Psychometric properties of the goniometric assessment of the Dart Thrower’s Motion

Abstract

Introduction

The Dart Thrower’s Motion is an important movement for hand function. A goniometric clinical measure of Dart Thrower’s Motion has been developed. However, its validity and reliability in people with wrist and hand injury is not known. This study investigated the inter-rater and test–retest reliability and criterion validity of the Dart Thrower’s Motion measure.

Methods

A cross-sectional design was used. Thirty-five participants with hand or wrist injury completed the goniometric assessment of the Dart Thrower’s Motion and goniometric wrist active range of motion assessment three times in a hand clinic. Two assessors and a reader to record the results were involved. Participants also completed the patient-rated wrist and hand evaluation.

Results

The intraclass correlation coefficients were 0.70–0.83 and 0.91–0.92, respectively for inter-rater and test–retest reliability in the injured hands indicating moderate to high reliability. The Pearson correlation coefficients between the Dart Thrower’s Motion measure and wrist active range of motion assessment ranged from 0.45 to 0.73, and with patient-rated wrist and hand evaluation ranged from −0.36 to −0.53. The results indicate that goniometric assessment of the Dart Thrower’s Motion has acceptable criterion validity.

Conclusion

The goniometric assessment of Dart Thrower’s Motion can be considered a valid and reliable clinical measure for measuring the impact of the injury to one’s hand and wrist range of motion and function. It shows its clinical utility in people with hand and wrist injury. It is hoped this simple measure can be eventually implemented in clinical settings, allowing for an increased understanding of an individual’s functional use of the hand and wrist.

Keywords

Dart Thrower’s Motion outcome measure wrist function hand function psychometric properties

Introduction

The hand and wrist are complex structures, comprising anatomical and biomechanical characteristics which allow for the execution of flexible and intricate movements required in hand function.¹ More than 8000 hand and wrist injuries are reported each year in the Danish population that accounts for 14–30% of all treated patients in emergency care,² and there were 32.3% of hand and wrist injuries among over 50,000 work-related injury hospitalizations in Australia from 2002 to 2004.³ These injuries have a detrimental impact on an individual’s daily hand function.

It is becoming increasingly recognized that many functional tasks, such as pouring from a jug or tying the shoelaces, adopt a specific rotation of the wrist along an oblique plane, executing a smooth transition from radial extension to ulnar flexion of the wrist.⁴ This oblique wrist motion is defined as the Dart Thrower’s Motion (DTM). The movement has also been described as a 45° supinated arc from the flexion-extension movement of the wrist.⁵ The presence of the DTM in functional tasks has been confirmed in in-vivo motion analysis studies, indicating that tasks such as hammering a nail and twisting a lid from a jar moved through the DTM plane.^4,6,7

Despite the fact that the DTM is considered important for functional tasks, the DTM has received little attention in clinical assessment and treatment literature. Goniometric assessment of active range of motion (AROM) has been identified as the most consistent measurement of an individual’s joint range of motion, with studies reinforcing its high intra- and inter-rater reliability (ICCs of 0.72–0.91).^8–10 However, goniometric AROM assessment of wrist and finger movements reflects less closely the composite range of motion required in hand function. In comparison, the Patient Rated Wrist and Hand Evaluation Measure (PRWHE) is used to assess the patient perceived performance of everyday tasks and pain in the wrist and hand after injury.¹¹ Studies indicate this measure is commonly used by hand therapists as it has high validity and reliability and can be used as an outcome measure to map improvements.^12,13 It relies on patient report without the actual measurement of the person’s performance.

Whilst both of these assessments offer an excellent analysis of current ROM and hand function after an injury, they do not have the complexity to include a composite of movements such as the DTM. As the DTM is a significant movement essential to hand function, there is a need to use the DTM as a clinical measure. Bugden has proposed a simple, useful measure to assess an individual's DTM range.⁵ It makes use of a goniometric instrument, taking measurements of both DTM movements of radial extension and ulnar flexion with the person holding a light hammer. The use of a light hammer is important as it simulates a functional task of holding a tool or object. It is thought that the use of the hammer in the described measurement makes it easy to perform the functional movement of DTM.^5,14 Cliff and Rust¹⁵ recently investigated the intra- and inter-rater reliability of a modified version of Bugden’s⁵ method in people with asymptomatic wrists, using the goniometric measurements of radial extension and ulnar flexion but without the use of a hammer. The study found a high intra- and inter-rater reliability (ICCs of 0.89–0.92; 0.81–0.83 respectively). However, it did not incorporate the use of a hammer that might affect the performance of the movement. Its test–retest reliability and validity were not tested. This study was also performed in people with no history of injury. The reliability and clinical utility of the DTM Measure in those with a wrist or hand injury are unknown.

