title: Morphomechanical alterations in the medial gastrocnemius muscle in patients with a repaired Achilles tendon: Associations with outcome measures.
abstract: BACKGROUND
  Functional deficits are found in ankles that have sustained an Achilles rupture. This study sought to evaluate and compare the morphomechanical characteristics of the medial gastrocnemius muscle in the legs of participants within six months of a unilateral Achilles repair to determine any correlations between those characteristics and objective outcomes and self-reported functional levels.
  
  
  METHODS
  Fifteen participants were assessed via measurements of muscle morphologies (fascicle length, pennation angle, and muscle thickness) in a resting state, the mechanical properties of the proximal aponeurosis of the medial gastrocnemius muscle, the pennation angle during ramping maximal voluntary isometric contractions (MVIC), the heel raise test, and the Taiwan Chinese version of the Lower Extremity Functional Scale (LEFS-TC) questionnaire. Findings Compared with the non-injured legs, the repaired legs showed a lower muscle fascicle length (mean 4.4 vs. 5.0cm) and thickness (1.7 vs. 1.9cm), lower stiffness of the GM tendon and aponeurosis (174.1 vs. 375.6N/mm), and a greater GM pennation angle (31.2 vs. 28.9°) during 90% MVIC (all p≤0.05). Correlations were found between the morphomechanical results and maximal heel raise heights or the LEFS-TC score, and between the symmetry ratios of the fascicle lengths and the LEFS-TC score. Interpretation There are decreases in fascicle length, muscle thickness and mechanical properties in the medial gastrocnemius muscles of the participants within the first six months after an Achilles repair. These morphomechanical alterations demonstrate associations with functional levels in the lower extremities and indicated the need for early mobilization of the calf muscles after the repair.
authors.affiliation: School and Graduate Institute of Physical Therapy, College of Medicine, National Taiwan University, Center of Physical Therapy, National Taiwan University Hospital, Taipei, Taiwan.
authors.forename: Wei-Chen
authors.initials: WC
authors.lastname: Peng
authors.affiliation: School and Graduate Institute of Physical Therapy, College of Medicine, National Taiwan University, Center of Physical Therapy, National Taiwan University Hospital, Taipei, Taiwan.
authors.forename: Yi-Ping
authors.initials: YP
authors.lastname: Chang
authors.affiliation: School and Graduate Institute of Physical Therapy, College of Medicine, National Taiwan University, Center of Physical Therapy, National Taiwan University Hospital, Taipei, Taiwan.
authors.forename: Yuan-Hung
authors.initials: YH
authors.lastname: Chao
authors.affiliation: Department of Rehabilitation Sciences, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong.
authors.forename: S N
authors.initials: SN
authors.lastname: Fu
authors.affiliation: Department of Orthopaedics, Clintec, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden.
authors.forename: Christer
authors.initials: C
authors.lastname: Rolf
authors.affiliation: Department of Medical Image, National Taiwan University Hospital, Department of Surgery, College of Medicine, National Taiwan University, Taiwan.
authors.forename: Tiffany Tf
authors.initials: TT
authors.lastname: Shih
authors.affiliation: Department of Business Administration, Hwa Hsia Institute of Technology, Taipei, Taiwan.
authors.forename: Sheng-Chu
authors.initials: SC
authors.lastname: Su
authors.affiliation: School and Graduate Institute of Physical Therapy, College of Medicine, National Taiwan University, Center of Physical Therapy, National Taiwan University Hospital, Taipei, Taiwan. Electronic address: hkwang@ntu.edu.tw.
authors.forename: Hsing-Kuo
authors.initials: HK
authors.lastname: Wang
mesh_terms: D000125:Achilles Tendon / Q000293:injuries* / Q000503:physiopathology / Q000601:surgery*; D000843:Ankle Joint / Q000502:physiology / Q000503:physiopathology; D003430:Cross-Sectional Studies; D004434:Early Ambulation; D005260:Female; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000473:pathology* / Q000502:physiology / Q000503:physiopathology*; D012421:Rupture / Q000503:physiopathology / Q000601:surgery; D016896:Treatment Outcome; D014463:Ultrasonography
keywords: Achilles rupture; Aponeurosis; Muscle morphology; Tendinous tissue; Viscoelasticity