Effectiveness of 3D-printed orthoses for traumatic and chronic hand conditions: A scoping review.

BACKGROUND: In the field of orthotics, the use of three-dimensional (3D) technology as an alternative to the conventional production process of orthoses is growing.
PURPOSE: This scoping review aimed to systematically map and summarize studies assessing the effectiveness of 3D-printed orthoses for traumatic and chronic hand conditions, and to identify knowledge gaps.
METHODS: The Cochrane Library, PubMed, EMBASE, CINAHL, Web of Science, IEEE, and PEDro were searched for studies of any type of 3D-printed orthoses for traumatic and chronic hand conditions. Any outcome related to the effectiveness of 3D-printed orthoses was considered. Two reviewers selected eligible studies, charted data on study characteristics by impairment type, and critically appraised the studies, except for case reports/series.
RESULTS: Seventeen studies were included: four randomized controlled trials, four uncontrolled trials, four case series and five case reports. Only three studies had a sample size >20. Impairments described were forearm fractures (n = 5), spasticity (n = 5), muscle weakness (n = 4), joint contractures (n = 2) and pain (n = 1). Four poor to fair quality studies on forearm fractures supported the effectiveness of 3D-printed orthoses on hand function, functionality, and satisfaction. One good quality study on spasticity demonstrated the effectiveness of 3D-printed orthoses on hand function. One poor quality pain study reported limited positive effects on satisfaction. Studies on muscle weakness and joint contractures showed no benefits.
CONCLUSION: Current literature addressing the effectiveness of 3D-printed orthoses for traumatic and chronic hand conditions consists primarily of small and poor methodological quality studies. There is a need for well-designed controlled trials including patient-related outcomes, production time and cost analyses.

Introduction

Hand function is important for the performance of activities. However, falls, cuts, or crush injuries may cause traumatic hand conditions, whereas chronic hand conditions can occur due to neuro-musculoskeletal disorders or long-lasting complaints resulting from traumatic hand conditions. Both types of hand conditions (including the wrist and fingers) may lead to impairments such as fractures, joint deformity, contractures, muscle weakness, spasticity, and/or pain [1-4]. These impairments may limit in performing activities of daily living like eating, dressing and writing, as well as work- and leisure-related activities [3-6]. Accordingly, this can seriously impact on participation and quality of life [5, 7, 8].

Orthoses, including casts, are commonly used in the treatment of traumatic and chronic hand conditions [9-11]. An orthosis is a rigid or semi-rigid device used for the purpose of support, alignment, prevention or correction of joint deformities, or to improve function or restrict motion of a movable body part [12]. For many centuries, plaster casts and, more recently, fiberglass casts have been used in the treatment of traumatic hand conditions [13, 14]. These casts are low cost, strong, and easy to apply [15], and research in distal radius fractures and ligament injuries has shown positive outcomes on bone healing, joint stability, pain reduction, joint motion, and muscle strength [14, 16]. Unlike traumatic hand conditions, where the orthosis is worn for a limited period of time, persons with chronic hand conditions mostly wear the orthosis permanently. Therefore, chronic hand conditions are commonly treated with custom fabricated orthoses of sustainable materials such as resin, leather, silicone or polypropylene [17]. In people with arthritis and post stroke, it has been shown that these orthoses can reduce impairments like pain, muscle weakness and spasticity, and increase the ability to use the affected hand in daily activities [18, 19].

Despite the benefits of casts and custom fabricated orthoses, complications and discomfort have also been reported, including skin lesions, improper fit, sweating due to low breathability, heavy weight, bulkiness, and not being waterproof [11, 15, 19]. Since casts and custom fabricated orthoses are handmade, the risks of complications and discomfort, especially skin lesions and improper fit largely depend on the practitioner’s skills and experience [11, 20]. Furthermore, the manufacturing of custom fabricated orthoses is a labor intensive and time consuming process [21].

In the last decade, the use of three-dimensional (3D) technology emerged in the field of orthotics, being a promising alternative to conventional orthoses. This technology involves three-dimensional scanning, modelling and printing, whereby materials are joined, layer by layer to manufacture 3D-printed orthoses [20]. So far, research into 3D-printed orthoses has mainly focused on the lower extremities, including two reviews on 3D-printed (ankle-)foot orthoses [21, 22]. These reviews concluded that 3D printing to manufacture (ankle-)foot orthoses seems to have potential benefits over conventional methods, in terms of improved comfort, fit and function. Furthermore, this technology allows to eliminate several steps from the conventional manufacturing process of custom fabricated orthoses, and may improve efficiency by a shorter production time and lower costs [20, 21, 23]. While previous studies on the effects of 3D-printed orthoses for the upper extremities also indicated some of these benefits [24-26], a synthesis of the results on the effectiveness of 3D-printed orthoses for the upper extremities, specifically traumatic and chronic hand conditions is currently lacking.

A preliminary literature search conducted on September 4 2020, in PubMed, JBI Evidence Synthesis, Open Science Framework, the Cochrane Database of Systematic Reviews and the PROSPERO database identified that to date, no scoping or systematic reviews on 3D-printed hand orthoses have been performed and none are currently underway. Since the use of 3D printing in manufacturing hand orthoses is quite recent and literature lacks high quality and homogeneous studies to perform a systematic review, we decided to perform a scoping review. The objective was to systematically map and summarize the research done on the effectiveness of 3D-printed orthoses for traumatic and chronic hand conditions, and identify any existing gaps in knowledge and needs for future research.

Methods

This review was conducted in accordance with the JBI methodology guidance for scoping reviews, using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses–Scoping Reviews (PRISMA-ScR) checklist [27]. The protocol was registered on September 4 2020, with the Open Science Framework (https://osf.io/t9rxn/).

Eligibility criteria

Population

We included studies on participants of any age with traumatic or chronic hand (including wrist and fingers) conditions, respectively due to traumatic injuries or chronic neurological, neuromuscular or musculoskeletal disorders.

Interventions

We focused on all types of 3D-printed hand orthoses, whether as a single intervention or combined with other interventions. Studies using orthoses with only small 3D-printed parts, and studies on 3D-printed prostheses and myoelectric orthoses were excluded. In order to be fully inclusive, studies involving any type of comparator or even none were included.

Outcome measures

We included each outcome measure related to the effectiveness of 3D-printed hand orthoses, and also inventoried reported adverse events.

Types of studies

Primary research articles of all types of study designs were included. Studies were restricted to the English language, and only full-text publications were included. Ongoing studies, conference abstracts and posters were excluded.

Search strategy

A preliminary limited search of The Cochrane Library and PubMed databases was conducted by two reviewers (EL, TO) to identify appropriate keywords and medical subject headings (MeSH). Subsequently, we formulated a broad search strategy for PubMed combining the keywords and MeSH terms related to 1) 3D-printing, 2) upper extremity body parts and 3) orthoses (S1 Appendix). This search strategy was adapted for the other indexed databases. On September 17 2020, a literature search was conducted by one reviewer (EL) on the following databases: The Cochrane Library, PubMed, EMBASE, Web of Science, IEEE, CINAHL and PEDro. This search was updated on January 30 2021.

The retrieved search results were listed in Rayyan, a web-based literature screening program [28], and duplicates were removed. The search was supplemented through scanning the reference lists of included studies.

