Are casts needed? Are splints supportive enough? Let's hear what the science says.
The most common upper limb fractures occur in the wrist and hands. The treatment is a debated topic and there have been many studies comparing casts to splints.
- The majority of the studies found no differences in the outcome between casting and splinting of hand and wrist fractures [1, 2, 3, 4].
- The authors conclude that the physicians should choose the material and method with which they feel most comfortable [3, 4].
- Children: One study found no difference for children between 5 and 12 years . In another trial, children in the splint group reported higher levels of satisfaction, preference, and convenience on 10-point visual analog scale 
- A recent systematic review and meta-analysis of randomized controlled trials by Doornberg concluded that there was no evidence from the trials on physician-based or patient-based outcome to favour any non-operative treatment method for acute scaphoid fractures .
Based on the evidence, it seems like splints and casts do not have large differences in treatment outcomes for upper extremity fractures.
With lower extremity fractures there are much fewer studies reported.
- Saleh et. al. reported in a study in which patients treated with a splint regained mobility significantly more quickly and preferred the splint to the plaster cast. The range of dorsiflexion at the ankle improved more rapidly after treatment in the splint and patients were able to return to normal activities sooner. Recovery of the power of plantar flexion was similar in the two treatment groups and no patient had excessive lengthening of the tendon. One re-rupture occurred in each group. 
- A more recent review by Boutis et. al. also concludes that when children present to a paediatric emergency department (ED) with wrist or ankle fractures it is recommended to use removable splints also in lower extremities. Children managed better with removable splint devices as opposed to traditional casting for specific wrist and ankle fractures and had less functional morbidity, enjoyed a more rapid return to baseline activities and resulted in a more cost-effective use of healthcare resources. 
A spica cast is a special type of cast used to immobilize the hip joints and/or the thigh. It is often used to promote healing of a damaged hip joint or fractured femur. The spica cast varies depending on the intended use, but it usually extends from the mid-chest to below the knee. Although the cast may seem bulky and awkward, it serves a very specific purpose: to immobilize the hip(s) or broken bone, and maintain the corrected position .
 Stewart HD, Innes AR and Burke FD (1984) Functional cast-bracing for colles’ fractures. A comparison between cast-bracing and conventional plaster casts. J bone joint surg; 66-B(5):749-753.
 Davidson JS, Brown DJ, Barnes SN and Bruce CE (2001) Simple treatment for tortus fractures of the distal fadius. J bone joint surg; 83-B(8):1173-1175.
 Wik TS, Aurstad ÅT and Finsen V (2009) Colles’ fracture: Dorsal splint or complete cast during the first 10 days? Injury; 40:400-404.
 Graftstein E, Stenstorm R, Christenson J, Innes G, MacCormack R, Jackson C, Stothers K and Goetz T (2010) A prospective randomized controlled trial comparing circumferential casting and splinting is displaced Colles fractures. Can J Emer Med;12(3):192-200.
 Boutis, K., Willan, A., Babyn, P., Goeree, R., & Howard, A. (2010). Cast versus splint in children with minimally angulated fractures of the distal radius: a randomized controlled trial. CMAJ : Canadian Medical Association journal = journal de l'Association medicale canadienne, 182(14), 1507–1512. https://doi.org/10.1503/cmaj.100119
 Williams KG, Smith G, Luhmann SJ, Mao J, Gunn JD 3rd, Luhmann JD. A randomized controlled trial of cast versus splint for distal radial buckle fracture: an evaluation of satisfaction, convenience, and preference. Pediatr Emerg Care. 2013 May;29(5):555-9. doi: 10.1097/PEC.0b013e31828e56fb. PMID: 23603644.
|7] Doornberg JN, Buijze GA, Ham SJ, Ring D, Bhandari M and Poolman RW (2011) Nonoperative treatment for acute scaphoid fractures: A systematic review and Meta-analysis of Randomized controlled trials. J Trauma;71(4): 1073-1081.
 Saleh M, Marshall PD, Senior R and MacFarlane A (1992) The Sheffield splint for controlled early mobilization after rupture of the calcaneal tendon. J Bone Joint Surg (British); 74-B:206-209.
 Boutis K, William A, Babyn P, Goeree R, Howard A. (2010) Cast versus splint in children with minimally angulated fractures of the distal radius: a randomized controlled trial. CMAJ; 182(14):1507-1512.
 Colditz JC. Low-Temperature Thermoplastic Splints/Orthoses Made by Therapists: An Overview of Current Practice. The O&P EDGE, October 2004 (http://www.oandp.com/articles/2004-10_03.asp)