الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
The surgical management of the knee joint abnormalities has increased in recent years with paralleling improvements in surgical biologic reconstruction techniques. So the postoperative knee presents with its own set of clinical and imaging diagnostic challenges. The first step in our assessment should be always plain X-ray as it is available in most clinical institutions and it is a low cost and time-sparing examination. The knee arthrography has little role in modern imaging other than as an adjunct to examining the knee with CT or MR imaging. Sonography has a broad range of applications in the evaluation of patients who have pain after an orthopedic surgical procedure. Sonography can be used to evaluate for peri-prosthetic collections and the integrity of the regional tendons and ligaments. The dynamic capabilities of sonography allow it to be used to guide various therapeutic and diagnostic injections and evaluate the regional relationships between the soft tissue structures and implantable hardware. Although nuclear medicine scintigraphy largely has been replaced by MR imaging, it still plays an active role in some centers in the evaluation of painful arthroplasty with suspecting infection. The applicability of CT in evaluating postoperative patients is broad and can include the evaluation of radio-occult fractures, guiding diagnostic or therapeutic interventions, or the evaluation of osteolysis in painful arthroplasty. Multidetector CT arthrography of the knee has become a valuable imaging modality for the assessment of meniscal, ligamentous, and cartilaginous lesions of the knee but remain as substitution to MR arthrography when MR is contraindicated. MR is the investigation of choice in assessment of postoperative knee with excellent soft tissue characterization. MR can assess the expected postoperative changes as well as the complications with unexpected postoperative changes. Although MR imaging once were believed of limited value in evaluating the postoperative knee because of the imaging-related artifacts, recent advances in scanner technology and software have made great strides in eliminating or reducing theses artifacts, bringing these modalities to the forefront of postoperative knee imaging. MR arthrography of the knee has an important role the evaluation of the postoperative meniscus and the diagnosis and characterization of osteochondral lesions. Although arthrography introduces an invasive component to the imaging evaluation of the knee, it is an established method for optimizing diagnostic accuracy. Our understanding of the strengths and limitations of every imaging techniques that are available for investigating the post-operative knee is important and cooperation of these different techniques is required when selecting the most appropriate imaging algorithm to reach accurate diagnosis of the operation results and its possible complication. As final conclusion: • In ACL reconstruction graft we should start with plain X-ray to assess the bony tunnels and the position of the metal plugs. For the assessment of the graft integrity and complications we recommend routine MR imaging with limited use of CT arthrography if MR is contraindicated. • In assessment of meniscal repair, MR arthrography accuracy in diagnosis of recurrent tear reach about 85-92% when compared with conventional MR with accuracy about 66-80%. CT arthrography show sensitivity reach about 100% and disappointing specificity reaching 78%. • The imaging test of choice for evaluation of articular cartilage is MR imaging in the native and postoperative states as other imaging modalities have limited role in visualization and assessment of the articular cartilage. • In assessment of arthroplasty while plain radiographs are the main station of any imaging evaluation, other imaging modalities such as fluoroscopy, CT, MR, nuclear scintigraphy and sonography also have roles in the evaluation of specific complications of knee arthroplasty.