This study, therefore, aimed to investigate the inter-tester and test–retest reliability and criterion validity of the DTM measure developed by Bugden⁵ in people with wrist or hand injury. With a standardized method and tools used in the functional measurement, we hypothesized that the DTM measure would have good inter-tester and test–retest reliability, and correlate well with the results of the commonly used AROM assessment and PRWHE.

Methods

Participants

A sample of 35 participants was recruited through convenience sampling from Sydney Hospital’s hand clinic between April and June 2016 (Figure 1). The participants were aged 18–65 years old (mean = 39.3) (Table 1), had recently experienced a hand or wrist injury, or had undergone surgery at least six weeks prior. They were able to perform wrist and finger AROM and to grasp a small hammer. Exclusion criteria included neurological conditions or other conditions that might alter carpal mechanics. They did not require an orthosis 24-h a day. For participants with both hands injured, the lowest score (from either hand) for both the DTM measure and AROM assessment was recorded as their ‘injured hand’ only. Ethical approval was granted from South East Sydney Local Health District and Western Sydney University before commencing the study. All participants gave written informed consent before data collection commenced.

Figure 1.

Participant flow.

Table 1.

Participant characteristics.

	No. of participants (%)(n = 35)
Gender
Male	26 (74.3%)
Female	9 (25.7%)
Occupation
Office-based (e.g. IT worker)	17 (48.6%)
Trade (e.g. builder)	4 (11.4%)
Other (e.g. photographer)	14 (40%)
Injury location
Bones
Fingers	17 (48.6%)
Thumb	4 (11.4%)
Metacarpals	7 (20%)
Carpals	1 (2.9%)
Nerves	1 (2.9%)
Other	2 (5.7%)
Multiple injuries	3 (8.6%)
Hand injured
Right	20 (57.1%)
Left	14 (40%)
Both	1 (2.9%)

Assessors and blinding

One occupational therapist and one physiotherapist (with more than five years’ clinical experience in hand therapy) from Sydney Hospital’s hand clinic were recruited to be the two assessors (assessor 1 and assessor 2). One occupational therapy student was recruited to be the reader and recorder. To achieve blinding in assessments using a goniometer, this study adopted the method employed in LaStayo and Wheeler.¹⁶ It involves the use of a blinded goniometer and the use of an instrument reader and recorder to blind the assessors to the results.

Before commencement of the study, both assessors undertook training to standardize the verbal instructions provided to participants in performing the wrist movements involved and the correct placement of the goniometer for wrist AROM and the DTM measure. Further, a written package with standardized instructions for administering the assessments and pictures of the correct goniometric placements was provided. The occupational therapy student was also given training on the reading of the goniometer and recording of the results.

Instruments

A 15-cm goniometer with 2° increments was used in the DTM measure and AROM assessment. Its accuracy was reviewed and confirmed by measuring four random computer-generated angles between 0° and 180°. Following LaStayo and Wheeler’s¹⁶ blinding methods described above, a thick sheet of paper was inserted into one side of the goniometer’s axis to conceal the readings to the assessors and participants.

Measures

DTM measure

Following Bugden’s proposed method,⁵ participants grasped a small hobby hammer (25 cm long, weighing 167 g) with their fingers and thumb, across their distal palmar crease.

Radial extension and ulnar flexion were measured using a goniometer. Both movements have been described as bringing the wrist from a radially deviated-extended position (radial extension) to an ulnar deviated-flexed position (ulnar flexion) and were described to the participants as similar to using a hammer.⁴ To measure radial extension (Figure 2(a)) and ulnar flexion (Figure 2(b)), the moveable arm of the goniometer was placed along the radial aspect of the shaft of the second metacarpal. Its axis was placed on the area between the first and second dorsal compartments of the radial styloid, approximately 2 cm radial to Lister’s tubercle. The stationary arm was then placed along the radial aspect of the radius, 45° from Lister's tubercle.⁵

Figure 2.

(a) Radial extension measured with blinded goniometer and light hobby hammer. (b) Ulnar flexion measured with blinded goniometer and light hobby hammer.

Wrist AROM assessment

Active range of wrist extension, flexion and radial, ulnar deviation were measured using the standardized positioning recommended by the American Society for Hand Therapists guidelines.⁵

Patient-Rated Wrist and Hand Evaluation (PRWHE)

The PRWHE is a self-reported and simple questionnaire consisting of 15 items.¹¹ There are two subscales, one on pain and another on function in specific everyday tasks such as turning a doorknob and carrying objects and general everyday tasks such as personal care and work. Participants are asked to give a rating on the items using a scale from 0 (no pain or no difficulty) to 10 (worst or unable to do).

Procedure

All participants underwent one testing session. Before testing commenced, demographic data were collected. Participants were first given the PRWHE to complete. They then performed the wrist AROM assessment, followed by the DTM measure three times for their injured hand. For the first two times, assessor 1 conducted the assessments. Assessor 2 then completed the assessments for the third time.

