Biobased polyester versus synthetic fiberglass casts for treating stable upper limb fractures in children: a randomized controlled trial

Stable upper limb fractures, such as radius, ulna, or distal humerus fractures, are common pediatric orthopedic traumas that are traditionally managed with cast immobilization [1‐3]. The synthetic fiberglass cast composed of polyurethane and diisocyanate has been used worldwide and has superior patient satisfaction and clinical outcomes than plaster of Paris (POP) casts [4, 5]. Synthetic fiberglass casts are typically activated by water, resulting in a lightweight cast that offers enhanced strength and water resistance [6]. However, skin itchiness or irritation during the entire casting period is a common complaint of patients. In contrast, the materials in synthetic fiberglass casts have drawbacks: diisocyanate was proven to cause asthma [7] and polyurethane is not a biodegradable material and could increase the environmental burden. As the materials are not recyclable, the use of petroleum-based polymers has led to concerns worldwide [8]. In response, biobased materials have attracted considerable attention. A novel biobased cast design with larger ventilation holes [8] could theoretically decrease skin irritation, itchiness, and bad odors. This study aimed to evaluate patient satisfaction and clinical outcomes when casting with a novel biobased polymer versus synthetic fiberglass. We hypothesized that, compared to a synthetic fiberglass cast, immobilization using a biobased polyester cast could result in better patient satisfaction and achieve similar clinical outcomes in children with stable upper limb fractures.

The clinical trial was approved by the research ethics review committee of the author’s hospital (Number 110,245-F) and informed consent was obtained from the legal guardian of each patient. The trial was registered at ClinicalTrials.gov Protocol Registration and Results System (https://​www.​clinicaltrials.​gov/​; ID: NCT06102603; Date: 27/01/2022). Between February 2022 and November 2022, all children (age range, 4–15 years) with radiography-diagnosed stable upper limb fractures (including radius, ulna, and distal humerus fractures such as Garland type I supracondylar fractures of the humerus) [9] diagnosed at the orthopedic outpatient clinic or emergency room of a tertiary trauma center hospital were eligible for recruitment. Exclusion criteria included displaced or unstable fractures indicated for close or open reduction and fixation, previous surgeries to the affected upper limb, history of any chronic skin pathology (e.g., atopic dermatitis), and known allergy to cast materials.

Patients were randomized using a sealed envelope to either the biobased polyester cast group (MEDlite Thermo Casting Tape, Taipei Smart Materials, Taipei, Taiwan) or the fiberglass cast group (Scotchcast, 3 M Health Care, Maplewood, Minnesota, U.S.) (Fig. 1). A well-trained technician applied the long arm cast to the patients. Before the cast was applied, the same type of cotton stockinet and cotton padding was applied to all patients. In the biobased group, the cast was immersed in a bowl of water heated to around 60 °C for 3 min. Once the cast bandage had become pliable and soft, it was then wrapped around the affected limb. Typically, the biobased cast can retain its plasticity until it cools down, allowing us approximately 5–7 min to finalize the casting process depending on the room temperature. The elbow was flexion up to 90° and in a neutral position. Both groups were instructed not to let the cast become wet and cast care guidelines were given to patients and parents. The cast was kept on for approximately 3–4 weeks.

Standard radiographs of the affected region were taken at 1-week post-injury to control secondary displacement. All patients were reviewed for cast removal after 3 to 4 weeks, and standard radiographs were taken again. One author reviewed the radiography images. Complications, such as loss of reduction and further need for close or open reduction, nonunion, malunion, cubitus varus neurovascular injury, and any skin complication, such as rash or growth of hairs, were documented. The patient satisfaction questionnaire was completed at the time of cast removal with or without the help of parents or guardians. The questionnaire (1 [lowest] to 5 [highest]) included questions to rate comfort, weight, itchiness, heat retention, smell, and total satisfaction. It was not age-dependent and was easily understood by children (Table 1) [4]. The score of the questionnaire was recorded by a study nurse who was not aware of which type of casting material was used.