Journal of Orthopaedic Research®最新文献

Previous observations of multi-echo ultrashort echo time (UTE) magnetic resonance imaging (MRI) decay data from the Achilles tendon (AT) report an off-resonance non-water signal associated with non-collagenous extracellular matrix (ECM) constituents. This cross-sectional study investigates the relationship between this MRI-derived tissue matrix signal and mechanical stiffness of the AT in professional ballet dancers and non-dancer adults. Multiexponential analysis of multi-echo UTE MRI was used to quantify water components and an off-resonance AT matrix component. To compare AT structure with its functionality, shear wave elastography (SWE) ultrasound US was used to measure tendon stiffness along both longitudinal (V_L) and transverse (V_S) axes. 34 participants, including 15 ballet dancers and 19 non-dancers, were studied. Dancers exhibited significantly larger V_S (p = 0.013) compared to non-dancers, consistent with prior observations of a training effect in tendon from repeated loading with exercise. UTE-derived off-resonance relaxation component amplitude, β₃, was positively associated with V_L in dancers (p = 0.029) and V_S in non-dancers (p = 0.024), suggesting a microstructural role of this matrix component. While additional work is needed to unambiguously assign this off-resonance signal, these findings suggest its association with non-collagenous ECM and show potential for combined use of UTE and SWE imaging to assess tendon structure-function relationships and adaptations to mechanical loading in vivo.

High levels of physical activity or high BMI during puberty could negatively influence bone and cartilage development. Little is known about the effects of loading on patellar and femoral bone shape in a young population. Therefore, we aim to identify the association between 3D patella and femur shape and biomechanical loading in a young adolescent population. Participants were selected from an ongoing cohort study (Generation-R study). Participants that underwent knee-MRI at 13 years-old follow-up were included. Patellae and femora were segmented from these MRIs and using these 3D models, statistical shape modeling was performed. Generalized estimating equations were used to analyze the association between loading (BMI, physical activity and sports participation) and shape variation. Bonferroni correction was used to correct for multiple testing. 1912 participants underwent MRI of which 3638 patellae and 3355 femora were included in the statistical shape models. Nine patellar (modes 1–7, 10 and 11) and nine femoral (modes 1–3, 6–10 and 14) shape modes were associated with BMI. Sports participation at thirteen years old was associated with one patellar (mode 1) and two femoral (modes 1 and 6) shape modes. One shape mode (mode 12) was associated with sports participation at 9 and 13 years old. Sports participation and BMI were significantly associated with bone shape variations. BMI was associated with most shape variations found in our statistical shape models, emphasizing the significant impact of BMI on bone morphology during adolescence with implications for musculoskeletal health and injury prevention.

Innate immune responses within the joint are now known to play a key role in osteoarthritis (OA) pathogenesis. However, comparatively little is known regarding the role of adaptive immune responses in OA, and whether they may be important for initiating and sustaining progressive low-level joint inflammation. Therefore, we evaluated spontaneous osteoarthritis in horses to investigate whether antibodies recognizing live joint cells (chondrocytes, synoviocytes) were present in blood or synovial fluid, and to identify possible cellular target antigens. We found that horses with advanced OA had antibodies present in synovial fluid (SF) and plasma that recognized antigens expressed by chondrocytes and synoviocytes isolated from healthy joint tissues. Antibody concentrations correlated with clinical and arthroscopic scoring of OA severity. Antigenic targets for antibody recognition were expressed intracellularly and proteomic analysis of a prominent 60 kD protein band identified several proteins, including vimentin, calreticulin, and Hsp60, all of which are known to be antibody targets in patients with rheumatoid arthritis. Histological analysis of synovial biopsy samples from OA horses revealed the presence of numerous tertiary lymphoid structures with well-formed germinal centers, consistent with local antibody production within the joint synovium. Taken together, these studies in equine osteoarthritis revealed the presence of antibodies recognizing antigens expressed by live cells in the joint, which resembled similar immunologic processes recently described in rheumatoid arthritis. Broader questions raised by these findings include identification of triggers for local antibody production and new strategies to target this immune pathway in progressive OA.

