Pre-operative Planning for Shoulder Replacement Surgery

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Description

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Osteoarthrosis and rheumatoid arthritis, the two most common forms of arthritis, can lead to severe joint damage. The resulting pain and limited joint motion significantly restrict the patient in performing daily activities. In such cases, a joint replacement, i.e. a surgical procedure where parts of the joint are replaced with artificial components, may be indicated. A successful joint replacement leads to pain relief and improved joint mobility. In the following animation you can see the bones of the shoulder, how they deteriorate as a result of arthritis and how the bones are being replaced by a prosthesis: shoulderreplacement.wmv

The surgery is often successful with regards to pain relief, but far less successful with regards to joint mobility. Impingement complications occur frequently, especially with special prosthesis types such as the reverse (Delta) prosthesis. These complications can be avoided by careful planning of the surgery and by providing computer assistance during the surgery.

We have created a pre-operative planning system for the replacement of shoulder joints. It consists of automatic and manual planning functionality, and substitutes the traditional template-over-X-ray planning that is currently the standard for planning a shoulder replacement. The planning system is based on patient-specific surface models, which are extracted directly from the CT-data. The automatic planning functionality is based on the calculations of landmarks on the surface data, i.e. the center of rotation of the glenoid, the acromion, the angulus inferior, etc.. A video of the process can be seen here: automaticplanning.wmv

When the operation has been planned, the system calculates the post-operative bone-determined range of motion for the active planning. It visualises this with range of motion (ROM) envelopes. Subsequently, the surgeon can make adjustments to the planning. In the meantime, the ROM envelopes are redetermined and updated, thereby providing interactive feedback on the effects the adjustments have: romvisualisation.wmv

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We have implemented a new visualisation technique, which enables us to compare ROM of different plannings. Red and green surfaces on the envelopes denote deteriorations and improvements of ROM with respect to previous ROM envelopes. This gives a quick and intuitive interface for the surgeon to search for the optimal planning regarding ROM. We plan to extend the feedback of the system with other parameters, such as the bone density (for the fixation of the prosthesis) and soft tissue information. romcomparison.wmv

A validation experiment using cadaveric shoulders has been performed. We used the BrainLAB VV system and the VVLink module to perform motion tracking. The video provided below shows our tracking software; the laptop screen in the video shows how the virtual models move in correspondence with the physical bones. This enables us to record the occurrence of impingement, which were in turn compared to the simulated ROM of our planning software. The ROM simulations proved to be extremely accurate. validation.wmv

Besides the subjects described above, there are several subprojects that are still ongoing. This includes, but is not limited to, segmentation algorithms, application of the system to proximal humerus fractures and hip impingement, as well as other clinical problems. Lastly, several collaborations with well-known international institutes are currently being set up.

Future work includes the development of an intra-operative guidance system, using the BrainLAB hardware. This will enable the surgeon to perform the actual surgery in accordance with the pre-operative plan.

Notes

This research is being supported by the Dutch Rheumatoid Arthritis Foundation.

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Projects/ShoulderReplacement (last edited 2010-11-29 12:26:17 by CharlBotha)