Bone & Joint Research最新文献

Aims: The osteochondral cement line (OCL) plays a key role in joint integrity by attaching articular calcified cartilage (ACC) to underlying subchondral bone (SCB), whose predominant collagens are type 2 (Col-II) and type 1 (Col-I), respectively. Previous studies report contrasting evidence of the presence of collagen fibrils in the OCL, albeit in different species and joints. If present, collagen fibrils might provide a basis for osteochondral bonding in the organic phase. We aimed to study the morphological variations of the osteochondral cement line, to observe whether cartilage and bone collagen fibrils are present in the OCL, and whether they colocalize in a manner that could help explain how ACC attaches to SCB.

Methods: We used immunofluorescence, confocal microscopy, and deconvolution to image Col-I and Col-II collagen fibrils and measure their overlap and colocalization, in OCL harvested from equine and bovine femoral head, patella, and proximal and distal metatarsal condyles. Large mammalian species were chosen to have size and pathobiology relevant to human anatomy. Thousands to millions of Col-I/-II colocalizing complexes were observed per mm² of OCL over a tissue depth of 1 to 5 µm. Kruskal-Wallis with Dunn's post-hoc tests and Mann-Whitney U tests were conducted for intra- and interspecies statistical analysis.

Results: The areal volume (µm³/mm²) of Col-I/Col-II complexes was up to ten times greater in equine than bovine OCL (p = 0.016 to 0.029). Similarly, the number of Col-I/-II complexes and mean volume per complex differed significantly (p < 0.001 to 0.032 and p < 0.001 to 0.029, respectively) among anatomical sites between equine and bovine OCL. Gaps or tears near OCL were present uniquely in the bovine patella.

Conclusion: Col-I/Col-II overlap and colocalize at OCL, which could be a critical source of bond strength between cartilage and bone that should be considered when cartilage repair is attempted in clinical settings.

Aims: Our study explores the candy box (CB) technique with sutures and Nice knot as a novel treatment for inferior pole patellar fractures, potentially superior to traditional wire fixation.

Methods: CT data from five adult knee joints were extracted to create finite element models for inferior pole patellar fractures and four internal fixation models. These included CB technique combined with high-strength sutures and Nice knot (CB-H), CB technique combined with tendon sutures and Nice knot (CB-T), CB technique combined with steel wires (CB-S), and tension-band wiring combined with cerclage wiring (TBWC). Displacement and stress distribution during knee flexion and extension were compared. Physical models were created using 3D printing technology. These models were then subjected to static tensile test and dynamic fatigue test. Data from 21 patients treated with CB-H and 22 patients treated with TBWC were analyzed to assess the effectiveness.

Results: Finite element analysis (FEA) indicated that displacements for CB-H and CB-T were below the failure threshold in all knee joint states. Stresses on the patella and internal fixation were lower in the CB-H and CB-T groups compared with the CB-S and TBWC groups. Both static and dynamic biomechanical experiments confirmed that displacements of CB-H and CB-T also remained below the failure threshold. In clinical research, the CB-H group outperformed the TBWC group in operating time, intraoperative blood loss, length of incision and time to clinical union, and complication control.

Conclusion: The CB technique combined with sutures and Nice knot can provide sufficient fixation strength for inferior pole patellar fractures. This method enables early functional exercise and avoids the need for secondary surgery. It could be a promising alternative to traditional TBWC surgery.

Aims: Lateral locked plating of distal femoral fractures is widely reported, yet there remains a 9% to 19% incidence of mechanical failure. Obliquely directed "kickstand screws", from the metaphyseal portion of a plate toward far-sided articular subchondral bone, have been shown to improve construct stiffness. This study explores the impact of kickstand screws in a finite element analysis bone defect model, comparing plate and screw maximum stress and maximum locking screw forces either with or without the addition of kickstand screws.

Methods: A finite element analysis model of a lateral based femoral plate and fracture gap simulation was created, with material and construct data parameters regarding bone material, implant, and composite model identified. The addition of the upper, lower, or both kickstand screws in an anatomical precontoured lateral distal femoral plate were selected as the variables compared against the absence of kickstand screws. Screw and plate principal stresses (MPa) and locking screw mechanism force (N) were measured.

