BJJ News | I ssue 6 | M arch 2015
N. Verdonschot
innovations
The Twente Lower Extremity Model (TLEM)
he Twente Lower Extremity Model (TLEM), developed at the University of Twente is used to predict muscle and joint reaction forces during movement. M u s c u l o s ke l e t a l m o d e l s h ave m a ny applications in different fields, such as ergonomics, spor ts performance and orthopaedics. TLEMsafe is a project funded by the Seventh Framework Programme (FP7) of the European Commission, and seeks to build on the foundations of the original TLEM model to conduct operations safely and more predictably for patients who need extensive surgery. The objective of TLEMsafe is to integrate this musculoskeletal model with the MRI of a p a t i e n t t o s i mu l a t e s u r g e r y a n d i m p ro ve f u n c t i o n a l r e c o v e r y. Similar technology can already be used to plan anterior cruciate ligament reconstruction and meniscal surgery. These are smaller interventions, but for cases which involve the excision of a substantial tumour or the implantation of a prosthesis, the process becomes much more complex. In these circumstances, it is more difficult for a surgeon to formulate a precise operative plan and accurately predict recovery. For example, a patient may suffer from a tumour in the knee and is advised that it should be resected. Until now, surgeons have been unable to determine with any degree of accuracy how much of the surrounding muscle and bone can safely be removed while maintaining the function of the leg,
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or even if the leg should be amputated. The surgeon will, of course, explore every avenue in an attempt to prevent amputation and will probably recommend an implant. Problems can arise, however, such as infection, or if the leg becomes non-functional. TLEMsafe aims to avoid this and increase the chance of performing limb-salvage surgery by improving the safety and predictability of complex musculoskeletal surgery using a patientspecific navigation system. Workflow Principles (Fig 1) Starting from MRI scans at the Radboud University Medical Center, essential individual
patient-specific model to simulate different operative scenarios. For example, in the case of a tumour located close to the knee and affecting the quadriceps muscle, the surgeon could choose to transfer a muscle from the back of the thigh to the front to help the weakened quadriceps. Using this virtual system, the surgeon can transfer different muscles to different positions and predict the effect of each surgical option. Once the surgeon has reviewed the MRI scan and exploited the software to develop the best surgical plan, they can place that into a navigation system, developed by Brainlab, and perform the operation. The 3D system guides the surgeon in the operating theatre on the basis of the plan d e t e r m i n e d p re - o p e r a t i ve ly to achieve the best functional outcome for the patient. This work is still in the early stages, but we have proved the workflow principles on a cadaver. The next challenge is to apply it to patients. We are hoping to undertake this in the near future. Lastly, we have also developed a complex method to measure muscle metabolism using volumetric glucose consumption. We modelled this by injecting a patient with 18F-fluorodeoxyglucose, asking the patient to perform a walking exercise, and using a PET scan to measure muscle energy consumption in terms of the glucose metabolised. We are the first in the world to do this. By 3D mapping, we can accurately determine which muscles consume energy, and exactly how much. This is our most significant achievement towards the validation of these musculoskeletal model predictions.
Professor Dr Nico Verdonschot, Project Coordinator of the TLEMsafe project, discusses an innovative patientspecific surgical navigation system used for pre-operative planning and execution of complex musculoskeletal
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surgery details of the patient’s musculoskeletal system are extracted, using innovative algorithms specially developed by Materialise. All these data are then integrated by researchers at the University of Twente into the new version of the TLEM model and implemented into the modelling system provided by AnyBody Technology, in order to build a patient-specific musculoskeletal model. A n i n n o v a t i ve p re - p l a n n i n g s y s t e m developed by the Warsaw University of Technology allows the surgeon to use the