Our Weekly Checkup takes the temperature of the medical device industry’s three largest U.S. clusters: Massachusetts, California and Minnesota.

The MassDevice Indices are weighted according to market capitalization, based on the number of shares outstanding for each company from its most recent quarterly report and each Friday’s closing share price.

The Massachusetts index for the week ended Feb. 26 closed at 5.81, up 4.2 percent compared with the prior week. Since Jan. 1, 2009, when we began tracking these companies, the index has risen 31.2 percent.

The Minnesota index for the week ended Feb. 26 closed at 3.80, down 1.2 percent compared with the prior week. Since Jan. 1, 2009, when we began tracking these companies, the index has risen 28.7 percent.

The California index for the week ended Feb. 26 closed at 9.29, up 0.88 percent compared with the prior week. Since Jan. 1, 2009, when we began tracking these companies, the index has risen 119.0 percent.

We also create a composite index of the three regional indices and compare it with four other indices (the S&P 500, the Dow Jones Industrial Average, the Dow’s IHI medical devices index and the NASDAQ exchange):

The Weekly Checkup also compares Monday morning’s opening share prices with their value when the markets close Friday afternoon to calculate the biggest gainers and losers.

Here are the 20 firms that posted the biggest share price gains and losses during the week ended Feb. 26:

The 10 biggest gainers:

1. NuVasive Inc.: 33.7% (open $29.91; close $40.00)
2. Millipore Corp.: 32.6% (open $71.19; close $94.41)
3. Interleukin Genetics Inc.: 26.1% (open $0.92; close $1.16)
4. Biolase Technology Inc.: 18.3% (open $1.69; close $2.00)
5. NxStage Medical Inc.: 17.9% (open $9.03; close $10.65)
6. Cambridge Heart Inc.: 15.4% (open $0.13; close $0.15)
7. Oculus Innovative Sciences Inc. (Micromed): 13.9% (open $1.65; close $1.88)
8. HepaLife Technologies Inc.: 13.3% (open $0.15; close $0.17)
9. Hypertension Diagnostics Inc.: 11.8% (open $0.17; close $0.19)
10. Hologic Inc.: 9.8% (open $15.71; close $17.25)

Sources: Google Finance and Yahoo! Finance.

And the 10 biggest losers:

1. World Heart Inc.: -30.8% (open $4.00; close $2.77)
2. Imaging3 Inc.: -20.3% (open $0.74; close $0.59)
3. Intraop Medical Corp.: -18.2% (open $0.22; close $0.18)
4. Athenahealth Inc.: -15.2% (open $43.46; close $36.84)
5. Viking Systems Inc.: -15.0% (open $0.20; close $0.17)
6. Patient Safety Technologies Inc.: -14.8% (open $1.35; close $1.15)
7. Acusphere Inc.: -14.3% (open $0.07; close $0.06)
8. Cardica Inc.: -13.6% (open $1.98; close $1.71)
9. Conceptus Inc.: -11.6% (open $22.20; close $19.63)
10. American Superconductor Corp.: -11.4% (open $31.59; close $28.00)

Sources: Google Finance and Yahoo! Finance.

Disclaimer: MassDevice.com’s rankings do not reflect an opinion of companies’ health, prospects or viability. They are intended to provide a snapshot of publicly traded medical device companies and in no way constitute a recommendation to buy or sell any particular security, portfolio of securities, transaction or investment strategy.