September 2017

Rand study backs advanced device use

The Santa Monica, CA-based nonprofit Rand Health in September epublished a study showing advanced prostheses used by transfemoral amputees produce significant improvements in physical function and significant reductions in the incidence of falls and osteoarthritis (OA) in the contralateral limb compared with less-advanced devices (see, “Knee OA in amputees: Biomechanical and technological considerations,” March, page 18).

The authors did a literature review of the clinical and economic impacts of microprocessor-controlled knees (MPK) and non-MPKs, convened technical expert panel meetings, compiled the input parameters required, and constructed and implemented a simulation model over a 10-year period for unilateral transfemoral amputees with a Medicare Functional Classification Level of 3 and 4.

The study found 26% of patients who received MPKs will fall per year compared with 82% of patients receiving non-MPK limbs. Of these, 10.4% are medical falls with a range of mean costs: 7% result in death ($27,338); 40% result in major injuries with inpatient and/or skilled nursing facility treatment ($23,363); and the remaining 53% have minor injuries ($1091).

There are 22 fall-related deaths per 10,000 patient years for the non-MPK amputees, and four fall-related deaths per 10,000 patient years for the MPK amputees. Simulation data show 66 injurious falls with MPKs, and 289 with non-MPKs. MPK-wearing amputees have a lower incidence of OA due to lower vertical ground force (14% for MPK vs 20% for non-MPK).

MPK users gain about .09 life years per person over 10 years compared with non-MPK users, but about .91 quality-adjusted life years per person. Because of the higher cost of MPK devices, overall annual cost is $15,083 per MPK patient and $13,382 per NMPK patient, a net increase of $1702 based on current payment levels for devices and repair services.

The economic benefits of MPKs are comparable to those of total knee replacement and better than the implantable cardioverter defibrillator, the authors wrote. They concluded MPKs provide good value for money from a societal perspective.

The study, which was fund­ed by the American Orthotic and Prosthetic Association, is available at

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