Selection of studies

Two reviewers (EL, TO) independently screened titles and abstracts using the predetermined eligibility criteria to include or exclude studies. Each excluded article was labeled with an exclusion reason in Rayyan. If there was any doubt, the full-text was retrieved. To resolve uncertainties about potentially relevant studies, the reviewers directly contacted the authors. Conflicts regarding inclusion status were resolved by discussion, but if no consensus was achieved, a third reviewer (MB) made the final decision. A PRISMA flow diagram was used to give an overview of the study selection process.

Data extraction

Each study was charted by one reviewer (EL) using a data extraction table designed in Microsoft Excel. The charted data was verified by a second reviewer (TO), after which the data extraction table was refined. The following characteristics were extracted: study type, subjects (number, age, diagnosis), intervention(s) (orthosis type, duration of wearing), comparator, and measurement time points.

Critical appraisal of studies

To interpret the results along with the knowledge about the methodological quality of the included studies, the randomized controlled trials (RCTs) and non-randomized studies (NRSs) except for case series/reports were critically appraised. We used the Modified Downs and Black checklist for the critical appraisal as it can be applied to assess the methodological quality of both RCTs and NRSs [29]. The checklist contains 27 items grouped in five sections; reporting, external validity, internal validity-bias, internal validity-confounding, and power. Two reviewers (EL, TO) independently assessed the studies. Disagreements were resolved with a consensus procedure, if necessary, with the third reviewer (MB). The maximum score achievable for RCTs is 28 and for NRSs it is 24, since items 21–24 are not applicable. To guide interpretation of results, scores ≥24 were considered as excellent quality; scores 20–23 good quality; scores 15–19 fair quality; scores ≤14 poor quality [30].

Synthesis of results

For traumatic and chronic hand conditions separately, we grouped studies by type of impairment. Data were narratively synthesized by reporting the number of studies for each impairment type, sample size, associated diagnoses, and type of orthoses provided. Key findings were presented by assessed outcomes. Identified research gaps in the existing literature were addressed in the Discussion.

Results

The selection process of the search results is presented in a PRISMA-ScR flow diagram (Fig 1). The searches of the electronic databases yielded 546 records. After duplicates were removed, the titles and abstracts of 374 records were screened. Subsequently, 55 full-text articles were retrieved and assessed for eligibility. Seventeen studies (published between 2017 and 2020) fulfilled the eligibility criteria [24–26, 31–44]. After checking the reference lists of these studies, five articles were considered potentially relevant, but none of them fulfilled the eligibility criteria.

Fig 1

PRISMA-ScR flow diagram.

Characteristics of included studies

Of the seventeen included studies, four were RCTs [25, 26, 33, 40], and thirteen were NRSs, including four uncontrolled clinical trials (UCTs) [24, 32, 34, 38], four case series [41-44], and five case reports [31, 35–37, 39] (Table 1). Sample sizes ranged from 1 to 60 participants. Only three studies had a sample size >20 [25, 26, 33]. For traumatic hand conditions, only studies on forearm fractures were identified (n = 5) [24, 31–34], whereas studies on chronic hand conditions (n = 12) targeted spasticity [26, 35–38], muscle weakness [26, 39–42], joint contractures [43, 44], and pain [25]. Of the four types of 3D-printed orthoses reported, wrist-hand orthoses (WHOs) were the most frequently investigated. Ten studies (59%) did not use a comparator. Characteristics of each study and information regarding the 3D printing process, tabulated by impairment type, are presented in Table 2. Notable are the many variations in design within the four orthoses types.

Table 1

Study characteristics overview.

	n/N	(%)
Type of study
Randomized controlled trial	4/17	(24%)
Non-randomized study	13/17	(76%)
Uncontrolled clinical trial	4/13	(31%)
Case series	4/13	(31%)
Case report	5/13	(38%)
Sample size >20	3/17	(18%)
Traumatic hand conditions	5/17	(29%)
Forearm fractures	5/5	(100%)
Chronic hand conditions	12/17	(71%)
Spasticity	5/12	(42%)
Muscle weakness	4/12	(33%)
Contractures	2/12	(17%)
Pain	1/12	(8%)
Type of orthosis
Wrist-hand-finger orthosis	4/17	(24%)
Wrist-hand orthosis	9/17	(53%)
Hand-finger orthosis	2/17	(12%)
Finger orthosis	2/17	(12%)
Comparator type
No comparator	10/17	(59%)
Non-use of orthosis	3/17	(18%)
Prefabricated orthosis	2/17	(12%)
Low-temperature orthosis	1/17	(6%)
Cast and conventional orthosis	1/17	(6%)

Table 2

Study characteristics by type of impairment.

