BACKGROUND:Unaccustomed exercise triggers skeletal muscle damage,but produces a specific training effect that reduces muscle re-injury to reduce pain-muscle memory. OBJECTIVE:Based on the etiology of delayed onset muscle soreness,to review the existence and possible mechanism of skeletal muscle memory in delayed onset muscle soreness and to present new insights into the prevention and treatment of delayed onset muscle soreness. METHODS:The first author searched in PubMed,Embase,Web of Science,CNKI and WanFang databases for relevant literature published from January 1990 to December 2022.The keywords were"DOMS,skeletal muscle memory,exercise skeletal muscle adaptation,repeat turn effect,exercise and autophagy,autophagy and inflammation"in English and Chinese,respectively.A total of 102 articles were finally included for review. RESULTS AND CONCLUSION:The etiology of delayed onset muscle soreness is currently believed to be an acute inflammatory response due to metabolic disorders,mechanical injury and oxidative stress,while exercise-induced skeletal muscle memory can reduce delayed onset muscle soreness and exercise re-injury.When the duration,frequency and intensity of centrifugal training are gradually increased,symptoms of the injury can be minimized or even avoided.Therefore,based on the mechanism of exercise-induced skeletal muscle memory,it is the future research direction to find more effective ways to prevent and alleviate exercise-induced muscle injury.This review aims to(1)clarify the existence of exercise-induced skeletal muscle memory;(2)explore the possible mechanisms of exercise-induced skeletal muscle memory and propose the relationship between this memory and skeletal muscle autophagy;and(3)provide new strategies for the prevention and treatment of delayed onset muscle soreness by improving the level of skeletal muscle autophagy.

Objective For patient-specific open-wedge high tibial osteotomy(OWHTO),a novel anatomical fixation plate was designed,and the effects of geometric parameters and material selection on biomechanical fixation were studied.Methods A patient-specific OWHTO anatomical fixation plate was designed and constructed,and the effects of design parameters(thickness,width,and length of the fixation plate)and four different materials(stainless steel,titanium alloy,magnesium alloy,and PEEK)on the biomechanics of the OWHTO fixation system were studied using finite element analysis.The biomechanical differences between the anatomical fixation plate and TomoFix fixation plate were also compared.Results The thickness had a greater effect on the micromotion of the osteotomy space than the length and width of the fixation plate did.Titanium alloy or magnesium alloy fixation plates were more conducive than stainless steel and PEEK materials in obtaining reasonable stability and mechanical transfer simultaneously.Compared with that of the TomoFix plate,the maximum von Mises stress of the anatomical fixation plate was reduced by 13.5%;the maximum von Mises stress of the screws and tibia was increased by 9.8%and 18.4%,respectively;and the micromotion at the maximum osteotomy space cc was increased by 49.3%.Conclusions Anatomical fixation plates have a positive effect on reducing the stress-shielding effect and improving biomechanical properties under the premise of ensuring stability.This study provides a reference for the development of OWHTO anatomical fixation plates.

Rosuvastatin(RVS)is an excellent drug with anti-inflammatory and lipid-lowering properties in the aca-demic and medical fields.However,this drug faces a series of challenges when used to treat atherosclerosis caused by hyperhomocysteinemia(HHcy),including high oral dosage,poor targeting,and long-term toxic side effects.In this study,we applied nanotechnology to construct a biomimetic nano-delivery system,macrophage membrane(M?m)-coated RVS-loaded Prussian blue(PB)nanoparticles(MPR NPs),for improving the bioavailability and targeting capacity of RVS,specifically to the plaque lesions associated with HHcy-induced atherosclerosis.In vitro assays demonstrated that MPR NPs effectively inhibited the Toll-like receptor 4(TLR4)/hypoxia-inducible factor-1α(HIF-1α)/nucleotide-binding and oligomerization domain(NOD)-like receptor thermal protein domain associated protein 3(NLRP3)signaling pathways,reducing pyroptosis and inflammatory response in macrophages.Additionally,MPR NPs reversed the abnormal distribution of adenosine triphosphate(ATP)-binding cassette transporter A1(ABCA1)/ATP binding cassette transporter G1(ABCA1)/ATP binding cassette transporter G1(ABCG1)caused by HIF-1α,promoting cholesterol efflux and reducing lipid deposition.In vivo studies using apolipoprotein E knockout(ApoE-/-)mice confirmed the strong efficacy of MPR NPs in treating atherosclerosis with favorable bio-security,and the mechanism behind this efficacy is believed to involve the regulation of serum metabolism and the remodeling of gut microbes.These findings suggest that the synthesis of MPR NPs provides a promising nanosystem for the targeted therapy of HHcy-induced atherosclerosis.

