They determined MRI had higher sensitivity (84% versus 31%) but lower specificity (85% versus 96%) for patellar component loosening than did radiography [131]. MRI and CT have both been shown to be more sensitive for detection of osteolysis than radiographs [116]. MRI with metal artifact reduction techniques can detect osteolysis that is not visible on radiographs, even around the femoral component [96]. An MRI investigation of 11 TKA suspected of osteolysis on radiographs (and subsequently confirmed by surgery) found 10 cases with osteolysis at MRI and confirmed at surgery, 5 cases with additional osteolytic lesions detected on MRI, and 9 cases in which lesions were larger on MRI than on radiographs [97]. MRI can also show synovial changes due to particle disease before osteolytic lesions become apparent [22]. When effective, metal suppression can be used, and MRI can allow direct visualization of ligaments and tendons about the knee [93]. US Knee US has no significant role in assessing for aseptic prosthesis loosening and is not typically used for the assessment of osteolysis. US can be used to evaluate synovitis and soft tissues about the joint and to guide joint aspiration [132]. US is not typically used for assessment of instability but can be used to visualize and assess the medial and lateral collateral ligaments in the setting of TKA [133]. WBC Scan and Sulfur Colloid Scan Knee In-111 WBC, Tc-99m labeled WBC, and Tc-99m sulfur colloid knee scans are not useful for evaluation of aseptic knee prosthetic loosening. WBC/marrow studies are used to differentiate prosthetic loosening from acute infection and can be performed without or with a corresponding bone scan, the latter without altering the WBC/marrow results [127]. A negative WBC scan negates an acute neutrophilic infection but may be falsely negative in chronic infection [101].
Imaging After Total Knee Arthroplasty. They determined MRI had higher sensitivity (84% versus 31%) but lower specificity (85% versus 96%) for patellar component loosening than did radiography [131]. MRI and CT have both been shown to be more sensitive for detection of osteolysis than radiographs [116]. MRI with metal artifact reduction techniques can detect osteolysis that is not visible on radiographs, even around the femoral component [96]. An MRI investigation of 11 TKA suspected of osteolysis on radiographs (and subsequently confirmed by surgery) found 10 cases with osteolysis at MRI and confirmed at surgery, 5 cases with additional osteolytic lesions detected on MRI, and 9 cases in which lesions were larger on MRI than on radiographs [97]. MRI can also show synovial changes due to particle disease before osteolytic lesions become apparent [22]. When effective, metal suppression can be used, and MRI can allow direct visualization of ligaments and tendons about the knee [93]. US Knee US has no significant role in assessing for aseptic prosthesis loosening and is not typically used for the assessment of osteolysis. US can be used to evaluate synovitis and soft tissues about the joint and to guide joint aspiration [132]. US is not typically used for assessment of instability but can be used to visualize and assess the medial and lateral collateral ligaments in the setting of TKA [133]. WBC Scan and Sulfur Colloid Scan Knee In-111 WBC, Tc-99m labeled WBC, and Tc-99m sulfur colloid knee scans are not useful for evaluation of aseptic knee prosthetic loosening. WBC/marrow studies are used to differentiate prosthetic loosening from acute infection and can be performed without or with a corresponding bone scan, the latter without altering the WBC/marrow results [127]. A negative WBC scan negates an acute neutrophilic infection but may be falsely negative in chronic infection [101].