of a treatment protocol based on conservative therapy for fragility fractures of the pelvis.

PURPOSE: In an aging society, fragility fractures of the pelvis (FFP) have increased significantly. However, there is no clear consensus on the timing and criteria for transitioning from conservative treatment to surgery for these fractures. Thus, we aimed to investigate the effects of our treatment protocol for FFP based on conservative treatment. METHODS: We conducted a retrospective study including 74 patients with FFP at our institution between 2015 and 2021. All patients were treated conservatively for the first two weeks. During this period, only wheelchair transfer was allowed. If the patient could not walk after this period, surgery was performed. Fracture type (Rommens classification), walking ability, presence of complications after admission, presence of fracture union, and surgical treatment was investigated. Patients were divided into two groups: a stable group (type I/II) and an unstable group (type III/IV). RESULTS: Fracture union was achieved in all patients. Thirteen patients developed complications after being admitted to our hospital; seven showed decreased walking ability, and six required surgeries. The stable and unstable groups comprised 47 and 27 patients, respectively. There were no statistically significant differences between the groups regarding the percentage of patients who developed complications or experienced decrease in walking ability. The percentage of patients who required surgery was significantly higher in the unstable group (p < 0.05). CONCLUSION: Our FFP management protocol was effective regardless of fracture type. It is important to provide a period for careful assessment of instability, and to try to prevent fracture progression.

Pulsed Electromagnetic Fields and Tissue Engineering of the Joints.

BACKGROUND: Bone and joint formation, maintenance, and regeneration are regulated by both chemical and physical signals. Among the physical signals there is an increasing realization of the role of pulsed electromagnetic fields (PEMF) in the treatment of nonunions of bone fractures. The discovery of the piezoelectric properties of bone by Fukada and Yasuda in 1953 in Japan established the foundation of this field. Pioneering research by Bassett and Brighton and their teams resulted in the approval by the Food and Drug Administration (FDA) of the use of PEMF in the treatment of fracture healing. Although PEMF has potential applications in joint regeneration in osteoarthritis (OA), this evolving field is still in its infancy and offers novel opportunities. METHODS: We have systematically reviewed the literature on the influence of PEMF in joints, including articular cartilage, tendons, and ligaments, of publications from 2000 to 2016. CONCLUSIONS: PEMF stimulated chondrocyte proliferation, differentiation, and extracellular matrix synthesis by release of anabolic morphogens such as bone morphogenetic proteins and anti-inflammatory cytokines by adenosine receptors A2A and A3 in both in vitro and in vivo investigations. It is noteworthy that in clinical translational investigations a beneficial effect was observed on improving function in OA knees. However, additional systematic studies on the mechanisms of action of PEMF on joints and tissues therein, articular cartilage, tendons, and ligaments are required.

Optimization of Methods for Articular Cartilage Surface Tissue Engineering: Cell Density and Transforming Growth Factor Beta Are Critical for Self-Assembly and Lubricin Secretion.

OBJECTIVE: Lubricin/superficial zone protein (SZP)/proteoglycan4 (PRG4) plays an important role in boundary lubrication in articular cartilage. Lubricin is secreted by superficial zone chondrocytes and synoviocytes of the synovium. The specific objective of this investigation is to optimize the methods for tissue engineering of articular cartilage surface. The aim of this study is to investigate the effect of cell density on the self-assembly of superficial zone chondrocytes and lubricin secretion as a functional assessment. DESIGN: Superficial zone chondrocytes were cultivated as a monolayer at low, medium, and high densities. Chondrocytes at the three different densities were treated with transforming growth factor beta (TGF-ß)1 twice a week or daily, and the accumulated lubricin in the culture medium was analyzed by immunoblots and quantitated by enzyme-linked immunosorbent assay (ELISA). RESULTS: Cell numbers in low and medium densities were increased by TGF-ß1; whereas cell numbers in high-density cell cultures were decreased by twice-a-week treatment of TGF-ß1. On the other hand, the cell numbers were maintained by daily TGF-ß treatment. Immunoblots and quantitation of lubricin by ELISA analysis indicated that TGF-ß1 stimulated lubricin secretion by superficial zone chondrocytes at all densities with twice-a-week TGF-ß treatment. It is noteworthy that the daily treatment of TGF-ß1 increased lubricin much higher compared with twice-a-week treatment. CONCLUSIONS: These data demonstrate that daily treatment is optimal for the TGF-ß1 response in a higher density of monolayer cultures. These findings have implications for self-assembly of surface zone chondrocytes of articular cartilage for application in tissue engineering of articular cartilage surface.

