High hip center bipolar hemiarthroplasty for non-reconstructable pelvic discontinuity

Copyright © Informa Healthcare Ltd 2009. ISSN 1745–3674. Printed in Sweden – all rights reserved. DOI 10.3109/17453670902876797 Patient 1 A 79-year-old woman with bilateral lower extremity weakness due to cervical myelopathy presented at our department in 2002 after multiple reconstructive procedures in both hips for developmental dysplasia of the hip. In 1993, a bulk allograft in combination with an acetabular cage and a cemented cup were used to treat the left massive acetabular bone loss. The defect was type IVb by the classification of the American Academy of Orthopaedic Surgeons (D’Antonio et al. 1989) and Berry et al. (1999). In 2000, the acetabular construct failed mechanically while the existing cemented femoral stem remained well fixed (Figure 1A). Removal of the acetabular hardware was followed by implantation of a whole acetabular allograft. The allograft was stabilized with plates and screws, and a new cemented cup was inserted. 2 years later, allograft fracture and acetabular failure occurred again. In 2002, a high hip center bipolar hemiarthroplasty was performed via a standard posterior hip approach. Failed acetabular component and hardware were removed but the femoral stem was left in situ as it was found to be stable. Capsular and periacetabular scar tissues were preserved as much as possible to create a soft tissue cavity to seat the bipolar head into. A 60-mm bipolar femoral head was inserted onto the femoral component to articulate with the periacetabular soft tissues in a high hip center mode. Its position was further augmented with capsular repair around the neck of the prosthesis (capsular noose). A femoral condyle allograft was fixed to the ilium to serve as posterior superior acetabular wall. Postoperatively, the patient was advised to gradually increase her weight bearing using a walker or crutches. No casts or braces were applied. Within 6 months, the bipolar component migrated out of the acetabulum and articulated with the iliac soft tissues (Figure 1B). Although the patient had limb shortening, she had no pain and declined further surgery. The right hip required 7 reconstructive procedures, which led to pelvic discontinuity (type IVb) and resection arthroplasty in 1999 (Figure 1A). In 2000, a re-implantation was performed by using a reinforcement ring with a cemented polyethylene cup and a long cemented femoral prosthesis. 4 years later the acetabular construct failed. A 56-mm diameter bipolar head was inserted onto the previously implanted and stable femoral stem and articulated with the soft tissues adjacent to the lateral ilium (Figure 1B). After surgery, the patient was able to transfer independently and ambulate short distances in her home with a walker. At 3 years postoperatively (right hip) and 5 years postoperatively (left hip) the patient had no pain, relatively equal leg lengths, and could sit comfortably. Due to complete loss of lower extremity motor function associated with failed spine surgery and cervical myelopathy, the patient was non-ambulatory. However, the Harris hip score (HHS) of the patient’s left hip had improved from 39 preoperatively to 58 postoperatively. Similarly, the HHS of the patient’s right hip increased from 14 preoperatively to 58 postoperatively.