Author, Year	Study Design	Subjects N included (n analyzed), age, diagnosis	3D-printing process	Intervention (I) and Comparator (C) orthosis type and wearing time	Co-intervention	Baseline and follow-up
Traumatic hand conditions
Forearm fractures
Abreu de Souza et al. 2017 [31]	Case Report	n = 1 (1), 24 yrs, distal radius fracture	Geometry acquisition: hand-held 3D laser scanner and MeshLab softwareDesign: freely available online models3D printing: not specifiedMaterial: PLA	I: Static circular 3D-printed WHO, 45 daysC: No comparator	Surgery prior to 3D-printed orthosis prescription	One-time point measurement
Chen et al. 2017 [32]	UCT	n = 10 (10), range 5–78 yrs, distal forearm fracture	Geometry acquisition: CT or MRI of both armsDesign: self-designed software3D printing: SLS or stereo lithographyMaterial: PP and PA	I: Static circular 3D-printed WHO, 6 weeksC: No comparator	1 week plaster cast prior to 3D-printed orthosis prescription	T0 = 2 weeksT1 = 6 weeksT2 = 7 weeks
Chen et al. 2020 [33]	RCT	n = 60 (60), range 5–78 yrs, distal forearm fracture	Geometry acquisition: CT or MRI of both armsDesign: Self-designed software, Solidworks 2015, Workbench 18.03D printing: SLSMaterial: PA	I: Static circular 3D-printed WHO, 5 weeksC: Group 1: plaster cast, 6 weeksGroup 2: conventional orthosis, 6 weeks	1 week plaster cast prior to 3D-printed orthosis prescription	T0 = 2 weeksT1 = 6 weeksT2 = 3 months
Guida et al. 2019 [24]	UCT	n = 18 (18), mean age 11.9 yrs, nondisplaced metaphyseal distal radius fracture	Geometry acquisition: 3D laser scannerDesign: Rhinoceros v5 software3D printing: FDMMaterial: thermoplastic modified ABS and polycarbonate	I: Static circular 3D-printed WHO, 4 weeksC: No comparator	48-72h immobilization prior to 3D-printed orthosis prescription	T0 = BaselineT1 = 4 weeks
Janzing et al. 2020 [34]	UCT	n = 5 (3), age ≥ 50 yrs, dorsally dislocated distal radius fracture	Mirrored geometry acquisition: 3D optical scannerDesign: Blender open source software3D printing: FDMMaterial: PLA	I: Static 3-point 3D-printed WHO, 5 weeksC: No comparator	None	T0 = 2–3 daysT1 = 1 weekT2 = 3 weeksT3 = 5 weeks
Chronic hand conditions
Spasticity
Lee et al. 2018 [35]	Case Report	n = 1 (1), 19 yrs, hemiparesis and spasticity post subdural hematoma	Mirrored geometry acquisition: 3D optical scannerDesign: Geomagic Freeform Software3D printing: FFFMaterial: TPU	I: Static 3D-printed WHO with 3D-printed assistive devices (pen holder, typing device), 1 monthC: Prefabricated assistive orthosis	None	One-time point measurement
Rosenmann et al. 2017 [36]	Case Report	n = 1 (1), child, unknown age, upper limb spasticity due to cerebral palsy	Geometry acquisition: 3D scanned plaster castDesign: 3ds MAX software3D printing: not specifiedMaterial: PLA	I: Static volar 3D-printed WHFO, wearing time not reportedC: No comparator	None	One-time point measurement
Schmitz et al. 2019 [37]	Case Report	n = 1 (1), 11 yrs, hand spasticity due to cerebral palsy	Geometry acquisition: plaster cast scanned with 3D hand-held laser scannerDesign: Meshmixer software3D printing: FDMMaterial: PETG	I: Static circular 3D-printed WHO, wearing time not reportedC: Non-use of orthosis	None	One-time point measurement
Wang et al. 2018 [38]	UCT	n = 18 (13), mean age 68.3±4.9 yrs, hand spasticity post stroke	Mirrored geometry acquisition: hand palm sand mold scanned with hand-held 3D optical scannerDesign: 3D Max software3D printing: FDMMaterial: PLA	I: Static volar 3D-printed HFO after daily rehabilitation training,3 months 3x ±2h/dayC: No comparator	Rehabilitation training	T0 = BaselineT1 = 3 weeksT2 = 3 months
Zheng et al. 2020 [26]	RCT	n = 44 (40), adults, wrist flexor spasticity post stroke	Geometry acquisition: optical scannerDesign: Unigraphics NX 8.0 software3D printing: not specifiedMaterial: light-activated resin	I: Static circular 3D-printed WHFO, 6 weeks 4–8 h/dayC: Volar low-temp thermoplastic WHFO, 6 weeks 4–8 h/day	Conventional rehabilitation, 40 min 5x/week for 6 weeks	T0 = BaselineT1 = 3 weeksT2 = 6 weeks
Muscle weakness
Chae et al. 2020 [42]	Case Series	n = 2 (2), 55, 59 yrs, neuropathy1. carpal tunnel syndrome2. ulnar neuropathy wrist after surgery	Geometry acquisition: CT + MIMICS Medical v17 softwareDesign: Geomagic Freeform Software3D printing: FFFMaterial: TPU	I: 1. Static radial 3D-printed WHO, 2 weeks2. Static semi-circular 3D-printed WHO, 8 weeksC: No comparator	1. None2. Surgery prior to 3D-printed orthosis prescription	T0 = BaselineT1 =1. 2 weeks2. 8 weeks
Chang et al. 2018 [39]	Case Report	n = 1 (1), 33 yrs,upper extremity motor impairment post stroke	Mirrored geometry acquisition: hand-held 3D scannerDesign: Computer Aided Design software3D printing: FDMMaterial: PLA	I: Dynamic dorsal 3D-printed WHFO, 1 month during functional trainingC: No comparator	None	T0 = BaselineT1 = 1 month
Huang et al. 2019 [40]	RCT	n = 10 (10), age >20 yrs, upper limb hemiparalysis post stroke	Mirrored geometry acquisition: 3D scannerDesign: Meshmixer software3D printing: not specifiedMaterial: not specified	I: Task-oriented approach (TOA) for upper limb training wearing dynamic dorsal 3D-printed HFO, 30 min 2x/week for 4 weeksThereafter, 2-week home program (≥30 min/day)C: Same TOA and home program as intervention group, non-use of orthosis	None	T0 = BaselineT1 = 4 weeksT2 = 6 weeks
Portnova et al. 2018 [41]	Case Series	n = 3 (at T1 n = 2), limited mobility digits, able to extend wrist against gravity due to spinal cord injury	Geometry acquisition: tape measureDesign: SolidWorks software3D printing: FFFMaterial: PLA	I: Dynamic wrist driven dorsal 3D-printed WHFO, 10 minC: Non-use of orthosis	None	T0 = 2nd visitT1 = 3rd visit
Joint contractures
Arulmozhi et al. 2018 [44]	Case Series	n = 3 (3), 46, 55, 63 yrs, rheumatoid arthritis1. and 2. Boutonniere deformed and swollen digits3. swan neck deformity	Geometry acquisition: vernier caliperDesign: Solidworks 2013 software3D printing: FDMMaterial: ABS or Flex-PLA	I: 1. Static circular 3D-printed FO2. and 3. Static 3-point 3D-printed FOWearing time not reportedC: No comparator	None	T0 = 1 weekT1 = 1 month
Nam et al. 2018 [43]	Case Series	n = 3 (3), 21, 39, 37 yrs, post burn1. deformity all digits.2. claw hand deformity digits 3–5, 3. mallet finger deformity 2nd digit	Geometry acquisition: rulerDesign: Thingiverse, and Rhinoceros 5.0 or Simplify3D software3D printing: FDMMaterial: PLA or TPU	I: 1. Static 3D-printed FO digit 2 and 5, 24h/d2. Static 3-point 3D-printed FO digit 3 and 43. Static 3-point 3D-printed FOWearing time not reported for cases 2 and 3C: No comparator	1. Other rehabilitation management3. Prior to 3D-printed FO, plastic orthosis which gave skin irritation	T0 = BaselineT1 = 18 months
Pain
Kim et al. 2018 [25]	RCT	n = 22 (20), adults, overuse syndrome in upper wrist area	Geometry acquisition: held-hand 3D scannerDesign: Geomagic Touch and Freeform software3D printing: FFFMaterial: TPU	I: Static circular 3D-printed WHO, 1 weekC: Prefabricated WHO, 1 week	None	T0 = BaselineT1 = 1 week

Abbreviations: RCT: randomized controlled trial, UCT: uncontrolled clinical trial, WHO: wrist-hand orthosis, WHFO: wrist-hand-finger orthosis, HFO: hand-finger orthosis, FO: finger orthosis, CT: Computed Tomography, MRI: Magnetic Resonance Imaging, SLS: selective laser sintering, FDM: fused deposition modeling, FFF: fused filament fabrication, ABS: acrylonitrile butadiene styrene, PETG: polyethylene terephthalate glycol, PLA: polylactic acid, TPU: thermoplastic polyurethane, PP: polypropylene, PA: polyamide.

Results of critical appraisal

Four RCTs [25, 26, 33, 40] and four UCTs [24, 32, 34,38] were critically appraised. The quality scores, presented in Table 3, ranged from 11 to 21. With a score of 21/28, the RCT of Zheng et al. was considered of good methodological quality [26]. This was the only study that reported a power calculation, although it was found to be insufficient. Most RCTs and UCTs did not consider any confounders. Scores were low for blinding and the overall external validity, and concealment of allocation treatment was unclear in three of four RCTs [25, 33, 40]. Additionally, three of four UCTs did not undertake statistical analyses [32, 34, 38].

Table 3

Critical appraisal of studies.

