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Mechanical basis for tensioning tendon transfers in tetraplegia

English title Mechanical basis for tensioning tendon transfers in tetraplegia
Applicant Fridén Jan
Number 152828
Funding scheme Project funding (Div. I-III)
Research institution Schweizer Paraplegiker-Forschung AG
Institution of higher education Swiss Paraplegic Research - SPF
Main discipline Surgery
Start/End 01.09.2014 - 31.08.2018
Approved amount 73'320.00
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Keywords (4)

tendon transfer; tetraplegia; muscle; surgery

Lay Summary (German)

Lead
Der Sehnentransfer ist ein chirurgischer Eingriff, der einige Funktionen der oberen Extremitäten bei Tetraplegikern wieder herstellen kann. Der wichtigste Schritt während der Operation ist es, den Spendermuskel mit der richtigen Spannung an die neue Stelle zu befestigen. Denn der transferierte Muskel kann nur dann maximale Kraft produzieren, wenn er in seinem optimalen Bereich arbeitet. Bis jetzt gibt es keine objektiven Richtlinien für diesen wichtigen Schritt, und die Chirurgen befestigen den Muskel nach ihrem subjektiven „Gefühl“ der „optimalen“ Spannung.Das Ziel dieser Studie ist es, die mechanischen Eigenschaften der Spendermuskeln zu bestimmen, so dass objektive Richtlinien für das optimale Spannen dieser Muskeln aufgestellt werden können.
Lay summary

Inhalte und Ziele des Forschungsprojekts

Der Sehnentransfer ist eine Operation, durch die einige Funktionen der Arme und Hände bei Tetraplegikern wieder hergestellt werden können. Der wichtigste Schritt während der Operation ist es, den Spendermuskel mit der richtigen Spannung an die neue Stelle zu befestigen. So wird die Länge des Muskels und somit seine Funktion festgelegt. Obwohl dieser Schritt sehr wichtig ist, gibt es dafür keine objektiven Richtlinien und die Chirurgen müssen den Muskel nach ihrem „Gefühl“ der „optimalen“ Spannung befestigen.

Um objektive Richtlinien schaffen zu können, müssen die mechanischen Eigenschaften jener Muskeln bekannt sein, die am häufigsten transferiert werden. Deshalb wird intraoperativ die Beziehung zwischen Sarkomerlänge und Spannung der Spendermuskeln (Brachioradialis, Extensor Carpi Radialis Longus) untersucht. Zusätzlich wird sechs Monate nach der Operation untersucht, ob Änderungen in Sehnen-/Muskellänge stattgefunden haben.

 

Wissenschaftlicher und gesellschaftlicher Kontext des Forschungsprojekts

Das Projekt befasst sich mit der Grundlagenforschung der Architektur und des Verhaltens der beiden Spendermuskeln. Das Wissen aus dieser Studie kann auf weitere Muskeln und Operationstechniken angewendet werden.

Die objektiven Richtlinien für die Muskelspannung während eines Sehnentransfers unterstützen den Chirurgen bei der Durchführung der Operation. Somit werden die Operationen einheitlich durchgeführt und das Erlernen dieser Operation wird erleichtert. Durch das Anwenden der Richtlinien wird der transferierte Muskel in seinem optimalen Bereich arbeiten und kann somit mehr Kraft produzieren. Im Alltag hat der Patient so mehr Greifkraft und wird somit unabhängiger in seinem Handeln.

Direct link to Lay Summary Last update: 07.04.2014

Responsible applicant and co-applicants

Employees

Collaboration

Group / person Country
Types of collaboration
Ursina Arnet / Schweizer Paraplegiker Forschung Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
- Exchange of personnel
Richard Lieber, Tim Tirrell / Muscle Physiology Laboratory, University of California, San Diego United States of America (North America)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
Salhgrenska University Hospital Gothenburg Sweden (Europe)
- Research Infrastructure
Shirley Ryan AbilityLab United States of America (North America)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
Christian Wisianowsky / Schweizer Paraplegiker Zentrum Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
- Exchange of personnel