Cyclin-Dependent Kinase Inhibitor-1-Deficient Mice are Susceptible to Osteoarthritis Associated with Enhanced Inflammation.

Osteoarthritis (OA) is a multifactorial disease, and recent data suggested that cell cycle-related proteins play a role in OA pathology. Cyclin-dependent kinase (CDK) inhibitor 1 (p21) regulates activation of other CDKs, and recently, we reported that p21 deficiency induced susceptibility to OA induced by destabilization of the medial meniscus (DMM) surgery through STAT3-signaling activation. However, the mechanisms associated with why p21 deficiency led to susceptibility to OA by the STAT3 pathway remain unknown. Therefore, we focused on joint inflammation to determine the mechanisms associated with p21 function during in vitro and in vivo OA progression. p21-knockout (p21-/- ) mice were used to develop an in vivo OA model, and C57BL/6 (p21+/+ ) mice with the same background as the p21-/- mice were used as controls. Morphogenic changes were measured using micro-CT, IL-1ß serum levels were detected by ELISA, and histological or immunohistological analyses were performed. Our results indicated that p21-deficient DMM-model mice exhibited significant subchondral bone destruction and cartilage degradation compared with wild-type mice. Immunohistochemistry results revealed p21-/- mice susceptibility to OA changes accompanied by macrophage infiltration and enhanced MMP-3 and MMP-13 expression through IL-1ß-induced NF-κB signaling. p21-/- mice also showed subchondral bone destruction according to micro-CT analysis, and cathepsin K staining revealed increased numbers of osteoclasts. Furthermore, p21-/- mice displayed increased serum IL-1ß levels, and isolated chondrocytes from p21-/- mice indicated elevated MMP-3 and MMP-13 expression with phosphorylation of IκB kinase complex in response to IL-1ß stimulation, whereas treatment with a specific p-IκB kinase inhibitor attenuated MMP-3 and MMP-13 expression. Our results indicated that p21-deficient DMM mice were susceptible to alterations in OA phenotype, including enhanced osteoclast expression, macrophage infiltration, and MMP expression through IL-1ß-induced NF-κB signaling, suggesting that p21 regulation may constitute a possible therapeutic strategy for OA treatment. © 2017 American Society for Bone and Mineral Research.

Modulation of Superficial Zone Protein/Lubricin/PRG4 by Kartogenin and Transforming Growth Factor-ß1 in Surface Zone Chondrocytes in Bovine Articular Cartilage.

