A volunteer sample was recruited from Holland Bloorview’s Connect2Research database. Eligible participants were called and the first four child-parent dyads who gave informed assent/consent were enrolled. A sample size of 4 to 5 participants is considered appropriate for mixed methods case study research (16). With respect to eligibility, all children needed to be 7–17 years old, have a diagnosis of HCP with involvement of the UL, and normal or corrected to normal vision and hearing. Children could not have received constraint induced movement therapy in the past six months, or botulinum toxin injections or active UL therapy within three months of study enrolment.

To address objective 1, we calculated the extent to which children met their weekly PTG, and in how many weeks this goal was achieved. For Phase 1, journal field notes from the weekly monitoring phone calls with DC documented technical barriers, as well as each participant’s lived experience with BB during each week of the intervention. All functional measures were assessed and scored by the study’s OT assessor at the end of each assessment session. To limit bias, the assessor was not involved in the intervention. To address objective 2, clinical assessment scores were visually compared at baseline, post-intervention and follow up for each participant. Results were interpreted based on their minimally clinical important difference (MCID) when available. Specifically, for the COPM, a change of 2 points is considered a MCID (25). Smallest detectable change and MCIDs are not yet available for the CHEQ; however, previous studies have considered a 10% positive change in percent of bimanual activities performed independently to be clinically important for children with CP (33). A MCID for aROM of 10 degrees was used. The mean grip strength from three successive trials was used, and a MCID of at least 10 mm Hg was considered (34). In absence of MCID estimates, the smallest detectable change (SDC) was applied for the AHA [i.e., 5 logit units (27)] and BBT [i.e., 2 blocks in the more affected hand (30)].

The in-person interviews with the parents and children in Phase 1, were done separately immediately following the post-intervention clinical assessment. Two researchers conducted the interviews (AH for 2 dyads, and BR for 1 dyad). Both interviewers were male, part of the BB research and development team, had experience working with families and children with disabilities and experience conducting interviews. Neither had met the participants before the interview. The participants were not made aware of the involvement of the interviewer with BB in order to limit any hesitation in expressing concerns or negative experiences that they may have had with BB.

The monitoring therapist (DC) met with the interviewer beforehand to discuss the participant dyad and provide an overview of the family’s experiences with BB over the 12-week intervention (e.g., technical barriers experienced, changes/modifications in the program made). Each parent and child interview lasted between 20 and 30 min and was audio-recorded. Semi-structured, open-ended questions (Supplementary Appendix B) explored participants’ experiences (e.g., enjoyment of the videogame/therapy mode), perceived value (e.g., usefulness of the intervention for hand/arm therapy), and motivational factors facilitating adherence to the intervention, as well as their perspectives on identifying their own PTGs.

To address objective 3, verbatim transcripts from interviews were independently coded by DC (pediatric physiotherapist and PhD student), a research assistant (RA, master’s in occupational therapy student), and one of the co-authors (EB, primary investigator with over 15 years of experience conducting childhood disability research). All coders identified as female. Interviews were analyzed using a descriptive, inductive thematic approach (17). NVivo software was used to manage the data. Initial interpretations of the data were discussed by DC and EB, and codes developed based on emerging themes from participants’ responses. Text segments were assigned codes, and then grouped into potential themes and sub-themes to show patterns in participant responses. Participant characteristics (e.g., socio-economic status, age) were considered to understand the context of the individual’s experiences and perspectives. Code-recode, peer examination and field/reflexive notes were used to ensure qualitative rigour (35).

Integration of the quantitative and qualitative strands occurred at the methods, results and interpretation levels. Team members (DC, EB, FVW, SM) involved in the integration process had a (clinical) background in childhood disability, quantitative, qualitative, and/or mixed methods expertise. At the methods level, a nested sample from phase 1 was used in phase 2 (i.e., connecting, all participants who completed Phase 1 were included in Phase 2). Additionally, data from the weekly phone calls informed the post intervention interview guide (i.e., building) (36). For example, parents were asked about the main barriers they faced when weekly PTGs were not met, and children were asked to further comment on game features, and how/if they helped them in achieving their PTGs. Data sets were analyzed separately first and then merged and compared for interpretation to address our research objectives (Figure 1). In the results below, a narrative, weaving approach has been used whereby qualitative and quantitative results are presented together for each dyad and organized according to the themes identified from the qualitative descriptive thematic analysis. Finally, at the interpretation level, both datasets were merged to allow presentation of the results across dyads. Joint displays visually represent the insights gained from analyzing and bringing together quantitative and qualitative data (37). Pseudonyms were given to the participants for confidentiality and clarity of reading their narrative summaries.

Marco identified a PTG of 15 min/day, 3 times a week, achieved in 10 of 12 weeks. Schoolwork was the main factor that impeded reaching the weekly PTG, but Marco usually made up for missed play time the following week as seen in the computer logs and described during the weekly phone calls.

