Preprocedural Planning
A thorough preoperative medical evaluation of patients undergoing total knee arthroplasty (TKA) is important for preventing potential complications in the perioperative period. The evaluation should be completed in an elective preadmission clinic well before the date for surgery. This allows for a careful and unhurried assessment with adequate time for investigations, specialist anesthetic and medical opinion, and consent. It also allows operating schedules to be reorganized if patients are deferred from surgery.
Most patients who undergo TKA are elderly and have various comorbid conditions. Patients must have good cardiopulmonary function to withstand anesthesia and to withstand a blood loss of 1000-1500 mL over the perioperative period. Routine preoperative electrocardiography (ECG) should be performed on elderly patients. Patients with ischemic heart disease, congestive heart failure, and chronic obstructive airway disease should be seen by a medical specialist or anesthetist. Patients with significant peripheral vascular disease should be seen by a vascular surgeon.
Patients should have completed an informed consent for surgery and fully understand the risks and possible complications of the procedure. They should have had all medical conditions optimized before surgery and should be free of intercurrent infections. Two units of blood should be available for perioperative transfusion, either from the blood bank or, preferably, as predonated blood. Full medical and surgical backup must be available in case unforeseen complications occur.
Laboratory studies
Preoperative laboratory evaluation should include the following:
-
Complete blood count (CBC)
-
Erythrocyte sedimentation rate (ESR)
-
Serum electrolytes
-
Renal function studies
-
Prothrombin time (PT) and activated partial thromboplastin time (aPTT)
-
Urinalysis and urine culture
Urinalysis is performed to exclude occult urinary tract infection (UTI). Routine preoperative coagulation studies are not necessary except in patients with a history of bleeding, alcoholism, or previous liver disease.
Imaging studies
Radiographic views for the assessment of the patient with knee arthritis include the following:
-
Standing anteroposterior (AP) view
-
Lateral view
-
Patellofemoral (skyline) view (see the image below)
-
Long leg radiographs to assess malalignment - Helpful for preoperative planning
-
Standing radiographs with the knee in extension or in 45º of flexion (Rosenberg view) - Can improve the sensitivity of detection of cartilage degeneration
Total knee arthroplasty. Skyline view of patellofemoral joint demonstrating lateral and medial osteophytes and lateral subluxation of patella.
Loss of joint space, cysts, subchondral sclerosis, and osteophytes confirm the diagnosis of osteoarthritis (see the image below).
Routine chest roentgenography is not usually recommended as a screening tool. However, it is indicated in patients with cardiopulmonary disease or in patients with clinical signs identified in the preadmission clinic.
Other preoperative tests
ECG is performed in elderly patients and in patients with a history of cardiac issues.
More sophisticated imaging modalities in the investigation of knee arthritis are of occasional benefit for the assessment of significant bone loss or bone infection and include the following:
-
Indium white blood cell (WBC) scanning
-
Computed tomography (CT)
-
Magnetic resonance imaging (MRI)
-
Bone densitometry
Equipment
Different types of TKA prostheses are available (see the image below). These include the following:
-
Fixed bearing
-
Medial pivot
-
Rotating platform and mobile bearing
-
Posterior cruciate ligament (PCL)-retaining
-
PCL-substituting
Patient Preparation
Anesthesia
TKA may be performed with the patient under regional or general anesthesia. Selection of regional or general anesthesia is made following preoperative discussion between the anesthetist and the patient, with some input from the surgical team. This decision is affected partly by the medical condition of the patient, though there remain questions regarding whether and to what extent regional and general anesthesia are significantly different with respect to cardiovascular outcomes, cognitive function, or mortality.
Results from a large retrospective study indicated that patients undergoing knee or hip arthroplasty have better perioperative outcomes with spinal or epidural anesthesia than with general anesthesia. [14, 15] The study examined the types of anesthesia designated in 382,236 patient records; 11.1% of the patients received neuraxial anesthesia, 74.8% received general anesthesia, and 14.2% received a combination of these. Although the number of 30-day deaths was small for all three types of anesthesia, it was significantly lower in patients who had the neuraxial or combined forms than in those who received pure general anesthesia (0.10%, 0.10%, and 0.18%, respectively).
