orthosis
noun
or·tho·sis ȯr-ˈthō-səs 
plural orthoses ȯr-ˈthō-ˌsēz
: an external medical device (such as a brace or splint) for supporting, immobilizing, or treating muscles, joints, or skeletal parts which are weak, ineffective, deformed, or injured
a lower extremity orthosis
spinal orthoses
see orthotic entry 2 
Example Sentences
Recent Examples on the Web There are a few different reasons why your child’s pediatrician might recommend helmet-molding therapy (sometimes referred to as cranial orthosis). 
Korin Miller, SELF, 4 Dec. 2018 The orthosis had to allow upward movement of the ankle while preventing patients from pointing or rising up on their toes. Kelly Mcbride, Cincinnati.com, 15 Sep. 2017 Unfortunately, Smith’s injury timeline is approaching a year-and-a-half, and his continued use of an ankle foot orthosis (AFO) brace indicates that may be a permanent need. Profootballdoc, sandiegouniontribune.com, 9 May 2017
Korin Miller, SELF, 4 Dec. 2018 The orthosis had to allow upward movement of the ankle while preventing patients from pointing or rising up on their toes. Kelly Mcbride, Cincinnati.com, 15 Sep. 2017 Unfortunately, Smith’s injury timeline is approaching a year-and-a-half, and his continued use of an ankle foot orthosis (AFO) brace indicates that may be a permanent need. Profootballdoc, sandiegouniontribune.com, 9 May 2017 Word History
Etymology
New Latin, from Greek orthōsis straightening, from orthoun to straighten, from orthos
First Known Use
1958, in the meaning defined above
Medical Definition
orthosis
noun
or·tho·sis ȯr-ˈthō-səs
plural orthoses -ˌsēz
: an external medical device (such as a brace or splint) for supporting, immobilizing, or treating muscles, joints, or skeletal parts which are weak, ineffective, deformed, or injured
an upper extremity orthosis
spinal orthoses
see orthotic