title: Biomechanical and Clinical Correlates of Stance-Phase Knee Flexion in Persons With Spastic Cerebral Palsy.
abstract: OBJECTIVE
  To identify biomechanical and clinical parameters that influence knee flexion (KF) angle at initial contact (IC) and during single limb stance phase of gait in children with spastic cerebral palsy (CP) who walk with flexed-knee gait.
  
  
  METHODS
  Retrospective analysis of gait kinematics and clinical data collected from 2010-2013.
  
  
  METHODS
  Motion & Gait Analysis Laboratory at Lucile Packard Children's Hospital, Stanford, CA.
  
  
  METHODS
  Gait analysis data from persons with spastic CP (Gross Motor Function Classification System [GMFCS] I-III) who had no prior surgery were analyzed. Participants exhibiting KF ≥20° at IC were included; the more-involved limb was analyzed.
  
  
  METHODS
  Outcome measures were analyzed with respect to clinical findings, including passive range of motion, Selective Motor Control Assessment for the Lower Extremity (SCALE), gait kinematics, and musculoskeletal models of muscle-tendon lengths during gait.
  
  
  METHODS
  KF at IC (KFIC) and minimum KF during single-limb support (KFSLS) were investigated.
  
  
  RESULTS
  Thirty-four participants met the inclusion criteria, and their data were analyzed (20 males and 14 females, mean age 10.1 years, range 5-20 years). Mean KFIC was 34.4 ± 8.4 degrees and correlated with lower SCALE score (ρ = -0.530, P = .004), later peak KF during swing (ρ = 0.614, P < .001), and shorter maximal muscle length of the semimembranosus (ρ = -0.359, P = .037). Mean KFSLS was 18.7 ± 14.9 and correlated to KF contracture (ρ = 0.605, P < .001) and shorter maximal muscle length of the semimembranosus (ρ = -0.572, P < .001) and medial gastrocnemius (ρ = -0.386, P = .024). GMFCS correlated more strongly to KFIC (ρ = 0.502, P = .002) than to KFSLS (ρ = 0.371, P = .031). Linear regression found that both the SCALE score (P = .001) and delayed timing of peak KF during swing (P = .001) independently predicted KFIC. KF contracture (P = .026) and maximal length of the semimembranosus (P = .043) independently predicted KFSLS.
  
  
  CONCLUSIONS
  Correlates of KFIC differed from those for KFSLS and suggest that impaired selective motor control and later timing of swing-phase KF influence knee position at IC, whereas KF contracture and muscle lengths influence minimal KF in single-limb support, findings with important treatment implications.
authors.affiliation: Department of Orthopaedic Surgery, Stanford University School of Medicine, Stanford, CA; Motion & Gait Analysis Laboratory, Lucile Packard Children's Hospital, Stanford, CA; Department and Research Institute of Rehabilitation Medicine, Yonsei University College of Medicine, Seoul, Korea(∗).
authors.forename: Dong-wook
authors.initials: DW
authors.lastname: Rha
authors.affiliation: Department of Orthopaedic Surgery, Stanford University School of Medicine, Stanford, CA; Motion & Gait Analysis Laboratory, Lucile Packard Children's Hospital, Stanford, CA; Department of Bioengineering, Stanford University, 770 Welch Rd, Suite 400, Stanford, CA 94304(†). Electronic address: kcct@stanford.edu.
authors.forename: Katelyn
authors.initials: K
authors.lastname: Cahill-Rowley
authors.affiliation: Department of Orthopaedic Surgery, Stanford University School of Medicine, Stanford, CA; Motion & Gait Analysis Laboratory, Lucile Packard Children's Hospital, Stanford, CA(‡).
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Young
authors.affiliation: Motion & Gait Analysis Laboratory, Lucile Packard Children's Hospital, Stanford, CA(¶).
authors.forename: Leslie
authors.initials: L
authors.lastname: Torburn
authors.affiliation: Department of Orthopaedic Surgery, Stanford University School of Medicine, Stanford, CA; Motion & Gait Analysis Laboratory, Lucile Packard Children's Hospital, Stanford, CA; Department of Mechanical Engineering, Stanford University, Stanford, CA(§).
authors.forename: Katherine
authors.initials: K
authors.lastname: Stephenson
authors.affiliation: Department of Orthopaedic Surgery, Stanford University School of Medicine, Stanford, CA; Motion & Gait Analysis Laboratory, Lucile Packard Children's Hospital, Stanford, CA(∗∗).
authors.forename: Jessica
authors.initials: J
authors.lastname: Rose
mesh_terms: D000293:Adolescent; D001696:Biomechanical Phenomena; D002547:Cerebral Palsy / Q000175:diagnosis / Q000503:physiopathology*; D002648:Child; D002675:Child, Preschool; D005260:Female; D005684:Gait / Q000502:physiology*; D006801:Humans; D007719:Knee Joint / Q000502:physiology*; D008297:Male; D016059:Range of Motion, Articular / Q000502:physiology*; D012189:Retrospective Studies; D055815:Young Adult