Complications of prosthetic surgery in the dysplastic hip.

The complications of prosthetic surgery in the dysplastic hip have specific features that are related to the conditions that make the realization of an implant technically complex; the altered primary acetabular and femoral morphology, the sequelae of previous non-substitutive surgery, and the consequent possible upsetting of joint biomechanics. It is possible to distinguish between complications relative to the skeleton, joint biomechanics, and soft tissues. Prosthetization of the acetabular skeletal aspect may encounter frequent errors in reconstruction (incongruous reaming-too much or too little-the improper use of bone grafts), errors in orientation of the acetabular component (excessive verticalization and anteversion) that are considered early complications. The same technical errors may cause late complications in the implant, or its migration. At the femoral level the particular shape of the medullary canal and of the femoral neck may lead to defects in orientation in anteversion and fracture of the diaphysis. Possible complications of a biomechanical nature are essentially to be related to changes in the center of rotation in both a craniocaudal and a mediolateral sense and or to the heterometry of the limbs. In the soft tissues, muscle tension may become too much or too little, in relation to recovery of joint biomechanics; in cases with significant lengthening neurologic deficit may occur. Accurate preoperative planning (traditional x-rays and CT scan), the choice of the most suitable surgical route of access, and the different prosthetic models that adapt best to the different morphological situations, the expertise of the surgeon, are all essential elements in monitoring complications.