Clinical History, Examination and Blood Test Results

  • Step 7 case 11 presents a 69-year-old gentleman who was referred to our service after a failed right hip revision at 1-day post-op.

  • His initial presenting complaint (prior to the failed revision) was the sensation of something moving in his groin on the background of a right total hip replacement 20-years prior. His primary total hip replacement was indicated due to osteomyelitis and septic arthritis of his right native hip joint due to tuberculosis. The components moving in his groin were causing him pain and led to a limp.

  • Infection was excluded following negative microbiological culture of a right hip joint aspirate.

  • The loose acetabular component was revised with exchange of the cup and liner using a 60mm cup and trabecular titanium augment with bone allograft. This dislocated the day after surgery. The sciatic nerve remained intact.

  • Due to the reconstruction complexities of this failed revision, he was referred to our service. He was comfortable at rest and neurovascularly intact.


Imaging Results

PRE-OP RADIOGRAPH 

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PRE-OP CT SCAN

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This AP radiograph demonstrates rotation of the acetabular cup one day post-operatively.

CT scan demonstrating the rotated acetabular component.


Diagnosis

  • Failed acetabular revision with complex anatomy requiring a custom acetabular component.


Treatment (Stage 1)

  • We planned a two stage procedure because the metal obscured the acetabular bone which prevented an accurate CT reconstruction and increased the risk that the custom implant would not fit.

  • Stage one - Removal of the femoral and acetabular components.


Imaging Outcomes (Stage 1)

POST-OP RADIOGRAPHS

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POST-OP CT SCAN

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The AP radiograph demonstrates the gridlestone procedure with retention of the cement mantle.

This CT scan was used to plan the custom acetabular implant. Removal of the previous metal components allowed for better characterisation of the acetabular bone.

 

HEMIPELVIC DEFECT

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This is the 3D model of the patients hemipelvis reconstructed from the CT scan taken after the girdlstone procedure. Without the metallic implants, there is less metal artefact allowing for a more precise planning CT.

 

Treatment (Stage 2)

  • Stage two - Implantation of the 3D printed titanium acetabular implant.

 

IMPLANT DESIGN

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TRABECULAR TITANIUM

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This series of images shows the 3D design of the implant created specifically for this patient. The areas in blue will be manufactured out of trabecular titanium to encourage bony ingrowth and osseointegration of the implant.

This image shows the structure of the 3D printed trabecular titanium metal used to produce these implants. This is designed to contact the bone to allow for bony ingrowth to occur.

 

Key surgical steps

  •  Posterior approach through the old incision

    • Extensive scarring noted around the hip

  • Psoas and Gluteus Maximus released with nerve protested

  • Acetabular preparation

    • Reaming 60 and 62mm in two domes

  • Insertion of custom component with good screws

  • Dual mobility bearing inserted

  • Cement in cement femoral stem

    • Exeter stem

  • Wash with savlon and normal saline

  • Close with ethibond, vicryl and clips


Imaging Outcomes (Stage 2)

POST-OP RADIOGRAPHS

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This radiograph shows the custom implant in situ. The Exeter stem has been cemented into the old mantle.

POST-OP CT SCAN

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The post-operative CT scan demonstrates optimal positioning of the acetabular component.

 

POST-OP RADIOGRAPHS (1-MONTH)

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POST-OP EOS (6-MONTHS)

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The 1-month post operative radiographs demonstrate that the implant is stable and sitting against the bone mantle.

The 6-month post-operative EOS demonstrates that there is no leg length discrepancy in a functional position.


Clinical Outcomes

  • The patient is yet to return to clinic for review.


Learning Points

  • Poor acetabular bone stock that is obscured by metal components (socket, augment and head) should be considered for a two-stage procedure.