OBJECTIVE: Superficial zone protein (SZP)/lubricin/PRG4 functions as a boundary lubricant in articular cartilage to decrease friction and wear. As articular cartilage lubrication is critical for normal joint function, the accumulation of SZP at the surface of cartilage is important for joint homeostasis. Recently, a heterocyclic compound called kartogenin (KGN) was found to induce chondrogenic differentiation and enhance mRNA expression of lubricin. The objective of this study was to determine whether KGN can stimulate synthesis of SZP in superficial zone, articular chondrocytes. DESIGN: We investigated the effects of KGN and transforming growth factor-ß1 (TGF-ß1) on articular cartilage and synovium of the bovine knee joint by evaluating SZP secretion by enzyme-linked immunosorbent assay analysis. Monolayer, micromass, and explant cultures of articular cartilage, and monolayer culture of synoviocytes, were treated with KGN. SZP accumulation in the medium was evaluated and mRNA expression was measured through quantitative polymerase chain reaction. RESULTS: TGF-ß1 stimulated SZP secretion by superficial zone chondrocytes in monolayer, explant, and micromass cultures as expected. In addition, SZP secretion was inhibited by IL-1ß in explant cultures, and enhanced by TGF-ß1 in synoviocyte monolayer cultures. Although KGN elicited a 1.2-fold increase in SZP mRNA expression in combination with TGF-ß1, KGN neither stimulated any significant increases in SZP synthesis nor prevented catabolic decreases in SZP production from IL-1ß. CONCLUSIONS: These data suggest that the chondrogenic effects of KGN depend on cellular phenotype and differentiation status, as KGN did not alter SZP synthesis in differentiated, superficial zone articular chondrocytes.

Oxidative stress-induced apoptosis and matrix loss of chondrocytes is inhibited by eicosapentaenoic acid.

Eicosapentaenoic acid (EPA) is an antioxidant and n-3 polyunsaturated fatty acid that reduces the production of inflammatory cytokines. We evaluated the role of EPA in chondrocyte apoptosis and degeneration. Normal human chondrocytes were treated with EPA and sodium nitroprusside (SNP). Expression of metalloproteinases (MMPs) was detected by real-time polymerase chain reaction (PCR) and that of apoptosis-related proteins was detected by western blotting. Chondrocyte apoptosis was detected by flow cytometry. C57BL/6J mice were used for the detection of MMP expression by immunohistochemistry and for investigation of chondrocyte apoptosis. EPA inhibited SNP-induced chondrocyte apoptosis, caspase 3 and poly(ADP-ribose) polymerase cleavage, phosphorylation of p38 MAPK and p53, and expression of MMP3 and MMP13. Intra-articular injection of EPA prevented the progression of osteoarthritis (OA) by inhibiting MMP13 expression and chondrocyte apoptosis. EPA treatment can control oxidative stress-induced OA progression, and thus may be a new approach for OA therapy.

Cyclin­dependent kinase inhibitor p21 does not impact embryonic endochondral ossification in mice.

Endochondral ossification at the growth plate is regulated by a number of factors and hormones. The cyclin­dependent kinase inhibitor p21 has been identified as a cell cycle regulator and its expression has been reported to be essential for endochondral ossification in vitro. However, to the best of our knowledge, the function of p21 in endochondral ossification has not been evaluated in vivo. Therefore, the aim of this study was to investigate the function of p21 in embryonic endochondral ossification in vivo. Wild­type (WT) and p21 knockout (KO) pregnant heterozygous mice were sacrificed on embryonic days E13.5, E15.5 and E18.5. Sagittal histological sections of the forearms of the embryos were collected and stained with Safranin O and 5­bromo­2'­deoxyuridine (BrdU). Additionally, the expression levels of cyclin D1, type II collagen, type X collagen, Sox9, and p16 were examined using immunohistochemistry, and the expression levels of p27 were examined using immunofluorescence. Safranin O staining revealed no structural change between the cartilage tissues of the WT and p21KO mice at any time point. Type II collagen was expressed ubiquitously, while type X collagen was only expressed in the hypertrophic zone of the cartilage tissues. No differences in the levels of Sox9 expression were observed between the two groups at any time point. The levels of cyclin D1 expression and BrdU uptake were higher in the E13.5 cartilage tissue compared with those observed in the embryonic cartilage tissue at subsequent time points. Expression of p16 and p27 was ubiquitous throughout the tissue sections. These results indicate that p21 may not be essential for embryonic endochondral ossification in articular cartilage of mice and that other signaling networks may compensate for p21 deletion.

Arthroscopic ankle arthrodesis for treating osteoarthritis in a patient with kashin-beck disease.

