title: Acetabular Prosthetic Protrusio after Bipolar Hemi-Arthroplasty of the Hip: Case Report and Review of the literature.
abstract: BACKGROUND
  Bipolar hemi-arthroplasty of the hip is a commonly performed procedure in elderly patients with intra-capsular fracture of the neck of the femur with good short-term results for pain relief, return to activity and morbidity. The incidence of intra-pelvic prosthesis migration or protrusion is rare and one of the inciting factors is chronic low-grade sepsis. Acetabular prosthesis protrusion poses a difficult and challenging surgical problem due to surrounding neurovascular structures.
  
  
  METHODS
  We present a case report of 60-year-old Chinese female suffering from chronic sepsis of the hip joint causing acetabular prosthetic protrusion with a concomitant peri-prosthetic femoral shaft fracture secondary to a fall, 5 years post index surgery of bipolar hemiarthroplasty for an intra-capsular neck of femur fracture. This patient subsequently underwent a two-stage revision total hip arthroplasty. We aim to discuss the diagnostic approach and surgical management of this complex case of infected protruded bipolar hip hemi-arthroplasty.
  
  
  CONCLUSIONS
  We highlight three recommendations from this clinical experience. Firstly, there should be a high index of suspicion for chronic infection in protruded prostheses following low energy trauma. Secondly, pre-operative planning for infected protruded prosthetic hips is essential, including arteriogram and a two-staged procedure to tackle possible soft tissue complications. Thirdly, the combined use of serological markers, fluid aspiration as well as intra-operative frozen section is important in the management of PJI and to confirm bacterial eradication before re-implantation.
authors.affiliation: Department of Orthopaedic Surgery, Singapore General Hospital, Outram Road, S169608, Republic of Singapore.
authors.forename: Jason Bt
authors.initials: JB
authors.lastname: Lim
authors.affiliation: Department of Orthopaedic Surgery, Singapore General Hospital, Outram Road, S169608, Republic of Singapore.
authors.forename: Chia Liang
authors.initials: CL
authors.lastname: Ang
authors.affiliation: Department of Orthopaedic Surgery, Singapore General Hospital, Outram Road, S169608, Republic of Singapore.
authors.forename: Hee Nee
authors.initials: HN
authors.lastname: Pang
keywords: Acetabular; Bipolar; Hemiarthroplasty; Infection; Protrusio