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Papers by Caroline Yntema

Research paper thumbnail of Behandeling van de ziekte van Sever, een literatuuroverzicht

Research paper thumbnail of Towards understanding knee joint laxity: Errors in non-invasive assessment of joint rotation can be corrected

Medical Engineering & Physics, 2014

The in vivo quantification of rotational laxity of the knee joint is of importance for monitoring... more The in vivo quantification of rotational laxity of the knee joint is of importance for monitoring changes in joint stability or the outcome of therapies. While invasive assessments have been used to study rotational laxity, non-invasive methods are attractive particularly for assessing young cohorts. This study aimed to determine the conditions under which tibio-femoral rotational laxity can be assessed reliably and accurately in a non-invasive manner. The reliability and error of non-invasive examinations of rotational joint laxity were determined by comparing the artefact associated with surface mounted markers against simultaneous measurements using fluoroscopy in five knees including healthy and ACL deficient joints. The knees were examined at 0 • , 30 • , 60 • and 90 • flexion using a device that allows manual axial rotation of the joint. With a mean RMS error of 9.6 • , the largest inaccuracy using non-invasive assessment was present at 0 • knee flexion, whereas at 90 • knee flexion, a smaller RMS error of 5.7 • was found. A Bland and Altman assessment indicated that a proportional bias exists between the non-invasive and fluoroscopic approaches, with limits of agreement that exceeded 20 •. Correction using average linear regression functions resulted in a reduction of the RMS error to below 1 • and limits of agreement to less than ±1 • across all knees and flexion angles. Given the excellent reliability and the fact that a correction of the surface mounted marker based rotation values can be achieved, non-invasive evaluation of tibio-femoral rotation could offer opportunities for simplified devices for use in clinical settings in cases where invasive assessments are not justified. Although surface mounted marker based measurements tend to overestimate joint rotation, and therefore joint laxity, our results indicate that it is possible to correct for this error.

Research paper thumbnail of Non Invasive Assessment of Knee Joint Rotational Laxity is Reliable but Not Necessarily Accurate

LAXITY IS RELIABLE BUT NOT NECESSARILY ACCURATE Philippe Moewis, Heide Boeth, Markus O. Heller, C... more LAXITY IS RELIABLE BUT NOT NECESSARILY ACCURATE Philippe Moewis, Heide Boeth, Markus O. Heller, Caroline Yntema, Ralf Doyscher, Tobias Jung, Rainald M. Ehrig, William R. Taylor Julius Wolff Institute, Charité – Universitätsmedizin Berlin, Center for Sports Science and Sports Medicine Berlin, Germany; Center for Musculoskeletal Surgery (CMSC), Berlin; Sports Traumatology & Arthroscopy Service Center for Musculoskeletal Surgery, Charité Berlin; Zuse Institute Berlin (ZIB); University of Southampton, England; ETH Zürich, Switzerland Introduction The in vivo quantification of rotational laxity (RL) of the knee joint is of critical clinical importance due to the necessity for the early identification of disease progression and the evaluation of therapy outcome [Kupper, 2007]. While invasive approaches have been used to study RL, non invasive methods are attractive particularly in healthy or underage cohorts. This study aimed to elucidate the accuracy and reliability of non invasive skin ...

Research paper thumbnail of Incidence of calcaneal apophysitis in the general population

European Journal of Pediatrics, 2014

Calcaneal apophysitis, or Sever&a... more Calcaneal apophysitis, or Sever's disease, is a traction apophysitis. It is a frequent cause of heel pain in children. Knowledge about the exact incidence of calcaneal apophysitis in the general population, however, is lacking. Cross-sectional study. From 34 general practices, records of patients between 6 and 17 years old, visiting the general practitioner (GP), were analysed. Diagnoses of calcaneal apophysitis were counted using computerised registration networks of GPs in 2008, 2009 and 2010. There were 16,383 SOAP files searched and a number of 61 children with calcaneal apophysitis were established over the years 2010, 2009 and 2008, showing an incidence of 3.7 in 1,000 registered patients. This is the first report on incidence rates of calcaneal apophysitis in general practice. With an incidence of 3.7 in 1,000 registered patients, it is a common pathologic entity, which requires more research on pathophysiology and therapy. The actual incidence may even be higher due the strict inclusion criteria of this study.