Study	Reporting										External validity			Internal validity–bias							Internal validity–confounding						Power	Quality score
	1	2	3	4	5*	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27
RCT
Chen et al. [33]	1	1	1	1	1	1	1	1	1	1	0u	0u	0u	0	0	1	1	1	1	0	0u	1	1	0u	0	1	0u	17 Fair
Huang et al. [40]	1	1	1	1	0	1	0	0	1	1	0u	0u	0u	0	0u	1	1	1	1	1	0u	0u	1	0u	0	1	0u	14 Poor
Kim et al. [25]	1	1	1	1	0	1	1	0	1	1	0u	0u	0u	0	0u	1	1	1	0u	1	0u	0u	1	0u	0	1	0u	14 Poor
Zheng et al. [26]	1	1	1	1	0	1	1	1	1	1	0u	0u	1	0	1	1	1	1	1	1	1	1	1	1	0	1	0	21 Good
UCT
Chen et al. [32]	1	1	1	1	1	0	0	1	1	0	0u	0u	0u	0	0	1	1	0	1	0	NA	NA	NA	NA	0	1	0u	11 Poor
Guida et al. [24]	1	1	1	1	0	1	1	1	1	1	0u	0u	0	0	0	1	1	1	1	1	NA	NA	NA	NA	0	1	0u	15 Fair
Janzing et al. [34]	1	1	1	1	0	1	0	1	1	0	0u	0u	0u	0	0	1	1	0	1	1	NA	NA	NA	NA	0	1	0u	12 Poor
Wang et al. [38]	0	1	1	1	0	1	1	1	1	0	0u	0u	1	0	0u	1	1	0u	0	1	NA	NA	NA	NA	0	0	0u	11 Poor

RCT: randomized controlled trial, UCT: uncontrolled clinical trial.

Item scores: 1 = Yes; 0 = No; 0u = Unable to determine; NA = Not applicable.

*item 5: 2 = Yes; 1 = Partially; 0 = No.

Identified outcomes related to the effectiveness of 3D-printed orthoses were hand function, functionality, satisfaction, production time, and costs. Furthermore, adverse events were reported. Hand function included the sub-items pain, range of motion (ROM), pinch and grasp force, motor function, and spasticity. Functionality included the sub-items manual dexterity, performance in activities of daily living (ADL), and disability in ADL. An overview of the outcomes as assessed in each study is presented in Table 4.

Table 4

Outcomes investigated in the included studies.

Study	Hand function							Functionality			Participants’ satisfaction	PT	PC	Adverse events
	Pain	ROM	Pinch force	Grasp force	Motor function	Spasticity	Swelling	Manual dexterity	Performance in ADL	Disability in ADL
Forearm fractures
Abreu de Souza et al. [31]												✓	✓
Chen et al. [32]											✓			✓
Chen et al. [33]	✓	✓		✓							✓			✓
Guida et al. [24]	✓									✓	✓
Janzing et al. [34]	✓									✓	✓			✓
Spasticity
Lee et al. [35]									✓		✓
Rosenmann et al. [36]											✓		✓
Schmitz et al. [37]									✓			✓
Wang et al. [38]	✓	✓		✓	✓	✓
Zheng et al. [26]	✓	✓			✓	✓	✓				✓
Muscle weakness
Chae et al. [42] *			✓	✓					✓		✓
Chang et al. [39]					✓
Huang et al. [40]			✓	✓				✓
Portnova et al. [41]			✓					✓	✓		✓	✓	✓
Joint contractures
Arulmozhi et al. [44]		✓									✓
Nam et al. [43]		✓								✓
Pain
Kim et al. [25]	✓								✓		✓

ROM: range of motion, ADL: activities of daily living, PT: production time, PC: production costs.

* Chae et al. reported a VAS score, however it was not specified which item was scored. Despite that authors were contacted, this information could not be obtained.

Traumatic hand conditions

Orthoses for forearm fractures. Of the five studies targeting forearm fractures, four examined the effects of a 3D-printed circular WHO [24, 31–33], and one of a 3-point WHO [34].

Hand function. Hand function was reported in three of five studies. In Chen’s RCT, pain, ROM, grasp force and return to activity were collectively assessed with the Cooney modification of the Green and O’Brien score [33]. The 3D-printed orthosis group scored significantly better (85% had good/excellent results) compared to the plaster cast group (65%, p = 0.014) and the conventional orthosis group (70%, p = 0.035). Guida’s UCT assessed pain with the pain subscale of the Patient-Rated Wrist Evaluation (PRWE) and Visual Analogue Scale (VAS), reporting a significant decrease of pain after four weeks of treatment with the 3D-printed circular WHO (PRWE-pain: mean difference (MD) 19.7; VAS: MD 5.48, p<0.001) [24]. In Janzing’s UCT, two of three participants had complete pain relief on the 100mm VAS after five weeks of immobilization with the 3D-printed 3-point WHO, while the third participant reported pain increase caused by a pressure point [34].

Functionality. Disability in ADL was assessed in two studies [24, 34]. Guida’s study reported a significant improvement on the PRWE function subscale after treatment with the 3D-printed circular WHO (MD 17.7, p<0.001) [24]. Janzing et al. used the Katz-index, showing that after three weeks of immobilization with the 3D-printed 3-point WHO, all three participants were independent in ADL [34].

Satisfaction. Four studies assessed satisfaction [24, 32–34]. Chen’s UCT used a self-designed questionnaire, scoring 11.5 (15 = highest score) with wearing a 3D-printed circular WHO [32]. In their RCT, using the same questionnaire, satisfaction scored significantly higher for the 3D-printed orthosis group (8.65±1.040) compared to the plaster cast (6.85±1.137) and conventional orthosis group (8.10±1.252) (p≤0.001) [33]. Guida et al. reported good satisfaction with wearing a 3D-printed WHO for two items assessed (both scored 4/5 points) [24]. Janzing’s UCT used a 100mm VAS, and reported positive scores on wearing comfort of the 3-point WHO for two participants (90/100mm) and a negative score for one participant (10/100mm) because of a pressure point [34].

Production time and costs. One case report from Brazil showed that printing time of the circular 3D-printed WHO was 45 minutes and material costs were 2.40 USD [31].

Adverse events. Of all the included studies, only three measured adverse events [32-34]. Chen’s UCT investigated pressure sores, stability of immobilization, blood circulation and pressure-related discomfort of the 3D-printed WHO with a questionnaire. The mean score was 9.8 (12 = no complications) [32]. In Chen’s RCT, the 3D-printed group had significantly less complications compared to the plaster cast and conventional orthosis groups (p = 0.005), although the scores of separate items did not differ between groups [33]. Janzing et al. excluded two of five participants because of a secondary fracture displacement. Another participant reported a pressure point with skin redness and pain [34].

Chronic hand conditions

Orthoses for spasticity. Five studies evaluated 3D-printed orthoses for wrist and/or hand flexor spasticity, caused by stroke [26, 38], cerebral palsy [36, 37], and a subdural hematoma [35]. In these studies, the effects of wrist-hand-finger orthoses (WHFOs), WHOs, and hand-finger orthoses (HFOs) were examined.

Hand function. Two studies assessed hand function in terms of spasticity, pain, ROM and motor function [26, 38]. Zheng’s RCT showed a significant reduction of spasticity on the Modified Ashworth Scale in stroke patients receiving a 3D-printed WHFO and conventional rehabilitation compared to those receiving a thermoplastic WHFO and conventional rehabilitation after six weeks (Z = -0.681, p = 0.02) [26]. In Wang’s UCT, also in stroke survivors, a significant reduction of spasticity between baseline and three months of wearing a 3D-printed HFO (p<0.05) was found [38].

