Clinical History, Examination and Blood Test Results

  • Acetabular step 7 case 12 presents a 79-year-old lady who presented with swelling in her left thigh.

  • 18-months prior to her referral she had developed swelling in her left thigh with fevers, malaise and night sweats. This was on the background of a left total hip replacement. DVT and malignancy were excluded. A CT scan showed a large collection around the left hip and a raised inflammatory marker:

    • CRP = 198 mg/L (normal is less than 10)

  • Sepsis surrounding her left THR was suspected and she underwent a wash out procedure at her local hospital. Samples grew Pseudomonas aeruginosa so she was discharged on Meropenem and referred to our service.


Imaging Results

PRE-OP RADIOGRAPHS

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PRE-OP CT SCAN

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The radiograph demonstrates some scalloping on the lateral aspect of the left proximal femur. Lytic areas are evident surrounding the cement mantle of the Exeter stem. The acetabular component has a constrained liner.

CT scan demonstrating a huge radiolucent pseudotumour surrounding her left hip and proximal femur.


Diagnosis

  • Her case and imaging was reviewed by the infection Multi-Disciplinary Team (MDT).

  • The diagnosis of an infected left total hip replacement with massive bony destruction was made.


Treatment (Stage 1)

  • The decision was made to treat her pseudomonas infection by a two stage procedure. The first stage was to remove the old metal work, implant a proximal femoral spacer and treat the infection with an antibiotic regimen of Meropenem, Amikacin and Teicoplanin.

  • This procedure was done in conjunction with vascular surgeon, Alex Loh, to protect the femoral vessels.


Imaging Outcomes (Stage 1)

POST-OP RADIOGRAPHS

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POST-OP CT SCAN

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Post-operative radiographs demonstrate the new proximal femoral spacer in situ.

This CT scan was taken to plan for the custom acetabular component, now the acetabular metal work had been removed.

 

2-days later this construct dislocated. The patient was mobilising at home with a zimmer frame when she felt a pop in her left hip. This didn’t cause severe pain but it was uncomfortable.


Treatment (Repeat of Stage 1)

  • A girdle stone procedure was completed and a skeletal traction pin implanted.

Key surgical steps:

  • Dislocated spacer was removed with ease

  • Proximal cement removed from the femur

  • Wash with saline and aqueous chlorhexidine

  • Debridement of the membranous layers

  • Instillation of 4g of Vancomycin and 1g of Gentamicin in Stimulan beads

  • A skeletal traction pin was inserted into the distal femur


Imaging outcomes (repeat of stage 1)

POST-OP RADIOGRAPHS

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This demonstrates the girdlestone procedure with the surrounding antibiotic beads.

 

Treatment (stage two)

  • Stage two was carried out 11-weeks after the girdlestone procedure. A proximal femoral replacement and a custom 3D printed trabecular titanium acetabular component was implanted.

 

HEMIPELVIC DEFECT

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IMPLANT DESIGN

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The hemipelvic defect has been reconstructed in 3D from the original planning CT scan.

The implant has been designed to fit the large acetabular defect. The blue highlights areas which are made from the trabecular titanium material to enhance osseointegration.

 

TRABECULAR TITANIUM

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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.

 

Imaging Outcomes (Stage 2)

POST-OP RADIOGRAPHS

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The post-operative radiographs show good bony contact surrounding the acetabular component. All of the screws are optimally positioned. The proximal femoral replacement is now in situ.

POST-OP CT SCAN

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


Clinical Outcomes

  • 6-week review – The wound had healed well, with a small non-discharging sinus present in the wound. Her inflammatory markers had reduced to a CRP of 27. On clinical examination of the joint, there was no pain on internal or external rotation. She was able to mobilise with the use of a walking frame.

  • 2-month review – At 2-months she had moved to using two crutches from the zimmer frame. The CRP remained stable.


Learning Points

  • This patient had destruction of all muscles of the proximal 20 cm of proximal femur due to a previous metal debris inflammatory reaction. Further revision risked instability and she managed to cope without 20 cm of proximal femur and skeletal traction for 3 months before her definitive operation. Extreme soft tissue instability requires very good acetabular fixation which can be more easily achieved with a custom made implant.