Other factors also infiuence the direction and size of the
resultant force A change m the position ofthe pulleys will
alter its direction The general changing position of the
patient may also affect the direction of the resultant force
in the same way However, the literature is unclear how
the position of the patient should be maintained Larson
& Gould (1974) suggest that hip flexion be maintained at
20° and surest placing two pillows imder the thigh to
maintam this angle Precise measurement methods are
unavailable