OASIS 1: Retrospective Analysis of Four Different Microprocessor Knee Types


Journal of Rehabilitation and Assistive Technologies Engineering
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James H. Campbell, PhD1, Phillip M. Stevens, MEd1,2, Shane R. Wurdeman, PhD1,3

  1. Department of Clinical and Scientific Affairs, Hanger Clinic, Austin, TX, USA
  2. School of Medicine, University of Utah, Salt Lake City, UT USA
  3. Department of Biomechanics, University of Nebraska at Omaha, Omaha, NE, USA


Outcomes ASsessment and DISsemination (OASIS) 1 is the first in what is intended to be a series of studies comparing the effectiveness of a variety of orthotic and prosthetic components across different patient groups to ultimately impact and enhance patient outcomes.


To compare outcomes from four common microprocessor knee models.

Design (n=602)

Patient Inclusion Criteria:

  • 18 years or older
  • Lower limb amputation
  • Currently using a prosthesis
  • Must have received one of the noted MPK models prior to outcomes assessment

Patient Demographics:

  • 68 Rheo users, 178 each/ C-Leg, Orion, and Plié
  • Among users of the C-leg, Plié, and Rheo, vascular disease/diabetes was most common amputation etiology specified
  • Plié users comprised the highest percentage of females (31.46%)
  • Rheo users comprised the highest percentage of employed individuals. (32.35%)

Table 1: Descriptive data for individuals using different microprocessor knees.


Figure 1

C-Leg users reported the greatest median mobility, however there were no statistical differences between any of the four user groups (H=2.91, p=0.406).

Figure 2

Patient Satisfaction
Satisfaction with amputee status, from PEQ, showed C-Leg and Orion users reported highest median satisfaction. No statistical differences between the four groups (H=4.43, p=0.219).

Figure 3

Quality of Life
For quality of life, factor level differences were noted between the four knee categories (H=10.15, p=0.0170). Post-hoc analysis revealed significant C-Leg users reported greater quality of life versus Plié (p=0.010).

Figure 4

Injurious Falls
419 MPK users analyzed – the lowest percentage of individuals to report an injurious fall for which the individual sought medical attention were the C-Leg and Orion users.

Figure 5

Outcomes with Aging
There was a consistent pattern of modest declines in mobility with aging across all MPKs.


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Authors from Hanger Clinic

James Campbell, PhD

SVP and Chief Clinical Officer, Hanger Clinic

Dr. Campbell has 40 years of experience in the orthotics and prosthetics profession with distinction in leadership and research. He serves as Hanger’s Chief Clinical Officer.

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Phil Stevens, MEd, CPO/FAAOP

Director, Clinical & Scientific Affairs, Hanger Clinic

Mr. Stevens develops evidence-based clinical programs for Hanger Clinic, designed to help patients improve their orthotic and prosthetic outcomes.

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Shane Wurdeman, PhD, CP, FAAOP (D)

Director, Clinical Research, Hanger Clinic

Dr. Wurdeman has published numerous studies in peer-reviewed journals. In addition to his research work, he continues to manage a patient case load with Hanger Clinic.

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