There are different risks associated with different types of surgery. Each person has an individually different risk profile and many of the risks are worsened by overall medical issues. Hip and knee replacement tend to have a higher risk of blood clot due, in part, to the decrease in activity after the procedure. If the clot stays in the leg, then it is usually treated with anticoagulant medication for 3-6 months. If the clot travels into the lungs, then there are more involved treatments. Most surgeons use some form of blood thinner in the first few weeks after surgery to help reduce the chance of clotting. There are some rare genetic disorders that can increase the risk of clots, and you should bring that to your surgeon’s attention if you have been diagnosed with one. The best way to avoid a clot after surgery is by walking!
There is a risk of infection with any procedure, generally around 1% in most studies. That risk can double or triple if you have diabetes. Less time in surgery can help reduce the risk, and all patients are given intravenous antibiotics at the time of surgery as well.
We also worry about stiffness after knee surgery, and physical therapy is critical in helping to decrease the chance of that happening. There is a higher risk of stiffness in a knee that has had previous major surgery (like ACL reconstruction). There may be as many as 10% of people who still have some pain or stiffness after knee replacement permanently.
Hip replacement patients have less than a 1% chance of dislocation of the prosthesis. This chance is probably lower with anterior approach surgery. There is also a risk of leg length difference after surgery depending on how stable the hip is during surgery. If this happens, you may want a heel insert for your shoe on the shorter side.
For most people, it is important to have an in-depth discussion with your primary care physician, depending on what medical issues you deal with. Even if you consider yourself to be a healthy person, most surgeons will want a thorough medical evaluation before considering such a major surgery to make sure that you are in the best medical situation possible. This will give you an opportunity to uncover and address any risk factors that may make surgery more dangerous for you.
I have had more than one patient who felt that they had “no medical problems”, and then subsequently a major heart issue surfaced in the pre-surgical evaluation. Getting these issues picked up and addressed beforehand helps to reduce the risks of surgery.
While it is impossible to completely eliminate the risks of undergoing surgery, you will want to control as many of the variables as possible beforehand to put yourself in the best situation going forward.