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Case of the Month

A 56-year-old lady suffered a motor vehicle accident 2 years ago and sustained a posterior wall and posterior column right sided acetabular fracture. Initially, open reduction and internal fixation of her acetabular fracture was performed with a posterior column plate. Unfortunately, she had a tumultuous post-operative period with multiple irrigation and debridement operations of her right hip for infection. Eventually, she had removal of her hardware after 6 months. Following this, she progressively worsened with regards to walking and right hip pain. At presentation, she could only ambulate using a wheelchair.

There is no significant past medical history and she was working as a secretary prior to the accident.

AP radiograph of her pelvis:

Question: What are your thoughts on the radiograph?

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Answer: There is complete avascular necrosis of the right femoral head

After counselling, the patient opted for a total hip replacement (THR).

Question: What is this patient at risk of if THR is considered and how would the surgeon prepare for these?

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1. Infection –blood markers (ESR, CRP, WCC) performed pre-operatively. Consider aspiration of the hip for microscopy, cultures and antibiotic sensitivity. Prepare for intra-operative specimen biopsies and potential change to a two-staged arthroplasty.

2. Dislocation/Poor acetabular bone stock – Further imaging to quantify adequacy (CTs). If necessary, prepare for augmentation of the acetabulum. Care should be taken to avoid negative acetabular cup orientation to facilitate bone stock inadequacy.

3. Sciatic/Neurovascular injury – Care during exposure of the hip and to avoid excessive lengthening to prevent nerve injury.

During surgery, there were significant superior and posterior wall/column acetabular deficiencies. The decision was made to augment the postero-superior portion with trabecular metal and the rest of the acetabulum using impaction bone grafting. We used a cemented cup and uncemented stem (hybrid THR) with a metal head. She underwent a gradual weight bearing rehabilitation programme and, at 6 months' follow-up, is pain free, ambulating using one crutch and happy with her outcome.

Pelvic radiographs 6 months following surgery:

Managing acetabular deficiencies in total hip replacement:

1. Contained (cavitary) defects

   1. Impaction bone grafting

   2. Cement augmentation

2. Segmental defects

   1. Structural bone grafts (autografts/allografts)

   2. Porous metal augments

3. Uncontained or combination defects

   1. Structural bone grafts

   2. Flexible reconstruction meshes (turning uncontained to a contained defect) followed by impaction bone grafting

   3. Porous metal cups/shells/augments

   4. Customised tri-flange prostheses (in extreme cases)

1. van  Egmond  N,  De  Kam  DC,  Gardeniers  JW,  Schreurs BW. Revisions of extensive acetabular defects with impaction grafting and a cement cup.  Clin  Orthop  Relat  Res.  2011;469:562-73
2. Issack  PS,  Nousiainen  M,  Beksac  B,  Helfet  DL,  Sculco TP,  Buly  RL. Acetabular component revision in total hip arthroplasty. Part II: management of major bone loss and pelvic discontinuity. Am J Orthop (Belle Mead NJ). 2009;38:550-6
3. Abolghasemian  M,  Tangsataporn  S,  Sternheim  A, Backstein  D,  Safir  O,  Gross  AE. Combined trabecular metal acetabular shell and augment for acetabular revision with substantial bone loss:  a mid-term review. Bone Joint J. 2013;95-B:166-72
4. Gross AE, Goodman S.  The  current  role  of  structural grafts  and  cages  in  revision  arthroplasty  of  the  hip.  Clin Orthop Relat Res. 2004;(429):193-200