Table 2

Factor analysis results for the respective binarised 9 items of the AOFAS-AHS and the binarised 18 items of the FFI-D: rotated factor weights for the 9+18 items after identification of three joint factors by means of the variance maximisation criterion

(Binarised) score itemsFactor and factor weight
12
‘Pain and disability’
3
‘Mobility and gait function’
AOFAS-AHS ‘pain’0.810
AOFAS-AHS ‘activity restriction’0.807
AOFAS-AHS ‘walking distance’0.597
AOFAS-AHS ‘walking surfaces’0.780
AOFAS-AHS ‘gait abnormality’0.747
AOFAS-AHS ‘sagittal motion’0.747
AOFAS-AHS ‘hindfoot motion’0.780
AOFAS-AHS ‘ankle-hindfoot stability’0.480
AOFAS-AHS ‘alignment’0.508
FFI-D pain ‘worst pain’0.792
FFI-D pain ‘pain in the morning’0.446
FFI-D pain ‘pain while walking barefoot’0.741
FFI-D pain ‘pain while standing barefoot’0.620
FFI-D pain ‘pain while walking with shoes’0.741
FFI-D pain ‘pain while standing with shoes’0.704
FFI-D pain ‘pain at the end of the day’0.824
FFI-D pain ‘pain during the night’0.477
FFI-D disability ‘problems while walking outside’0.656
FFI-D disability ‘problems while walking on uneven ground’0.846
FFI-D disability ‘problems while walking distances ≥1 km’0.846
FFI-D disability ‘problems while walking up the stairs’0.690
FFI-D disability ‘problems while walking down the stairs’0.767
FFI-D disability ‘problems while walking on tiptoes’0.767
FFI-D disability ‘problems while standing up from a chair’0.442
FFI-D disability ‘problems while walking fast or during running’0.846
FFI-D disability ‘problems during leisure activities or sports’0.846
FFI-D disability ‘problems while wearing special shoes (high heels, sandals etc)’
  • Factor weights <0.500 have been omitted to emphasise the rotation-based aggregation of the 9+18 items into three factors, a posteriori declared representing ‘pain and disability’ (factor 2) and ‘mobility and gait function’ (factor 3), respectively.

  • AOFAS-AHS, Ankle-Hindfoot Scale of the American Orthopaedic Foot and Ankle Society; FFI-D, Foot Function Index.