الفهرس 
APPLIED SURGICAL ANATOMY OF THE ACETABULUMOnly 14 pages are availabe for public view
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Abstract
Revision arthroplasty of the acetabulum is one of the most challenging prob¬lems in orthopaedic surgery today. The goals of acetabular revision are to restore anatomy and provide stable fixation for the new acetabular compo¬nent. The most important parameter affecting the surgeon’s ability to achieve this is bone stock. Bone stock deficiency must be identified and classified to plan appropriately for the surgery (120).
The American academy of orthopedic surgeons classification of acetabular defects or the system described by paporsky et. al offers a useful categorization of defects and development of revision strategy (4).
Bone stock deficiency can be classified as contained (cavitary) or un-contained (segmental). A contained defect is cavitary in that the acetabulum is ballooned out and weakened but the columns are intact. An uncontained defect is segmental in that there is full-thickness loss of bone involving the acetabular rim and the adjacent anterior or pos¬terior column (120).
Most bone defects can be defined by routine radiographs but on oc¬casion Judet views are helpful to define the anterior and posterior columns (121). The final definition of the defect only can be made intraoperatively and may be more extensive than was anticipated (122), The surgeon must allow for this in planning for resource needs.
Most orthopaedic surgeons throughout the world agree on the use of morcellized allograft bone to restore bone stock for contained defects (46)(47)(123) If contact can be made with 50% host bleeding bone, an uncemented cup can be used (46) (64). If contact cannot be made with 50% host bone, a cemented cup can be used (83)Or a reinforcement ring is used as a buttress to support the impacted bone and a cup is cemented into the ring. A roof reinforcement ring of the Muller type is used if it can be stabilized against host bone superiorly and inferomedially. If the defect is a contained global defect affecting the entire acetabulum, then a reconstruction ring that extends from the ilium to the ischium should be used. (120).
In the treatment of uncontained defects the use of large or oblong cups (86) (124) may be effective if adequate contact can be made with bleeding host bone. A high hip center is another alternative if adequate contact can be made with host bone (35).
Large bone defects have raised the need for bone substitution beyond the capac¬ity of autogenous transplants. The current practice for prosthetic reconstitution relies typically on modular metallic devices and bone graft techniques, but the long-term persistent problem is degradation of the interface between the bones and implant. Biological ingrowth surfaces have become a standard prosthetic element in reconstructive hip surgery. A material’s properties, three-dimensional archi¬tecture, and surface texture all play integral parts in its biological perfor¬mance . A porous tantalum biomaterial, trabecular metal devices, with similar structure and mechanical properties as bone represents, a new option with the potential of enhanced biological incorporation and greater struc¬tural integrity as well as provide a structural scaffold in cases of severe bone deficit (6).