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 and each Friday’s closing share price.

The Massachusetts index for the week ended July 15 closed at 6.41, down 1.6 percent compared with the prior week. Since Jan. 1, 2009, when we began tracking these companies, the index has risen 44.7 percent.

The Minnesota index for the week ended July 15 closed at 3.88, down 2.9 percent compared with the prior week. Since Jan. 1, 2009, when we began tracking these companies, the index has risen 31.6 percent.

The California index for the week ended July 15 closed at 10.47, down 1.8 percent compared with the prior week. Since Jan. 1, 2009, when we began tracking these companies, the index has risen 146.6 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 July 15:

The 10 biggest gainers:

1. AdvanSource Biomaterials Corp.: 11.11% (open $0.09; close $0.10)
2. Vision-Sciences Inc. : 6.56% (open $2.44; close $2.60)
3. Hansen Medical Inc. : 4.78% (open $4.39; close $4.60)
4. Cynosure Inc.: 4.39% (open $12.07; close $12.60)
5. Rochester Medical Corp. : 3.88% (open $8.76; close $9.10)
6. LeMaitre Vascular Inc.: 3.31% (open $7.26; close $7.50)
7. Vascular Solutions Inc. : 2.88% (open $12.17; close $12.52)
8. Oculus Innovative Sciences Inc. (Micromed): 2.42% (open $1.65; close $1.69)
9. MKS Instruments Inc.: 1.81% (open $24.81; close $25.26)
10. Staar Surgical Company : 1.69% (open $5.34; close $5.43)

Sources: Google Finance and Yahoo! Finance.

And the 10 biggest losers:

1. Cambridge Heart Inc.: -9.95% (open $0.20; close $0.18)
2. Uroplasty Inc. : -5.17% (open $8.90; close $8.44)
3. Patient Safety Technologies Inc. : -3.57% (open $1.40; close $1.35)
4. Cardica Inc. : -3.13% (open $3.19; close $3.09)
5. icad Inc.: -2.91% (open $1.03; close $1.00)
6. Thermage Inc. (Solta Medical Inc.): -2.67% (open $2.62; close $2.55)
7. Brooks Automation Inc.: -2.35% (open $10.22; close $9.98)
8. Interleukin Genetics Inc.: -2.31% (open $0.39; close $0.38)
9. American Superconductor Corp.: -2.16% (open $7.87; close $7.70)
10. World Heart Inc. : -2.11% (open $0.95; close $0.93)

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.