Journal of Orthopaedic Research®最新文献

Total knee replacement (TKR) is a successful intervention for relieving pain and improving quality of life. In this context, mid-flexion instability and paradoxical anterior femoral movement remain challenging. However, the role of implant design in cruciate-sacrificing (CS) scenarios is unclear. Therefore, this study investigated the influence of newly developed CS TKR designs on mid-flexion stability and anterior-posterior (AP) translation using a musculoskeletal multibody simulation during squat motion. The multibody model of the lower extremity, which represented the knee joint with ligaments and muscle structures, was previously validated using instrumented knee data. It was used to analyze newly developed (oneKNEE® cruciate-retaining (CR)/CS and medial-stabilized (MS)) and clinically established (Columbus® ultra-congruent (UC) and P.F.C.™ Sigma® CR) TKR designs. For this purpose, the overall femoral AP translation and tibial internal-external rotation during squat motion (flexion from 0° to 90°) in the CS condition were evaluated. During mid-flexion, the P.F.C.™ Sigma® CR exhibited greater anterior femoral translation than the Columbus® UC, with posterior movement starting at 35.5° (3.4 mm anterior) versus 20° (2.1 mm). In contrast, the oneKNEE® CR/CS and MS designs showed continuous posterior femoral movement (reduced paradoxical translation), with anterior-to-posterior turning points at 9° (1.2 mm) and 13° (0.8 mm) during squat motion, respectively, without inhibiting internal-external rotation. The kinematics of the oneKNEE® designs were achieved by combining the single-radius femoral design and steep anterior ramp of the tibial components. These designs reduced paradoxical anterior femoral movement in mid-flexion in the CS condition, while not restricting tibial internal-external rotation.

This finite element study evaluated the biomechanical performance of asymmetric metaphyseal cones in large Type 2a/b medial tibial defects simulating medial tibial plateau fractures during acute total knee arthroplasty, to determine thresholds for safe clinical application. A finite element model of a tibia with tibial baseplate, asymmetric metaphyseal cone, and short cemented stem was utilised. Sixteen medial fracture patterns (AORI Type 2a/b defects) were simulated with unsupported surface area ratios from 0% to 60%. Two physiological loading scenarios (walking and stair descending) were applied. Implant stability was evaluated through tangential and normal micromotions at the bone-cone coating interface, with thresholds of 150 μm for osseointegration and 50 μm for long-term stability. Bone mechanical response was quantified through principal strain distributions. Tangential and normal micromotions increased with defect size but remained below critical thresholds, with maximum tangential micromotion of 36 μm during stair descending at a 60% ratio. Micromotions and bone strain demonstrated a threshold effect at approximately 52% ratio, beyond which both parameters increased substantially. At a 60% ratio during stair descending, 0.11% and 0.12% of bone volume exceeded tension and compression thresholds, respectively. Asymmetric metaphyseal cones maintain sufficient stability for managing medial tibial plateau fractures during acute total knee arthroplasty, with interface micromotion below critical thresholds even in severe defects. The recommended maximum unsupported area ratio is 52%, providing a clear quantitative threshold for clinical decision-making.

Polyetheretherketone (PEEK) is a member of the polyaryletherketone (PAEK) family of semi-crystalline thermoplastics that is increasingly considered as an alternative to metals for use in permanent implants. Another member of the PAEK family, polyetherketoneketone (PEKK), has many similar properties to PEEK, but can vary in its crystallization kinetics due to its varying terephthalic and isophthalic acid (T/I) ratios during manufacturing. We hypothesized that PEKK's differences in chemical structure may produce a better surface for cell adhesion, increasing in vitro osteoblastic performance when compared to PEEK. Solid and porous samples were printed under comparable conditions and cultured with MC3T3-E1 mouse pre-osteoblasts for up to 28 days. A laser confocal microscope was used to evaluate surface roughness of samples as one possible explanation for differences in in vitro performance. Micro-CT was used to visualize the accuracy in printing of porous samples when compared to a digital model. PEKK samples were found to have significantly increased cell attachment, normalized alkaline phosphatase activity, and osteoblastic mineralization at multiple time points (p < 0.05). PEKK samples were also found to be significantly smoother than PEEK samples on the micron scale. Based on micro-CT images, PEKK samples were found to more closely resemble the desired triply periodic minimal surface geometry than PEEK samples. This study suggests that PEKK should be considered in future studies investigating the biological performance of PEEK due to PEKK's encouraging in vitro biocompatibility.

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.