Regarding pain, Zheng et al. found no difference on the VAS after six weeks treatment between 3D-printed WHFOs and thermoplastic WHFOs (p = 0.637) [26]. Wang et al. also found no difference on the VAS after three months of wearing a 3D-printed HFO [38].

For ROM, Zheng’s study showed significantly improved passive wrist extension (MD 7.0 degrees, p<0.001) and ulnar deviation (MD 4.2 degrees, p = 0.028) for 3D-printed WHFOs compared to thermoplastic WHFOs, while wrist flexion (p = 0.194) and radial deviation (p = 0.303) did not differ [26]. Wang’s UCT reported no difference in active and passive ROM of the wrist and fingers after using a 3D-printed HFO. Also, grasp force showed no difference [38].

Motor function, assessed in Zheng’s RCT with the wrist and hand subscales of the Fugl-Meyer Assessment-Upper Extremity (FMA-UE), significantly improved in the group wearing 3D-printed WHFOs compared to those wearing thermoplastic WHFOs (MD 1.3, p<0.001) [26].

Wang et al. used the Brunnstrom approach, showing a significant improved hand movement pattern (p<0.05) with wearing 3D-printed HFOs [38].

In addition, Zheng et al. measured swelling with a four-point scale, reporting a significant decrease in favour of the group wearing 3D-printed WHFOs (Z = -4.806, p<0.001) [26].

Functionality. In Lee’s case report, performance in ADL of a patient with a subdural hematoma was evaluated for three tasks of the Jebsen Hand Function Test (JHFT) after using a 3D-printed WHO for one month, showing a clear reduction in time needed on the simulated feeding task [35]. In Schmitz’s case report on a patient with cerebral palsy, improvements in 3/7 JHFT subtests were observed, and a total reduction of 58 seconds while wearing the 3D-printed WHO compared to no orthosis [37].

Satisfaction. Three studies reported on satisfaction. Zheng’s RCT used the Quebec User Evaluation of Satisfaction with Assistive Technology (QUEST) questionnaire, showing no significant difference between stroke patients using 3D-printed WHFOs and those using thermoplastic WHFOs (p = 0.243) [26]. The device component of the QUEST was used in Lee’s case report, showing higher scores for satisfaction on all three assessed JHFT tasks for the 3D-printed WHO compared to the prefabricated orthosis [35]. In Rosenmann’s case report on a child with cerebral palsy, the 3D-printed WHFO was described as fun to use, fashionable, light and customizable, yet it was hard to wear and remove, smelly and lead to pressure points [36].

Production time and costs. Schmitz’s case report indicated that the entire production process of the 3D-printed WHO took 23 hours [37]. Rosenmann et al. reported an estimated cost of 10 USD for their 3D-printed WHFO [36].

Orthoses for muscle weakness. Four studies evaluated 3D-printed orthoses for wrist and/or hand muscle weakness, caused by stroke [39, 40], spinal cord injury [41], and peripheral nerve injuries [42]. Types of orthoses evaluated were dynamic dorsal 3D-printed WHFOs and HFOs, and a static 3D-printed WHO.

Hand function. Three of four studies evaluated muscle force [40-42]. In Huang’s RCT in stroke survivors, palmar pinch force at six weeks significantly increased in the group wearing a 3D-printed HFO in addition to a task-oriented approach and homework program compared to baseline (p = 0.041), while no significant change was noted in the group only receiving a task-oriented approach and homework program and between groups. Lateral pinch force and grasp force significantly increased in both groups, but did not differ between groups [40]. In Portnova’s case series in spinal cord injury, two participants increased their pinch force by 122.2% and 13.3% while wearing a 3D-printed WHFO compared to no orthosis, and the third participant was able to perform this grasp for the first time [41]. In Chae’s case series, both participants with peripheral nerve injury improved 6 kilos in grasp force after using the WHO, and one of them also improved 2 and 1 kilos in respectively lateral and pinch force [42]. Chang et al. used the FMA-UE to assess motor function in a stroke survivor, reporting an improvement in score from 15 to 19 after using the 3D-printed WHFO [39].

Functionality. Two studies examined manual dexterity, assessed with the Box and Blocks Test (BBT) [40, 41]. Huang’s study observed no significant difference for stroke survivors wearing 3D-printed WHOs in addition to a task-oriented approach and homework program compared to the group wearing no orthosis [40]. In the case series in spinal cord injury, two of three users improved on the BBT while wearing the 3D-printed WHFO compared to no orthosis [41]. Two participants also improved on performance in ADL as assessed with the JHFT. Chae et al. used showed a decrease in JHFT total time for both participants with peripheral nerve injury after wearing the 3D-printed WHO [42].

Satisfaction. Two case series assessed satisfaction [41, 42]. In the study on spinal cord injury, patients rated the 3D-printed WHFO in terms of function, aesthetics and comfort on a 10-point scale, resulting in average scores of 6.8, 7.7, and 7.7 [41]. Chae et al. used the Korean QUEST 2.0, showing a score of 4.62 and 4.08 out of 5 for the 3D-printed WHO in both peripheral injury patients [42].

Production time and costs. The case series on spinal cord injury from the United States reported that production time of the 3D-printed WHFO took 8–9.2 hours and cost were 15–20 USD for materials, while production time of the conventional metallic orthosis took 11 hours and cost were 140 USD [41].

Orthoses for joint contractures. Two case series examined the effect of 3D-printed finger orthoses (FOs) for finger joint contractures due to burn injury [43] and rheumatoid arthritis [44].

Hand function. Both case series assessed hand function in terms of ROM. The study in rheumatoid arthritis found no difference in finger joint ROM with wearing the 3D-printed FO [44]. Nam et al. reported improvements of active finger flexion and extension in two of three hand burn patients with wearing the 3D-printed FO [43].

Functionality. In the case series in hand burn patients, disability in ADL was measured with the Modified Barthel Index in two of the three participants. The total score improved for the first user (84 to 91/100), but not for the second user (95/100) [43].

Satisfaction. The case series in rheumatoid arthritis assessed satisfaction, reporting that one user felt that the FO had a correct fit, reduced stiffness, but was heavy weight. The second user considered the FO comfortable and lightweight and easy to use. The third user experienced an initial malaise, but felt comfortable gradually [44].

Orthoses for pain. One RCT focused on the effects of 3D-printed WHOs on wrist pain in overuse syndrome [25].

Hand function. Wrist pain was assessed with the PRWE pain subscale, showing no significant difference between 3D-printed WHOs compared to prefabricated WHOs.

Functionality. Performance in ADL was assessed with the JHFT. No difference was noted in overall score. The 3D-printed WHO group was significantly slower on the simulated feeding task (p = 0.01).

Satisfaction. Satisfaction was assessed with the Orthotics and Prosthetics Users’ Survey (OPUS). The 3D-printed WHO group showed significant improvements compared to the prefabricated WHO group on 2/28 items; “Put toothpaste on brush and brush teeth” (p = 0.036) and “Dial a touch tone phone” (p = 0.004).

Discussion

This scoping review summarized the literature investigating the effectiveness of 3D-printed orthoses for traumatic and chronic hand conditions, identifying 17 studies meeting the inclusion criteria. The vast amount of studies (n = 12) focused on 3D-printed orthoses for different types of impairments in chronic hand conditions.