Results: The addition of the upper kickstand screw or both kickstand screws led to an approximate 40% reduction of stress in the metaphyseal hole closest to the fracture. The addition of the lower, upper, and both kickstand screws led to a 23%, 32%, and 34% reduction of maximum stress in the metaphyseal screws, respectively. The addition of the lower kickstand screw led to a 19% reduction, while the upper or both kickstand screws led to a 23% reduction of maximum force experienced by the locking mechanism.

Conclusion: The addition of kickstand screws improves the mechanical performance of the construct, with reduced stresses experienced by the plate and metaphyseal screws. Furthermore, the maximum forces on the locking screw mechanism were shown to be significantly reduced, providing a protective effect to the polyaxial locking mechanism of the metaphyseal screw.

Aims: This study aimed to identify and compare the microRNA (miRNA) profiles of exosomes derived from human induced pluripotent stem cells (iPSCs), bone marrow mesenchymal stem cells (BMSCs), and adipose tissue-derived stem cells (ADSCs) (hiPSC-Exos, hBMSC-Exos, and hADSC-Exos), and their functional effects on human articular chondrocytes (hACs).

Methods: hiPSC-Exos, hBMSC-Exos, and hADSC-Exos were collected from the appropriate cells cultured in 10% bovine exosome-depleted fetal bovine serum (de-Exo-FBS) for 48 hours. Next-generation sequencing (NGS) and bioinformatics were used to analyze the small RNA profiles of these exosomes. The biological functions of hACs were examined after a 12-day treatment with exosomes.

Results: hBMSC-Exos and hADSC-Exos had similar miRNA profiles but were largely different from hiPS-Exos. There were 17 highly expressed miRNAs in hiPSC-Exos, 13 miRNAs in hADSC-Exos, and 11 miRNAs in hBMSC-Exos. Among them, seven miRNAs overlapped between the hBMSC-Exos and hADSC-Exos, and only three of them (hsa-miR-16-5p, hsa-miR-25-3p, and hsa-miR-93-5p) overlapped among all three exosomes. The putative target genes of the three overlapping exosomal miRNAs, and high-scoring target genes, including MAN2A1, ZNFX1, PHF19, GPR137C, ENPP5, B3GALT2, FNIP1, PKD2, and FBXW7, were identified. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses revealed that these genes are involved in cell growth, bone ossification, and cartilage development/differentiation, possibly via the mitogen-activated protein kinase (MAPK) signalling pathway. Accordingly, we confirmed the biological effect on cartilage differentiation and found that hiPSC-Exos, hBMSC-Exos, and hADSC-Exos maintained hAC viability, prevented senescence, promoted the formation of a normal cartilage matrix (glycosaminoglycan and type II collagen), and downregulated fibrocartilage matrix (type I collagen) in normal hACs. Comparatively, hBMSC-Exos had the greatest effect on hAC function.

Conclusion: Bioinformatics revealed differences and possible mechanisms of action of exosomes derived from pluripotent hiPSCs, multipotent hADSCs, and multipotent hBMSCs, and these exosomes effectively suppressed cell senescence and promoted normal functional extracellular matrix formation in hACs. Further investigations of the different functions of exosomes from pluripotent-hiPSCs other than those from multipotent-hMSCs are needed.

Aims: Tendon healing is a considerable challenge in hand surgery, and the outcome depends on the function of tenocytes and homeostasis of the extracellular matrix. Although microtubule dynamics play crucial roles in various cellular processes, their function in tenocytes remains unknown. This study aimed to investigate the effects of microtubule-targeting agents (paclitaxel and vincristine) on tenocytes, focusing on their influence on tenocyte proliferation and extracellular matrix synthesis. The regulatory effects of microtubule polymerization on tendon healing were also evaluated in vivo.

Methods: A total of 200 four-week-old female C57BL/6 mice were euthanized. Tenocytes were isolated from the flexor digitorum profundus tendons of the index, middle, and ring fingers of the hind paws. The tendon cells were exposed to various concentrations (0, 10, 25, 50, 100, and 200 nM) of paclitaxel or vincristine for 24, 48, 72, and 96 hours, respectively. A rat tendon injury model was established by transecting and repairing the flexor digitorum longus (FDL) tendon, and a paclitaxel-loaded GleMA hydrogel delivery system was applied locally.

