Interrater and Intrarater Reliability of Finger Goniometric Measurements

Participants

Twenty-seven people participated in the study. Participants were briefed on the study, and written informed consent was obtained before any data were collected. This study was reviewed and approved by the university’s and hospital’s institutional review boards before data collection.

Participants completed a brief survey that included questions about their age, gender, hand dominance, and past medical history related to upper-extremity injury. Participants were included if they were ≥19 years old and had no history of hand or finger injuries. They were excluded if they had a history of arthritis or fractures of the upper extremity, Raynaud’s syndrome, carpal tunnel syndrome or carpal tunnel release, or other neurological problems related to the upper extremity. Using healthy participants in this study controlled for the variations in ROM that can be present with injured digits, depending on the variety and a range of severity of injuries. Three participants were excluded from the study because they had a history of upper-extremity injury. Of the 24 participants enrolled in the study, 4 participants were lost because of schedule conflicts on the second day of data collection. Therefore, a total of 20 participants (14 women and 6 men) completed this study. Mean age of the participants was 45 yr (standard deviation [SD] was 15 yr). Eighteen of the participants were right-hand dominant, and 2 were left-hand dominant.

Raters

Each of the 10 therapists used at this hand clinic was invited to participate in this study. Eight raters volunteered; however, one rater did not obtain measurements on many of the participants and was dropped from the analysis. Of the seven raters included in the study, six were occupational therapists and one was a physical therapist. Four of the seven therapists were certified hand therapists. Six currently worked as hand therapists in the same hand clinic, and one was formerly used by the hand clinic but currently worked as a full-time academician. All raters had completed protection of human participants training. One rater had completed her doctoral degree; all others had completed their bachelor’s degree. Raters’ years of clinical experience were 3–5 yr (n = 1), 11–15 yr (n = 3), 16–20 yr (n = 2), and >20 yr (n = 1). When asked about hand therapy experience (defined as a caseload of >50% of hand/upper extremity experience), only one of the seven therapists reported ≤5 yr of experience, and one therapist reported >20 yr of experience. Five raters had used the Rolyan finger goniometer for >1 yr, one had used it 6 mo to 1 yr, and one rater was using it for the first time in this study.

Instruments

Raters used the white-and-blue plastic Rolyan finger goniometer (Figure 1). The units of measurement are in degrees with a resolution of 2° increments. The long arm of the goniometer is 3.75 in., and the short arm is 0.75 in. The scale of the goniometer ranges from 30° of hyperextension to 120° of flexion.

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Figure 1.

Measuring active range of motion of the proximal interphalangeal joint of the middle finger using the Rolyan finger goniometer.

Position for Measuring ROM

Each participant sat at a hand treatment table with his or her elbow supported on the table. The shoulder was in a position of 45°–60° flexion, neutral rotation, and 0°–15° of adduction. The forearm was in neutral rotation (in a transverse plane) with the wrist in 5°–15° extension. The following bony landmarks were used to measure the middle finger of the dominant hand:

Dorsal placement of the goniometer was used as recommended by the American Society for Hand Therapists (Casanova, 1992) and Norkin and White (2003). This placement was preferred by 73% of hand therapists surveyed by Groth and Ehretsman (2001).

Procedure

An informational session describing the procedure for proper alignment of the goniometer for the three joints was described verbally and demonstrated physically 2 days before the study. A photograph of each joint and the goniometer, along with a brief description, were printed on one page for quick reference during the study. These materials were also presented during the informational session. This information was posted in the department, and a second copy was filed in a specially prepared manual along with a rationale and full proposal of the study. A pilot study was conducted 1 mo before data collection to practice the procedures, assess the amount of time needed, and work out other logistical issues associated with repeated testing of the participants. During the pilot study, raters demonstrated to the investigators their ability to follow the protocol.