On four occasions (as shared during the weekly calls), the videogame “froze” or did not load properly following which Marco simply restarted the computer and continued play. Marco’s mom (Marta) continuously encouraged Marco to meet his PTG. He used the multiplayer function in eight play sessions. Marta reported that “he was more happy when someone would play with him”. At the end of the 12-week program, Marco exceeded his total intervention PTG by 10%, achieving 596 min.

Marco’s most played games were Wizard’s Adventure, Bootle Band and Bubble Lab. He reported enjoying games with a high degree of challenge.—“in Wizard’s Adventure, there were always new waves of new enemies coming at you, and it was fun, you know.” Marta perceived that he also played the games that would get him the most points. Marta noticed he reached a plateau in the second part of the intervention. In response, at week 5 the research team (AK, DC) decided to switch him from time mode (default, mini-game finishes after 2 min) to life mode (mini-game finishes after you lose a set number of lives). This change was exciting to him because he felt more challenged describing it as “good hard”. Marco lost some interest towards the end of the intervention because he had unlocked and played all of the mini-games. At week 10, Marco said—“I am getting very good at all the games; my scores are very high”. His mother explained he was playing “extra” because he really wanted to reach level 100 before the end of the intervention. He made it to level 101.

Marco and his mother identified his COPM goals together (Table 2) and reported clinically important improvements in performance on 2 of the 3 goals post-intervention that were sustained at follow-up and attributed to the BB intervention. Changes in UL outcomes are presented in Table 3.

Marta thought the intervention was “very good for him [Marco]” because he constantly needed to work with his affected arm. She saw some improvements in Marco’s strength and confidence using his affected side, a decrease in asking for help to complete tasks, and being less bothered by things he had difficulty doing. He was also able to finish more tasks on his own. Marta told a story about a time Marco was able to perform an activity of daily living independently that he would usually ask for help on– “ …I (saw?) … the confidence to do it [i.e., using his affected hand to complete the activity of daily living in a social setting] and I think it’s the most important thing, yeah”.

Marco reported a preference for this type of therapy which did not involve travel; however, he recognized that not having an in-person therapist to answer questions could be a limitation. Marta found it beneficial that Marco could participate in the intervention on his own time while in his comfort zone (i.e., home). Recommendations for improvement offered by Marco and Marta were: (1) a better explanation of how to play some of the games.

(2) adding more achievements to the game (e.g., if you buy more gear, you get more points or a new mini-game), and (3) having more mixed-reality games. Marta thought the game was “childish” for Marco’s age, and “it wasn’t that much attractive” compared to the other videogames he usually plays. Marta thought it would benefit the intervention to have added gaming challenges to BB.

Initially Alma was excited to play BB. Alma and Ana decided on a PTG of 20 min, 4 times a week. After week 1, the PTG was decreased to 3 times weekly, as Alma and her mother found that 4 times a week was onerous due to schoolwork and other responsibilities. Alma played on weeks 1 (once, 24 min), 2 (twice, total of 33 min) and 6 (once, 4 min). She did not play during weeks 3 and 4. Alma reported the videogame was “a bit too childish” and sometimes it was difficult to understand how to play some of the mini-games. She mentioned some games were “boring”, and others “hard”. However, Alma reported that she usually could figure them out after playing for a while. The monitoring therapist explained over the phone how to play the one game Alma reported struggling with, and referred Alma and her mother to the section of the user manual where they could find more detailed information with pictures. There were no reported technical barriers.

Ana reported trying to encourage her daughter to play because she thought BB was good for her. Alma said she enjoyed the multi-player option, but the play logs indicated limited use of this feature. During the home visit at week 6, Alma expressed that she did not want to continue with the study because of lack of time and loss of interest in the videogame.

Alma and her mother decided the COPM goals together (Table 4). Alma did not complete the post-intervention assessments or interviews. Baseline assessments scores are presented in Table 5.

Ivan and Iker identified a PTG of 20 min a day, 3 times per week. Whenever Ivan had a busy week, he tried his best to make up for the lost playtime later. He achieved his weekly PTG in 8/12 weeks. Overall, he played 945 min over the 12 weeks, an extra 31% above his total intervention PTG. The timing of the intervention was considered the “perfect time” by Ivan’s family, as it was summer vacation. Sometimes, Ivan would want to do preferred recreational activities instead of playing BB, but with some encouragement from his parents he would get started after which “he would really enjoy it”. The weekly call from the monitoring therapist also helped Ivan engage with BB, since as Iker said: “It’s coming [the encouragement to play] from another person also [not only from his parents]”.

