The Story

“Tanveet first came to me with a very complicated orthopaedic history. She had undergone 25 operations to her right hip alone, and required a previous hospital stay of 365 days where she required 15 different operations. Initially she had undergone a right metal-on-metal hip resurfacing but ran into complications. She developed an adverse reaction to metal debris, which required many operations for debridement. During this process her right hip resurfacing became infected, and multiple washouts were required until she needed a proximal femoral replacement. The soft tissue damage caused to her right hip was so extensive that she required a vertical rectus abdominis myocutaneous flap in order to cover her soft tissue defect.

She presented to my clinic aged 76 with a painful dislocating right hip. She also noticed that her right leg felt shorter than her left. At this point she was completely chair-bound and unable to walk. Her right hip joint had very little stability, and the current construct of a proximal femoral replacement with a flanged cup was not providing her with any mobility.'“

  • Examination revealed that she was chair-bound and unable to walk. She transferred with the aid of a leg calliper due to her sciatic nerve palsy.

  • Blood tests revealed an ESR of 26mm/H and a CRP of 19mg/L.


The investigation

Examination in clinic was very limited due to Tanveet’s pain and her poor mobility. She was completely chair bound and unable to walk. She was able to transfer to the examination couch with the aid of a leg calliper secondary to sciatic nerve palsy.

In clinic we performed some basic inflammatory markers which were raised, suggesting the possibility of an infection. CRP = 19mg/L and ESR = 26mm/H.


The Evidence

Anteroposterior plain radiographs of the pelvis. The top image shows a located proximal femoral replacement in a custom trial-flange-flange acetabulum. The bottom image shows that this has dislocated due to instability, causing the patient pain.

 

Above is a pre-operative long leg film. Note that there is a 4.5cm  block under the right foot.


Diagnosis

  • A painful, dislocating, shortened and infected right proximal femoral replacement.

  • The plan was for a two stage revision for her right hip.


Treatment - First Stage

  • She underwent first stage revision surgery in July 2016. An articulating spacer was not used because of the soft tissue destruction. Imaging after the first stage provided good quality CT images to plan and make a custom made acetabular implant. This implant was chosen to maximise the fixation so that a constrained liner with dual mobility articulation was possible whilst minimising the risk of implant loosening.

  • Samples from the first stage surgery grew Pseudomonas and Proteus. The patient received a 6 week course of Cefazidimine and her CRP at the end of this was 11mg/L. The sinus however was still discharging.

  • The patient was discussed at the Bone Infection MDT at the Royal National Orthopaedic Hospital and the decision was made to repeat the first stage of the revision.


Imaging Outcomes - First Stage

POST-OP RADIOGRAPH (FIRST STAGE)

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Anteroposterior radiograph of the pelvis from September 2016. The metal work has been removed on the right side.

POST-OP CT (FIRST STAGE)

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This CT was used to design and plan the acetabular component of this revision surgery. It was also used in the planning of the proximal femoral replacement.

 

3D MODEL OF RIGHT HEMIPELVIS

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This 3D model of the patients right hemipelvis has been recreated from the post-operative first stage computer tomography scan demonstrating a Paprosky 3B pelvic defect.

 

Treatment - Second Stage

ACETABULAR IMPLANT DESIGN

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This shows a 3D representation of the custom acetabular component. It is made using trabecular titanium which encourages bony ingrowth into the implant. Look at acetabular case 8 for more information.

METS PROXIMAL FEMORAL REPLACEMENT

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The METS proximal femoral replacement system is a modular proximal femoral replacement with a cemented stem and HA collar to achieve initial stability and encourage bony ingrowth.

  • She underwent 2nd stage revision surgery with a custom made, 3D printed titanium acetabular and proximal femoral replacement. She was delighted at being able to transfer and take some steps.


Imaging Outcomes - Second Stage

POST-OP RADIOGRAPHS

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 These radiographs are from 6 months after the operation showing the METS proximal femoral replacement articulating with the custom Trabecular Titanium acetabular implant. Both components are well fixed and well positioned.

POST-OP CT

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Scroll through the post-operative computer tomography scan. This shows the acetabular component with good contact to the host bone and a well-positioned proximal femoral replacement.

 

3D RECONSTRUCTION

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This is a computer generated 3D reconstruction of the proximal femoral replacement and custom acetabular implant in situ, produced from the post-operative computer tomography scan.

POST-OP EOS SCAN

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This is a full body post operative EOS scan which demonstrates the standing functional position of the implant.

 

Clinical Outcomes

  • She was delighted at being able to transfer from bed to chair comfortably: the first time in 5 years. She was able to walk with two crutches across the clinic room – May 2017

  • She has no pressure sores.

  • Infection still on going at this point.


Learning Points

  • ARMD and infection is one of the hardest hip problems to resolve.

  • Custom made acetabular implants increase the chance of implant fixation when there is high stress due to a constrained liner and several soft tissue destruction.