Posterior Acetabular Reconstruction Can Sometimes Lead To Retroverted Cup Placement In Complex Total Hip Arthroplasty.

Abstract

Introduction: Acetabular fractures with uncontained posterior wall and posterior column bone loss make orientation of the acetabular component difficult during total hip arthroplasty (THA). When the posterior buttress is deficient, the socket tends to settle in retroversion, which alters hip biomechanics, promotes edge loading and accelerated polyethylene wear, and predisposes to anterior impingement and instability. Structural femoral head autograft restores bone stock in such defects, but its influence on final cup version is seldom documented. To our knowledge, this is the first series to specifically highlight persistent cup retroversion despite anatomic autograft reconstruction of the posterior wall.

Case report: Three men of Indian ethnicity, aged 47, 35, and 59 years, presented with post-traumatic arthritis 2-8 months after acetabular fractures sustained in road traffic accidents; all had been managed conservatively elsewhere. Imaging showed uncontained posterosuperior defects classified as Paprosky grade 2B, American Academy of Orthopaedic Surgeons segmental posterior and superior, and Gross type 3. Associated injuries included femoral head fracture with posterior dislocation, of Pipkin type 4 in two patients. All were treated by primary THA through the posterior approach. The posterior wall defect was reconstructed with femoral head structural autograft secured with partially threaded cannulated cancellous screws, supplemented by a reconstruction plate in one patient, followed by a porous-coated hemispherical shell with a 10° elevated-rim liner and an uncemented femoral stem. Post-operative radiographs showed stable fixation in all patients. Computed tomography at follow-up demonstrated cup retroversion of 5°, 19°, and 7° from neutral. Pain relief and functional improvement were achieved in all three patients; one sustained a posterior prosthetic dislocation at 2 months, treated by closed reduction, and the other two had mild residual discomfort and a mild gait abnormality.

Conclusion: Posterior acetabular bone loss predisposes to retroversion of the acetabular component during THA even after structural autograft reconstruction, with attendant risks of impingement, edge loading, and dislocation. Meticulous pre-operative planning, intraoperative verification of cup version against bony landmarks and fluoroscopy, and readiness to use stability-enhancing bearings are recommended, with cross-sectional imaging to document final component orientation.