Iker indicated Ivan’s favorite games were Color fill, Jetpack Bootle and Wizard’s Adventure. Ivan reached level 112 by the end of week 12. Ivan had fun and grew in confidence playing the game as the intervention progressed. He learned how to play by himself and “that was something that I [Iker] was very happy to see him doing”. Having a sense of ownership and control over the game “the power to say yes or no [when and with who to play]” was motivating and increased his confidence in playing. Iker described BB as “fun to play” for Ivan and his family, who often play together (12 multiplayer play sessions). There were no reports of technical difficulties during the intervention.

Ivan’s COPM goals were identified by his father (Table 6). Changes in UL outcomes are detailed in Table 7. Iker perceived that BB allowed for a lot of movement repetitions, requiring Ivan to use his right hand to play. “I'm surprised (…) this can do a lot of movements”. Iker noticed several improvements on how Ivan used his hemiplegic hand: more spontaneous use and confidence in his ADLs (especially when using his toothbrush) and during videogame play, and a small improvement in the use of his affected hand’s fingers.

At the beginning of the study Iker was “nervous” about using the videogame since he was concerned he would not be able to solve possible technical difficulties, or help his child understand how to play BB. They found “the flexibility and the simplicity of the game” very helpful to support Ivan’s play with BB. They did not need additional support from the research team to use BB. However, they indicated that it was reassuring to know that they could reach out for assistance if needed. For Ivan and his family, this was their first experience with videogames, and they “loved” the game; “for him is playing but for us [parents] is therapy”. Iker felt “very strongly [positive]” about this modality of therapy. Ivan had been waiting for UL therapy for several years. Iker “never thought” this would be a way of providing therapy for his son, but he found it very helpful (e.g., no waiting time, integrated within the family schedule, easy to use) and would recommend it to other parents because “you get the therapy while you’re playing”. Removing travel barriers and the low-risk intervention were very important to Iker. The family lived far from the hospital and taking Ivan to in-person therapy necessitated time off work. Recommendations for BB included the addition of more content to the videogame (e.g., more levels and mini-games)– “at some point he [Ivan] finished playing with all the different things [mini-games]”. Yet, Iker reported that reaching Level 100 did not hamper Ivan’s motivation to keep playing.

Leo’s PTG was 15 min/day, 4 times a week. This goal was achieved in 6 of 12 weeks. Leo had some weeks where it was hard to find the time to play (sickness, school, extracurricular activities), especially when one of his caregivers was away for work, however he still ended up achieving 701 min of active play time out of his 720 min total intervention PTG. Leo incorporated playing BB in his morning routine, usually before going to school. If he did not manage to play in the morning it was difficult to fit it in the rest of his day given his many extracurricular activities.

Two technical difficulties were reported at weeks 2 and 4 (mixed reality object not detected). The research team tried to troubleshoot this by phone. At week 4 the problem persisted and a home visit was scheduled to fix it (AK). This caused some frustration for Leo according to his mother, because he had to wait to play the mini-game.

Leo’s favourite games were Wizard’s Adventure (which Lory referred to as “quite the work out”), Bootle Kart, Astro Bootle, Jetpack Bootle, and Paint Baller. Leo needed some encouragement and supervision from his parents to play the game purposefully, since in the first few weeks he liked to “intentionally bump into things [the obstacles] to get that big reaction”, according to Lory. Leo was highly motivated by his chances of unlocking new games each week, winning against the computer, leveling up and collecting in-game rewards (i.e., game features). He needed some reminders to engage in playing BB, since he had other commercial videogames to play with. Nevertheless, Lory reported that most of the time it was Leo who took the initiative to play. He used the multiplayer option for 13 play sessions with his family, but also enjoyed playing against the computer and “beating” the Bootle. Lory mentioned that playing together improved his attention span towards the game. Overall, Leo was very proud of reaching level 92 because he “worked really hard to get there.”.

Lory identified the two COPM goals (Table 8). Changes in UL outcome measures are shown in Table 9. Lory thought BB was mostly useful for reminding him to use his arm. She was unsure if it had helped him improve in his ADLs but noticed some “progression” with zipping up a jacket. Throughout Leo’s interview, there was an overall perceived value of usefulness. He felt playing BB helped him use his hand better, which motivated him to play.

Leo enjoyed this type of therapy, especially the fact that he did not need to travel. Leo was also aware of the time expense of in-person therapy experienced by his mother “and everyday I would have to come here, my mother would too”. For Lory, this type of therapy was a way to make home-therapy fun, and to decrease the pressure of the parent having to be the “home therapist”. Lory mentioned that she and her husband would usually try to be present while Leo was playing BB as their “together activity” but sometimes “it was like oh, you need to do that while I’m making dinner” which appeals to the busy family dynamic with two young children. Recommendations for improving the system related to adding more competitive and action-driven mini-games that could be played with a more diverse movement repertoire.