During the DTM measure and wrist AROM assessment, all participants were required to sit upright in a chair, place their forearm on a table and flex their elbow at 90°. The assessors followed the training guidelines provided and gave the standardized instructions. The participants were given an example of the movements and were given the opportunity to practise the movements before their measurements were taken. They were not given any encouragement to enhance their performance. Following the blinding procedures, the assessors were asked to advise the reader of when the measurement should be recorded.^8,16 To reduce fatigue and its potential impact on the results, participants were given a 2-min break between each round of measures. Participants were also asked throughout the sessions of any pain they might be experiencing and testing would be stopped for the measurement if pain occurred.

Statistical analysis

Descriptive statistics were reported for all data collected. Both inter-tester and test–retest reliability of the DTM measure were analyzed using intraclass correlation coefficients (ICC_2,1). An ICC value between 0.5 and 0.75 represents moderate reliability, a value between 0.75 and 0.9 indicates good reliability, and a value greater than 0.90 indicates excellent reliability.¹⁷

To analyze the criterion validity of the DTM measure, Pearson correlation statistics (r) were calculated. All p values were adjusted using a Bonferroni correction for the number of comparisons made. For the comparisons between the DTM measure and the AROM assessment, the p value was adjusted to equal or less than 0.006. For the comparisons between the DTM measure and the results of the PRWHE, the p value of equal to or less than 0.003 was regarded as significant.

Results

Mean radial extension and ulnar flexion of the DTM measure taken by assessor 1 were 56.3 and 19.3, respectively. For the ROM assessment, the mean wrist extension and flexion were 66.4 and 67.2; the mean radial and ulnar deviation were 21.3 and 33.4, respectively (Table 2).

Table 2.

Results of DTM measure and ROM assessment for injured hand.

	Injured hand Mean (SD)
	First round	Second round	Third round
Assessments	First assessor	First assessor	Second assessor
DTM
Radial extension (^o)	56.3 (14.3)	54.7 (13.7)	55.8 (13.4)
Ulnar flexion (^o)	19.3 (10.5)	20.0 (11.7)	23.0 (10.0)
ROM
Wrist extension (^o)	66.4 (9.6)	67.42 (8.6)	61.6 (13.6)
Wrist flexion (^o)	67.2 (19.9)	65.8 (22.6)	63.5 (13.1)
Radial deviation (^o)	21.3 (7.0)	20.3 (6.2)	21.0 (9.2)
Ulnar deviation (^o)	33.4 (9.8)	33.8 (7.5)	27.8 (9.4)

DTM: Dart Thrower’s Motion measure; ROM: range of motion assessment; SD: standard deviation.

Reliability of the DTM measure

For the injured hand measured, both radial extension and ulnar flexion achieved moderate to good inter-rater reliability, with ICCs of 0.83 (95% confidence interval (CI) 0.68–0.91) and 0.70 (95% CI 0.41–0.85), respectively. High test–retest reliability was achieved, revealing ICCs of 0.91 (95% CI 0.83–0.96) for radial extension and 0.92 (95% CI 0.84–0.96) for ulnar flexion.

Validity

Significant correlations were found between the DTM measure and wrist AROM assessment for the injured hand demonstrating the criterion validity of the DTM measure. Ulnar flexion of the DTM measure and ulnar deviation of the AROM assessment had a significant moderate correlation (r = 0.57, p ≤ 0.0001).

Significant correlations were found between the radial extension of the DTM measure in the injured hand and a question in the ‘Function’ section of the PRWHE, asking the participant to rate their difficulty of carrying a 4.5 kg (10 lb) object in their injured hand (r = −0.53, p = 0.001). There was a borderline significant correlation in ulnar flexion and another question in the ‘Function' section of the PRWHE, asking the participant’s difficulty of performing their usual activities of personal care (r = −0.36, p = 0.03).

Discussion

Whilst DTM is required in everyday tasks when using the hand and wrist, there is limited evidence focusing on a DTM measure that can be used in clinical practice. The majority of studies only discussed the anatomical and biomechanical characteristics executed in the movement or involved the use of equipment that is expensive and inaccessible for therapists.^6,18 With the DTM measure developed by Bugden,⁵ the results of this study demonstrate that goniometric assessment of the DTM is a reliable assessment for measuring the impact of the injury to one’s hand and wrist range of motion and function. Its validity is also shown to be satisfactory.