Results: We found that both paclitaxel-induced microtubule polymerization and vincristine-induced depolymerization increased the viability of tenocytes. However, only paclitaxel treatment facilitated cell proliferation and stimulated the reorganization of microtubules. Additionally, the expression of cyclin-dependent kinase 1 (CDK1), type III collagen (Col III), and matrix metalloproteinase-3 (MMP-3) was significantly higher when the cells were treated with paclitaxel rather than vincristine treatment. In vivo analysis study using a hydrogel-paclitaxel delivery system revealed significantly improved digit flexion function, increased expression of Col III and MMP-3, and enhanced tissue repair in a rat FDL tendon injury model.

Conclusion: Paclitaxel-mediated microtubule polymerization promotes tenocyte proliferation and extracellular matrix synthesis, ultimately improving tendon healing in a rat model of flexor tendon injury. These improvements were associated with elevated expression of Col III and MMP-3 in tenocytes.

Aims: The aim of the study was to investigate the effect of systematic lumbar traction, applied in 20 sessions over four weeks, on the size of vertebrae, bone mineral density (BMD), and bone turnover markers in women with chronic low back pain (LBP).

Methods: A total of 30 women with low back pain underwent 20 sessions of lumbar traction with a load of 25% to 30% of their body weight. Total body and lumbar spine BMD was measured using dual-energy X-ray absorptiometry, and bone turnover markers were determined using enzyme-linked immunosorbent assay (ELISA) with serum samples collected before the first traction session and 72 hours after the last traction session.

Results: After traction, decreased BMD and T-scores, a decreased mean vertebra width, and an increased mean height of L1-L4 segments were observed. The concentration of cross-linked C-telopeptide of type I collagen (CTXI) increased, while the concentration of receptor activator for nuclear factor κ B ligand (RANKL) decreased significantly after four weeks of traction. Sclerostin and procollagen 1 N-terminal propeptide (P1NP) concentrations remained unchanged.

Conclusion: Our study is the first to show the influence of traction forces on BMD and markers of bone metabolism. Future research with a longer follow-up period after traction is needed to better explore the direction of change.

Aims: To use CT images and segmentation of the skin and muscles of the upper leg to determine a reliable location for measuring thigh circumference (TC) to assess the upper leg muscle volume and cross-sectional area (CSA).

Methods: This research analyzed 140 limbs from 77 patients (22 male and 55 female) who had undergone CT imaging before hip surgery. The skin and individual upper leg muscles were automatically segmented from the CT images to measure the TC and CSA of each upper leg muscle across all axial slices. TC and CSA were measured from the patella upward at 1 cm up to 20 cm intervals, resulting in 21 analyses per limb. The volume of each muscle was calculated by adding the CSAs across all axial slices. Pearson's correlation was used to analyze the relationship between muscle volume and CSA to identify the level with the strongest correlation as the "reliable" level. The correlation coefficient and the regression equation were calculated.

Results: The reliable level for muscle CSAs exhibiting the strongest correlation varied across the muscles, ranging from 9 to 20 cm from the patella. However, strong correlations were found between each muscle's TC, ranging from 0.64 to 0.83. In terms of muscle volume, 10 cm above the patella was found to be the reasonable level for predicting the volume of each muscle from TC. Moderate to strong correlations (ranging from 0.57 to 0.70) were found between the TC. To predict the muscle volume of the whole upper leg (cm³), the following equation was used: (TC at 10 cm from the patella) × 114.7-2,194.9.

Conclusion: TC measurement 10 cm above the patella is suitable for assessing upper leg muscle volume. Modifications in measurement levels across muscles may be needed to assess muscle CSAs.

Aims: This study aimed to investigate the relationship between physical activity (PA) and the risk of osteoarthritis (OA) and its subtypes.

Methods: We included participants from the UK Biobank aged 37 to 73 years from February 2006 to June 2010. Baseline PA levels were categorized as high (≥ 3,000 metabolic equivalent of task (MET)-min/week), moderate (600 to < 3,000 MET-min/week), or low PA (< 600 MET-min/week) based on current public health guidelines. The associations between PA and OA and its main subtypes (hand, hip, and knee OA) were analyzed using Cox-proportional hazard models. The mediating role of BMI was tested under a causal counterfactual framework.