Data collection occurred on 2 days scheduled 3 wk apart. Each participant was measured by no more than four raters in 1 day to avoid participant fatigue, soreness, or changes in ROM caused by repeated measurements. On the second day of data collection, the participant was measured by the remaining raters. Participants were scheduled within three time sessions. All raters began measuring at the same time in each session. Measurements for one session took approximately 35–45 min. Raters’ stations were separated from each other so that they could not hear other conversations, and each rater recorded data on a separate sheet of paper. Each participant had at least 5 min of rest between each rater. Order effects were controlled for by using a partial Latin Square Design (Portney & Watkins, 2009). Therefore, each participant was measured by four raters on 1 day and returned 3 wk later to have the remaining raters take measurements. Each rater measured each participant 3 times.

Each rater asked the participant to actively make a composite fist by saying “make a fist as best you can.” Measurements of the middle finger of the dominant hand were taken at the MCP, PIP, and DIP joints. Raters were then asked to extend actively (A) by saying “straighten your fingers all the way.” Alternating between active fisting and active extension was incorporated into the design to avoid fatigue from actively holding a fist for an extended period of time.

Passive (P) ROM measurements were then taken for flexion and extension for three trials. The participants were instructed, “Now relax your fingers and let me move them. I will measure them passively. Tell me if I am hurting you.” Passive ROM measurements were performed using a joint blocking technique to assess the joint tissues rather than extrinsic tightness that may be present. Hyperextension was not measured passively to simulate the clinical setting and avoid stretching further into an abnormal position.

Raters were surveyed on the specific methods they used for measuring ROM during the study as a follow-up to assess the consistency of the procedures. When assessing MCP flexion, all raters reported aligning the long arm of the goniometer over the dorsal midline of the proximal phalanx. When asked about DIP flexion, all raters reported aligning the long arm of the goniometer over the dorsal midline of the middle phalanx. However, there was some discrepancy with regard to assessing PIP flexion. Four raters aligned the long arm of the goniometer over the dorsal midline of the proximal phalanx, two raters aligned the long arm of the goniometer over the dorsal midline of the middle phalanx, and one rater aligned the long arm of the goniometer over the midline of the proximal phalanx for active motion and used the midline of the middle phalanx for passive motion. When raters were asked whether they maintained the wrist in neutral flexion or extension when measuring ROM of the fingers (neutral is defined as 5° of flexion to 15° of extension), six raters responded that they did. One rater reported that the wrist was in >15° of extension when she took measurements.

Statistical Analyses

Data were analyzed using SPSS Version 15 Software (SPSS Inc., Chicago). Descriptive statistics are reported as means and SD. Repeated-measures analysis of variance (ANOVA) for each dependent ROM measure by rater (seven raters) and trial (three trials) was conducted. Those analyses with a significant Mauchley’s Test of Sphericity (tests to determine whether variances across trials and raters are relatively equal and correlated; Portney & Watkins, 2009) used the Greenhouse–Geisser correction (an adjustment of degrees of freedom is made; Portney & Watkins, 2009) when reporting level of significance for either the main effects or the interaction effect of that measure. Least significant difference tests for each main-effect significant difference were used. Reliability (interrater:rater, and intrarater:trial) was assessed by the intraclass correlation coefficient (ICC). Specifically, the intrarater analysis was as follows:

The interrater analysis was as follows:

The ICC Model 3 (Portney & Watkins, 2009), in which raters from a particular clinic were chosen nonrandomly, was used. Model 3 treats raters as a fixed effect and participants as random effects. Intraclass reliability is a measure of reliability obtained through ANOVAs measuring the correspondence and agreement between ratings (Portney & Watkins, 2009). Single-measure ICCs are reported. Coefficient of variation (CV) and 95% confidence intervals (CI) measures were calculated for each rater by type of measurement. Method error (ME) and the coefficient of ME (CV_ME) were calculated for Trials 2 and 3 for each ROM measurement for each rater. Trials 2 and 3 were used because ME and CV_ME require the use of difference scores to measure the stability of measures (Portney & Watkins, 2009). Using the latter two trials would likely produce the most stable measurements: The rationale was that in a clinical setting, learning effects would be minimal because many measurements with the goniometer would have been made. The equations for these measurements, as described in Portney and Watkins (2009), are as follows:

Results were deemed significant for two-tailed tests if p < .05.