Moderate to good inter-rater reliability of the DTM measure was identified in the participants with a wrist or hand injury. The standardized instructions and the light hammer used could have resulted in this good inter-rater reliability. However, it is postulated that further detailed instructions on the placement of the goniometer might further improve its inter-rater reliability. The study by Cliff and Rust¹⁵ showed good inter-rater reliability in asymptomatic wrists. Our study showed good inter-rater reliability in radial extension and moderate inter-rater reliability in ulnar flexion on the injured hand. It is possible that the DTM measure would yield higher reliability when it is tested in people without any wrist and hand injury. A good clinical utility in people with hand and wrist injury was demonstrated with satisfactory inter-rater reliability of the DTM measure in this study.

This study demonstrated excellent test–retest reliability in both radial extension and ulnar flexion. Although there is no previous study on its test–retest reliability to compare with, this study’s results are in agreement with studies looking at similar wrist goniometric assessments for individuals with a hand and wrist injury. Bashardoust Tajali et al.¹⁹ demonstrated moderate to high intra-rater, inter-rater and inter-instrument reliabilities with ICCs ranging from 0.64 to 0.97. However, it is important to acknowledge that fatigue may have played a role in the participant’s performance as the method required multiple rounds of assessments.²⁰

For criterion validity, this study chose to use the goniometric wrist AROM assessment and the PRWHE as a gold standard for comparison. These two assessments are commonly used in clinical practice to assess an individual’s physical and functional performance after a hand and wrist injury. Moderate correlations were found between the DTM measure and the wrist AROM assessments. The DTM wrist flexion and extension and wrist radial and ulnar deviation movements use similar anatomical structures to execute their movements. Moritomo et al.²¹ believe there are similar isolated scaphotrapezio-trapezoidal ligament movements during both the DTM and wrist flexion-extension and radio-ulnar deviation. Furthermore, Moritomo et al.⁴ demonstrate similar muscular execution during both sets of movements. The similar execution of muscular structures during each of these movements could explain the correlations between the wrist AROM assessment and the DTM measure. The goniometric assessment of the DTM evaluates the functionally important movement of the DTM. Together with traditional goniometric assessment of wrist flexion-extension and radial-ulnar deviation, the assessor may gain increased insight into the participants’ functional performance.

When comparing with the PRWHE, criterion validity of the goniometric assessment of the DTM was shown to be satisfactory with moderate correlations between the two assessments. Both significant and borderline significant correlations for the injured hands occurred in the ‘Function’ section of the PRWHE, asking the participant to rate their difficulties with performing usual and specific activities. The results are in agreement with a previous study comparing hand and wrist assessments using a goniometer and the PRWHE, with correlations occurring in the same range (r = −0.35 to −0.63).¹⁹ The moderate correlations with the ‘Function’ section of the PRWHE demonstrate that the DTM measure could provide a satisfactory reflection of the impact of injury on function.¹¹

The method used in the study, involving Bugden’s method and protocol to measure the DTM, has proven to provide reliable results and the DTM measure can be satisfactorily validated against other high-quality tools. It is a simple measure with a procedure that is easy to follow, meaning clinicians could easily adopt it into their clinical settings.

The study has some limitations. Due to the need to fit into the hand clinic’s schedule and participants’ availability, this study involved three rounds of assessments with only very short breaks. This could have impacted the results by decreasing the participant’s performance due to increasing fatigue.¹⁰ The different times of the day (e.g. early morning compared to midday) for which each session occurred could have also affected the results, as some participants may have performed differently at different times.

The study was conducted with a small group of 35 participants. Individuals with either a hand and wrist injuries were selected. However, participants with hand injuries (e.g. a metacarpal fracture) accounted for 28 out of the 35 participants, with only one participant having a wrist injury (e.g. a carpal bone fracture). It is possible that the results of this study may have been impacted by this relatively small sample size and the selection criteria. This could be a reason for only moderate correlations occurring between the DTM measure and the wrist AROM assessment. Moreover, only the ICCs were reported, the report of absolute reliability measures such as using a Bland Atman plot or the smallest detectable difference was not feasible due to the small sample size.

Conclusion

The DTM measure can produce reasonably valid and reliable results and has shown satisfactory clinical utility in people with a hand and wrist injury. It is hoped this simple measure can be eventually implemented in clinical settings, allowing for an increased understanding of an individual’s functional use of the hand and wrist. Future research could include a further investigation into the validity of the DTM measure to discriminate between people with different levels of wrist and hand function.

Footnotes

Acknowledgments

The authors would like to thank the staff and patients in the Hand Therapy Unit, Sydney Hospital for their support and participation.

Declaration of Conflicting Interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

Ethical approval

Ethics approval was granted from South East Sydney Local Health District and Western Sydney University before commencing the study.

Informed consent

All participants gave written informed consent before data collection commenced.

Guarantor

KPYL.

Contributorship

All authors researched literature and conceived the study, were involved in protocol development, gaining ethical approval, patient recruitment and data analysis. MP and KPYL wrote the first draft of the manuscript. All authors reviewed and edited the manuscript and approved the final version of the manuscript.

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