Two photographs from the same patient depict contractures in the left small finger and the right middle finger. Chiu HY: A method of two-dimensional measurement for evaluating finger motion impairment. A description of the method and comparison with angular measurement. J Hand Surg Br. 1995, 20: 691-695. 10.1016/S0266-7681(05)80138-X. For further reflection of intra-goniometer (i.e., intra-rater ) reliability, proportions of clinically non-meaningful ≤ 5-degree differences between the measurements obtained with the same tool in the 2 trials were calculated for each rater. Similarly, for the assessment of inter-goniometer reliability, proportions of ≤ 5-degree differences between measurements of the same rater with different instruments within the same trial were found. The observed proportions of the ≤ 5-degree differences were tested against proportion of 0.95 for statistical significance by one sample binomial tests. The reference value was estimated by calculating the LL of 99% CI for population proportion [ 49] using the largest previously employed sample sizes reaching 60 [ 32] and a generous assumption that the earlier sample proportion of ≤5-degree measurement differences was 0.99. Counts of the raters who passed the binomial tests were obtained for intuitive comparison. To assess the inter-goniometer ≤ 5-degree agreement, only the raters who passed the binomial test in both trials were included. Additionally, the best raters were selected by matching the individual successful raters across the three ≤ 5-degree agreement subgroups (i.e., across the inter-goniometer and the two intra-goniometer subgroups). Analysis of the study parts B

Eliasziw M, Young SL, Woodbury MG, Fryday-Field K: Statistical methodology for the concurrent assessment of interrater and intrarater reliability: using goniometric measurements as an example. Phys Ther. 1994, 74: 777-788. Bruton A, Conway JH, Holgate ST: Reliability: What is it and how is it measured?. Physiotherapy. 2000, 86: 94-99. 10.1016/S0031-9406(05)61211-4. Hamilton GF, Lachenbruch PA: Reliability of goniometers in assessing finger joint angle. Phys Ther. 1969, 49: 465-469. Goniometer. (2008, August 30). In Wikipedia, The Free Encyclopedia. Retrieved 11:12, September 14, 2008, from http://en.wikipedia.org/wiki/Goniometer.Ellis B, Bruton A, Goddard JR: Joint angle measurement: a comparative study of the reliability of goniometry and wire tracing for the hand. Clin Rehabil. 1997, 11: 314-320. 10.1177/026921559701100408. A pilot exploration employing a healthy subject and 17 raters was performed to elucidate possible technical problems of the study.

In the replicate study parts A, the subjects used their individual try-angle sets at the 10 evaluation stations (Figure 1, Additional file 2). The values of the angles of individual try-angles were randomly distributed across the finger joints and across the subjects. The angles of the individual try-angles of the same subject were of different magnitude, and none of the subjects had the same combination of the angle magnitudes (Additional file 3). Raters of the study parts A had to obtain twice the MCP, PIP, and DIP joint angles in each of the two positions (flexion and extension) by using both goniometers (Additional file 2) . Chiu HY, Su FC, Wang ST, Hsu HY: The motion analysis system and goniometry of the finger joints. J Hand Surg Br. 1998, 23: 788-791. 10.1016/S0266-7681(98)80098-3. For continuous variables, the most common measure of relative reliability is intraclass correlation coefficient (ICC) accompanied by appropriate analysis of variance (ANOVA) [ 40]. Differently from the previous studies, which used the popular models of ICCs described by Shrout and Fleiss [ 42], the current investigation employed concurrent assessment of reliability proposed by Eliasziw et al. [ 43]. Unlike calculating the traditional ICCs, the method of concurrent assessment allows simultaneous estimation of intra-rater and inter-rater reliability along with the hypothesis testing in cases when multiple raters evaluate multiple subjects and perform more than one measurement per subject. In respect to the traditional models, the concurrent methodology has been cited as a more advantageous approach [ 44]. The paper goniometer and the standard goniometer can be used interchangeably by non-professional raters for evaluation of normal finger joints. The obtained results warrant further research to assess clinical performance of the paper strip technique.Walter SD, Eliasziw M, Donner A: Sample size and optimal designs for reliability studies. Stat Med. 1998, 17: 101-110. 10.1002/(SICI)1097-0258(19980115)17:1<101::AID-SIM727>3.0.CO;2-E. Exploratory data analysis included obtaining descriptive statistics, searching for outliers, and assessing the normality of distribution of the appropriate data sets by means of Shapiro-Wilk tests and the analysis of histograms and Q-Q plots. Analysis of the study parts A Ideal for measuring cervical rotation, anteroposterior flexion, and lateral flexion of the cervical spine. The study included two procedurally different parts, which were replicated by assigning 24 medical students to act interchangeably as 12 subjects and 12 raters. A larger component of the study was designed to compare goniometers side-by-side in measurement of finger joint angles varying from subject to subject. In the rest of the study, the instruments were compared by parallel evaluations of joint angles similar for all subjects in a situation of simulated change of joint range of motion over time. The subjects used special guides to position the joints of their left ring finger at varying angles of flexion and extension. The obtained diagrams of joint angles were converted to numerical values by computerized measurements. The statistical approaches included calculation of appropriate intraclass correlation coefficients, standard errors of measurements, proportions of measurement differences of 5 or less degrees, and significant differences between paired observations. Results

Lefevre-Colau MM, Poiraudeau S, Fermanian J, Mayoux-Benhamou MA, Bargy F, Revel M: Reliability of two goniometers in assessing rheumatoid finger mobility: Relationship between mobility and disability. Eura Medicophys. 2001, 37: 3-10. Record measurements correctly (both active and passive range of motion should be measured and recorded respectively). [1] The pre-publication history for this paper can be accessed here: http://www.biomedcentral.com/1471-2474/14/17/prepub Glasgow C, James M, O‘Sullivan J, Tooth LR: Measurement of joint stiffness in the hand: a preliminary investigation of the reliability and validity of torque angle curves. Br J Hand Ther. 2004, 9: 11-12.

Single-Axis Finger Electronic Goniometer

In the replicate study parts A, 2x2x10 (trial x goniometer x rater) and 2x10 (goniometer x rater) repeated measures ANOVAs were run for each position-joint and trial-position–joint data set, respectively, to assess the main effects and interactions of goniometer, trial, and rater. The sphericity assumption was tested by using Mauchly’s test with appropriate epsilon adjustments.

Milanese S et al. Reliability and concurrent validity of knee angle measurement: Smart phone app versus universal goniometer used by experienced and novice clinicians. Manual Therapy, 2014; 5: 1–6.

Shrout PE, Fleiss JL: Intraclass correlations: uses in assessing rater reliability. Psychol Bull. 1979, 86: 420-428.