Clinical History, Examination and Blood Test Result

  • Case 2 is a 64-year-old gentleman who presented in 2010 with a painful right metal-on-metal Birmingham hip resurfacing. He had bilateral resurfacings done in 2002 on the right and 2003 on the left.

  • Examination revealed an antalgic gait.

  • He had a blood cobalt level of 71ppb, a chromium level of 37ppb and CRP was 1.3mg/L.


Imaging Results

PRE-OP RADIOGRAPHS

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These two anteroposterior (AP) radiographs demonstrate the change in acetabular bone stock over 8 years.  Image A is post-operative and image B shows acetabular osteolysis and migration of the femoral and acetabular components of the right hip.

 

PRE-OP MRI

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The pre-op MARS MRI revealed wasting of the muscles surrounding the right hip and a fluid filled mass 3cms in diameter. Left hip has normal muscle bulk and no psuedotumour..


Diagnosis

  • Painful loose metal-on-metal right hip replacement secondary to osteolysis and metal debris disease.

  • Additional psuedotumour with hip abductor muscle wasting.


Treatment

  • He underwent revision surgery to replace his total hip resurfacing with a cemented C stem, acetabular augments and pelvic plating.

  • He had ceramic on ceramic bearings.

  • The intraoperative images show bone necrosis around the implants.

 

THREE INTRAOPERATIVE IMAGES

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This is an image of the explanted Birmingham hip resurfacing.

This shows the explanted acetabular cup. The grey/silver soft tissue sitting on the cup is full of metal ions.

This is an image looking down into the acetabular cavity. This demonstrates severe metalosis of the acetabulum, as the tissue has been stained by the metal wear particles from the metal-on-metal hip resurfacing. You can also identify the scale of the acetabular defect from this image, as there is discontinuity in the medial wall of the acetabulum.


Imaging Outcomes

POST-OP RADIOGRAPH 

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This is a post-operative AP radiograph from the right revision procedure. The stem is well positioned within the cement mantle. A plate has been used to support the acetabular defect.

 

Clinical Outcomes

  • After the reconstruction of the right hip, the patient was able to walk with a stick and straight leg raise. He had a good range of stable motion in both hips and was able to stand on the right leg.

  • 2 years after revision he single-handedly sailed his small yacht across the Atlantic ocean.

This graph represents how the blood metal ion levels change after the metal on metal implant on the right side had been removed.


Learning Points

  • Raised blood metal ions can be indicative of metal debris disease. This can lead to osteolysis, muscle wasting and pain within the joint and surrounding soft tissues. After revision metal ion levels decay exponentially with a 50% reduction after 50 days.

  • Reconstruction of the acetabular bone stock and cup position can be achieved using augments and pelvic plating.