title: Are muscle volume differences related to concentric muscle work during walking in spastic hemiplegic cerebral palsy?
abstract: BACKGROUND
  Individuals with spastic hemiplegic cerebral palsy are typically high functioning and walk without assistive devices. The involved limb is usually smaller and shorter, although it is not clear whether the difference in muscle volume has an impact on walking capacity.
  
  
  OBJECTIVE
  We determined the volume of muscles important for propulsion and related that volume to concentric muscle work during walking on the hemiplegic and noninvolved sides in patients with cerebral palsy.
  
  
  METHODS
  We studied 46 patients (mean age, 17.6 years; range, 13-24 years) with spastic hemiplegic cerebral palsy. We assessed muscle volume using MRI and concentric muscle work in the sagittal plane from the hip, knee, and ankle using three-dimensional gait analysis. Patients were classified by Winters' criteria to assess the involvement of cerebral palsy and movement pattern during walking.
  
  
  RESULTS
  On the hemiplegic side, muscles were smaller, except for the gracilis muscle, and concentric muscle work from the ankle plantar flexors, knee extensors, and hip flexors and extensors was lower compared to the noninvolved side. Hip extensor work was higher on the hemiplegic and the noninvolved sides compared to a control group of 14 subjects without cerebral palsy. Hemiplegic to noninvolved volume ratios correlated with work ratios (r = 0.40-0.66). The Winters classification and previous calf muscle surgery predicted work ratios.
  
  
  CONCLUSIONS
  Our observations of smaller muscles on the hemiplegic side and changes in muscle work on both sides can help us distinguish between primary deviations that may potentially be treatable and compensatory mechanisms that should not be treated.
authors.affiliation: Department of Orthopaedics, Skaraborg Hospital, Ädelstensvägen 3B, 541 42 Skövde, Sweden. jacques.riad@vgregion.se
authors.forename: Jacques
authors.initials: J
authors.lastname: Riad
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Modlesky
authors.forename: E M
authors.initials: EM
authors.lastname: Gutierrez-Farewik
authors.forename: Eva
authors.initials: E
authors.lastname: Broström
mesh_terms: D000293:Adolescent; D002547:Cerebral Palsy / Q000150:complications / Q000473:pathology*; D003430:Cross-Sectional Studies; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006429:Hemiplegia / Q000473:pathology* / Q000503:physiopathology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009119:Muscle Contraction / Q000502:physiology; D009128:Muscle Spasticity / Q000473:pathology / Q000503:physiopathology; D018482:Muscle, Skeletal / Q000473:pathology* / Q000503:physiopathology; D016138:Walking; D055815:Young Adult