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[Дедок Михаил]

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http://www.wheelessonline.com/ortho/paprosky_classification_of_acetabular_defects

Paprosky classification of Acetabular Defects

 - based on the severity of bone loss and the ability to obtain cementless fixation for a given bone loss pattern;
            - determines ability of remaining host bone to provide initial stability to a hemispherical cementless acetabular component until ingrowth occurs;
    - classification based of integrity of:
            - kohler line (ilioischial line):   position of the implant relative to the Kohler line
                  - defined as a line connecting most lateral aspect of pelvic brim and most lateral aspect of obturator foramen on AP of pelvis;
                  - medial migration of the component relative to the Kohler line represents a deficiency of the anterior column;
                  - grade 1: medial aspect of the implant is lateral to the Kohler line;
                  - grade 2: there is migration to Kohler line or slight remodeling of iliopubic and ilioischial lines without a break in continuity;
                  - grade 3:
                        - migration medial to the line with Grade-3 migration;
                        - w/ extensive medial migration, consider angiography or CT w/ IV contrast and consider   possible need for intrapelvic mobilization of vessels;
            - osteolysis of teardrop:
                  - indicates bone loss from inferior and medial aspect of acetabulum, and inferior aspect of anterior column, lateral aspect of pubis, and medial wall;
                  - moderate osteolysis includes partial destruction of the structure with maintenance of the medial limb of the teardrop;
                  - severe involvement means complete obliteration of the teardrop;
            - osteolysis of ischium:
                  - osteolysis is quantified by measuring distance from most inferior extent of lytic area to superior obturator line;
                  - indicates bone loss from the inferior aspect of the posterior column, including the posterior wall;
            - acetabular component migration (superior migration of the hip center);
                  - superior migration is measured as the distance in millimeters (adjusted for magnification) relative to the superior obturator line;
                  - superior migration of the hip center represents bone loss in the acetabular dome involving the anterior and posterior columns;
                  - superior and medial migration indicates a greater involvement of the anterior column;
                  - superior and lateral migration indicates a greater involvement of the posterior column;

- Classifications:
    - type I: rim is intact w/ no significant distortion of the rim
            - acetabulum is hemispherical but there may be small focal areas of contained bone loss;
            - anterior and posterior columns are intact;
            - hemispherical cementless implant is almost completely supported by native bone and has full inherent stability;
            - there is no migration of the component and no evidence of osteolysis in the ischium or teardrop;
            - kohler line has not been violated (medialmost aspect of the component is lateral to the Kohler line);
    - type II: distorted but intact rim with adequate remaining bone to support a hemispherical cementless implant;
            - type IIa:
                  - anterior and posterior columns are supportive and the rim is intact
                  - bone loss is superior and medial;
                  - defect the hip center is migrated superior
                  - migration is less than 3 cm above the obturator line;
                  - failed component migrates into a cavitary defect medial to the thinned remaining superior rim;
                  - most defects are treated with particulate allograft because the defect is contained;
            - type IIb:
                  - anterior and posterior columns will support an implant but there is a small superior rim defect which is not contained;
                  - remaining anterior and posterior rims and columns are supportive for an implant;
                  - superior rim is deficient for less than one third of the rim circumferene;
                  - migration is less than 3 cm above the obturator line directly superior or in combination with lateral migration;
                  - femoral head allograft may be appropriate but majority of segmental defects are not grafted;
                          - particulate graft is not an option with the Type IIB defects because there is no buttress to contain the graft;
            - type IIc:
                  - there is medial wall defects and migration of the component medial to Kohler's line;
                  - rim of the acetabulum is intact and will support the component;
                  - reconstructions involve particulate graft placed medially;
                  - if the medial membrane is not a sufficient buttress for the particulate graft, then insert a wafer of femoral head into the defect;
                        - graft is then placed over the wafer butress;
    - type III:
            - acetabular rim is not adequate for initial stability of the component;
            - allograft is necessary to help restore deficient host bone (inorder to restore stability of the implant);
            - posterior column may require reconstruction;
            - type IIIa:
                  - characterized by greater than 3 cm of superior migration of the femoral component cephalad to the superior obturator line,
                          moderate teardrop and ischial lysis, and an intact Kohler line;
                  - host bone is adequate for ingrowth but the acetabular rim is not entirely supporative;
                  - defects are associated with a nonsupportive superior dome
                  - anterior and posterior columns remain intact, but hemispherical shell will have less than 50 percent host bone contact;
                  - migration of implant is superior and lateral;
                  - surgical options include: figure 7 shape distal femoral allograft, use of a bilobed implant or a trabecular metal acetabular component with a superiorly
                          placed trabecular metal augment, or cup placement in the high hip center;
            - type IIIb:
                  - there is less than 40% of host bone available for ingrowth;
                  - rim defect is greater than 1/2 circumference;
                  - failed component has migrated superior and medial;
                  - high risk of occult pelvic discontinuity (posterior column reconstruction necessary)
                  - massive allografting and reconstruction cages are typically needed;




Дедок Михаил