The Story

“Lisa first presented to my clinic with ongoing pain and stiffness in both of her hips and her lower back. This was causing her to limit her normal day to day activities. She was only 49-years old when she presented, much younger than the average age for primary hip replacement in the UK, 67-years old. For this reason, we had to position her implant with the greatest precision to try and increase the longevity of her implant.

She had very complicated hip anatomy. She was born with coxa vara of the femoral neck. On top of this, osteoarthritis had developed into end stage disease, leaving her with acetabulae protrusio and a ring of acetabular osteophytes.

This was hugely impacting her life, as she loved hiking and running. The pain she was experiencing was preventing her from being able to do this, and she was keen to get back to sport after her operation.”


The Investigation

Needed from clinic letters - Rob to collect from TLC


The Evidence

Coronal CT demonstrating end stage osteoarthritis in both hips. The pre-operative scan was used to plan the procedure and design the patient specific instrumentation for Lisa’s operation. This instrumentation guides the surgeon in the femoral neck cut and the reaming angle of the acetabulum.

EOS was ordered pre-operatively to help plan the procedure. This patient has varus femoral necks. Patients with varus femoral necks are at an increased risk of post-operative leg length discrepancy, so understanding their functional anatomy pre-op is vital for surgical planning.


The Diagnosis

Lisa had bilateral end stage osteoarthritis at a young age requiring bilateral total hip arthroplasty.


The Plan

We planned to perform a primary total hip replacement using advanced CT planning and patient specific instrumentation (PSI).

The preoperative CT scan was analysed and used to plan the optimum femoral stem and acetabular cup for Lisa. Using a computer reconstructed 3D model of Lisa’s pelvis, instrumentation specific to Lisa’s anatomy was designed to guide the surgeon when making the femoral cut and reaming the acetabulum. This case will focus on the femoral side. To learn about the acetabular side, see OFF THE SHELF CUP: CT Planning for Patient Specific Instrumentation.

The PSI jigs are 3D printed from plastic and are sterilised before being used intraoperatively. They locate to specific bony landmarks identified on the pre-operative CT scan. The femoral jig fits over the femoral head and neck. Two pins can be used to secure the jig. It shows the surgeon the optimum position for making the femoral cut and the optimum angle to make the cut at. Provided the jig is correctly located, this helps to improve the accuracy of the cut.

We planned to replace her left hip first, followed by her right with time for post-operative recovery in between

PSI femoral jig sat on a 3D printed model of the patient’s proximal femur. This jig is designed for the posterior surgical approach, and is also complementary to the patient’s anatomy. It is used to aid in the cutting of the femoral neck, to ensure the position and the angle of the neck cut is correct. 

PSI femoral jig - This series of three photos shows the intraoperative use of the femoral jig. Image one shows the placement of the femoral jig on the posterior of the proximal femur. Image two shows the jig, pinned in place, being used as a cutting guide to remove the femoral head. Image three shows the femoral head being removed with the jig attached.


The First operation

Rob to get more information from TLC.


The first outcome

 

Anteroposterior plain radiograph demonstrating the left total hip replacement in situ. The position of the implant is good.

 

The Second operation

  • Rob to get more info from TLC


The Second outcome

Anteroposterior and lateral plain radiographs demonstrating both of the hip replacements in situ. Both are in the planned position.

Coronal CT scan showing final position of the implants.

Post-operatively the patient was happy with her bilateral hip replacements. She is undergoing physiotherapy with the aim to return to running.


The Verdict

“Lisa’s case was a complex primary hip replacement. There were three main challenges:

  • Young patient under 50

    • It is important that this implant lasts for this patient due to her age. This may need to last for up to 50-years, which no one can promise, but using patient specific instrumentation can guide the surgeon in achieving an optimal position in complex cases

  • Reconstructing the medial acetabular wall and the hip COR

    • This is due to the protrusio acetabulae, meaning the native acetabulae are more medial than normal

  • Avoiding leg length discrepancy

    • Coxa vara increases the risk of a post-operative leg length discrepancy

Other important operative considerations for Lisa included:

  • Ring osteophytes and protrusio acetabulae can result in a “captive” hip: this risks fracture of the femur or posterior acetabular wall if care not taken during dislocation during hip replacement. This can be avoided if the osteophytes are removed before dislocation or the neck is cut before dislocation.

  • For cases of protrusion, bone graft from the femoral head (autograft) can be used (sliced) to place in the floor of the acetabulum.

For Prof to review and add to!


Evidence for this treatment

  • Needed


In closer detail

  • Needed