Effect of 40 Hz Magnetic Field Application in Posttraumatic Muscular Atrophy Development on Muscle Mass and Contractions in Rats.

Muscle atrophy refers to the deterioration of muscle tissue due to a long-term decrease in muscle function. In the present study, we simulated rectus femoris muscle atrophy experimentally and investigated the effect of pulsed electromagnetic field (PEMF) application on the atrophy development through muscle mass, maximal contraction force, and contraction-relaxation time. A quadriceps tendon rupture with a total tenotomy was created on the rats' hind limbs, inhibiting knee extension for 6 weeks, and this restriction of the movement led to the development of disuse atrophy, while the control group underwent no surgery. The operated and control groups were divided into subgroups according to PEMF application (1.5 mT for 45 days) or no PEMF. All groups were sacrificed after 6 weeks and had their entire rectus femoris removed. To measure the contraction force, the muscles were placed in an organ bath connected to a transducer. As a result of the atrophy, muscle mass and strength were reduced in the operated group, while no muscle mass loss was observed in the operated PEMF group. Furthermore, measurements of single, incomplete and full tetanic contraction force and contraction time (CT) did not change significantly in the operated group that received the PEMF application. The PEMF application prevented atrophy resulting from 6 weeks of immobility, according to the contraction parameters. The effects of PEMF on contraction force and CT provide a basis for further studies in which PEMF is investigated as a noninvasive therapy for disuse atrophy development. © 2022 Bioelectromagnetics Society.

[Effect of acupotomy intervention on the morphology and ultrastructure of rectus femoris muscle in rabbits with knee osteoarthritis].

OBJECTIVE: To observe the effect of acupotomy on the morphology and ultrastructure of rectus femoris muscle in rabbits with knee osteoarthritis and to reveal the possible therapeutic mechanism involved in the effect of acupotomology on the treatment of knee osteoarthritis(KOA). METHODS: Twenty-four male New Zealand rabbits aged 6 months and weighed (2.0±0.5) kg were randomly divided into blank group, model group and acupotomy group, 8 rabbits in each group. KOA model was established by modified Videman method with left hind limb extended plaster immobility for 6 weeks. In acupotomy group, the transfascial focal points of quadriceps femoris muscle were released by acupotomy under the guidance of Jingjin theory for 4 times and once a week, and the treatment points include Hedingci, Binwaixia, Binneixia. Blank group and model group were fed normally without intervention. One week after the end of the intervention, the pennation angle(PA), muscle thickness(MT), cross-sectional area(CSA) and strain ratio(SR) of rectus femoris were measured by ultrasound. HE staining was used to observe the changes of the tissue morphology, the number of muscle fibers and the average area of muscle fibers. The myofibril of rectus femoris, sarcomere and myofilament were observed by transmission electron microscope. RESULTS: The PA of rectus femoris muscle in the blank group was (9.05±0.21)°. The MT was(1.09±0.09) cm and the CSA was(1.30±0.01) cm2. The PA of rectus femoris muscle in the model group was (3.06±0.15)°. The MT was (0.71±0.02) cm and the CSA was(0.77±0.02) cm2. The PA of rectus femoris muscle in the acupotomy group was (6.94±0.28)°. The MT was (0.80±0.05) cm and the CSA was(0.94±0.03) cm2. The muscle PA, MT and CSA of rectus femoris in the model group were significantly smaller than those in the blank group (P<0.05). Those in acupotomy group were significantly increased compared with those in model group (P<0.05). The SR of rectus femoris muscle was 1.19±0.02 in the blank group, 3.50±0.05 in the model group and 1.99±0.07 in the acupotomy group. The elastic SR of the model group was significantly higher than that of the blank group (P<0.05). These in acupotomy group was significantly lower than that in model group(P<0.05). The results of HE staining showed:in blank group, the fascicles of rectus femoris were arranged neatly, the number of beam of muscle fibers within the fixed visual field was 94.38±3.50 and the average CSA was(0.75±0.22) mm2. In model group, the fascicles of rectus femoris with different sizes were disorganized with a small amount of inflammatory cell infiltration, the number of beam of muscle fibers within the fixed visual field was 196.63±2.62 and the average CSA was(0.26±0.03) mm2. Compared to the blank group, a significant increase in the number of muscle fibers in the fixed field in the model group (P<0.05) and the average CSA decreased significantly(P<0.05). In acupotomy group, the rectus femoris fascicles in the acupotomy group tended to be arranged in a more orderly manner, with the inflammatory cells decreased, the number of beam of muscle fibers within the fixed visual field was 132.88±4.61 and the average CSA was(0.70±0.07) mm2. Compared to the model group, a significant decrease in the number of muscle fibers in the fixed field in the model group(P<0.05) and the average CSA increased significantly(P<0.05). The results of transmission electron microscope showed:compared with the blank group, the overall arrangement of the myofibrils of the rectus femoris in the model group was less structured. There was fracture between the muscle fibers and the sarcomere, the myofilaments were disordered, and the fracture of the Z line was discontinuous. Compared with the model group, the myofibrillar texture of rectus femoris in acupotomy group was clearer, and the Z line was more continuous. CONCLUSION: Based on the jingjin theory, the release of quadriceps femoris by acupotomy can effectively improve the morphology and structure of rectus femoris, and promote the repair and reconstruction of chronic skeletal muscle injury in rabbits with KOA, which may be one of the mechanisms of acupotomy in the treatment of KOA.

