University of Pittsburgh

Evidence - Surface Height

Raising or lowering the target height by 10cm was found to have signficiant kinematic effects such as: 

  • Peak angular displacement of the trailing shoulder flexion and elbow extension
  • Additional shoulder extension angular displacement and velocity at the leading arm
  •  Trailing upper limb exposed to greater mean vertical force (median values: men=32% body weight [BW]; women = 27% BW) than the leading upper limb (median values: mean = 24.5%; women = 23%) during a transer. 

Gender difference trend (p=.045) for the vertical force component recorded underneath the trailing hand with the men having to counteract a greater relative loading force than the women. (Forslund, 2007)

Other research, by Gagnon et al., has found that transfers between surfaces of the same height have similar mean vertical reaction force values underneath the trailing (29.4% BW) and leading (31.9% BW) hands whereas there was a significant difference for the peak values with the highest forces being recorded underneath the trailing hand (trailing = 44.5% BW; leading = 39.6% BW) during the lift phase as shown below.  

(BW = Body Weight)

When the height of the target seat was raised by 10cm:

  • For the trailing hand, higher vertical reaction force values (mean = 34.1% BW; peak = 48.6% BW) were recorded with high target seat compared to level transfer (mean = 29.4% BW; peak = 44.5% BW). 
  • The vertical reaction forces values were slightly reduced underneath the leading hand when transferring to the high target seat (mean = 30.3% BW; peak = 36% BW) in cmoparison to the same height (mean = 31.9% BW; peak = 39.6% BW). 
  • Peak magnitude of the vertical reaction force component upon landing was found to be elevated on avaerage (same = 87.8% BW; high = 86.6% BW), which may contribute to the development of secondary upper limb or skin integrity impairments respectively. 

(Gagnon, 2008)

Although uneven transfers are sometimes necessary, patients should try to avoid performing these very high or very low transfers on a regular basis

  • When not performing a level transfer, a transfer board may be useful
  • Transferring in front of the rear wheel and NOT over will reduce the height the patient must lift themselves during the transfer. (Rice et al., 2013)
  • Removing/moving the armrest before transfer will provide the patient with an unobstructed transfer path

 

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