Achilles tendinopathy limits mobility and decreases quality of life. Physical therapy (eccentric muscle loading) improves tendon function; however, the underlying mechanisms are unknown. This study investigated the effect of load magnitude and treatment duration in a mouse Achilles tendinopathy model. We hypothesized that loading would upregulate signaling and metabolic transcriptional networks associated with improved tendon healing. Mice were randomly assigned to muscle loading groups (50 or 100% body weight (BW)) or age-matched injured/untreated (IU) and naïve control groups. Following induction of Achilles tendinopathy via paired TGFB-β1 injections, loading was performed for 1, 2, or 4 weeks, mice euthanized, and Achilles tendons harvested for transcriptomics. The exercised groups exhibited relatively converging transcriptional patterns at 4 weeks, while the IU group was tightly associated with the naïve group over time, and diverging from both exercised groups at 2 and 4 weeks. Two weeks of exercise at either 50 or 100% BW load resulted in uniquely expressed gene networks not present in unexercised controls. Comparative assessment of the expression profile and functional annotation of networks across groups revealed that exercise differentially affected the innate immune response, sensory innervation and collagen biosynthesis during tendon repair. Ingenuity Pathway Analysis further suggests that 50% BW loading is associated with a shorter pro-inflammatory response and early matrix deposition in healing tendons compared to 100% BW loading. The transcriptional alterations seen in response to 50% BW eccentric muscle loading support the benefits of controlled loading exercises when treating Achilles tendinopathy.

Rotator cuff tear is a common disease, and surgical repair is often conducted, but the re-tear rate after surgery is still high. Mechanical stress is the key factor that promotes tendon healing, but the optimal exercise protocol to induce rotator cuff healing is unknown. This study aimed to elucidate the effects of postoperative exercise initiation timing on tendon healing and muscle degeneration after rotator cuff tear and reconstruction by controlling the shoulder joint motion with immobilization and exercise intervention. A total of 110 Wistar rats were used in this study and the supraspinatus tendon tear and reconstruction were performed. Animals were divided into five groups: (1) Sham surgery (Sham), (2) Cage activity (CA), (3) Immobilization (IM), (4) Immobilization + Early exercise (IM + EE), (5) Immobilization + Delayed exercise (IM + DE). At postoperative 3 and 6 weeks, the specimens were harvested for histological analysis and biomechanical testing. At 3 weeks, histological analysis using the Movin score was significantly higher in the IM + EE group compared to the IM group. Also, fiber arrangement was significantly higher in the CA, IM + DE group compared to the IM group. At 6 weeks, IM + EE had higher vascularity than the IM group and decreased collagen stainability than the IM + DE group. The results of biomechanical testing showed no significant differences between Sham and IM + EE at 3 weeks and Sham and IM at 6 weeks. Our results suggested that intermittent exercise under immobilization, particularly intermediate-intensity exercise intervention such as treadmill exercise from the inflammatory phase, was shown to delay the tendon healing process.

In revision hip arthroplasty, modular stems enable intraoperative adjustment of the biomechanics of the hip to ensure a stable joint function even in complex anatomical cases. Modular stem junctions, however, carry the risk of junction degradation due to corrosive processes or even junction breakage. Fretting-corrosion has been mentioned as precursor of junction breakage but has hardly been systematically assessed. To investigate relations between corrosion and fretting, and implant and patient specific parameters and connection strength, respectively, a collection of 53 retrieved modular hip stems of different implant systems was investigated. Corrosion and fretting at the stem-neck taper connection were rated with a modified Goldberg score. Taper contamination was assessed with a similar scoring system. If the hip stems were still joint to the neck piece, the push-out force to detach the parts was recorded as a measure for taper junction strength. A multivariate regression analysis revealed that corrosion and fretting were significantly affected by implantation time, taper contamination, body weight and implant system. Taper junction strength was not altered by corrosion or fretting but by taper contamination. The results indicate that implant geometry parameters are not related to the extent of corrosive degradation at the junction, but taper contamination significantly increased corrosion at taper surfaces. This underlines the importance of the cleanliness of the taper surfaces during hip stem assembly for a long-term stability of the modular implant.

