Clinical History, Examination and Blood Test Results

  • A 55-year-old male presented with pain in his native left hip. 36 years previously he had a conservatively managed left acetabular fracture with damage to the sciatic nerve.

  • The pain affected his mobility and had reduced his ability to cycle and play tennis. He was still able to walk a few miles per day and cycle short distances, but this caused considerable pain.

  • He had an asymptomatic right hip resurfacing, done for osteoarthritis.

  • He was referred to our service because the anatomy of his left hip was complex, with a posterior facing socket, creating a reconstruction challenge.

  • On examination;

    • He walked with a stick.

    • Significant leg length discrepancy noted and a left shoe raise was in place.

    • Trendelenburg gait was observed.

    • The left leg was stiff.

    • He was able to straight leg raise on the left side but had little abduction or rotation of the joint.

    • No abnormalities were detected in the right hip joint.

    • He had reduced sensation in dermatomes L4, L5 and S1 on the left side in keeping with his sciatic nerve injury.

    • A scar was noted on the left lower leg associated with previous tendon transfer surgery to correct a foot drop.


Imaging Results

PRE-OP RADIOGRAPHS

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PRE-OP CT SCAN

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There is severe osteoarthritis of the left hip with very disrupted anatomy due to previous acetabular fracture. There is good acetabular bone stock and a high centre of rotation. The right hip resurfacing has a loose femoral component which has fixed in a stable position.

The planning CT scan (to design the custom acetabular implant) revealed a significantly abnormal left acetabulum with postero-superior dislocation of the left femoral head leading the neo-acetabular formation at the posterior of the left iliac blade. The neo-acetabulum is retroverted by 22 degrees.


Diagnosis

  1. Left hip OA secondary to acetabular fracture

  2. Left sciatic nerve injury secondary to acetabular fracture

  3. Loose right femoral Birmingham hip resurfacing femoral component


Treatment

HEMIPELVIC DEFECT

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IMPLANT DESIGN

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The hemipelvic defect has been constructed from the planning CT scan above. This shows the degree of deformity within the acetabulum and aids in designing a custom implant.

The implant is designed to fit the patients anatomy and reconstruct the hip to match the contralateral centre of rotation.

 

TRABECULAR TITANIUM

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This demonstrates the trabecular titanium which is 3D printed as part of the manufacturing process of the implant.

 
 

Key surgical steps

  • Extensive posterior approach

    • Nerve stimulator was used in this case

  • Acetabular prep

    • PSI cutting guides were used for the bony prep of the acetabulum. They had a good fit.

    • 3 areas of reaming was completed

    • PSI guide of implant fitted well

  • Definitive implant was then secured with all screws as planned

  • Dual mobility liner was used

  • Cemented femoral C-stem was used on the femoral side with a ceramic head

  • Stable and good leg length

  • Nerves were assessed and well-functioning

  • Wash with savlon and normal saline

  • Close with vicryl, monocryl and glue


Imaging Outcomes

POST-OP RADIOGRAPH

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POST-OP CT SCAN

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Post-operative AP radiograph demonstrating the implant in situ.

The CT scan shows the custom implant in situ. This sits at the same craniocaudal level as the contralateral side. The custom implant extends superiorly to fill the neo-acetabulum. There is no evidence of periprosthetic fracture to the femoral component.

 

POST-OP EOS (9-WEEKS)

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The post-op EOS demonstrates that the patient has no leg length discrepancy when standing.

 

Clinical Outcomes

  • 9-weeks post op – The patient was recovering well demonstrating good wound healing. He was walking with two crutches and was able to straight leg raise. He was very happy with the correction of his leg length discrepancy. A plan was made to wean off the crutches, continue to rehabilitate with an exercise bike and palates and review in 6-months.


Learning Points

  • The anatomy of the acetabulum was severely distorted by the previous acetabular fracture. The main volume of bone was posterior but placing the new socket here would have risked dislocation, early fatigue of the implant and increased wear of the bearing surfaces.

  • This is a primary implant and took over 12 months for the patient and I to be confident that surgery was the correct decision. Neither of us have regrets, he is very happy.