title: Compensatory muscle activation caused by tendon lengthening post-Achilles tendon rupture.
abstract: OBJECTIVE
  The purpose of this study was to establish a relationship between the lengthening of the Achilles tendon post-rupture and surgical repair to muscle activation patterns during walking in order to serve as a reference for post-surgical assessment.
  
  
  METHODS
  The Achilles tendon lengths were collected from 4 patients with an Achilles tendon rupture 6 and 12 months post-surgery along with 5 healthy controls via ultrasound. EMG was collected from the triceps surae muscles and tibialis anterior during overground walking.
  
  
  RESULTS
  Achilles lengths at 6 and 12 months post-surgery were significantly longer (p < 0.05) on the involved side compared to the uninvolved side, but there were no side-to-side differences in the healthy controls. The integrated EMG (iEMG) of the involved side was significantly higher than the uninvolved side in the lateral gastrocnemius at 6 months and for the medial gastrocnemius at 12 months in the patients with Achilles tendon rupture; no side-to-side difference was found in the healthy controls. The triceps surae muscles' activations were fair to moderately correlated to the Achilles lengths (0.38 < r < 0.52).
  
  
  CONCLUSIONS
  The increased Achilles tendon length and iEMG from the triceps surae muscles indicate that loss of function is primarily caused by anatomical changes in the tendon and the appearance of muscle weakness is due to a lack of force transmission capability. This study indicates that when aiming for full return of function and strength, an important treatment goal appears to be to minimize tendon elongation.
authors.affiliation: University of Delaware, 126 Spencer Lab, Newark, DE, 19716-3140, USA, suydam@udel.edu.
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Suydam
authors.forename: Thomas S
authors.initials: TS
authors.lastname: Buchanan
authors.forename: Kurt
authors.initials: K
authors.lastname: Manal
authors.forename: Karin Gravare
authors.initials: KG
authors.lastname: Silbernagel
mesh_terms: D000125:Achilles Tendon / Q000293:injuries / Q000601:surgery*; D001696:Biomechanical Phenomena; D004576:Electromyography; D005260:Female; D006801:Humans; D007866:Leg / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction; D018908:Muscle Weakness / Q000503:physiopathology; D018482:Muscle, Skeletal / Q000503:physiopathology* / Q000601:surgery; D011184:Postoperative Period; D012421:Rupture; D013708:Tendon Injuries / Q000503:physiopathology / Q000601:surgery*; D058971:Tenotomy