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
Tetrahand World Congress Talk given at a conference THE RELATIONSHIP BETWEEN SARCOMERE LENGTH AND PASSIVE TENSION OF BRACHIORADIALIS AND EXTENSOR CARPI RADIALIS LONGUS IN VIVO 21.08.2018 Nottwil, Switzerland Arnet Ursina; Fridén Jan;
International Federation of Societies for Surgery of the Hand (IFSSH) Talk given at a conference Combination of nerve and tendon transfers 24.10.2016 Buenos Aires, Argentina Fridén Jan;
British Spinal Cord Injury Society Annual Meeting Talk given at a conference Hand Reconstruction in Tetraplegia 23.06.2016 Oswestry, Great Britain and Northern Ireland Fridén Jan;
SPF Research Colloquium Individual talk Optimal tensioning during tendon transfers 16.09.2014 Nottwil, Switzerland Arnet Ursina;


Self-organised

Title Date Place
Tetrahand World Congres 21.08.2018 Nottwil, Switzerland

Knowledge transfer events

Active participation

Title Type of contribution Date Place Persons involved
Medizinaltarif-Kommission Schweiz Talk 01.03.2018 Nottwil, Switzerland Fridén Jan;


Abstract

Background: The most common procedures to regain finger movement in persons with tetraplegia are the reconstruction of pinch (thumb flexion) and grasp (finger flexion) by tendon transfer. After this surgery, patients have increased range of motion and force in the treated joints. The tensioning of a muscle during tendon transfers is the most important step. It is critical to the patient outcome because it sets the resting length and the operating range of the muscle and ultimately defines the muscle’s function. The following points provide strong support for the statement that tensioning is critical and more research is needed: - Every surgery book emphasizes the importance of tensioning but the instructions differ between authors.- Muscles can only produce high forces within a certain known range of sarcomere length.- Transferred muscles are often overstretched so that they generate less than 30% of maximum force.- Overstretched muscles have an inhibited ability to “adjust” to their altered length. Even though tensioning is most critical, there are no objective guidelines for this step. Thus far, hand surgeons have to tension muscles according to a subjective “feeling” of “optimal” tension, which is unique and unpredictable among muscles. It is thus important to define the passive mechanical properties and behavior of the most commonly transferred muscles (brachioradialis (BR), donor muscle for grasp and extensor carpi radialis longus (ECRL), donor muscle for pinch) to establish objective tensioning guidelines.Aims: A1: To determine the relationship between sarcomere length and passive tension. A2: To evaluate changes in muscle and tendon length six months after tendon transfer. A3: To evaluate the accuracy of muscle volume determination using ultrasound measurements. The results will allow to set guidelines on optimal tensioning during tendon transfers (A1), ensure the persistence of the set sarcomere length (A2) and make the recommendations practicable for clinical routine (A3).Methods: 16 patients from the Swiss Paraplegic Centre and the Sahlgrenska University Hospital, Gothenburg, undergoing a tendon transfer with the BR and/or the ECRL as a donor, will be included.- A1: During surgery, the tendon of the donor muscle will be pulled to six given distances and the pulling force will be measured with a force transducer. Simultaneously sarcomere length will be measured by laser diffraction. The pulling force will be related to the physiological cross section area of the muscle (relative tension), which will be obtained one month after surgery by MRI. The relative tension will be correlated to sarcomere length. Since optimal sarcomere length is known, the corresponding relative tension can be determined. - A2: Two stainless steel sutures will be inserted into the donor and recipient tendon. The distance between the markers will be measured intraoperatively and six months postoperative (X-ray). The difference will be analyzed. - A3: One month after surgery, muscle length and muscle cross sectional area of the BR and ECRL will be measured with ultrasound at predefined points. Muscle volume will be calculated from these variables and will be compared to the muscle volume obtained by MRI measurements. Relevance: The new objective tensioning guidelines, resulting from the knowledge from this study, will make the surgery more standardized and less dependent on surgeons’ experience. In future, surgeons conducting tendon transfers can measure the tendon tension intraoperatively to meet the muscle’s optimal resting length. With this, the transferred muscle is working in its appropriate range and is able to produce more force. This will result in decreased need for assistance and technical aids and increases the patient’s independence and satisfaction.
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