SUMMARY
Background. Animal models of muscle injury have primarily relied on methods which do not mimic the chronic scarring that typically occurs adjacent to the myotendinous junction (MTJ). The goal of this study was three-fold: (i) to create a strain-induced in vivo model of rectus femoris MTJ injury in rats; (ii) to document clinical manifestations of injury using longitudinal tracking of individual animals via voluntary and compulsory (treadmill) mobility analyses and (iii) to validate and assess the model for persistent scarring through serial histologic assessment and development of a semi-quantitative grading scheme to characterize injury response over time.
Methods. Strain-induced MTJ injury was generated in male Sprague Dawley rats via needle tension directed along the transverse axis between the rectus femoris muscle and distal tendon that attaches to the patella. Animals received mobility assessments (gait analysis using a DigiGait Treadmill System and weight bearing using a Tekscan Rodent Walkway System) at days 0, 1, 3, 6, 13, 20, and 27 of the experimental protocol.
Rats were euthanized at 1, 3, 7, 14, and 28 days post-injury (n = 6 rats per time-point) and hindlimbs were processed for histology.
Results. Significant changes in locomotor parameters included injured and contralateral limb paw area, max dA/dt (limb deceleration/breaking time), stride time, stance time, force time impulse, and fore/hind symmetry, and injured limb maximum force. The most significant and consistent histologic finding was a pathologic fibrotic adhesive lesion at the muscle and tendon interface along the proximal aspect of the patella just distal to the injury site. This lesion was composed of reactive fibroblasts, disorganized collagen fibers, vascular profiles, and a myxomatous ground substance stroma. Conclusions. This work is the first to characterize the clinical and pathologic development of a chronic model of rectus femoris MTJ injury, which resulted in altered mobility likely caused by a straininduced fibrotic scar along the anterior patella. Notably, both the functional and pathologic changes recapitulated the course of injury progression similar to what is described in humans. This work provides a unique model to study MTJ injury mechanisms for the identification of enhanced treatment options for patients who suffer from activity-related muscle conditions.
Clinical and Histologic Manifestations of a Novel Rectus Femoris Myotendinous Junction Injury in Rats
K. J. Sikes, K. M. Andrie, A. McConnell, S. Wist, S. Smith, B. Cole, D. D. Frisbie, K. S. Santangelo
Original Article, 600-613
Keywords: animal model, gait analysis, histopathology, myotendinous junction, quadriceps rectus femoris,
Table of Content: Vol. 11 (No.4) 2021 October/December
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Clinical and Histologic Manifestations of a Novel Rectus Femoris Myotendinous Junction Injury in Rats
K. J. Sikes, K. M. Andrie, A. McConnell, S. Wist, S. Smith, B. Cole, D. D. Frisbie, K. S. SantangeloOriginal Article, 600-613 -
Effects of Prolonged Sitting Interventions on Chronic Low-Grade Inflammation in Adults: a Protocol for a Systematic Review
S. Azharuddin, Chythra R. Rao, B. Chandrasekaran, S. J PedersenSummary, 614-627 -
Resveratrol Treatment Protects Tendons from Obesity and Insulin Resistance Effects
T. M. Da Ré Silva, S. H. Ferreira da Cruz, D. Majolli Andre, P. Pires Marques, L. Prado de Oliveira, C. Pedrozo Vieira, F. Da Ré GuerraOriginal Article, 628-634 -
Does the Antimalarial Drug Quinine Contribute to Muscle Fibro/Adipogenic Progenitor Fibrogenesis?
J. H. Jay, M. Liu, X. Liu, B. T. Feeley, C. S. SabatiniOriginal Article, 635-640 -
Mechanical Properties of Muscles and Tendons in Asymptomatic Individuals with Generalized Joint Hypermobility
S. Taş, T. F. Dikici, A. Aktaş, A. AraciOriginal Article, 641-647 -
Whole-Body Vibration, Morphological and Antioxidant Effects on the Diaphragm Muscle of Obese Rats
M. de Campos Oliveira, M. Laís Boaretto, A. Barbosa, A. T. Bittencourt Guimarães, G. R. Flor Bertolini, M. M. Torrejais, R. M. CostaOriginal Article, 648-656 -
Whole-Body Vibration Promotes Beneficial Changes on the Anterior Tibial Muscle Histomorphometry of Hypothalamic Obese Rats
M. F. Zazula, C. Bergmann Kirsch, J. L. Theodoro, C. de Toni Boaro, D. F. Saraiva, S. Gonçalves de Oliveira, B. Zanardini de Andrade, A. L. Peretti, K. Naliwaiko, G. R. Flor Bertolini, R. M. Costa, L. de Fátima Chasko RibeiroOriginal Article, 657-665 -
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The Effects of SARS-CoV-2 Pandemic Countermeasures on Patients Receiving Infiltrative Treatment for Musculoskeletal Disorders: a Study from an Italian Cohort
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M. R. Goh, Y. H. D. Lee, C. C. R. Teo, J. NylandOriginal Article, 685-693 -
The Injured Limb Presents Lower Values in Foot Structure Measurements 6 Years After an Achilles Tendon Rupture
A. Brorsson, U. Sædís Jónsdóttir, D. Nygren, N. Larsson, R. TranbergOriginal Article, 694-703 -
Functional Performance of Ankles Between Male and Female Practitioners of Resistance Exercise
M. Braz, A. Souto MaiorOriginal Article, 704-711 -
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M. Saeidi, H. Yavari, H. R. FatehOriginal Article, 712-718 -
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Efficacy of a 6-Week Supervised Strengthening Exercise Program with EMG-Biofeedback in Patients with Muscular Dystrophy: a Randomized Controlled Trial
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Results of Lisfranc’s Surgery in Athletic Patients
A. Saxena, L. Shou, M. FournierCase Report, 736-741 -
Radial versus Combined Shockwave Therapy in the Management of Proximal Hamstring Tendinopathy: Similar Functional Outcomes in Running Cohort
P. H. Yun, S. DeLuca, D. Robinson, A. Park, C. Rosenberg, M. J. Kohler, A. S. TenfordeOriginal Article, 742-748 -
Two-Stage Flexor Pollicis Longus Tendon Reconstruction Using Pedicled Palmaris Longus Tendon Graft
Ö. F. Kümbüloğlu, F. Canşah Barışhan, H. Mustafa ÖzdemirOriginal Article, 749-755 -
Location of the Flexor Carpi Radialis Myotendinous Junction: a Cadaveric Study
K. Panwar, D. Lara, M. Trzeciak, E. G. Huish JrOriginal Article, 756-758 -
Incidence of Accessory Brachialis Muscle, Variations in its Insertion and Relation with Surrounding Neurovascular Structures
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