Objective To study the effects of different posterior slope installations of unicompartmental knee arthroplasty(UKA)prostheses on the loading and motion of the knee joint and insert wear.Methods A combined approach involving the UKA musculoskeletal multibody dynamic,finite element,and wear prediction models was used to investigate the effects of five different posterior slope installation positions of the UKA prosthesis on the postoperative knee joint force and motion,insert contact stress,linear wear depth,and wear volume.Results At a 0° posterior slope,the maximum von Mises stress of the insert was 24.84 MPa,maximum contact stress was 47.61 MPa,and volumetric wear after 5 million cycles(MC)was 47.29 mm3.As the posterior slope angle of the UKA prosthesis increased,the internal rotation and posterior translation during the gait cycle increased,the medial joint force during the swing phase increased,the von Mises and contact stresses of the insert after 5 MC decreased significantly,and the wear area,maximum linear wear depth,and volumetric wear volume of the insert were consequently reduced.Compared to the 0° posterior slope,the linear wear depths of the insert at the 3°,5°,and 7° posterior slopes decreased by 17.8％,19.2％,and 20.6％,respectively.The volumetric wear volumes of the inserts decreased by 24.5％,30.9％,and 34.3％,respectively.Conclusions Installing a UKA prosthesis with a posterior slope exceeding 3° significantly increases internal rotation and posterior translation during the gait cycle,further reducing the articular volumetric wear of the polyethylene insert.

Objective To investigate the biomechanical effects of the backside design of tibial trays on the bone-prosthesis fixation interfaces in unicompartmental knee arthroplasty(UKA).Methods Finite element models of medial knee arthroplasty were constructed using a fixed UKA prosthesis.The knee joint load and joint motion under walking motion were considered as boundary conditions,and the differences in tibial von Mises stress,contact stress,and micromotion of the bone-prosthesis fixation interface of the UKA tibial trays with big keel,small keel,two-peg with fin,three-oblique peg,and three-upright peg types were compared.Results At the maximum medical knee force moment,compared to the two-peg with fin type,the tibial von Mises stress,contact stress,and micromotion of the bone-prosthesis fixation interface decreased by 8%and 15.9%and increased by 9.9%for the big keel type;decreased by 12.3%and increased by 7.5%and 0.9%for the small keel type;decreased by 10%,10.5%,and increased by 1.2%for the three-oblique peg type;and decreased by 7.7%,14.7%,and 1.6%for the three-upright peg type,respectively.However,the maximum micromotion of the bone-prosthesis fixation interface occurred at 21%of the gait cycle.Compared to the two-peg with fin type,the micromotion of the bone-prosthesis fixation interface increased by 11.6%for the big keel type,increased by 1.6%for the small keel type,decreased by 0.4%for the three-oblique peg type,and decreased by 2.3%for the three-upright peg type.Conclusions To improve the long-term fixation effects of tibial prostheses,it is recommended to focus on a two-upright peg with fin or small keel designs when UKA tibial trays are designed,which can effectively balance the stress transfer and interface micromotion,thereby ensuring prosthesis stability and reducing the risk of aseptic loosening.

