title: The reliability of a smartphone goniometer application compared with a traditional goniometer for measuring first metatarsophalangeal joint dorsiflexion.
abstract: BACKGROUND
  Adequate sagittal plane motion of the first metatarsalphalangeal joint (1st MTPJ) is important during normal gait and goniometric measurement is commonly used as a diagnostic and outcome assessment tool. We aimed to determine the intra and inter-rater reliability together with the concurrent validity of a universal plastic goniometer (UG) and a smartphone applicationlication (Dr G) for the measurement of dorsiflexion at the 1st MTPJ.
  
  
  METHODS
  Measurement of joint position and passive range of motion of the 1st MTPJ dorsiflexion was compared using a UG and DrG goniometer. A double-blind repeated measures design was utilized, with intraclass correlation coefficient (ICC) used to determine levels of reliability.
  
  
  RESULTS
  For joint position good intra-rater reliability (ICC >0.861) and good inter-rater reliability (ICC >0.823) was noted. However, the Dr G application consistently measured lower angles (mean 27.8° (SD 8.37)) than the UG (mean 32° (SD 11.7)) and these associations were significant (r = 0.399, p < 0.001). For passive range of motion, the mean total range of dorsiflexion motion (from maximum plantarflexed position to maximum dorsiflexed position) was 82.8° (SD 12.2) for the UG and 82.9° (SD 11.3) for the Dr G application. Both instruments demonstrated high levels of intra-rater reliability (ICC >0.809). Inter-rater reliability was moderate to good for the UG (ICC 0.693 (95 % CI 0.580 to 0.788)) and good for the Dr G application (ICC 0.708 (95 % CI 0.597 to 0.799)).
  
  
  CONCLUSIONS
  Moderate to high intra and inter-rater reliability of joint position and passive 1st MTPJ motion can be achieved with traditional and smartphone-based goniometric measurement. The Dr G application may provide a slightly higher reliability, but devices should not be used inter-changeably as significant variation in measurement between devices may occur.
authors.affiliation: School of Health Science, 49 Darley Rd, Eastbourne, BN20 7UR UK.
authors.forename: Simon J
authors.initials: SJ
authors.lastname: Otter
authors.affiliation: School of Health Science, 49 Darley Rd, Eastbourne, BN20 7UR UK.
authors.forename: Brunilda
authors.initials: B
authors.lastname: Agalliu
authors.affiliation: School of Health Science, 49 Darley Rd, Eastbourne, BN20 7UR UK.
authors.forename: Nicola
authors.initials: N
authors.lastname: Baer
authors.affiliation: School of Health Science, 49 Darley Rd, Eastbourne, BN20 7UR UK.
authors.forename: Georgie
authors.initials: G
authors.lastname: Hales
authors.affiliation: School of Health Science, 49 Darley Rd, Eastbourne, BN20 7UR UK.
authors.forename: Katrina
authors.initials: K
authors.lastname: Harvey
authors.affiliation: School of Health Science, 49 Darley Rd, Eastbourne, BN20 7UR UK.
authors.forename: Keeley
authors.initials: K
authors.lastname: James
authors.affiliation: School of Health Science, 49 Darley Rd, Eastbourne, BN20 7UR UK.
authors.forename: Richard
authors.initials: R
authors.lastname: Keating
authors.affiliation: School of Health Science, 49 Darley Rd, Eastbourne, BN20 7UR UK.
authors.forename: Warren
authors.initials: W
authors.lastname: McConnell
authors.affiliation: School of Health Science, 49 Darley Rd, Eastbourne, BN20 7UR UK.
authors.forename: Rachel
authors.initials: R
authors.lastname: Nelson
authors.affiliation: School of Health Science, 49 Darley Rd, Eastbourne, BN20 7UR UK.
authors.forename: Saddaf
authors.initials: S
authors.lastname: Qureshi
authors.affiliation: School of Health Science, 49 Darley Rd, Eastbourne, BN20 7UR UK.
authors.forename: Steven
authors.initials: S
authors.lastname: Ryan
authors.affiliation: School of Health Science, 49 Darley Rd, Eastbourne, BN20 7UR UK.
authors.forename: Abigail
authors.initials: A
authors.lastname: St John
authors.affiliation: School of Health Science, 49 Darley Rd, Eastbourne, BN20 7UR UK.
authors.forename: Heather
authors.initials: H
authors.lastname: Waddington
authors.affiliation: School of Health Science, 49 Darley Rd, Eastbourne, BN20 7UR UK.
authors.forename: Katie
authors.initials: K
authors.lastname: Warren
authors.affiliation: School of Health Science, 49 Darley Rd, Eastbourne, BN20 7UR UK.
authors.forename: Duane
authors.initials: D
authors.lastname: Wong
keywords: Biomechanics Cell phone; First metatarsophalangeal joint; Reproducibility of results