Muscle does not drive persistent posttraumatic elbow contracture in a rat model

• Published in: Muscle & nerve Vol. 58; no. 6; pp. 843 - 851
• Main Authors: Dunham, Chelsey L., Chamberlain, Aaron M., Meyer, Gretchen A., Lake, Spencer P.
• Format: Journal Article
• Language: English
• Published: United States Wiley Subscription Services, Inc 01.12.2018
• Subjects: Animals; Brachial Plexus Neuropathies - complications; Collagen Type I - metabolism; Connective Tissue Growth Factor - genetics; Connective Tissue Growth Factor - metabolism; contracture; Contracture - physiopathology; Disease Models, Animal; Elbow; Extracellular Matrix - metabolism; Extracellular Matrix - pathology; Fibrosis; Functional Laterality; Gene expression; Gene Expression Regulation - physiology; Immobilization; Injuries; Laminin - metabolism; Male; Matrix Metalloproteinase 2 - genetics; Matrix Metalloproteinase 2 - metabolism; mechanics; Mechanics (physics); Morphology; muscle; Muscle Proteins - genetics; Muscle Proteins - metabolism; Muscle, Skeletal - physiopathology; Muscles; Range of Motion, Articular - physiology; Rats; Rats, Long-Evans; Soft Tissue Injuries - complications; Soft Tissue Injuries - pathology; Soft tissues; Time Factors; Tissue Inhibitor of Metalloproteinase-2 - genetics; Tissue Inhibitor of Metalloproteinase-2 - metabolism; Tissues; Transforming Growth Factor beta3 - genetics; Transforming Growth Factor beta3 - metabolism; contracture; elbow; fibrosis; mechanics; gene expression; muscle
• ISSN: 0148-639X; 1097-4598
• DOI: 10.1002/mus.26344

ABSTRACT Introduction: Posttraumatic elbow contracture is clinically challenging because injury often disrupts multiple periarticular soft tissues. Tissue specific contribution to contracture, particularly muscle, remains poorly understood. Methods: In this study we used a previously developed animal model of elbow contracture. After surgically inducing a unilateral soft tissue injury, injured limbs were immobilized for 3, 7, 21, and 42 days (IM) or for 42 IM with 42 days of free mobilization (42/42 IM–FM). Biceps brachii active/passive mechanics and morphology were evaluated at 42 IM and 42/42 IM–FM, whereas biceps brachii and brachialis gene expression was evaluated at all time points. Results: Injured limb muscle exhibited significantly altered active/passive mechanics and decreased fiber area at 42 IM but returned to control levels by 42/42 IM–FM. Gene expression suggested muscle growth rather than a fibrotic response at 42/42 IM–FM. Discussion: Muscle is a transient contributor to motion loss in our rat model of posttraumatic elbow contracture. Muscle Nerve 58:843–851, 2018