Article
Volumetric, cellular and genic expression modifications of FDP striated muscle following flexor tendon division in a rodent model
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Authors
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Guillaume Bacle
- CHRU, Hôpital Trousseau, Inserm U1253, Tours, France
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David McCombe
- Bernard O'Brien Institute Of Microsurgery, VHSA, Melbourne, Australia
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Eugene Ek
- Bernard O'Brien Institute Of Microsurgery, VHSA, Melbourne, Australia
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Stephen Tham
- Bernard O'Brien Institute Of Microsurgery, VHSA, Melbourne, Australia
| Published: | February 6, 2020 |
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Outline
Text
Background: Repairing of divided flexor tendons with an ad integrum hand flexion function is still a challenge. Moreover, due to initial extensive lesions or misdiagnosed injuries, repairs could be delayed or need tendon reconstruction with lower functional results than acute management.
Tenotomy has been studied across a wide range of species and always results in decreased muscle mass. Apart from the rotator cuff muscles in shoulder, fiber type and fat composition, myogenic and adipogenic expressions have not been investigated about digit flexor muscle bellies following tendon division.
Objectives/Interrogation: In order to explain the lower results following delayed repair or flexor tendon reconstructions, we hypothesised that flexor tendon division are linked to muscle impairment with decreased muscle mass, decreased cross sectional area of muscle fibers and increased fatty invasion.
Methods: We used a rodent as animal model. Thirty two white New Zealand rabbits have been used and shared in eight groups of 4 rabbits after approval of the local Animal Ethics Committee. A complete division of FDP tendon has been made and four time points assessment at 1, 2, 4 and 6 weeks. A control group with only a skin incision (SHAM procedure) for each time point has been assigned.
The muscle wet mass, muscle volume, adipogenic and myogenic gens expression and histology have been assessed for each group.
Results and Conclusions: The muscle wet mass and volume decreased significantly at one week, four weeks and six weeks between experimental and sham groups. We noted a highly significant increase of myogenic master genes expression at two weeks with a likely inhibition feedback afterward. Adipogenic genes expression were slightly increased within the two first weeks and down regulated thereafter.
Histologic works showed decreased cross sectional area of muscle fiber without fatty invasion. We assisted also to a switch between the overall amount of slow and fast muscle fibers with a significant increase of fast fibers.
Decrease of mechanical stress applied in the muscle by tendon division is related to decreased muscle mass and volume from the first week. An attempt to reverse alterations is shown by upregulation of master myogenic genes within the two first weeks and fast fiber type increase. On the other hand, no muscle fatty invasion has been noted.