Effect of acupotomy intervention on the morphology and ultrastructure of rectus femoris muscle in rabbits with knee osteoarthritis / 中国骨伤

OBJECTIVE@#To observe the effect of acupotomy on the morphology and ultrastructure of rectus femoris muscle in rabbits with knee osteoarthritis and to reveal the possible therapeutic mechanism involved in the effect of acupotomology on the treatment of knee osteoarthritis(KOA).@*METHODS@#Twenty-four male New Zealand rabbits aged 6 months and weighed (2.0±0.5) kg were randomly divided into blank group, model group and acupotomy group, 8 rabbits in each group. KOA model was established by modified Videman method with left hind limb extended plaster immobility for 6 weeks. In acupotomy group, the transfascial focal points of quadriceps femoris muscle were released by acupotomy under the guidance of Jingjin theory for 4 times and once a week, and the treatment points include Hedingci, Binwaixia, Binneixia. Blank group and model group were fed normally without intervention. One week after the end of the intervention, the pennation angle(PA), muscle thickness(MT), cross-sectional area(CSA) and strain ratio(SR) of rectus femoris were measured by ultrasound. HE staining was used to observe the changes of the tissue morphology, the number of muscle fibers and the average area of muscle fibers. The myofibril of rectus femoris, sarcomere and myofilament were observed by transmission electron microscope.@*RESULTS@#The PA of rectus femoris muscle in the blank group was (9.05±0.21)°. The MT was(1.09±0.09) cm and the CSA was(1.30±0.01) cm2. The PA of rectus femoris muscle in the model group was (3.06±0.15)°. The MT was (0.71±0.02) cm and the CSA was(0.77±0.02) cm2. The PA of rectus femoris muscle in the acupotomy group was (6.94±0.28)°. The MT was (0.80±0.05) cm and the CSA was(0.94±0.03) cm2. The muscle PA, MT and CSA of rectus femoris in the model group were significantly smaller than those in the blank group (P<0.05). Those in acupotomy group were significantly increased compared with those in model group (P<0.05). The SR of rectus femoris muscle was 1.19±0.02 in the blank group, 3.50±0.05 in the model group and 1.99±0.07 in the acupotomy group. The elastic SR of the model group was significantly higher than that of the blank group (P<0.05). These in acupotomy group was significantly lower than that in model group(P<0.05). The results of HE staining showed:in blank group, the fascicles of rectus femoris were arranged neatly, the number of beam of muscle fibers within the fixed visual field was 94.38±3.50 and the average CSA was(0.75±0.22) mm2. In model group, the fascicles of rectus femoris with different sizes were disorganized with a small amount of inflammatory cell infiltration, the number of beam of muscle fibers within the fixed visual field was 196.63±2.62 and the average CSA was(0.26±0.03) mm2. Compared to the blank group, a significant increase in the number of muscle fibers in the fixed field in the model group (P<0.05) and the average CSA decreased significantly(P<0.05). In acupotomy group, the rectus femoris fascicles in the acupotomy group tended to be arranged in a more orderly manner, with the inflammatory cells decreased, the number of beam of muscle fibers within the fixed visual field was 132.88±4.61 and the average CSA was(0.70±0.07) mm2. Compared to the model group, a significant decrease in the number of muscle fibers in the fixed field in the model group(P<0.05) and the average CSA increased significantly(P<0.05). The results of transmission electron microscope showed:compared with the blank group, the overall arrangement of the myofibrils of the rectus femoris in the model group was less structured. There was fracture between the muscle fibers and the sarcomere, the myofilaments were disordered, and the fracture of the Z line was discontinuous. Compared with the model group, the myofibrillar texture of rectus femoris in acupotomy group was clearer, and the Z line was more continuous.@*CONCLUSION@#Based on the jingjin theory, the release of quadriceps femoris by acupotomy can effectively improve the morphology and structure of rectus femoris, and promote the repair and reconstruction of chronic skeletal muscle injury in rabbits with KOA, which may be one of the mechanisms of acupotomy in the treatment of KOA.