Periprosthetic joint infection (PJI) is a devastating complication of total joint arthroplasty (TJA), one of the most frequently performed surgical procedures worldwide. Management of acute PJI commonly involves debridement, antibiotics, and implant retention (DAIR), though failure rates remain high due to antibiotic-tolerant biofilms. Chronic PJI is typically treated with two-stage revision using antibiotic-loaded spacers, but this approach carries substantial morbidity, especially during the interstage period. Preventative strategies include preoperative patient optimization, antibiotic prophylaxis, tranexamic acid, antiseptic skin preparation, and local antibiotic powders and rinses. To improve outcomes, emerging innovations include biofilm-active antimicrobial agents, targeted postoperative antibiotic delivery, intraarticular irrigation protocols, and one-stage revision strategies. While biofilm is a significant contributor to persistent infection, technologies to combat this problem include antibacterial implant surfaces, mechanically disruptive shockwave and magnetic fields, bioactive glass, and induction heating. In cases of treatment failure, salvage options remain limited, but novel approaches such as pathogen-specific bacteriophage therapy offer promising new directions.

Female athletes are significantly more likely to tear their anterior cruciate ligament (ACL) compared to their male counterparts. While there are several potential reasons for this, previous data from our lab demonstrated that female ACL explants have an impaired remodeling response to loading, which may prevent the repair of fatigue damage and lead to increased ACL rupture. The objective of this study was to identify the biological mechanisms driving the impaired remodeling of female ACLs to cyclic loading, including the role of estrogen. ACLs were harvested from male and female New Zealand white rabbits and cyclically loaded in a tensile bioreactor, followed by bulk RNA-sequencing. Additional ACL explants treated with or without estradiol were analyzed using RT-qPCR to determine the regulatory effect of estrogen on markers for tissue remodeling and inflammatory cytokines with cyclic loading. We found that female ACLs exhibited significantly fewer differentially expressed genes in response to loading compared to male ACLs. Additionally, multiple mechanotransduction pathways were enriched with loading only in the male ACLs. While a few estrogen-related pathways were enriched in both male and female ACLs with loading, the expression of tissue remodeling markers was not different between estrogen treatment and vehicle control. Together, our findings highlight specific mechanotransduction pathways that may be responsible for the muted biological response of female ACLs to load, which provides a potential explanation for the increased rate of ACL tears in women.

As dual mobility hips become more popular, there is a clinical need to investigate design features that will impact tribocorrosion of these devices. While previous studies have investigated both corrosion and wear damage, the effect of device size on fretting corrosion response has yet to be evaluated. In this study, we compare two implants of the same design (EMPHASYS Hip Solution) but with different-sized acetabular cups (66 mm vs 44 mm) representing the range of sizes typically used. We hypothesized that the smaller implant would perform better due to the smaller taper engagement area and the smaller moments imparted during normal activities. Each device underwent a physiologically representative intermittent cyclic load between 400 N and 4000 N in 50,000 cycle increments with pauses in between, up to a total of 3,000,000 cycles and 110 h at 9 Hz in phosphate-buffered saline (PBS). Under potentiostatic control (−50 mV vs Ag/AgCl), fretting corrosion currents were generated and monitored with intermittent measurement of baseline currents. Post-testing, solution ion levels were measured using inductively coupled mass spectrometry (ICP-MS). Results showed there was no difference between devices when comparing average current, average cumulative charge, average decay constant (s-), total volume lost and solution ion levels. We report a total volume loss of 0.0028 ± 0.0015 mm³ and 0.0052 ± 0.0035 mm³ for the 66 mm and 44 mm implants, respectively. The devices had only minor evidence of fretting or corrosion damage. These results suggest there is no difference in fretting corrosion performance based on implant size.

Arthroplasty is most often performed to alleviate pain and restore function in patients with end-stage degenerative joint disease. Uncemented implant fixation is increasingly used in total knee and total ankle arthroplasty. Implantation using interference press-fit is a manufacturer-recommended guideline for achieving stable primary fixation in uncemented applications, which is important to prevent long-term implant failure due to aseptic loosening. However, when evaluating implant–bone interfacial mechanics, many studies have not modeled press-fit implantation. This can lead to gross underestimation of primary implant fixation stability, limiting the clinical applicability of findings. The goal of this paper is to highlight the importance of simulating press-fit implantation when evaluating primary orthopedic implant stability using finite element analysis in uncemented arthroplasty. Experiences gained in modeling press-fit implantation in total knee and total ankle arthroplasty by two different active research groups are shared in this context.