Research paper thumbnail of Behandeling van de ziekte van Sever, een literatuuroverzicht

Research paper thumbnail of Towards understanding knee joint laxity: Errors in non-invasive assessment of joint rotation can be corrected

Medical Engineering & Physics, 2014

The in vivo quantification of rotational laxity of the knee joint is of importance for monitoring... more The in vivo quantification of rotational laxity of the knee joint is of importance for monitoring changes in joint stability or the outcome of therapies. While invasive assessments have been used to study rotational laxity, non-invasive methods are attractive particularly for assessing young cohorts. This study aimed to determine the conditions under which tibio-femoral rotational laxity can be assessed reliably and accurately in a non-invasive manner. The reliability and error of non-invasive examinations of rotational joint laxity were determined by comparing the artefact associated with surface mounted markers against simultaneous measurements using fluoroscopy in five knees including healthy and ACL deficient joints. The knees were examined at 0 • , 30 • , 60 • and 90 • flexion using a device that allows manual axial rotation of the joint. With a mean RMS error of 9.6 • , the largest inaccuracy using non-invasive assessment was present at 0 • knee flexion, whereas at 90 • knee flexion, a smaller RMS error of 5.7 • was found. A Bland and Altman assessment indicated that a proportional bias exists between the non-invasive and fluoroscopic approaches, with limits of agreement that exceeded 20 •. Correction using average linear regression functions resulted in a reduction of the RMS error to below 1 • and limits of agreement to less than ±1 • across all knees and flexion angles. Given the excellent reliability and the fact that a correction of the surface mounted marker based rotation values can be achieved, non-invasive evaluation of tibio-femoral rotation could offer opportunities for simplified devices for use in clinical settings in cases where invasive assessments are not justified. Although surface mounted marker based measurements tend to overestimate joint rotation, and therefore joint laxity, our results indicate that it is possible to correct for this error.

Research paper thumbnail of Non Invasive Assessment of Knee Joint Rotational Laxity is Reliable but Not Necessarily Accurate

LAXITY IS RELIABLE BUT NOT NECESSARILY ACCURATE Philippe Moewis, Heide Boeth, Markus O. Heller, C... more LAXITY IS RELIABLE BUT NOT NECESSARILY ACCURATE Philippe Moewis, Heide Boeth, Markus O. Heller, Caroline Yntema, Ralf Doyscher, Tobias Jung, Rainald M. Ehrig, William R. Taylor Julius Wolff Institute, Charité – Universitätsmedizin Berlin, Center for Sports Science and Sports Medicine Berlin, Germany; Center for Musculoskeletal Surgery (CMSC), Berlin; Sports Traumatology & Arthroscopy Service Center for Musculoskeletal Surgery, Charité Berlin; Zuse Institute Berlin (ZIB); University of Southampton, England; ETH Zürich, Switzerland Introduction The in vivo quantification of rotational laxity (RL) of the knee joint is of critical clinical importance due to the necessity for the early identification of disease progression and the evaluation of therapy outcome [Kupper, 2007]. While invasive approaches have been used to study RL, non invasive methods are attractive particularly in healthy or underage cohorts. This study aimed to elucidate the accuracy and reliability of non invasive skin ...

Research paper thumbnail of Incidence of calcaneal apophysitis in the general population

European Journal of Pediatrics, 2014

Calcaneal apophysitis, or Sever&a... more Calcaneal apophysitis, or Sever's disease, is a traction apophysitis. It is a frequent cause of heel pain in children. Knowledge about the exact incidence of calcaneal apophysitis in the general population, however, is lacking. Cross-sectional study. From 34 general practices, records of patients between 6 and 17 years old, visiting the general practitioner (GP), were analysed. Diagnoses of calcaneal apophysitis were counted using computerised registration networks of GPs in 2008, 2009 and 2010. There were 16,383 SOAP files searched and a number of 61 children with calcaneal apophysitis were established over the years 2010, 2009 and 2008, showing an incidence of 3.7 in 1,000 registered patients. This is the first report on incidence rates of calcaneal apophysitis in general practice. With an incidence of 3.7 in 1,000 registered patients, it is a common pathologic entity, which requires more research on pathophysiology and therapy. The actual incidence may even be higher due the strict inclusion criteria of this study.