Outpatient Surgery Magazine, providing current information on Surgical Services, Surgical Facility Administration, Outpatient Surgery News and Trends, OR Excellence and more.
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O C T O B E R 2 0 2 0 • O U T P A T I E N T S U R G E R Y . N E T • 5 3 The key is getting knee replacements right the first time because fixing a poorly done knee never quite works out. Surgeons can improve how it feels and functions, but the joint will never be as good as it could have been. Achieving positive, patient-pleasing results demands understanding several factors that impact outcomes. • Cement vs. cementless fixation. There's a revival of cementless fixation in knee implants, which concerns me because I saw the problems of the first cementless knee wave decades ago. In certain areas of the body, cementless fix- ation works great. For example, most hip replacements involve cementless fixation. It's easier and faster, but more importantly, it's beneficial to the patient. Bone almost always ingrows into the implant, and remains ingrown for a long time. The technique retains bone stock better than cement does. Cementless fixation of the knee, however, is associated with many problems. The blood supply around the knee isn't as good as it is around the hip, a factor that leads to a poorer ingrowth rate. Early after their surgeries, some total knee patients expe- rience lack of ingrowth: 1% or 2% of patients on the femoral side of the knee and 3% to 5% of patients on the tibial side, which is a lot. Then there's the difficulty of diagnosing what's wrong if the patient isn't doing well and is unhappy after surgery. With cementless hips, it's easy; you take an X-ray, and because of the anatomy you can see if implant components are ingrown with bone. With cementless knees, it's exceedingly difficult, if not impossible, to know if the implant is ingrown. Maybe the patient is experiencing post-op discom- fort because the surgeon didn't align the implant properly or its components are loose. Perhaps the patient developed scar tissue. There are countless possible reasons, but you can't see them on the X- ray. Surgeons are often forced to reopen the joint to assess the situation. Another problem with cementless fixation: Wear from the implant pieces gets into the bone and causes destructive osteolysis. Cement acts as a bar- rier to those particles. With cementless fixation, that barrier is gone, so the patient is more likely to develop osteolytic lesions. If the patient ever needs a revision surgery, the bone behind the prosthesis remains stronger with cement fixation. Cementless fixation for knees went away when these problems became evident. Its recent come- back is mostly about the push for "quicker, easier, more efficient." You don't need to mix the cement, wait for it to dry and clean it up, so it saves up to 30 minutes a case. However, patients pay the price. Cementless fixation on knees helps the surgeon more than the patient. • Preventing infections. Surgical site infections are a terrible problem, but fortunately they occur in less than 1% of cases. It's always top of mind for surgeons because when an infection occurs, it's a disaster for the patient and needs to be addressed quickly. The infection is sometimes introduced intraoperatively; sometimes it's a local invasion, meaning the incision didn't close quickly enough and bacteria entered; sometimes it's hematologic. Once bacteria get into a knee replacement, the body has a hard time fighting it. Best case, you reopen the knee, thoroughly wash it out, and administer IV antibiotics for four to six weeks. Sometimes, though, you must remove the prosthesis, so the patient has no knee function until the infection goes away, and before reinsertion of a new implant a few months later. Midwest Orthopaedics at Rush INDIVIDUAL APPROACH Dr. Berger customizes his standard multimodal pain management framework to opti- mize recovery for every patient.