Patients who have epidural anesthesia have been shown to develop fewer perioperative deep vein thromboses. Whether this has any overall positive benefit to the patient is not known. Another benefit of epidural anesthesia is the presence of an indwelling catheter for 48-72 hours postoperatively for pain control, which eliminates the need for excessive amounts of centrally acting analgesics.
Adverse effects of continuous postoperative epidural analgesia include the following [16, 17] :
-
Pruritus
-
Urinary retention
-
Nausea
-
Vomiting
-
Epidural hematoma (rare)
In a study by Shum et al, continuous femoral nerve block for analgesia, compared with no femoral nerve block, resulted in less pain, higher satisfaction, and lower morphine use in patients immediately after TKA. [17] At 2-year follow-up, no significant differences in functional outcome were identified.
IIfeld et al found that a 4-day ambulatory continuous femoral nerve block, using a portable infusion pump, helped decrease time to discharge after TKA. [18] In a multicenter, triple-masked, placebo-controlled study, patients received a continuous femoral nerve block with perineural ropivacaine 0.2% from surgery until the following morning, at which time they were randomized either to continue perineural ropivacaine (n = 39) or to switch to normal saline (n = 38). Time to reaching three predefined discharge criteria (adequate analgesia, independence from intravenous opioids, and ambulation 30 m) was reduced by an estimated 20% in the patients receiving ambulatory analgesia.
Positioning
Afterb preoperative cleaning of the leg, the patient is set up on the operating table in a supine position (see the image below).
Monitoring & Follow-up
Follow-up depends on the surgeon, the patient, and the healthcare system. [19] A typical example would be surgical follow-up appointments at 6 weeks, 3 months, 6 months, 1 year, 2 years, 5 years, 10 years, and thereafter as appropriate. This would be modified for each patient according to age, degree of activity, and presence of complications.
Satisfactory knee function is usually restored after TKA, and the majority of patients are able to return to low-impact sporting activity. [20, 21] Long-term studies have confirmed satisfactory functional scores and shown a 91-96% prosthesis survival rate at 14-15 years of follow-up. No difference has been established between PCL-retaining and PCL-substituting designs. Cementless designs have not had the same length of follow-up, but studies at 10-12 years have reported a 95% prosthesis survival rate. [6, 9, 10, 22, 23]
-
Total knee arthroplasty. Total knee replacement prosthesis before implantation.
-
Total knee arthroplasty. Radiograph demonstrating posttraumatic osteoarthritis.
-
Total knee arthroplasty. Radiograph demonstrating features of osteoarthritis.
-
Total knee arthroplasty. Photograph of patient with varus deformity of right knee and valgus deformity of left knee.
-
Total knee arthroplasty. Lateral radiograph demonstrating severe patellofemoral osteoarthritis.
-
Total knee arthroplasty. Sagittal MRI showing anterior and posterior cruciate ligaments.
-
Total knee arthroplasty. Skyline view of patellofemoral joint demonstrating lateral and medial osteophytes and lateral subluxation of patella.
-
Total knee arthroplasty. Radiograph demonstrating proximal tibial valgus osteotomy created to offload medial compartment of knee.
-
Total knee arthroplasty. Radiograph demonstrating distal femoral varus osteotomy.
-
Total knee arthroplasty. Radiograph demonstrating medial unicompartmental replacement. Note relative preservation of lateral joint compartment.
-
Total knee arthroplasty. Patient on operating table before surgery.
-
Total knee arthroplasty. Intraoperative photograph showing trial components with patella everted.
-
Total knee arthroplasty. Radiograph of uncemented hydroxyapatite-coated total knee replacement. No gaps are present in bone-prosthesis junction, indicating incorporation of bone onto prosthesis.
-
Total knee arthroplasty. Definitive components in situ.
-
Total knee arthroplasty. Satisfactory knee flexion 6 weeks postoperatively.
-
Total knee arthroplasty. Skyline views of both knees showing lateral patella tilt and subluxation in both knees. This patient required patellofemoral resurfacing procedure and realignment because of persistent anterior knee pain in postoperative period.
-
Total knee arthroplasty. Electromicrograph showing incorporation of bone (red) onto surface of hydroxyapatite.