The clinical performance and failure issues are significantly influenced by prosthetic malposition in unicompartmental knee arthroplasty (UKA). Uncertainty exists about the impact of the prosthetic joint line height in UKA on tibial insert wear. In this study, we combined the UKA musculoskeletal multibody dynamics model, finite element model and wear model to investigate the effects of seven joint line height cases of fixed UKA implant on postoperative insert contact mechanics, cumulative sliding distance, linear wear depth and volumetric wear. As the elevation of the joint line height in UKA, the medial contact force and the joint anterior-posterior translation during swing phase were increased, and further the maximum von Mises stress, contact stress, linear wear depth, cumulative sliding distance, and the volumetric wear also were increased. Furthermore, the wear area of the insert gradually shifted from the middle region to the rear. Compared to 0 mm joint line height, the maximum linear wear depth and volumetric wear were decreased by 7.9% and 6.8% at -2 mm joint line height, and by 23.7% and 20.6% at -6 mm joint line height, the maximum linear wear depth and volumetric wear increased by 10.7% and 5.9% at +2 mm joint line height, and by 24.1% and 35.7% at +6 mm joint line height, respectively. UKA prosthetic joint line installation errors can significantly affect the wear life of the polyethylene inserted articular surfaces. Therefore, it is conservatively recommended that clinicians limit intraoperative UKA joint line height errors to -2-+2 mm.
Humans ; Arthroplasty, Replacement, Knee ; Knee Joint ; Knee Prosthesis ; Mechanical Phenomena ; Polyethylene ; Osteoarthritis, Knee/surgery* ; Tibia/surgery* ; Biomechanical Phenomena

Objective To investigate the effects of design parameters such as neck-shaft angle, femoral offset and anteversion angle of total hip arthroplasty ( THA) prosthesis on contact forces of the hip. Methods A musculoskeletal multi-body dynamic model of THA was established based on AnyBody software. The effects of single or multiple factors on hip contact force were studied when the neck-shaft angle, eccentricity and anteversion angle varied within ±10°, ±20 mm and ±10°, respectively. Results The maximum hip contact force increased by 26. 08% when femoral offset was reduced by 20 mm. The maximum hip contact force increased by 5. 99% when the neck-shaft angle increased by 10°. When the anteversion angle increased by 10°, the hip contact force decreased at 0% -24% of gait cycle, with the peak decreasing by 19. 16% . However, the hip contact force was significantly increased at 38% -70% of gait cycle, with the peak increasing by 67. 78% . Conclusions In extramedullary design of the femoral stem, based on reconstruction of the patient’s anatomical parameters, the offset of the femoral stem can be appropriately increased, and the neck-shaft angle and anteversion angle can bereduced to avoid increasing forces on the hip.

Objective Aiming at the medial prosthetic loosening failure and lateral cartilage degeneration after unicompartmental knee arthroplasty ( UKA), the effects of prosthetic installation errors of joint line in UKA on knee contact mechanics and kinematics during different physiologic activities were studied using musculoskeletal multi-body dynamic method. Methods Taking the medial natural joint line as 0 mm error, six installation errors ofjoint line including ±2 mm, ±4 mm and ±6 mm were considered respectively, and seven musculoskeletal multi body dynamic models of medial UKA were established, to comparatively study the variations in knee contact mechanics and kinematics during walking and squatting. Results At 70% of walking gait cycle, compared with 0 mm error, the medial prosthetic contact force was increased by 127. 3% and the contact force of the lateral cartilage was decreased by 12. 0% under 2 mm elevation in joint line, the medial prosthetic contact force was close to 0 N, but the lateral cartilage contact forces were increased by 10. 1% under 4 mm reduction in joint line. The tibiofemoral total contact forces were increased by 19. 7% and decreased by 14. 2% under 2 mm elevation and 2 mm reduction in joint line, respectively. At the 100°knee flexion during squatting, compared with 0 mm error, the medial prosthetic contact force and the tibiofemoral total contact force increased by 31. 6% and 11. 1% under 2 mm elevation in joint line, and decreased by 24. 5% and 8. 5% under 2 mm reduction in joint line, respectively. The change in the lateral cartilage contact force was not marked. Moreover, at 70% of walking gait cycle, the varus angle decreased, the internal rotation and the anterior translation increased along with the elevation of joint line in UKA, while it was just the opposite along with the reduction of joint line in UKA. The trends of the varus valgus movement and anterior-posterior translation during squatting were consistent with those during swing phase of walking, but the trend of the internal-external rotation was opposite. Conclusions In order to reduce the risk of medial prosthetic loosening failure and lateral cartilage degeneration, it is recommended that the installation error of joint line in UKA should be controlled in the range of -2 mm to +2 mm. This study provides theoretical basis for UKA clinical failure caused by changes in joint line

