SURGICAL PLANNING

orthoSIM offers to registered clinicians simulation services, as well as access to a powerful on-line archive of simulations and discussions on clinical cases.

The simulation process follows several steps:

• First of all, the user enters the simulation portal and introduces the input data (patient characteristics, implant to study and surgery protocol).
• Then, the service converts the entry parameters supplied by the users into a macro understandable by the simulation engine resident at the research lab, owner of the model.
• After simulation, the service converts the results or output parameters supplied by the FEM programme into relevant and understandable information for the user.

The interface has been designed to make the input process fast and easy. A clinical assessment group has collaborated in optimizing its performance.

INPUT PARAMETERS FOR SIMULATION (e.g. lumbar model)

All input parameters can be entered by the user directly through a standard browser (Microsoft Internet Explorer 6 or higher is recommended).

A clinical study has been made to obtain information about the most common lumbar spine pathologies treated with an implant, the most frequent surgical techniques and the information they manage to prepare a spine surgery. The resulting parameters have been classified into four input groups:

1- Characteristics of the patient.

The input parameters will serve to adapt the spine FE model to the characteristics of the patient and to define the implant configuration proposed by the user.

In this section the user must insert four evaluations of the patient:

• The height and weight of the patient.
• The spine morphology, there are two options for this evaluation, to insert the sagittal X-ray and click the anatomical landmarks directly, or introduce these data by means of a specialized clinical data management software (like Surgiview®).
• The patient imbalance, a scale of imbalance is proposed from no imbalance to very severe imbalance.
• The bone quality, a scale of bone quality is proposed from good quality to severe osteoporosis.

2- Pathology description.

• The pathology cases. A pathology list is proposed, grouping them in three types: spondyloarthrosis, spondylolisthesis and fractures.
• The affected level. The user will select the affected level in an interactive lumbar spine.
• The restoration estimation. For certain pathologies there could be a residual pathology once the spine is instrumented that the user must estimate, as the antero-posterior displacement or height loss.

3- Implant definition.

• Implant system. The user can chose the implant systems available. An implant system is classed in one of three groups: posterior fixation systems, anterior fixation systems and replacement devices.
• Implant configuration. For the posterior and anterior systems there are several aspects to define: the implant geometry, the implant configuration, the symmetry of the assembly and the use or not of the transversal connector.

4- Protocol associated to the implant surgery.

The surgery applied for an implant insertion could be different depending on the surgical technique. A standard surgery injury will be associated to the implant chosen by the user, but the user will have the option of modifying this injury manually.

The application offers the option of performing a comparative studies of two implant systems.

A shortcut menu with all the input sections is available during the whole input process to allow instant access to any step of the simulation input definition.

OUTPUT RESULTS OF SIMULATION (e.g. lumbar model)

The system delivers biomechanical results in graphical format showing the implant-patient behaviour, as well as reference values for equivalent success and failure cases.

Having the results within the normal limits doesn’t mean that no mechanical complication will occur. Having the results significantly above the normal limits indicates probable mechanical failure.

In the figure beneath, you can see an example of a possible output report delivered by the simulation engine. All reports are customised to the patient's and implant's characteristics.