Amount and quality of evidence

The current body of evidence is represented by a small number of studies, indicating a limited amount of research on 3D-printing to manufacture hand orthoses. Apparently, there is a growing interest in manufacturing 3D-printed hand orthoses, as the included studies were all published in the last four years. This novel technique is in an exploratory phase, as illustrated by the large proportion of case series and case reports (53%), mainly on 3D-printed orthoses for chronic hand conditions. Yet, these study types have a low level of evidence. The quality of evidence of the 4 RCTs [25, 26, 33, 40] and 4 UCTs [24, 32, 34, 38] was rated fair or poor in 7/8 studies, which likely influences the reliability of the results. Of all studies, mostly of small sample sizes, only one RCT showed good methodological quality [26].

Considering the methodological quality of the outcome measures studied, hand function and functionality were assessed with validated tools. Pain, measured with the VAS and PRWE, was the most frequently assessed hand function impairment. Functionality, the least often reported outcome, was mostly evaluated with the JHFT. Regarding satisfaction, three studies used the QUEST [26, 35, 42] and one study the satisfaction module of the OPUS [25], which are both validated and reliable tools [45]. Seven studies used a self-designed method to assess satisfaction, which may have influenced the reliability of the obtained results [24, 32–34, 36, 41, 44]. Only three case reports [31, 36, 37] and one case series [41] reported production time and costs, so information on these topics was limited. However, for the implementation of state-of-the-art technology like 3D-printed orthoses, information on cost- and time-savings besides the effectiveness is important [46] and should be assessed in future studies.

Summary of main results

The case reports and case series included in this review evaluated different types of 3D-printed hand orthoses, used non-validated tools to assess the outcomes and are of low level of evidence. Consequently, only the main findings of the clinical trials were summarized and discussed.

Orthoses for forearm fractures. Guida’s UCT and Chen’s RCT reported significant improvements on hand function [24, 33]. Since a composite score was used in Chen’s RCT of fair methodological quality, it cannot be determined though which item(s) improved [33]. The fair and poor methodological quality UCTs of Guida et al. and Janzing et al. demonstrated a positive effect on pain [24, 34]. However, bone healing generally occurs within four weeks of immobilization, reducing pain naturally. Since both studies were uncontrolled, the improvement cannot be merely attributed to the specific use of the 3D-printed orthosis. Both studies also reported positive findings on disability in ADL. Satisfaction was positively assessed in all four studies. Whether 3D-printed WHOs result in less adverse events than plaster casts and conventional orthoses is questionable, as the overall score in Chen’s RCT showed a significant difference in contrast to the scores of each separate item [33].

Orthoses for spasticity. The RCT and UCT on 3D-printed orthoses for spasticity could not be compared because of too much heterogeneity [26, 38]. Wang’s poor methodological quality UCT demonstrated a significant improved movement pattern and spasticity reduction after using a 3D-printed HFO [38]. Zheng’s good methodological quality RCT showed that 3D-printed WHFOs combined with rehabilitation therapy significantly gives better outcomes on spasticity, ROM, motor function and swelling than thermoplastic WHFOs combined with rehabilitation, while there was no benefit on satisfaction [26].

Orthoses for muscle weakness. Huang’s poor methodological quality RCT demonstrated that wearing a dynamic 3D-printed HFO in addition to a task-oriented approach and homework program has no beneficial effect on muscle force and manual dexterity in stroke survivors [40].

Orthoses for joint contractures. As no trials investigated the effectiveness of 3D-printed orthoses for joint contractures, conclusions cannot be made for this hand condition.

Orthoses for pain. One RCT of poor methodological quality showed that 3D-printed WHOs have no beneficial effect on pain reduction and functionality compared with prefabricated WHOs. There was a limited positive effect on satisfaction due to the small size of the 3D-printed WHO, snug fit and design that enabled water drainage [25].

Gaps in knowledge

There were several gaps of knowledge identified. With regard to the outcomes on hand function, there is some evidence on the effectiveness of 3D-printed orthoses for forearm fractures and spasticity, but not for other hand conditions. Also, functionality as an outcome was scarcely investigated, indicating a knowledge gap of 3D-printed orthoses on performance benefits. Additionally, there is a knowledge gap on costs and production time of 3D-printed orthoses. Only few studies investigated adverse events, which are important to discover with regard to the practical utility of 3D-printed orthoses. Furthermore, there is a knowledge gap regarding the long-term effectiveness of 3D-printed orthosis, as the maximum follow up was 3 months. Assessing the long-term effectiveness is especially relevant for persons with chronic hand conditions, since they usually wear orthoses permanently. Lastly, since only four of 17 studies were controlled [25, 26, 33, 40], it can be concluded that there is a lack of good quality randomized controlled trials on the effectiveness of 3D-printed orthoses compared with conventional options to judge their added value on all outcomes of relevance.

Limitations

Although we thoroughly followed the PRISMA-ScR checklist [27], there are some limitations that need to be addressed, such as the lack of searching for grey literature and the restriction to articles published only in English language. By excluding two RCTs published in Chinese and a case series in Portuguese [47-49], we may have omitted relevant findings.

Conclusion

In this scoping review, seventeen studies on the effectiveness of 3D-printed orthoses for traumatic and chronic hand conditions were mapped and summarized. There is a clear need for high-quality controlled clinical trials to thoroughly investigate patient-related outcomes like hand function, functionality, satisfaction and adverse events using validated tools. Besides, an accurate analysis of production time and costs is needed to determine if 3D-printed hand orthoses may be integrated into clinical practice.

Pubmed search strategy.

(DOCX)

Click here for additional data file.

Scoping review protocol.

(PDF)

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PRISMA-ScR checklist.

(PDF)

Click here for additional data file.

30 Jun 2021

PONE-D-21-10493

Effectiveness of 3D-printed orthoses for traumatic and chronic hand conditions: a scoping review

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Reviewer #1: Effectiveness of 3D-printed orthoses for traumatic and chronic hand conditions: a scoping review

Thank you for the opportunity to review this paper on systematically mapping and summarizing the research done on the effectiveness of 3D-printed orthoses for traumatic and chronic hand conditions. Scoping reviews require rigorous and transparent methods in their conduct to ensure that the results are trustworthy; It is recommended you consult papers like arskey and o'malley and reporting guidelines for scoping reviews to organize methods and reporting. It is recommended that if the authors have a question addressing the feasibility, appropriateness, meaningfulness or effectiveness of a specific treatment or practice, then a systematic review is likely the most valid approach. (Pearson A, Wiechula R, Court A, Lockwood C. The JBI model of evidence-based healthcare. International Journal of Evidence-Based Healthcare. 2005;3(8):207–15.). This review has critical appraisal - a feature of systematic reviews. It seems a hybrid method.

Considering the aim of this study to know the effectiveness of 3D-printed orthoses for traumatic and chronic hand conditions (page 6-l 106), conducting a systematic review is more relevant than a scoping review. However, if you want to char the approaches and methods used in the research - a scoping review is appropriate. A scoping review ften is performed to see fi the state of evidnence is ready for a systematic review- which i might suggest it is not.

Abstract

In results: here is the only place that the authors linked the results from appraising the evidence and narrative description of the extracted papers.

Introduction;

The main aim of the scoping reviews is to describe the nature and extent of the published research, not synthesis the available evidence.