Objective:To determine whether there is a correlation between the cross-sectional area (CSA) and the parameters as measured on nerve conduction studies.Methods:Twenty-one patients with neuromuscular diseases in Beijing Tiantan Hospital from March 3, 2022 to May 4, 2023 underwent ultrasound measurement of the CSA of the median nerves and ulnar nerves at the wrist, elbow and the upper arm, followed by nerve conduction studies (NCS). A linear regression model was performed to compare NCS and CSA.Results:A total of 180 sets of motor nerve conduction velocity (MCV) and CSA at the different sites including 102 sets of median nerve and 78 sets of ulnar nerve, 220 sets of compound muscle action potential (CMAP) amplitude and CSA at the different sites including 104 sets of median nerve and 116 sets of ulnar nerve, 60 sets of sensory nerve conduction velocity (SCV) and CSA and sensory nerve action potential (SNAP) amplitude and CSA at the wrist including 32 sets of median nerve and 28 sets of ulnar nerve were recorded. The linear correlation between MCV and CSA was statistically significant both in median nerve ( r2=0.10,adjusted r2=0.09, P=0.001) and in ulnar nerve ( r2=0.18,adjusted r2=0.17, P<0.001).When CSA>10 mm 2, the linear correlation between CMAP amplitude and CSA was statistically significant both in median nerve ( r2=0.09,adjusted r2=0.08, P=0.024) and ulnar nerve ( r2=0.19,adjusted r2=0.17, P=0.004). The correlation between CMAP and CSA was not statistically significant when CSA≤10 mm 2. And the correlations between SCV and CSA and between SNAP and CSA were not statistically significant. Conclusions:CSA can better show the characteristics of changes in motor nerve conduction especially in motor conduction velocity. It is suggested that its application prospect in demyelinating peripheral neuropathy with motor nerve damage may be more extensive.

The surgical installation accuracy of the components in unicompartmental knee arthroplasty (UKA) is an important factor affecting the joint function and the implant life. Taking the ratio of the medial-lateral position of the femoral component relative to the tibial insert (a/A) as a parameter, and considering nine installation conditions of the femoral component, this study established the musculoskeletal multibody dynamics models of UKA to simulate the patients' walking gait, and investigated the influences of the medial-lateral installation positions of the femoral component in UKA on the contact force, joint motion and ligament force of the knee joint. The results showed that, with the increase of a/A ratio, the medial contact force of the UKA implant was decreased and the lateral contact force of the cartilage was increased; the varus rotation, external rotation and posterior translation of the knee joint were increased; and the anterior cruciate ligament force, posterior cruciate ligament force and medial collateral ligament force were decreased. The medial-lateral installation positions of the femoral component in UKA had little effect on knee flexion-extension movement and lateral collateral ligament force. When the a/A ratio was less than or equalled to 0.375, the femoral component collided with the tibia. In order to prevent the overload on the medial implant and lateral cartilage, the excessive ligament force, and the collision between the femoral component and the tibia, it is suggested that the a/A ratio should be controlled within the range of 0.427-0.688 when the femoral component is installed in UKA. This study provides a reference for the accurate installation of the femoral component in UKA.
Humans ; Arthroplasty, Replacement, Knee ; Knee Joint/surgery* ; Knee Prosthesis ; Gait ; Rotation