This 'Classifications in Brief' article reviews the Paprosky system for grading acetabular bone loss in revision THA. Originally described in 1994 from 147 failed components, it classifies defects using four radiographic landmarks and the degree of hip center migration. The article covers each type's anatomic features, recommended reconstruction strategies, and the published evidence on reliability and validity.
Walk into any revision THA preop conference and Paprosky is the language everyone speaks. Before this system, acetabular defects were described volumetrically — how much bone was missing. Without linking defect location to specific implant needs.
Paprosky reframed the question: which supporting structures are deficient, and what will you need to reconstruct them? Each type maps directly to a graft type, fixation method, and implant strategy (Table 2 in the paper is worth memorizing).
In practice: when you see >2 cm of superolateral migration with an intact Kohler line on the preop film, that is a Type 3A. Plan for bulk distal femoral allograft and a reconstruction plate. When Kohler line is disrupted and migration is superomedial, you are in 3B territory. Anticipate pelvic discontinuity and the most complex reconstruction.
The reliability data matter too. Kappa values of 0.3–0.6 mean two surgeons looking at the same film will often classify differently. Use all four landmarks systematically, and know that dedicated training demonstrably improves agreement. Which is why learning this classification formally, not casually, changes your accuracy.
Classifications in Brief: Paprosky Classification of Acetabular Bone Loss
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This 'Classifications in Brief' article reviews the Paprosky system for grading acetabular bone loss in revision THA. Originally described in 1994 from 147 failed components, it classifies defects using four radiographic landmarks and the degree of hip center migration. The article covers each type's anatomic features, recommended reconstruction strategies, and the published evidence on reliability and validity.
Walk into any revision THA preop conference and Paprosky is the language everyone speaks. Before this system, acetabular defects were described volumetrically — how much bone was missing. Without linking defect location to specific implant needs.
Paprosky reframed the question: which supporting structures are deficient, and what will you need to reconstruct them? Each type maps directly to a graft type, fixation method, and implant strategy (Table 2 in the paper is worth memorizing).
In practice: when you see >2 cm of superolateral migration with an intact Kohler line on the preop film, that is a Type 3A. Plan for bulk distal femoral allograft and a reconstruction plate. When Kohler line is disrupted and migration is superomedial, you are in 3B territory. Anticipate pelvic discontinuity and the most complex reconstruction.
The reliability data matter too. Kappa values of 0.3–0.6 mean two surgeons looking at the same film will often classify differently. Use all four landmarks systematically, and know that dedicated training demonstrably improves agreement. Which is why learning this classification formally, not casually, changes your accuracy.