Kashin-Beck disease (KBD) is an endemic degenerative osteoarthritis. Death of cartilage and growth plate is the pathologic feature; therefore, KBD involves skeletal deformity and often results in osteoarthritis. Deficiency of selenium, high humic acid levels in water, and fungi on storage gains are considered the cause of KBD. The most frequently involved joints are ankles, knees, wrists, and elbows and symptoms are pain and limited motions of those joints. The main treatments for KBD are rehabilitation and osteotomy to correct the deformities because preventive treatment has not been established. In this report, we present a case of ankle osteoarthritis due to KBD and first describe arthroscopic ankle arthrodesis for treating osteoarthritis of KBD.

PTEN regulates matrix synthesis in adult human chondrocytes under oxidative stress.

Phosphatase and tensin homologue deleted on chromosome 10 (PTEN) was identified as an important tumor suppressor gene. PTEN functions as a negative regulator of phosphoinositol-3-kinase (PI3K)-Akt and MEK/ERK signaling. The PI3K-Akt pathway is critical for cell survival, differentiation, and matrix synthesis. Oxidative stress is considered a critical factor in the onset and progression of osteoarthritis (OA). Therefore, we investigated the function of PTEN in OA chondrocytes under oxidative stress. Chondrocytes were treated with insulin-like growth factor-1 (IGF-1) and/or tert-butyl hydroperoxide (tBHP), which causes oxidative stress. The expression levels of type2 collagen (Col2a1) and aggrecan were analyzed by real-time PCR, and phosphorylation of Akt and ERK1/2 was analyzed by Western blotting. Chondrocytes were treated with PTEN-specific small interfering RNA (siRNA), as well as IGF-1 and/or tBHP. PTEN and IGF-1 expressions in OA chondrocytes were increased. The downregulation of PTEN expression increased the expression levels of Col2a1 and aggrecan, and increased proteoglycan synthesis under oxidative stress. Oxidative stress decreased the phosphorylation of Akt and increased that of ERK1/2. The downregulation of PTEN expression increased Akt phosphorylation, but did not increase that of ERK 1/2. Our results suggest that PTEN regulates matrix synthesis via the PI3K-Akt pathway under oxidative stress.

Regulation of p38 MAPK phosphorylation inhibits chondrocyte apoptosis in response to heat stress or mechanical stress.

Activation of p38 MAPK has been associated with a stress response and with apoptotic processes. However, the function of p38 MAPK in chondrocytes is not clearly understood. In this study, we analyzed the expression of p38 MAPK in chondrocytes and investigated the function of p38 MAPK in response to heat stress and mechanical stress. Chondrocytes were isolated from human cartilage and cultured. Expression of p38 and phosphorylated p38 in cartilage of patients with osteoarthritis (OA) was compared to those in normal cartilage by immunohistochemistry and Western blotting. Human knee chondrocytes were exposed to heat stress or mechanical stress. Normal knee chondrocytes were pre-treated with SB203580 or p38 small interfering RNA (siRNA) before induction of heat stress or mechanical stress. Chondrocyte apoptosis was detected by TUNEL staining and Western blotting of cleaved caspases. OA and normal chondrocytes expressed p38; however, OA chondrocytes showed much higher phosphorylated p38 compared to normal chondrocytes. Heat stress or mechanical stress induced apoptosis and increased phosphorylated p38 in normal chondrocytes. The TUNEL positive cells and expression levels of phosphorylated p38 in response to stress decreased when chondrocytes were incubated with SB203580 or transfected with siRNA against p38. In conclusion, we have demonstrated that heat stress or mechanical stress increased chondrocyte apoptosis via phosphorylation of p38. Stress-induced chondrocyte apoptosis decreased due to inhibition of p38 MAPK activation. In contrast, the phosphorylation of p38 MAPK increased in OA chondrocytes. Our results show that down-regulation of p38 MAPK activation inhibits chondrocyte death induced by heat stress or mechanical stress.