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Table 4 Classification system for patients with long-term unreduced hip joint dislocation, secondary osteoarthritis and pseudoarthrosis

From: Diagnosis, preoperative evaluation, classification and total hip arthroplasty in patients with long-term unreduced hip joint dislocation, secondary osteoarthritis and pseudoarthrosis

Classification Characteristic Morphological characteristics of the original acetabulum Original acetabular bone deficiency Morphological characteristics of the proximal femur Proportion (%)
Type A Normal original acetabulum diameter, without bone deficiency Nearly normal (D/d > 0.8) Integral Nearly normal 6/16 (37.5)
Type B1 Normal original acetabulum diameter, partial bone deficiency Nearly normal (D/d > 0.8) Dome or posterior wall deficiency 4/16 (25.0)
Type B2 Atrophied original acetabulum, without bone deficiency Atrophied (D/d ≤ 0.8) Integral 5/16 (31.3)
Type C Severe bone deficiency or unidentified original acetabulum Normal, atrophied or unidentified Large dome and posterior wall deficiency, acetabular column deficiency 1/16 (6.3)
  1. D, contralateral acetabular diameter; d, original acetabular diameter