Clinical History, Examination and Blood Test Results

  • Step 7 case 3 demonstrates a 57-year old female who presented with a complicated orthopaedic history

  • Background of right developmental dysplasia of the hip which had been treated with a number of operations including osteotomies 

  • The patient has had two previous hip replacements on the right side. This has lead to a large right sided pelvic defect, with superior migration of the acetabular cup and a complete loss of the medial acetabular wall

  • The huge defect required a custom implant to allow for the joint to be reconstructed


Imaging Results

PRE-OP RADIOGRAPH

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Anteroposterior (AP) radiograph showed massive acetabular bone loss with superior migration of the right acetabular cup. This left the patient with a severe leg length discrepancy which is not quantifiable from this radiograph.

 

 

 

PRE-OP EOS (SITTING)

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Pre-op EOS sitting.png

This is an EOS image of the patient sitting (in a functional position). This again highlights the superior migration of the implant.

PRE-OP EOS (STANDING)

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HEMIPELVIS DEFECT

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These two images are the same. The red lines in the picture on the right highlight the leg length discrepancy in this lady while she is standing. This can be measured using software, and was found to be?

This is a 3D reconstruction (from a CT scan) of this patients right hemipelvis. This highlights the extent of her acetabular defect. The medial wall is completely missing however the anterior and posterior columns are still intact.


Diagnosis

  • A Paprosky 3B acetabular defect with considerable superior migration of the existing acetabular cup. The acetabulum is flattened and the medial acetabular wall is almost entirely missing.


Treatment

IMPLANT DESIGN

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TRABECULAR TITANIUM

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This series of images shows the design of the acetabular implant. The blue areas of the design highlight the trabecular titanium. Scroll through to see the implant in-situ. These images are produced as part of the planning and designing stage of the procedure.

This image shows the Trabecular Titanium used with these implants. In order to manufacture this structure, rapid prototyping, better known as 3D printing is utilised. This is made using electron beam sintering, which means the structure is continuous. The pores within the material have been shown to encourage bony ingrowth. 

 

Key surgical steps

  • Posterior approach to allow extensile exposure of acetabulum and femur.

  • Release of psoas and gluteus maximus from the femur, and abductors from the ilium.

  • Bone preparation with reamers according to 3D computer plan and checking using sterilised plastic 3D-printed models of the acetabular pre and post bony preparation.

  • 3D printed trabecular titanium implant secured with at least 3 good screws.

  • Dual mobility bearings 44mm.

  • Cement-in-cement, small sized stem to allow for adjustment of offset and leg length.

  • Wash.


Imaging Outcomes

POST-OP RADIOGRAPH

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This is the post-operative AP plane film radiograph taken post-operatively. The large custom implant is in situ filling the defect made by the superior migration of the old implant.

 

POST-OP EOS (SITTING) 

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This is a post operative sitting EOS image with the implant in situ.

 

POST-OP EOS (STANDING)

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POST-OP EOS COMPARISON

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The leg length discrepancy has been corrected using the 3D printed trabecular titanium implant

A comparison using EOS of the pre-operative and post-operative leg length discrepancy


Clinical Outcomes

  • At 8-weeks post-op, the pain in the patients right hip had been resolved and the joint had a full range of movement. There was some evidence of foot and ankle weakness

  • At one year post-op, clinically the leg lengths are almost equal, a huge improvement on the pre-operative discrepancy. The antalgic gait that was present pre-op is no longer present

  • The patient has returned back to the gym and is continuing her physiotherapy


Learning Points

  • The use of pre-operative and post-operative EOS scanning allows for accurate measurement of the change in leg length discrepancy 

  • Custom implants can be used to achieve an initial strong primary fixation in huge acetabular defects. This patient at 8-weeks post-op was pain free with a good range of movement