title: Leg length discrepancy in spastic hemiplegic cerebral palsy: a magnetic resonance imaging study.
abstract: BACKGROUND
  In patients with spastic hemiplegic cerebral palsy (CP) it can be difficult to clearly define whether deviations in gait pattern result from impaired motor control, leg length discrepancy (LLD), or are a consequence of secondary compensatory mechanisms. LLD is common and treatment can be considered. The goal was to investigate the degree of LLD in the lower limb including the pelvis, femur, tibia, talus, and calcaneus using magnetic resonance imaging (MRI).
  
  
  METHODS
  Forty-four patients with spastic hemiplegic CP and a mean age of 17.6 years (range, 13.0 to 23.0 y) participated in the study; of these 20 were female and 24 were male. All were classified as 1 on the gross motor classification scale and as Winters' type 1 or 2. On the basis of sagittal T1-weighted MRI images of the lower extremity, the length of the pelvis, femur, tibia, talus, and calcaneus was measured separately by 2 experienced observers and remeasured independently after a 2-week interval.
  
  
  RESULTS
  Eleven of the 44 patients had a hemiplegic lower limb that was more than 15 mm shorter. The mean difference was in the calcaneus (0.9 mm; P=0.003), talus (1.3 mm; P=0.006), and tibia (8.1 mm; P=0.000). Intraobserver comparison showed high reproducibility with intraclass correlation for the calcaneus (0.91), talus (0.84), tibia (0.99), femur (0.99), and pelvis (0.98). In the interobserver comparison, the corresponding inter class correlations were 0.95, 0.84, 0.99, 0.99, and 0.98.
  
  
  CONCLUSIONS
  This MRI study showed LLD in teenagers and young adults with hemiplegic CP. The main difference between the hemiplegic and noninvolved side was found in the tibia, but the calcaneus and talus also showed significant differences. The method proved to be reliable and the measurement of LLD should be considered in the management of hemiplegic CP. To be able to develop rational treatment plans, it is of importance to know the degree and location of LLD.
  
  
  METHODS
  Prospective cross-sectional diagnostic level 1 study.
authors.affiliation: Department of Orthopedics, Skaraborg Hospital Skövde, Sweden. jacques.riad@vgregion.se
authors.forename: Jacques
authors.initials: J
authors.lastname: Riad
authors.forename: Thröstur
authors.initials: T
authors.lastname: Finnbogason
authors.forename: Eva
authors.initials: E
authors.lastname: Broström
mesh_terms: D000293:Adolescent; D002547:Cerebral Palsy / Q000150:complications*; D003430:Cross-Sectional Studies; D005260:Female; D006429:Hemiplegia / Q000150:complications*; D006801:Humans; D007870:Leg Length Inequality / Q000175:diagnosis* / Q000209:etiology*; D008279:Magnetic Resonance Imaging; D008297:Male; D011446:Prospective Studies; D055815:Young Adult