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Simpleware Case Study: Bone-Preserving Custom Implant Design for Hip Joints
Overview
Acetabular osteolysis is a common complication of hip replacements, in which bone loss around an implant causes loosening and reduces long-term success. Causes of bone loss include deterioration of metal-on-polyethylene (MoP) bearings and peri-prosthetic infection, which trigger inflammation that degrades bone.
Traditional X-rays are not effective at detecting osteolysis, limiting early identification of bone loss. CT scans are more effective for assessing bone loss to plan revision treatments. Synopsys Simpleware users at the Royal National Orthopaedic Hospital (RNOH) use 3D printed custom implants to reconstruct severe bone defects and restore lost bone structures. A method developed collaboratively by RNOH, Synopsys, and implantcast GmbH aims to minimise bone removal and improve custom implant placement and surgical outcomes.
Highlights
- Custom workflows improve pre-surgical planning for complex orthopaedic cases
- AI-based segmentation in Simpleware software enables rapid design-to-surgery workflows
- Integration with design tools and post-op reviews creates a feedback loop that improves precision, reduces complication risks, and supports better long-term patient outcomes
Thanks to
Johann Henckel, Alister Hart, Anna Di Laura at the RNOH Surgical Technology Lab and UCL Mechanical Engineering.
Reference
Di Laura, A., Hart, A., Henckel, J., 2025. Advancing custom implant design: A bone-preserving, patient-specific approach, Orthopaedic Product News. 18 April 2025.
Advanced Custom Implant Design
In this workflow, RNOH surgeons identify complex patient cases– such as those involving significant bone loss – that require advanced surgical intervention. Implant designers at implantcast use Simpleware software to generate virtual bone models from CT scans of RNOH patients. AI-based segmentation and landmarking tools in Simpleware streamline this process, while manual editing options allow for handling severe imaging artifacts and other complex scenarios.
Custom implants are then designed and positioned within the bone models, ensuring a precise anatomical fit. The implantation procedure incorporates integrated surgical guides for accurate screw positioning; the prostheses are 3D-printed in titanium.
3D planning workflow for planning custom implants (Image courtesy of RNOH Surgical Technology Laboratory).
Pre-Surgical Planning and Post-Operative Care
A key benefit of this custom approach is the reduced need for bone removal compared to traditional implant designs, which often require aggressive resection. The precision of the implants enables optimized fixation, while the built-in guides improve intraoperative accuracy for screw trajectories tailored to each patient’s bone quality and anatomy.
This patient-specific fit improves implant stability and alignment and reduces the risk of both surgical and post-operative complications. After surgery, post-operative CT scans are used to confirm accurate implant positioning and evaluate outcomes such as the restoration of bone biomechanics. These insights feed back into the design process, continuously refining future implant planning.
Patient-specific 3D models improve implant design and placement, reducing the risk of surgical complications (Image courtesy of RNOH Surgical Technology Laboratory).
Conclusions
Custom 3D printed titanium implants are highly effective for reconstructing complex bone defects. Early intervention for osteolysis with metal-on-metal (MoM) implants is crucial to prevent progressive bone loss, with cross-sectional CT imaging playing a key role in assessing bone integrity.
The patient-specific approach developed by RNOH, Synopsys, and implantcast reduces planning time through AI-driven tools and rapid iterative design. This collaborative approach between surgeons and engineers supports optimal outcomes for each patient.
Learn More
- Watch the webinar From Scan to Surgery – with RNOH, Oqton, and implantcast showcasing patient-specific orthopedic device design.
- Explore RNOH and UCL’s research on Statistical Shape Modeling and Patient-Specific Designs.
- Read implantcast’s case study using Simpleware’s AI Automated Segmentation for Custom-Made Implants.
- Explore Simpleware Auto Segmentation Tools for faster, AI-driven model generation.