Search strategy:

Please indicate your keywords in your search strategy.

There is nothing about your criteria for inclusion/exclusion in this section.

Critical appraisal of the included studies is not part of conducting a scoping review. You cannot map the current status of evidence by excluding low-quality studies. However, despite using the appraisal tool, the authors did not use their appraisal results in their report.

Page 10, line 204-5, Please do not use the abbreviations for the first time in your manuscript (RCT, NRCT)

Table 1: What do you mean by chronic hand conditions?

Contractures are chronic deformities; why you separated these?

The ready-made orthosis is not a known name for hand therapists; you can use custom-made or prefabricated. Why did you separate splint from orthosis? Both are the same.

Critical appraisal is not part of scoping reviews. Look at: A scoping review on the conduct and reporting of scoping reviews. It was possible to conduct a systematic review and subgroup analysis with four RCTs based on the outcomes.

There is no information regarding the appraisal tool and how the authors used the extracted scores in their results.

The authors used the narrative method for reporting their results. There is no connection between the results from appraisal and the narrative results based on the impairment.

The reported results are not well organized, and the reader cannot link them to the original review questions and objectives.

There is no description for the table 3 and 4 in the manuscript.

Discussion

Page 26, line 432; why the authors included all published in the last four years? If this was part of the inclusion criteria, it should be mentioned.

Lines 439-450: all the discussion is about the outcomes. There is no information about the effectiveness of the 3D print orthosis neither in the results nor in the discussion.

Reviewer #2: This is a well written, methodologically robust review in an emrging area of orthotic practice.

A few comments

I find the terminology used to describe the population/conditions studied a little curious. Firstly it appears that the authors looked at wrist and hand conditions, rather than just hand. SO this needs to be adjusted throughout the text. Secondly they selected studies on pretty much any wrist and hand condition but then split them into ‘traumatic’ and ‘chronic’. ‘Traumatic’ and ‘non-traumatic’ would be more accurate, but I am not sure why the distinction was made. It would be easier to get an overview of the state of the evidence if all studies were combined and described according to the problems they aimed to address.

The method and results are excellent.

Discussion- there is a tendency to repeat the results eg the outcomes used and the results found. Try to avoid this. The summary of findings should be just that- a paragraph should cover it. What you found was low quality evidence from a small number of studies, mainly assessing WHO on chronic conditions. The studies of traumatic injuries (all wrist fractures) suggested an overall reduction in pain; disability and AE (compared to plaster casts) and that patients were satisfied. However it was unclear how much of this improvement was due to healing of the fracture, rather than the type of orthosis/cast. The findings for non-traumatic conditions were mixed and no conclusions could be drawn.

The assessment of quality could make it clearer why the quality was poor. I imagine that blinding and concealment of allocation was issue, not just the unpowered sample sizes.

The gaps in knowledge a little generous – there is nothing definitive about the evidence so far, so many more gaps remain! It is reasonable to highlight the lack of work considering the effects on function/disability but there also needs to be good quality randomised controlled trials for all other outcomes too! Good to see satisfaction and adverse events highlighted, but all studies need to be comparison with current practice. The bottom line is to work out what advantage/improvement a 3D-printed orthosis has over what is currently available- if any.

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21 Jul 2021

Reviewer #1

1. “Scoping reviews require rigorous and transparent methods in their conduct to ensure that the results are trustworthy; It is recommended to consult papers like Arskey and O'malley and reporting guidelines for scoping reviews to organize methods and reporting.”

Response: In 2015, the Joanna Briggs Institute (JBI) published a guidance document for the conduct of scoping reviews, which is based on the earlier work of Arksey and O’Malley (2005) and Levac and colleagues (2010). Besides a guidance for conducting a scoping review, the JBI also developed a reporting guideline for scoping reviews, the Preferred Reporting Items for Systematic Reviews and Meta-Analyses – Scoping Reviews (PRISMA-ScR) checklist [Tricco, 2018]. As described in the Methods section (page 6 lines 117-119), we followed the JBI guidelines and the PRISMA-ScR checklist for the conduct and reporting of our scoping review.

2. “It is recommended that if the authors have a question addressing the feasibility, appropriateness, meaningfulness or effectiveness of a specific treatment or practice, then a systematic review is likely the most valid approach. This review has critical appraisal - a feature of systematic reviews. It seems a hybrid method.”

Response: It is true that we included a critical appraisal, which is a feature of systematic reviews. However, for the conduct of our scoping review, we followed the JBI guidelines that state that also for scoping reviews there can be indications to identify the types of available evidence in a given field and to identify knowledge gaps. Also, the PRISMA-ScR checklist includes an optional item (item 12) ‘Critical Appraisal of Individual Sources of Evidence’. We decided to include this step in our scoping review, because in this way the results of the outcomes can be interpreted along with the knowledge about the methodological quality of the included studies. For clarification, we added this rationale in the ‘Critical appraisal of studies’ paragraph within the Methods section (page 9 lines 179-180).

3. “Considering the aim of this study to know the effectiveness of 3D-printed orthoses for traumatic and chronic hand conditions (page 6-l 106), conducting a systematic review is more relevant than a scoping review.”

Response: In the Introduction section (page 6 lines 109-111), we described the rationale for performing a scoping review instead of a systematic review. This rationale was supported by the review outcomes, as pooling the results of the outcomes would not be appropriate, because of the limited, heterogeneous, and mostly low/poor methodological quality of the studies.

4. “Abstract: “In results: here is the only place that the authors linked the results from appraising the evidence and narrative description of the extracted papers.”

Response: In the ‘Summary of main results’ paragraph of the Discussion section, we linked the results of the critical appraisal with the narrative description of the extracted papers (pages 28-30).

5. “Introduction: The main aim of the scoping reviews is to describe the nature and extent of the published research, not synthesis the available evidence.”

Response: We agree with the reviewer on this. In the last sentence of the introduction, we stated that our objective was to systematically map and summarize the published research on the effectiveness of 3D-printed orthoses for traumatic and chronic hand conditions, and to identify any existing gaps in knowledge and needs for future research. We didn’t include a synthesis of the available evidence.

6. “Search strategy: Please indicate your keywords in your search strategy.”

Response: The specified search string for PubMed was included in ‘S1 Appendix’. For clarification, we added the topics of the keywords and MeSH terms in the ‘Search strategy’ paragraph of the Methods section (page 8, lines 151-152).

7. “There is nothing about your criteria for inclusion/exclusion in this section.”

Response: The PRISMA-ScR checklist uses the subheading ‘Eligibility criteria’ to address the inclusion and exclusion criteria. We used the same subheading. The information on the inclusion and exclusion criteria can be found on page 7.

8. “Critical appraisal of the included studies is not part of conducting a scoping review. However, despite using the appraisal tool, the authors did not use their appraisal results in their report.”

Response: Please, see our response on comments 2 and 4.

9. “Page 10, line 204-5, Please do not use the abbreviations for the first time in your manuscript (RCT, NRCT)”

Response: The abbreviations (RCT, NRS) were already introduced in the paragraph ‘Critical appraisal of studies’ in the Methods section (page 9 lines 180-181).

10. “Table 1: What do you mean by chronic hand conditions?

The ready-made orthosis is not a known name for hand therapists; you can use custom-made or prefabricated. Why did you separate splint from orthosis? Both are the same.”

