Aims: To develop a hand function test for children with bilateral cerebral palsy (CP) measuring bimanual performance, including quantification of possible asymmetry of hand use. Method: The Both Hands Assessment (BoHA) content was developed through adaptation of the Assisting Hand Assessment (version 5.0). Data from 171 children with bilateral CP, 22-months to 13 years olds (75 females; mean age: 6 years and 6 months) classified at Manual Ability Classification System (MACS) levels I-III, was entered into Rasch measurement model analyses to evaluate internal scale validity and aspects of reliability. Results: Sixteen items (11 unimanual and 5 bimanual) exhibited evidence for good internal scale validity and item and person reliability when analyzed separately for children with asymmetric or symmetric hand use. By calibrating the BoHA logit measures into the same frame of reference through linking, the overall measure of bimanual performance is comparable between children with asymmetric or symmetric hand use, still allowing use of separate item difficulty hierarchies. Conclusions: The Both Hands Assessment (BoHA), showed strong evidence of internal construct validity for measuring effectiveness of bimanual performance and the extent of asymmetric hand use in children with bilateral cerebral palsy, MACS levels I-III.

Aims: To develop a revised edition of the Bimanual Fine Motor Function (BFMF 2), as a classification of fine motor capacity in children with cerebral palsy (CP), and establish intra- and interrater reliability of this edition. Methods: The content of the original BFMF was discussed by an expert panel, resulting in a revised edition comprising the original description of the classification levels, but in addition including figures with specific explanatory text. Four professionals classified fine motor function of 79 children (3–17 years; 45 boys) who represented all subtypes of CP and Manual Ability Classification levels (I-V). Intra- and inter-rater reliability was assessed using overall intra-class correlation coefficient (ICC), and Cohen's quadratic weighted kappa. Results: The overall ICC was 0.86. Cohen's weighted kappa indicated high intra-rater (к_w: >0.90) and inter-rater (к_w: >0.85) reliability. Conclusions: The revised BFMF 2 had high intra- and interrater reliability. The classification levels could be determined from short video recordings (<5 minutes), using the figures and precise descriptions of the fine motor function levels included in the BFMF 2. Thus, the BFMF 2 may be a feasible and useful classification of fine motor capacity both in research and in clinical practice.

Aim: To investigate the external validity of the Both Hands Assessment (BoHA), a new test evaluating bimanual performance in children with bilateral cerebral palsy (CP), by analysing its relationship to established measurements of hand function and self‐care skills.Method: In this cross‐sectional study, we recruited children with bilateral CP and manual ability corresponding to Manual Ability Classification System (MACS) levels I to III attending three habilitation units in Norway. All participants completed the BoHA. Unimanual capacity was assessed using the Bimanual Fine Motor Function (BFMF) classification, the Box and Block Test (BBT), and the Melbourne Assessment 2 (MA2). Self‐care skills were assessed with the Pediatric Evaluation of Disability Inventory (PEDI).Results: Thirty‐nine children (19 males, 20 females; mean age 8y 2mo, SD 2y 8mo; age range 2y 8mo–12y 6mo) were included. Spearman’s correlation coefficient (ρ) suggested high correlation between the BoHA and MACS (p=0.89; 95% confidence interval [CI] 0.79–0.94), BFMF classification (p=0.84; 95% CI 0.71–0.91), and BBT for the non‐dominant (p=0.85; 95% CI 0.68–0.95) and dominant hand (p=0.72; 95% CI 0.53–0.85). The Spearman’s ρ between the BoHA and the MA2 subscales varied between 0.48 and 0.83, while the PEDI’s ρ was 0.51 (95% CI 0.33–0.67).Interpretation: The BoHA provides valid measures of hand use as suggested by its high correlation with other activity‐based measures of hand function.