Research Summary

Strength and functional improvement using pneumatic brace with extension assist for end-stage knee osteoarthritis

Cherian, J.J., Bhave, A., Kapadia, B.H., Starr, R., McElroy, M.J., and Mont, M.A. (2015) J. Arthroplasty. 30(5): 747-53. doi: 10.1016/j.arth.2014.11.036.

Key Findings


Increased quadriceps strength

Brace users experienced a 54% gain to their quadriceps muscle strength.


Increased Hamstring strength

Brace users experienced a 24% gain to their hamstring muscle strength.

Functional test improvements

Brace users made significant improvements in three functional tests.

A novel pneumatic offloader brace (OA Rehabilitator) with an active swing-assist and neuromuscular retaining properties was evaluated across multiple patient outcomes in a prospective, randomized trial. After a minimum of 3 months, patients were assessed for changes in muscle strength, objective function, subjective function, pain, quality of life, and conversion to total knee arthroplasty. When compared with a matched cohort, the patients, all of whom had end-stage knee osteoarthritis (OA), showed significant improvements in muscle strength, several functional tests, and patient reported outcomes.

Relevance to Spring Loaded Braces

The novel brace in Cherian et al. (2015), the OA Rehabilitator, has been subsequently evaluated in comparison to a Spring Loaded knee brace. In a recent study, both braces were shown to reduce internal joint contact forces as a result of their offloading capabilities, although they differed to the degree to which they are able to offload the knee 1– Budarick, A.R. et al. (2020). J. Biomech. Eng. 142(1). While the OA Rehabilitator produced joint offloading equivalent to losing 5 lb of bodyweight, the Spring Loaded knee brace resulted in a reduction of joint forces equivalent to losing 45 lb of bodyweight. The subsequent study also compared their assistive moments across a range of brace flexion angles, with the Spring Loaded brace providing larger moments at higher angles than the OA Rehabilitator.

Multiple Forces Reduced

Each TCO brace model significantly reduced PF, TF, PC ligament, PT and QT forces during a deep knee bend test.

Reduced Joint Load

Each TCO brace model significantly reduced knee joint loads by at least 32% when compared to the non-braced condition.

Replicates & Extends Previous Research

Results corroborate the knee joint offloading capabilities of a TCO, as demonstrated in a previous study (Budarick et al. 2020).

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