Handheld Tissue Hardness Meters for Assessing the Mechanical Properties of Skeletal Muscle: A Feasibility Study.

OBJECTIVES: The purpose of this study was to examine the feasibility of using handheld tissue hardness meters to assess the mechanical properties of skeletal muscle. METHODS: This observational study included 33 healthy men (age, 22.4 ± 4.4 years) and 33 healthy women (age, 23.7 ± 4.2 years). Participants were placed in a supine position, and tissue hardness overlying the rectus femoris and the shear modulus of the muscle were measured on the right side of the body at 50% thigh length. In the same position, subcutaneous adipose tissue thickness and muscle thickness were measured using B-mode ultrasonography. To examine the associations of subcutaneous adipose tissue thickness, muscle thickness, and muscle shear modulus with tissue hardness, linear regression using a stepwise bidirectional elimination approach was performed. RESULTS: Stepwise linear regression revealed that subcutaneous adipose tissue thickness (r = -0.38, P = .002) and muscle shear modulus (r = 0.27, P = .03) were significantly associated with tissue hardness. CONCLUSIONS: Significant associations among adipose tissue thickness, muscle shear modulus, and tissue hardness show the limitations and feasibility of handheld tissue hardness meters for assessing the mechanical properties of skeletal muscles.

Calcific Tendinitis of the Rectus Femoris Around the Hip Joint

Purpose: To evaluate and introduce the technique of C-arm guided aspiration and an injection of a mixture of corticosteroid and local anesthesia for the treatment of calcific tendinitis of the rectus femoris around the hip joint. Materials and Methods: Between March 2003 and May 2005, C-arm guided aspiration and an injection of a mixture of corticosteroid and local anesthesia were performed on 5 patients and a local excision were performed in 1 patient for the treatment of calcific tendinitis of the rectus femoris. The minimum follow-up period was 6 months. The radiology evaluation revealed the presence and size of the calcification. The clinical evaluation involved checking the level of pain relief, range of motion, recurrence, complications. Results: The hip pain improved immediately after treatment. There were no recurrences or complications. Conclusion: The combined treatment of C-arm guided aspiration and an injection of a mixture of corticosteroid and local anesthesia is an effective method for treating calcific tendinitis of the rectus femoris, which can induce rapid symptom relief without any surgical morbidity.