Dataset Information

Clinical and Histologic Manifestations of a Novel Rectus Femoris Myotendinous Junction Injury in Rats.

ABSTRACT:

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 strain-induced 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.

SUBMITTER: Sikes KJ

PROVIDER: S-EPMC10726684 | biostudies-literature | 2021 Oct-Dec

REPOSITORIES: biostudies-literature

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Publications

Clinical and Histologic Manifestations of a Novel Rectus Femoris Myotendinous Junction Injury in Rats.

Sikes K J KJ Andrie K M KM McConnell A A Wist S S Smith S S Cole B B Frisbie D D DD Santangelo K S KS

Muscles, ligaments and tendons journal 20211001 4

<h4>Background</h4>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 as ...[more]

PMID: 38111789

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Project description:BackgroundRectus femoris injuries are common among athletes, especially in kicking sports such as soccer; however, proximal rectus femoris avulsions in athletes are a relatively rare entity.Purpose/hypothesisThe purpose of this study was to describe and report the results of an original technique of surgical excision of the proximal tendon remnant followed by a muscular suture repair. Our hypothesis was that this technique limits the risk of recurrence in high-level athletes and allows for rapid recovery without loss of quadriceps strength.Study designCase series; Level of evidence, 4.MethodsOur retrospective series included 5 players aged 31.8 ± 3.9 years with acute proximal rectus femoris avulsion injuries who underwent a surgical resection of the proximal tendon between March 2012 and June 2014. Four of these players had recurrent rectus femoris injuries in the 9 months before surgery, while 1 player had surgery after a first injury. Mean follow-up was 18.2 ± 12.6 months, and minimum follow-up was 9 months. We analyzed the age, sex distribution, physical examination outcomes, type and mechanism of injury, diagnosis, treatment and complications during surgery, postoperative follow-up, and time to return to play. The Lower Extremity Functional Scale (LEFS) and Marx scores were obtained at 3-month follow-up, and isokinetic tests were performed before return to sports. A telephone interview was completed to determine the presence of recurrence at an average follow-up of 18.2 months.ResultsAt 3-month follow-up, all patients had Marx activity scores of 16 and LEFS scores of 80. Return to the previous level of play occurred at a mean of 15.8 ± 2.6 weeks after surgery, and none of the athletes suffered a recurrence. Isokinetic test results were comparable between both sides.ConclusionThe surgical treatment of proximal rectus femoris avulsions, consisting of resection of the tendinous part of the muscle, is a reliable and safe technique allowing a fast recovery in professional athletes.

Dataset Information

Clinical and Histologic Manifestations of a Novel Rectus Femoris Myotendinous Junction Injury in Rats.

Background

Methods

Results

Conclusions

Publications

Clinical and Histologic Manifestations of a Novel Rectus Femoris Myotendinous Junction Injury in Rats.

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