Results: The median follow-up period was 12.50 years, with 25,036 incident total OA cases. Compared to low PA, we found no significant association between moderate PA and total OA risk. However, high PA significantly increased the risk of total OA by 19% (hazard ratio (HR) 1.19, 95% CI 1.15 to 1.23). This result is consistent with knee OA and hip OA, where HR was 1.25 (95% CI 1.19 to 1.31) for knee OA risk and 1.17 (95% CI 1.10 to 1.24) for hip OA risk, respectively. Moderate PA was associated with 14% (HR 0.86, 95% CI 0.76 to 0.97) reduction in the risk of hand OA. Moreover, we found that BMI mediated the association between PA and OA risk, with the mediating proportion for total OA, hand OA, knee OA, and hip OA, at 75.48%, 2.42%, 10.20%, and 51.39%, respectively.

Conclusion: These findings suggest that high levels of PA increased the risk of total OA, as well as knee and hip OA, while moderate levels of PA significantly mitigate the risk of hand OA. BMI appears to mediate the relationship between PA and OA risk. Future research should elucidate the underlying mechanisms.

Aims: Cemented polished taper fit (PTF) stems are the femoral implant of choice for total hip arthroplasty (THA) in many locations worldwide. There is increasing evidence that periprosthetic fracture may be the single major contributor to reoperation with these stems. The aim of this study was to demonstrate how mismatches at the implant-cement interface may occur and the subsequent effect of these incongruities on the contacting area and the forces transmitted to the cement mantle.

Methods: A parametric equation-based model was developed to determine the contact mismatch relative to axial stem rotations. This model was also used to calculate the restoration of contact surface area with stem subsidence for both a dual-taper and triple-taper geometry. A finite element analysis (FEA) was used to compare the effects of reduced contact area due to the incongruent hip implant-cement interface.

Results: The contact model showed a large decrease in surface contact area with even only a small rotation going from 100% at 0° to 50.00% at 2.5° for the dual-taper geometry, and from 100% at 0° to 50.20% at 2.5° for the triple-taper geometry. There was a gradual but small ongoing decrease in contact surface with increasing rotation for both the dual-taper and triple-taper geometries. For both taper designs, there was an increase in contact surface area with an increase in subsidence resulting in contact for up to a 5° mismatch being restored with 2 mm subsidence. FEA showed that with increasing mismatches and consequent contact area reduction, there was an increase in von Mises stress in the implant-cement interface of up to 235%.

Conclusion: With increasing mismatch, there was an increase in maximum stresses, total strain, and subsidence in the cement mantle, highlighting the importance of achieving an optimal implant-cement interface at the time of implantation of cemented PTF femoral stems.

Aims: Polytraumatized patients with severe limb injuries often develop complications, which are influenced by the surgical treatment strategy. For the initial fracture stabilization, Early Total Care (ETC) and Damage Control Orthopedics (DCO) are competing concepts, with the treatment choice depending on the patient's condition. Clear guidance factors remain lacking. Our study aimed to compare the effects of ETC and DCO strategies on fracture healing and functional gait behaviour in a rat multiple-trauma model.

Methods: A standardized rat multiple-trauma model was established, which included haemorrhagic shock, blunt chest trauma, and a femur fracture with subsequent reduction and fixation by group-specific operative strategies. Adult Sprague-Dawley male rats (n = 45) were randomly allocated to three groups: Sham (n = 9), ETC (primary intramedullary nailing (IN); n = 18), and DCO-IN (external fixation with conversion to IN at day 6 after the trauma; n = 18). Postoperative gait changes at different timepoints were analyzed using the CatWalk system. At seven, 21, and 42 days, the animals were euthanized to assess bone formation of the femur fracture histologically and via micro-CT. Biomechanical stability was assessed by a three-point bending test.

Results: Fixation conversion surgery in the DCO-IN group decreased callus formation, resulting in delayed fracture healing with reduced callus quality and poorer biomechanical properties compared to the ETC group. The DCO-IN group also exhibited poorer weightbearing and locomotor-function rehabilitation compared to the ETC group, consistent with the impaired fracture healing process.

Conclusion: These results demonstrate that conversion of the fixation method in the DCO strategy delays the callus formation process up to six weeks after trauma, potentially contributing to delayed rehabilitation and higher risk of nonunion in multiple-trauma patients. DCO should be limited to patients with contraindications for ETC, underlining the need for clear identification factors.