title: Influence of upper extremity assistance on lower extremity force application symmetry in individuals post-hip fracture during the sit-to-stand task.
abstract: METHODS
  Controlled laboratory study using a cross-sectional design.
  
  
  OBJECTIVE
  To compare lower extremity force applications during a sit-to-stand (STS) task with and without upper extremity assistance in older individuals post-hip fracture to those of age-matched controls.
  
  
  BACKGROUND
  A recent study documented the dependence on upper extremity assistance and the uninvolved lower limb during an STS task in individuals post-hip fracture. This study extends this work by examining the effect of upper extremity assistance on symmetry of lower extremity force applications.
  
  
  METHODS
  Twenty-eight community-dwelling elderly subjects, 14 who had recovered from a hip fracture and 14 controls, participated in the study. All participants were independent ambulators. Four force plates were used to determine lower extremity force applications during an STS task with and without upper extremity assistance. The summed vertical ground reaction forces (vGRFs) of both limbs were used to determine STS phases (preparation/rising). The lower extremity force applications were assessed statistically using analysis of variance models.
  
  
  RESULTS
  During the preparation phase, side-to-side symmetry of the rate of force development was significantly lower for the hip fracture group for both STS tasks (P<.001). During the rising phase, the vGRF impulse of the involved limb was significantly lower for the hip fracture group for both STS tasks (P = .045). The vGRF impulse for the uninvolved limb was significantly increased when participants with hip fracture did not use upper extremity assistance compared to elderly controls (P = .002). This resulted in a significantly lower vGRF symmetry for the hip fracture group during both STS tasks (P<.001).
  
  
  CONCLUSIONS
  Participants with hip fracture who were discharged from rehabilitative care demonstrated decreased side-to-side symmetry of lower extremity loading during an STS task, irrespective of whether upper extremity assistance was provided. These findings suggest that learned motor control strategies may influence movement patterns post-hip fracture.
authors.affiliation: Department of Physical Therapy, MGH Institute of Health Professions, Boston, MA 02129, USA. Jkneiss@mghihp.edu
authors.forename: Janet A
authors.initials: JA
authors.lastname: Kneiss
authors.forename: Jeff R
authors.initials: JR
authors.lastname: Houck
authors.forename: Susan V
authors.initials: SV
authors.lastname: Bukata
authors.forename: J Edward
authors.initials: JE
authors.lastname: Puzas
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena / Q000502:physiology; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006620:Hip Fractures / Q000503:physiopathology* / Q000534:rehabilitation; D006801:Humans; D035002:Lower Extremity / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D053580:Muscle Strength / Q000502:physiology; D018482:Muscle, Skeletal / Q000503:physiopathology; D034941:Upper Extremity / Q000503:physiopathology*