Although axial radiographs may be used to determine axial rotation of the femoral component [40], CT is most commonly used for this purpose. Leon-Munoz et al [41] have noted CT-scan-based 3-D models and, therefore, supine CT scan, underestimate the degree of deformity at the knee joint, both in varus and valgus; therefore Imaging After Total Knee Arthroplasty preoperative full-leg standing radiographs should be performed for patient-specific instrumentation assisted TKAs, as a complementary study, to analyze the position of the load-bearing axis. Radiographs cannot directly image post-TKA periprosthetic soft-tissue abnormalities. However, radiographic signs of extensor mechanism tendon tears include patella alta, patella baja, localized soft-tissue swelling, posterior subluxation of the tibia, bony avulsions, and dystrophic calcifications within the tendon [21,42]. US Knee There is insufficient evidence to support the use of ultrasound for the initial evaluation of TKA. WBC Scan and Sulfur Colloid Scan Knee There is insufficient evidence to support the use of white blood cell (WBC) scan and sulfur colloid scan for the initial evaluation of TKA. Variant 2: Suspected infection after total knee arthroplasty. Additional imaging following radiographs. Infection is a serious complication of joint arthroplasty and is reported in 0.8% to 1.9% of TKAs [43]. The frequency of infection is increasing as the number of primary arthroplasties increases [44]. Infection may be acute or delayed, with delayed infection defined as occurring at least 3 months postoperatively [45]. In a series, infection was responsible for 37.6% of early revisions and 21.9% of revisions performed >2 years after the initial operation [12]. Staphylococcus aureus and coagulase-negative Staphylococcus species, including Staphylococcus epidermidis, are the most common organisms associated with these infections [46]. Both clinical findings and laboratory tests may serve useful in addition to imaging studies.
Imaging After Total Knee Arthroplasty. Although axial radiographs may be used to determine axial rotation of the femoral component [40], CT is most commonly used for this purpose. Leon-Munoz et al [41] have noted CT-scan-based 3-D models and, therefore, supine CT scan, underestimate the degree of deformity at the knee joint, both in varus and valgus; therefore Imaging After Total Knee Arthroplasty preoperative full-leg standing radiographs should be performed for patient-specific instrumentation assisted TKAs, as a complementary study, to analyze the position of the load-bearing axis. Radiographs cannot directly image post-TKA periprosthetic soft-tissue abnormalities. However, radiographic signs of extensor mechanism tendon tears include patella alta, patella baja, localized soft-tissue swelling, posterior subluxation of the tibia, bony avulsions, and dystrophic calcifications within the tendon [21,42]. US Knee There is insufficient evidence to support the use of ultrasound for the initial evaluation of TKA. WBC Scan and Sulfur Colloid Scan Knee There is insufficient evidence to support the use of white blood cell (WBC) scan and sulfur colloid scan for the initial evaluation of TKA. Variant 2: Suspected infection after total knee arthroplasty. Additional imaging following radiographs. Infection is a serious complication of joint arthroplasty and is reported in 0.8% to 1.9% of TKAs [43]. The frequency of infection is increasing as the number of primary arthroplasties increases [44]. Infection may be acute or delayed, with delayed infection defined as occurring at least 3 months postoperatively [45]. In a series, infection was responsible for 37.6% of early revisions and 21.9% of revisions performed >2 years after the initial operation [12]. Staphylococcus aureus and coagulase-negative Staphylococcus species, including Staphylococcus epidermidis, are the most common organisms associated with these infections [46]. Both clinical findings and laboratory tests may serve useful in addition to imaging studies.