BOCA RATON, Fla. — A year ago, Bartolo Colon, once one of major league baseball’s more durable starting pitchers, looked close to the end of the line: he had struggled with injuries after 2005, and elbow surgery had kept him out of baseball for the entire 2010 season.

The Yankees signed Colon in January after he pitched during the off-season in the Dominican Republic. His fastball — often registering at 93 miles per hour or better — appeared to be back. The 37-year-old Colon has gone 2-1, with an earned run average of 3.81, since being inserted into the club’s starting rotation.

A doctor in Florida would like to take some of the credit. Joseph R. Purita, an orthopedic surgeon who runs a regenerative medicine clinic in Boca Raton, said he and a team of Dominican doctors that he led treated Colon in April 2010. Purita said he employed what he regards as one of his more pioneering techniques: he used fat and bone marrow stem cells from Colon, injecting them back into Colon’s elbow and shoulder to help repair ligament damage and a torn rotator cuff.

Purita said he flew to the Dominican Republic and performed the procedures for free, doing it at the behest of a medical technology company based in Massachusetts that he has done business with for several years. Purita, who has used human growth hormone in such treatments, said in an interview that that he had not done so in Colon’s case. The use of human growth hormone is banned by baseball.