Cost-Effectiveness of Community-Based Diet and Exercise for Patients with Knee Osteoarthritis and Obesity or Overweight.

OBJECTIVE: Obesity exacerbates pain and functional limitation in persons with knee osteoarthritis (OA). In the Weight Loss and Exercise for Communities with Arthritis in North Carolina (WE-CAN) study, a community-based diet and exercise (D + E) intervention led to an additional 6 kg weight loss and 20% greater pain relief in persons with knee OA and body mass index (BMI) >27 kg/m2 relative to a group-based health education (HE) intervention. We sought to determine the incremental cost-effectiveness of the usual care (UC), UC + HE, and UC + (D + E) programs, comparing each strategy with the "next-best" strategy ranked by increasing lifetime cost. METHODS: We used the Osteoarthritis Policy Model to project long-term clinical and economic benefits of the WE-CAN interventions. We considered three strategies: UC, UC + HE, and UC + (D + E). We derived cohort characteristics, weight, and pain reduction from the WE-CAN trial. Our outcomes included quality-adjusted life years (QALYs), cost, and incremental cost-effectiveness ratios (ICERs). RESULTS: In a cohort with mean age 65 years, BMI 37 kg/m2, and Western Ontario and McMaster Universities Osteoarthritis Index pain score 38 (scale 0-100, 100 = worst), UC leads to 9.36 QALYs/person, compared with 9.44 QALYs for UC + HE and 9.49 QALYS for UC + (D + E). The corresponding lifetime costs are $147,102, $148,139, and $151,478. From the societal perspective, UC + HE leads to an ICER of $12,700/QALY; adding D + E to UC leads to an ICER of $61,700/QALY. CONCLUSION: The community-based D + E program for persons with knee OA and BMI >27kg/m2 could be cost-effective for willingness-to-pay thresholds greater than $62,000/QALY. These findings suggest that incorporation of community-based D + E programs into OA care may be beneficial for public health.

Skipping has lower knee joint contact forces and higher metabolic cost compared to running.

BACKGROUND: The health benefits of running based exercise programs are plentiful however the high rate of injury in these programs often reduces or eliminates exercise participation. Skipping has shorter steps, reduced vertical ground reaction forces (GRFs), and lower knee extensor torques, compared to running forming the basis of the present hypothesis that skipping would have lower tibio-femoral and patello-femoral joint contact forces. RESEARCH QUESTION: The purpose of this study was to compare knee contact forces between skipping and running at the same speed. We also compared metabolic cost of these two gaits to examine the idea that the larger vertical displacement in skipping is a primary factor in its previously reported high metabolic cost. METHODS: The study evaluated joint contact forces through musculoskeletal modeling with GRF and 3D kinematic data and metabolic cost using oxygen consumption data from 20 young, healthy, trained participants as they skipped and ran on an instrumented treadmill at 2.68 m/s. RESULTS: Skipping, compared to running, had substantially lower tibio-femoral and patello-femoral joint contact forces and linear impulses on both per-step and per-kilometer (i.e. lower cumulative loads) bases and also 30% higher metabolic cost. The lower joint loads in skipping were directly associated with its shorter steps and the higher metabolic cost was directly associated to its larger vertical displacement through the stride. SIGNIFICANCE: As joint loads may predispose individuals to running related injuries, skipping presents an attractive alternative exercise modality with additional increased aerobic benefits.

Association between muscle activation and metabolic cost of walking in young and old adults.

BACKGROUND: The net metabolic cost of walking (C(w)) as well as the level of neural activation of agonist and antagonist leg muscles are higher in healthy old compared with young adults. This study examined the association between C(w) and agonist muscle activity and antagonist coactivity in young and old adults. METHODS: Young and old adults walked at 0.98 m/s on a treadmill set at 6% decline, level, and 6% incline, while C(w) and neural activation of leg muscles were measured. RESULTS: C(w) was 7.0% (incline), 19.2% (level), and 47.3% (decline) higher in old adults (overall 18.3%). Old (67.1%) versus young (40.1%) adults activated their leg muscles 67.3% more during the gait tasks and had 152.8% higher antagonist muscle coactivation (old: 67.1%, young: 19.9%). Agonist muscle activation was unrelated to C(w) on incline, but it explained up to 42% (level), 48% (decline), and 70% (three tasks combined) of variance in C(w). Antagonist coactivation accounted for up to 41% (incline), 45% (level), 59% (decline), 39% (three tasks combined) of variance in C(w). CONCLUSIONS: Age-related adaptations in the recruitment pattern of leg muscles during gait significantly contribute to the high C(w) in old adults. Clinical interventions optimizing the neural control of leg muscles during gait could reduce C(w) consequently the relative effort needed for exercise and activities of daily living in old adults.