Clinical History, Examination and Blood Test Results

  • Step 7 case 5 presents a 69-year old female with a complex right hip history. The initial acetabular cup was revised twice from the primary procedure to leave her with a 60mm trilogy shell and a constrained liner with a 32mm femoral head

  • She presented having noticed shortening in her right leg and pain in the right hip. This was seen radiographically. She was referred for a revision

  • Between the referral and the surgery, the patient fell causing a periprosthetic type C fracture to the right femur and dislocation of the replacement joint

  • This was managed with open reduction internal fixation using a distal femoral locking plate prior to the acetabular reconstruction

  • The patient underwent a CT scan after the right femoral fracture to plan her custom acetabular component


Imaging Results

PRE-OP SCANNOGRAM

Click on the image for a closer look

A pre-operative scannogram demonstrating the dislocation of the right implant from the constrained acetabular liner 

 

PRE-OP CT SCAN

Scroll through the images

The pre-operative CT demonstrates the posterior and superior migration of the femoral head from the acetabular component

 

HEMIPELVIS DEFECT

Scroll through the images

This is a 3D reconstruction of the patients right hemipelvis created from the above CT scan

 

Diagnosis

  • Right hip prosthesis dislocation from a constrained liner with a severe acetabular defect requiring custom reconstruction


Treatment

IMPLANT DESIGN

Click on the image for a closer look

 

TRABECULAR TITANIUM

Click on the image for a closer look

This series of four images shows the design of the custom trabecular titanium implant. This particular implant has a constrained liner. The green regions on the back of the implant show the regions to be made from the trabecular titanium metal

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

  • Explant of old stem and cup

  • 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

  • Femur reconstructed with a reclaim stem

  • Trochanter fracture fixed using fibre tape

  • Stable with a ceramic head a dual mobility bearing

  • Wash


Imaging Outcomes

POST-OP RADIOGRAPH

Click on the image for a closer look

This post-operative AP radiograph shows the custom made Trabecular Titanium implant in situ within the pelvis, taken directly post-operatively. This shows a good initial position of the implant

 

POST-OP RADIOGRAPH 6-WEEKS

Click on the image for a closer look 

This is another post-operative AP radiograph taken at the patient's 6-week follow-up review. The implant hasn't moved and is still sitting in an optimal position

 

3D RECONSTRUCTION OF IMPLANT IN PELVIS

Click on the image for a closer look

Sqaure post-op 3D model.png

This is a 3D reconstruction produced from the post-operative CT scan shown to the right. The opacity of the pelvis has been reduced to highlight the custom implant and femoral stem. Note the metal artefact surrounding the right femur due to femoral fracture plate

POST-OP CT SCAN 7-MONTHS

Scroll through the images

This is a post-operative CT scan taken at 7-months post-op. There is no migration of the implant compared to the pre-operative radiograph


Clinical Outcomes

  • At 6-months post-op the patient was mobilising with a single crutch into the clinic

  • The patient understood the extensive muscle damage to her right hip, but despite this was walking 1.5km a day to regain strength in the joint


Learning Points

  • This is a complex case with extensive metal work involved. The use of metal artefact reduction CT sequencing has allowed for accurate reconstruction of the pelvic defect pre-operatively