Between 2014 and 2015, 1,200 patients had hip and knee surgery at the QEII Health Sciences Centre in Halifax.

Jacqueline Umlah is one of those patients. 

“I’ve had two shoulder replacements, I've had a partial knee replacement in 2007, my hip replacement was September the fifth, 2014, and now my left knee is February the ninth, 2016," says Umlah. 

Umlah says she has been fortunate in her recovery, experiencing no complications. For many patients, that's not always the case. 

“So blood clots are a common complication that occur with people after this type of surgery,” says hematologist Dr. David Anderson.”Blood clots can either occur in the legs and cause swelling of the legs, or occur in the lungs and cause breathing difficulties.”

Dr. Anderson is the investigator sponsor of a research study looking at the prevention of blood clots in knee and hip replacement patients. 

Participants are given one of two treatments. 

“So one is based on an anticoagulant or a blood thinner which is called Rivaroxaban, and the other is a combination of a blood thinner and a readily available over the counter medication, Aspirin,” says Anderson. 

Doctors keep a close eye on their patients following surgery. 

“They kept constantly in touch with me and checking for swelling or any bruising, any problems,” Umlah says.

“The patients are followed for three months after the surgery,” Dr. Anderson tells CTV News. “If blood clots are going to occur, they will occur within three months of surgery.”

Dr. Anderson says this is a longstanding issue in orthopedic surgery. Studies in the field have been going on for decades looking at the different approaches to preventing blood clot complications. 

Dr. Anderson hopes this study will answer the question for good. 

“We expect the results of our study will change practice in that the better arm, the better treatment likely will be adopted by surgeons in the future.”

The follow up phase of the study will wrap up in July. The results are expected to be shared sometime next year.