Osteotomies around the hip: radiographic planning and postoperative evaluation

The management of the dysplastic hip represents a clinical and a technical challenge. There is a great deal of variation in the degree and direction of acetabular dysplasia, and the accurate determination of femoral head coverage is difficult. It is, therefore, important to measure and plan any osteotomy based on each patient's unique acetabular anatomy. A clear understanding of the underlying anatomic abnormalities is vital so that reconstruction can be appropriately planned. This understanding is facilitated by an appreciation of the imaging techniques available and their correct application. The initial imaging of the dysplastic hip is based on plain radiographs. These determine the diagnosis of dysplasia and give a good indication of its severity and of the degree of congruency, instability, and degenerative change. A number of indices have been defined on these radiographs to facilitate surgical planning and to evaluate surgical outcomes. Moreover, plain radiographs or fluoroscopy are usually the only modalities accessible during surgery. More complex imaging is necessary to define any associated lesions and to quantify the acetabular deficiency more accurately. Multiplanar imaging using CT scans and computer reconstructions reduces the need for complex spatial interpretation, facilitates preoperative planning, and allows preoperative simulation. The availability of more powerful computers has extended the use of these techniques to intraoperative surgical navigation. Continued progress and development of imaging techniques will further determine the type and degree of correction required for each hip and will help to stratify dysplastic hips for outcomes assessment. Ultimately, it will help orthopaedic surgeons to evaluate whether the success or failure of osteotomies around the hip are intrinsic to the techniques used or to the primary disease process or are related to the surgeon's failure to create a more normal biomechanical environment for the hip.