The Hand Accumulation aNd Dexterity FUnctional Limits–Shriners (HANDFULS): A New Clinically Feasible Measure of Hand Volume and In-Hand Manipulation for Children

Method

HANDFULS Test

The test kit consisted of an 8- × 8- × 1-in. felt-lined tray and at least 30 commercially available regular-sized (14 mm) glass marbles (Figure 2a). The continuous shape, standardized size, familiarity, and easy access of marbles offered a practical means to quantify palmar workspace volume. Caution should be taken, however, with younger children when using marbles because they can present a choking hazard.

OPEN IN VIEWER

Figure 2.

Testing with the HANDFULS hand outcome tool.

During testing, the tray was placed in front of the child, who was seated at a height that allowed approximately 90° bend in the angle of the elbow while resting the hands on the table. Several marbles were placed in the tray to begin. The amount of initial marbles placed in the tray was estimated to be more than what the child could initially hold in the hand based on visual assessment and ranged from five to 20 depending on the child’s hand size but always estimated to exceed the anticipated palmar workspace volume. The test was performed with one hand at a time, and the nontesting hand was placed on the child’s lap or held gently by an adult to avoid involvement. We used an electronic randomization application to determine which hand was tested first. The test consisted of two parts.

For the first part, the tester demonstrated the testing procedures and provided the child with the following verbal instructions:

Using the fingers of the chosen hand, pick up the marbles one at a time until your hand is comfortably full but not overstuffed. You should be able to hold all of the marbles in one hand with your knuckles pointing down and no marbles falling out. (Figure 2b)

This part was not timed, and the maximum number of marbles that the child could fit comfortably in their hand signified the palmar workspace volume for that hand. The marbles that fit in the child’s hand were counted and placed into the tray for the next step of testing.

The second part included the child picking up the marbles (the number of marbles determined from the first part of the test) while being timed. The child was given the following instructions:

Using the same hand you just used, pick up the marbles one at a time again, but this time you will be timed. Pick them up as fast as you can but be sure you are only picking up one at a time. The timer stops when you can hold all of them in your hand with your fingernails facing down and without dropping any. (Figure 2c)

The stopwatch started when the first marble was touched and ended when all marbles were secured in the hand with the fingernails facing down. The test was repeated three times with the same hand, and then both parts of the test were repeated for the other hand. The HANDFULS score was calculated separately for each hand using the total number of marbles that fit in the hand as the denominator and the time (averaged from three attempts) as the numerator for the following equation:

Average time (in seconds)/number of marbles = HANDFULS score (time per marble)

A lower score signifies greater proficiency with the test.

Results

A total of 192 children and adolescents between the ages of 2 and 20 yr were tested using the HANDFULS test. The average height, weight, hand span and circumference, and grip and key pinch strength for each group are presented in Table 1. There were statistically significant differences between the age groups for all these parameters (ps < .001).

The average palmar workspace volume (i.e., average number of marbles grasped) for all participants was 8.7 marbles (SD = 4.0, p ≤ .001), and the number of marbles grasped ranged from 3.3 to 14.2 across the age groups (Table 2). Average HANDFULS score (i.e., seconds per marble) across all participants was 1.4 s per marble (SD = 0.4, p ≤ .05) and ranged from 1.2 to 1.8, again most interpretable by age category. A lower score demonstrates greater proficiency with the test. The ANOVA showed significant differences by age (Table 2).

Normative values were reported by age group only and were not differentiated by dominant and nondominant or right and left hand because statistical significance for these comparisons was not consistent throughout the age groups, and the differences found were clinically unremarkable (see Tables A.1 and A.2 in the Supplemental Material, available online with this article at https://research.aota.org/ajot).

By linear regression, age, hand span, and hand circumference were significant predictors of palmar workspace volume and were included in the final model. For every year increase in age, palmar workspace volume increased by 0.16 marbles (p = .011), and for every 1 cm increase in hand span and hand width, participants were able to pick up 0.47 (p < .001) and 0.9 (p = .0025) additional marbles, respectively. Because hand size can vary by age, the following equation is provided as an alternative to using the suggested normative values, instead estimating the individual child’s expected palmar workspace volume based on anthropomorphic characteristics:

We found no significant associations between age, grip strength, pinch strength, or hand circumference and HANDFULS score (time per marble). By using the baseline palmar workspace volume in the equation for the HANDFULS score, age was indirectly considered through hand size; therefore, age was added back into the model with all other variables removed. With only age in the final model, for every year increase in age, HANDFULS score decreased by 0.02 s per marble (p < .001). Residual analysis for both the ANOVA and regression models revealed no problems with distributional assumptions. Histograms were approximately normal, and QQ plots showed conformity with the normal distribution with almost all points lying on the diagonal line.

Discussion

This study described HANDFULS, a newly developed hand function outcome measure that quantifies in-hand manipulation and palmar workspace volume. It can easily and quickly be administered in a clinical setting, demonstrates face validity, has moderately high test–rest reliability, and has been evaluated with children and adolescents ages 2 to 20 yr with typically developed, noninjured hands to provide age-normative reference values.

