title: Within-session reliability and smallest real difference of muscle strength following nerve transfers in patients with brachial plexus injuries.
abstract: OBJECTIVE
  To quantify the smallest real difference (SRD) of muscle strength in patients with brachial plexus injuries (BPI) after nerve transfer.
  
  
  METHODS
  This study enrolled 16 patients with BPI who had C5-C6 and C5-C7 root injuries and who received nerve transfer of the spinal accessory nerve to the suprascapular nerve and fascicles of the ulnar nerve to the branch of the musculocutaneous nerve that innervates the biceps muscle. The quantitative peak strength of the shoulder abductor, external rotator, and elbow flexor in both arms were measured by the hand-held dynamometer. The SRD of each muscle was determined from the values of the intraclass correlation coefficient and standard error of measurement.
  
  
  RESULTS
  In the involved arm, peak strength ranged from 18% of the noninvolved (shoulder external rotator) to 40% of the noninvolved (shoulder abductor). The intraclass coefficient for within-session reliability revealed good to excellent reliability for muscles, ranging from 0.86 to 0.99 and 0.87 to 0.91 in the involved and noninvolved arms, respectively. The SRD values were low for the shoulder external rotator (2.6 kg) and high for the elbow flexor (3.3 kg).
  
  
  CONCLUSIONS
  The hand-held dynamometer is a device with good to excellent reliability for measuring the objective strength of patients with BPI in a single session. The SRD values established in the current study are more applicable for patients achieving a Medical Research Council grading of 3 or higher and can be used to detect real changes occurring after intervention, which can thereby differentiate real changes from changes that could be attributed to random variation in the measurements.
  
  
  METHODS
  Diagnosis II.
authors.affiliation: Department of Biomedical Engineering, National Cheng Kung University, Tainan, Taiwan; Medical Device Innovation Center, National Cheng Kung University, Tainan, Taiwan.
authors.forename: Yi-Jung
authors.initials: YJ
authors.lastname: Tsai
authors.affiliation: Department of Orthopedics, E-DA Hospital, Kaohsiung, Taiwan.
authors.forename: Yuan-Kun
authors.initials: YK
authors.lastname: Tu
authors.affiliation: Department of Medical Research, E-DA Hospital, Kaohsiung, Taiwan.
authors.forename: Chih-Kun
authors.initials: CK
authors.lastname: Hsiao
authors.affiliation: Department of Biomedical Engineering, National Cheng Kung University, Tainan, Taiwan; Medical Device Innovation Center, National Cheng Kung University, Tainan, Taiwan. Electronic address: fcsu@mail.ncku.edu.tw.
authors.forename: Fong-Chin
authors.initials: FC
authors.lastname: Su
mesh_terms: D000328:Adult; D001132:Arm / Q000503:physiopathology*; D001917:Brachial Plexus / Q000293:injuries*; D020516:Brachial Plexus Neuropathies / Q000503:physiopathology / Q000601:surgery*; D005260:Female; D006801:Humans; D008297:Male; D053580:Muscle Strength / Q000502:physiology*; D053581:Muscle Strength Dynamometer; D016067:Nerve Transfer; D015203:Reproducibility of Results
keywords: Hand-held dynamometer; upper arm type; within-session reliability