Response: In the Introduction section, (page 4 lines 56-63), chronic hand conditions were explained. However, to be more clear about what we meant with chronic hand conditions, we modified the text. We agree with the reviewer that prefabricated is a better word then ready-made orthosis and that a splint is the same as an orthosis. Therefore, we replaced ready-made for prefabricated throughout the manuscript, and we changed splint into orthosis.

11. “Critical appraisal is not part of scoping reviews. There is no information regarding the appraisal tool and how the authors used the extracted scores in their results.”

Response: As explained in our response on comment 2, the most recent guidelines for conducting a scoping review include the option of a critical appraisal of the included studies. In the paragraph ‘Critical appraisal of the studies’ in the Methods section (page 9), we described that we used the Modified Downs and Black checklist as appraisal tool. In the paragraph ‘Results of critical appraisal’ (page 15), we presented the results of the critical appraisal and combined these results with the outcomes of the studies in the ‘Summary of main findings’ in the Discussion (page 28).

12. “The authors used the narrative method for reporting their results. There is no connection between the results from appraisal and the narrative results based on the impairment.”

Response: Please, see our response on comments 4 and 11.

13. “The reported results are not well organized, and the reader cannot link them to the original review questions and objectives.”

Response: The objective of our scoping review was to systematically map and summarize the research done on the effectiveness of 3D-printed orthoses for traumatic and chronic hand conditions, and identify any existing gaps in knowledge and needs for future research. The JBI suggests to map out the gathered information in a logical, diagrammatic or tabular form, and/or in a descriptive form. We presented a Prisma-ScR flow diagram and four tables, each of them linking to our objective. We choose to describe the results of the outcomes as they represent the effectiveness of the 3D-printed orthosis. Furthermore, in the Discussion we pointed out several gaps in knowledge.

14. “There is no description for the table 3 and 4 in the manuscript.”

Response: As suggested by the reviewer, we added a description for table 3 in the ‘Results of critical appraisal’ paragraph (page 15, line 237) and for table 4 in the ‘Synthesis of results’ paragraph (page 17, lines 254-255).

15. “Discussion: Page 26, line 432; why the authors included all published in the last four years? If this was part of the inclusion criteria, it should be mentioned.”

Response: We did not set an inclusion criterion for publication date. Yet, it appeared that all studies were published the last four years. This is a result, not an inclusion criteria.

16. “Lines 439-450: There is no information about the effectiveness of the 3D print orthosis neither in the results nor in the discussion.”

Response: In the paragraph ‘Synthesis of results’ in the Results section (page 17), we presented the identified outcomes related to the effectiveness of 3D-printed orthoses. These outcomes (hand function, functionality, satisfaction, production time, costs, adverse events) were further described and discussed in the Results and Discussion sections, and represent in fact the effectiveness of 3D-printed orthoses.

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Reviewer #2

1. “This is a well written, methodologically robust review in an emerging area of orthotic practice.”

Response: Thank you for the positive comment.

2. “I find the terminology used to describe the population/conditions studied a little curious. Firstly it appears that the authors looked at wrist and hand conditions, rather than just hand. So this needs to be adjusted throughout the text. Secondly they selected studies on pretty much any wrist and hand condition but then split them into ‘traumatic’ and ‘chronic’. ‘Traumatic’ and ‘non-traumatic’ would be more accurate, but I am not sure why the distinction was made.”

Response: For the readability of the manuscript, in the Introduction section and in the methods section, we defined that hand conditions include also the wrist and fingers, see page 4 lines 61-62 and page 7 line 128. Furthermore, we split the hand conditions into traumatic and chronic hand conditions to structure all the gathered information. A person who is more interested in using 3D-printed orthoses in traumatic hand conditions can focus on the results of this specific group, whereas a person interested in the use of 3D-printed orthoses for chronic hand conditions can directly read the information of this specific group. Lastly, we think that using ‘chronic’ hand conditions instead of ‘non-traumatic’ better expresses the fact that these conditions, caused by neuro-musculoskeletal disorders or long-lasting complaints resulting from traumatic hand conditions, will be permanent. Also, the term ‘non-traumatic’ would suggest that traumatic is the norm, while ‘chronic’ is more neutral encompassing a broad range of possible causes.

3. “The method and results are excellent.”

Response: We appreciate this compliment.

4. “Discussion: There is a tendency to repeat the results eg the outcomes used and the results found. Try to avoid this. The summary of findings should be just that- a paragraph should cover it. The assessment of quality could make it clearer why the quality was poor. I imagine that blinding and concealment of allocation was issue, not just the unpowered sample sizes.”

Response: As suggested by the reviewer, we reduced the amount of words in the ‘Summary of main results’ paragraph in the discussion (pages 28-30). Further, we agree with the reviewer on the reasons of the poor methodological quality of the studies and have specified this more in detail in the Results of critical appraisal (page 15).

5. “The gaps in knowledge are a little generous”

Response: We acknowledge the reviewer’s suggestion, and stated the gaps of knowledge somewhat more generous, specifically indicating the need for good quality randomized controlled trials on 3D-printed orthoses for all outcomes (pages 30-31).

Submitted filename: Response to reviewers.docx

Click here for additional data file.

23 Sep 2021

PONE-D-21-10493R1Effectiveness of 3D-printed orthoses for traumatic and chronic hand conditions: a scoping reviewPLOS ONE

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Reviewer #1: (No Response)

Reviewer #2: All comments have been addressed

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Reviewer #1: i think this acceptable based on response to prior review . I would like to see some details in their description chart about how the 3D printing was performed. It seems like one of the main point of this paper is that 3D splints made by a machine based on inputs from a human being (not splints made directly and custom fit by a therapist) were used so it would be important to have some details on not just for whom and what clinical condition ( which is in the chart); but also by whom, who did prescription, fitting, what device printed etc. There is a good description of clinical use but limited description of the 3D printing process and how it is different from typical practice which seems important given the topic. Otherwise looks great.

Reviewer #2: The authors have thoroughly addressed my comments in the original review. Apparently there is a minimum word count I have to reach in order to submit htis review. So here is some padding. How silly

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1 Oct 2021

APPENDIX - Reviewer comments

Reviewer #1

“I would like to see some details in their description chart about how the 3D printing was performed.”

Response: As suggested by the reviewer, we inserted a column in table 2 (pages 13-15) with information on the 3D printing process. No or limited information was described in the included studies on who prescribed the 3D-printed orthoses and who fabricated the orthoses. However, we were able to obtain information of the way of geometry acquisition, the software used, type of 3D printing, and material used.

Furthermore, on page 11 line 223, we specified that information regarding the 3D printing process is presented in table 2.

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Reviewer #2

The reviewer indicated that all comments have been thoroughly addressed.

________________________________________

Submitted filename: Response to reviewers_01.10.21.docx

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8 Nov 2021

Effectiveness of 3D-printed orthoses for traumatic and chronic hand conditions: a scoping review

PONE-D-21-10493R2

Dear Dr. Oud,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

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Kind regards,

David Benjamin Lumenta, MD PhD

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

Reviewers' comments:

10 Nov 2021

PONE-D-21-10493R2

Effectiveness of 3D-printed orthoses for traumatic and chronic hand conditions: a scoping review

Dear Dr. Oud:

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on behalf of

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Academic Editor

PLOS ONE