Similar to other available in-hand manipulation tests, we recorded the time to complete the HANDFULS test (Kruger et al., 2022). We found significant differences in speed between the age groups corresponding to results by Pehoski et al. (1997), who identified periods of rapid change with age and described how children at some ages substituted refined finger movement when performing the tasks. Other in-hand manipulation tests prioritize assessment of the quality of movement over time completion and incorporate multiple tasks, in some cases up to 55 activities (Klymenko et al., 2018; Kruger et al., 2022; Smith- Suzovsky & Exner, 2001). We did not specifically assess the qualitative aspects of how children of different ages accomplished the tasks, and although the quality of performance on a variety of tasks is important, the more complex and lengthy a test, the more challenging for test administration, in particular with pediatric patients who have decreased attention span (Klymenko et al., 2018). Furthermore, tests that require subjective observation or complex scoring can further limit the feasibility and interrater consistency. HANDFULS was designed to be a simple test with familiar items that could be completed by participants of a wide age range (2–20 yr) in a short amount of time.

Most of the current literature investigating in-hand manipulation was conducted with typical children or children with neurological or neuromuscular diagnoses such as developmental delay or upper extremity cerebral palsy, so those tests may not be applicable or feasible with children who have more acute hand injuries (Kruger et al., 2022). Although this study tested HANDFULS with children who had typically developed, noninjured hands as an initial research step, the test was designed to fill a clinical and research gap for a hand function measure useful with injured or deformed hands. In theory, the test offers assessments relevant to those populations but still requires specific testing and validation.

Unique to HANDFULS is that it offers a way to quantify palmar workspace. Through our clinical work, we observed that in-hand manipulation abilities may be impaired because of limitations in the physical functional space of the hand (Figure 1). This phenomenon is often observed as a result of soft tissue or scarring changes in the palmar area after traumatic or burn injury. Previous studies that have tried to quantify this space have involved either complex three-dimensional analysis (Curran et al., 2019) or mathematical equations within robotics (Kuo et al., 2009), which are not readily useful to clinicians. Therefore, to capture the construct of palmar workspace volume, a simple and clinically feasible method was needed. Using standard-size glass marbles and consistent testing instructions, HANDFULS provides a quantifiable measure of palmar workspace volume that can be considered in conjunction with in-hand manipulation.

One of the most commonly used measures of in-hand manipulation, the Test of In-Hand Manipulation (Pont et al., 2008), showed poor stability in test–retest reliability among typically developing children over a 2-wk interval. We evaluated test–retest reliability for HANDFULS for three performances within the same session and showed that HANDFULS demonstrated moderately high test–retest reliability for that interval. This serves as a start for testing the reliability of HANDFULS, but applying and testing it with children and adolescents over multiple time points and through growth and development are important next steps.

This study is an initial introduction to HANDFULS and was conducted with participants who had typically developed, noninjured hands and typical anatomy and range of motion. HANDFULS was developed as an alternative to current hand function tests and was meant to be clinically feasible and applicable to children and adolescents of varying ages and with varying hand problems. It is not known yet whether HANDFULS is appropriate for hands with atypical morphology (e.g., missing or amputated fingers), injuries, or impairments. A previous study testing hand function of children with symbrachydactyly found that children with fewer fingers were less likely to be able to complete an in-hand manipulation test according to the exact rules of the test (Goodell et al., 2016). Therefore, HANDFULS still needs to be tested and validated with people of all ages with injured and atypical hands.

The test was considered generally feasible for administration with children. However, younger children or children with attention difficulties may take longer to complete the test. HANDFULS scoring can be done immediately by mathematically calculating per the equation described earlier. The score is easily interpretable across different hand sizes and can be referenced for age-normative values with this article.

Limitations and Future Work

Data for this study were collected from children and adolescents from just one geographic area, which may present selection bias, and the results may not be generalizable to children and adolescents from other geographic areas and cultures or to adults. The size and material of the marbles were based on the manufacturer labeling and not independently verified; small variations may exist among manufacturers of 14-mm glass marbles. HANDFULS does not test every aspect of in-hand manipulation and is not representative of the breadth of tasks in many hand function test (Klymenko et al., 2018), but it does appear to capture the key components of translation and shift and, less often, rotation. The in-hand manipulation components tested with HANDFULS may not be as comprehensive as some of the currently available measures that address multiple functional tasks and quality of movement (Kruger et al., 2022). However, it provides a simple assessment of core components of in-hand manipulation, uses a familiar and relevant activity that can be applied across ages, and has the potential to be feasibly administered in clinical settings, including acute care.

We determined age groups with the intent to capture key periods of change in hand development; although the age groups were determined by experienced pediatric clinicians, there may be variations in hand development within the age groups. We evaluated only face validity and test–retest validity; therefore, HANDFULS should undergo additional evaluation of other forms of reliability, validity, sensitivity, and usefulness. HANDFULS should also be correlated with other functional tests and patient-reported outcome measures because the link between in-hand manipulation and functional measures is not well established (Kruger et al., 2022; Pont et al., 2009). Finally, although age-normative reference values were provided for individuals ages 2 to 20 yr, it is possible that the age groups with less than the anticipated 30 participants were underpowered and may not be fully representative of children of those ages.

Implications for Occupational Therapy Practice

This study offers a clinically feasible tool to measure two aspects of hand function: in-hand manipulation and palmar workspace volume. This study has the following implications for occupational therapy practice:

▪ HANDFULS can be used in clinical practice with children and adolescents as a quick and feasible tool to measure and monitor these hand function parameters.

Conclusion

This study introduced the basic testing procedures for HANDFULS, provided face validity and test–retest reliability, and offered reference values for children and adolescents with typically developed, noninjured hands as a foundation for further study. We propose HANDFULS as a simple, clinically feasible alternative for measuring in-hand manipulation as well as palmar workspace volume. The HANDFULS test can be used in clinical practice for patient evaluation or as a foundation for future research addressing hand function.

Supplemental Material