Complex primary hip

By Dr. Vivek Vachhani

Introduction :
Unlike other joints, the role of patient specific instruments in THR is less explored. We took this opportunity and developed a product which could help achieve accurate acetabular cup placement. The technology could reduce the error in version and inclination as well as give confidence to surgeon upto what size they can ream. It is also well documented that in cases with massive bone defects, such technology is effective.

Preop evaluation at the hospital:
49/M with the complain of pain in both hip and difficulties in walking. During physical examination it was observed that the patient was struggling to achieve complete range of motion. Pre-op X rays confirmed the arthritis in both hips. The surgeon reached out to Jajal Medical to explore the possibility of performing this case with our cup positioning guide.

CT scan was performed for both the hip using scan acquisition protocol. Region of interest was segmented with our imaging experts, preserving all the anatomical detailing which could have clinical significance. 3D model and animation was shared with surgeon for the initial 3D assessment of the case.

Dr. Vivek and our preop experts did extensive preop planning to ensure correct component alignment can be achieved. The requirements from the surgeon were:

• Need a tool for referencing the acetabular component alignment
• Self-explanatory Preop Model for preop assessment
• 3D version and inclination information
• Sizing interpretation and validation through physical template model including for femur
Design inputs was put into execution by preop experts. 3D animated of the planning along with complete planning report was shared.

The Printable Plan which consisted of acetabular model, component alignment guide, and femur model were dispatched in four working days and well before surgery ensuring the surgeon got enough time to evaluate the model. It was effectively put into execution in clinical environment by Dr. Vivek in following structured and cautious approach:
• Compare and evaluate the physical model with patient anatomy visually in OT. The 3D printed femur head model matched perfectly with actual patient’s anatomy giving confidence that these are very accurate models.
• After clean up of soft tissue the guide for cup positioning was placed
• Ensured that the stability of the guide was achieved before pin placement
• Feedback from the peer surgeons involved in the surgery on the reference pin alignment
• Reaming was done such that the reamer handle was parallel to referencing stiman pins
• Evaluating the size prediction by trials and confirming it with our template
• Evaluating the amount of reaming required by referring the range of reamed bone model

Post op Assessment:
Post-op X-ray images shows that using this cup positioning guide, Dr. Vivek was able to decide component alignment accurately. He also shared the significance of this product for new surgeons who are willing to adapt new and effective way for planning their complex primary cases. It has potential to provide new surgeons a confidence in the OR.

Dr. Vivek Vachhani
CEO, Vachhani Hospital, Gandhinagar, India
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