Total knee replacement (TKR) surgery is a common procedure designed to alleviate chronic pain and restore mobility in a severely damaged joint. Patients must complete a thorough pre-operative testing phase before the operation. This evaluation ensures the patient is medically fit for the procedure and anesthesia, helping to optimize the surgical outcome and minimize the risk of complications, such as infection or deep vein thrombosis. The preparatory tests gather essential information needed for the surgical team to create the safest and most effective treatment plan.
Diagnostic Imaging for Surgical Planning
Specialized imaging is required to assess the knee joint’s structural integrity and overall alignment. Standard X-rays are the mandatory starting point, specifically including standing weight-bearing views. These images show the extent of cartilage loss, the condition of the bone stock, and the severity of the arthritis. The standing view is important because it reveals the mechanical axis of the leg, illustrating how forces are distributed across the joint under natural load.
Surgeons use these X-rays for templating, estimating the correct size and position of the prosthetic components. For more complex cases, such as those with significant bone deformity, previous hardware, or unusual bone loss, advanced imaging may be necessary. A Computed Tomography (CT) scan provides a three-dimensional assessment of the bone structure, valuable for precise component sizing and rotational alignment. CT scans may also be used to create a patient-specific surgical plan or to guide robotic-assisted surgery.
Comprehensive Medical Clearance and Lab Work
Ensuring a patient is medically robust enough to withstand the stress of surgery and anesthesia involves several systemic health checks. Laboratory work begins with a Complete Blood Count (CBC), which measures red blood cells, white blood cells, and platelets. Hemoglobin and hematocrit levels are assessed to rule out anemia, which impacts the ability to tolerate blood loss during surgery and recover post-operatively.
A Comprehensive Metabolic Panel (CMP) evaluates kidney and liver function, as well as electrolyte balance. Proper function is necessary for safely metabolizing anesthetic agents and pain medications, and electrolyte imbalances can affect heart rhythm. Coagulation Studies, such as Prothrombin Time (PT) and International Normalized Ratio (INR), assess the blood’s clotting ability to manage the risk of excessive bleeding during and after the operation.
A thorough Cardiac and Pulmonary Assessment is required to screen for heart and lung issues that could complicate the procedure. An Electrocardiogram (EKG) is routinely performed to check for heart rhythm abnormalities. Patients with a history of cardiac issues may require formal clearance from a cardiologist, and those with respiratory conditions may need screening for issues like sleep apnea. All results are relayed to the anesthesiologist to formulate the safest anesthetic plan.
Targeted Infection Screening
The pre-operative phase aims to eliminate existing sources of infection that could migrate to the newly implanted joint, as prosthetic joint infection is a serious complication of TKR. Dental clearance is a mandatory requirement, involving an examination by a dentist to identify and treat active infections, such as abscesses or severe periodontal disease. If an infection is found, the necessary dental work must be completed and healed before the orthopedic surgery can proceed.
A urinalysis is a common screening tool that checks for the presence of bacteria in the urine, even if the patient is asymptomatic for a Urinary Tract Infection (UTI). An untreated UTI can introduce bacteria into the bloodstream, increasing the risk of infecting the new joint.
Patients are also screened for colonization with Staphylococcus aureus, including Methicillin-resistant Staphylococcus aureus (MRSA), which often resides in the nasal passages or on the skin. Screening is typically done with a nasal swab. If the test is positive, a decolonization protocol is initiated, usually involving intranasal mupirocin ointment and bathing with an antimicrobial wash like chlorhexidine gluconate in the days leading up to the surgery.