Study design and patients flow diagram.
mean shoulder abduction
The sample size calculation was based on the expected difference between the two devices on the mean shoulder abduction during the Box and Blocks Test. Based on observations made during recordings in routine clinical practice, the difference between the two mean shoulder abduction was estimated at 25°. To be able to detect such difference with a power of 90 using a threshold for statistical significance of 0.05, we needed to include 8 patients.The subjects were recruited during prosthetic medical appointments usually carried out at the rehabilitation center. During the inclusion period, all persons who met the inclusion criteria were invited to participate in the study by the investigating doctor. They received all the required oral and written information. All the subjects included in the trial signed the informed consent forms.The participants were randomly assigned (by choosing an envelope) to one of the two study arms, which differed by the order in which the two devices were fitted (Greifer then Axon-Hook or Axon-Hook then Greifer, 