The goal of musculoskeletal research is to translate scientific innovations from basic science to bedside applications. This process requires substantial investments in research and development, regulatory approvals, manufacturing, and commercialization of orthopaedic devices and solutions. Since 2020, less than 2% of annual National Institutes of Health (NIH) awards have supported musculoskeletal research. Limited public funding and institutional resources have driven clinicians and researchers to seek alternative partnerships. The orthopaedic industry frequently collaborates with clinician scientists to develop evidence demonstrating the safety, efficacy, and clinical benefits of products. Partnerships are generally classified as either "industry-initiated research" or "investigator-initiated research," with the initiating party determining the idea, study design, and data analysis. Funding, operational support, and oversight vary accordingly. Industry partners can provide financial and operational resources, while researchers contribute scientific expertise, fostering effective collaboration and execution of various preclinical and clinical studies. Successful collaboration requires navigating potential hurdles. Key considerations include selecting partners with aligned goals, mitigating perceived bias, managing conflicts of interest, clarifying data ownership and reporting responsibilities, determining publications or licensing rights, and understanding legal and compliance requirements. The purpose of this study is to provide practical insights for overcoming these barriers. By fostering strategic industry-academic collaborations, researchers can identify actionable approaches for securing support. Strengthening these partnerships for both basic science and clinical studies offers the potential to drive translational and applied research, address unmet clinical needs, and advance musculoskeletal care.

Patellar tendinopathy and bone-patellar tendon-bone autograft harvest for anterior cruciate ligament reconstruction are tendon injuries that impact long-term knee health. Diffusion tensor imaging (DTI) is a non-invasive magnetic resonance imaging (MRI) based approach with the potential to assess tendon microstructure. This study aimed to determine the inter-rater reliability of segmentations and test-retest repeatability of DTI metrics in pathological and contralateral patellar tendons. Ten participants received two bilateral knee MRI scans within a 7-day period. 3D CUBE proton density weighted images and DTI were acquired. Two raters segmented each of the first scans, and one rater segmented the second scans. Tendon masks were then bisected into proximal and distal regions of equal length and trisected into medial, lateral, and central regions of equal width. From the DTI acquisition, diffusivities and fractional anisotropy averages were extracted. Intraclass correlations (ICCs) for inter-rater reliability and test-retest repeatability were calculated for each metric separated by limb (pathological vs contralateral tendon). Excellent inter-rater reliability was observed for all DTI scalar metrics in all regions (ICCs from 0.920 to 0.994). Repeatability was poor to moderate in pathological tendons (0.164 to 0.709) and moderate to good in contralateral tendons (0.566 to 0.842). Statement of Clinical Significance: While clinical implications of altered DTI scalar metrics in pathological tendons require further investigation, findings from this study provide clinicians and researchers with a reliable method for capturing patellar tendon microstructure.

Ultrasound-guided tenotomy and debridement is a minimally invasive treatment with a low risk of complications for individuals with chronic Achilles tendinopathy. Yet the benefits of this procedure on pain, function, and pain-related psychological factors, as well as predictors of treatment success, remain understudied. A total of 56 individuals with chronic Achilles tendinopathy (mean (SD): age = 55.9 (11) years, BMI = 34.8 (8.2) kg/m², women = 68%) underwent baseline ultrasonography, followed by ultrasound-guided tenotomy and debridement, and rehabilitation. Participants reported pain (0-10), function (Foot and Ankle Ability Measure-ADL), kinesiophobia (Tampa Scale of Kinesiophobia-17), and pain catastrophizing (Pain Catastrophizing Scale) at baseline and for a year following the procedure. Baseline pain was 6.1 (2.2), kinesiophobia was 40.8 (7.1), pain catastrophizing was 13.7 (10.2), and function was 55.9 (17.3). By 6 weeks, there were decreases in pain (mean change (95% CI): -1.9 (-1.1 to -2.6), function: 14.4 (9.3-19.5), kinesiophobia: -5 (-3.2 to -6.9), and pain catastrophizing: -7 (-4.9 to -9.1)). Patient-reported outcomes were similar at 52 weeks (pain: -2.99 (-2.2 to -3.8), function: 25.1 (19.6-30.7), kinesiophobia: -7.5 (-6.1 to -11.4), catastrophizing: -8.5 (-6.1 to -10.8)) following the procedure. Haglund deformity (β: -13.1 (-0.6 to -25.5)) and intratendinous calcifications (β: -14.7 (-1.4 to -28.1)) were associated with smaller improvements in function. No procedure-related complications were reported. Clinical significance: Ultrasound-guided tenotomy and debridement for chronic Achilles tendinopathy may provide positive outcomes for pain, function, and pain-related psychological factors at 6-week and 1-year follow-up. Haglund deformity and tendon calcifications were associated with smaller improvements in function.