UvA-DARE is a service provided by the library of the University of Amsterdam (https://dare.uva.nl)
UvA-DARE (Digital Academic Repository)
Imaging of physeal stress in the upper extremity
(Ab)normal redefined
Kraan, R.B.J.
Publication date
2020
Document Version
Other version
License
Other
Link to publication
Citation for published version (APA):
Kraan, R. B. J. (2020). Imaging of physeal stress in the upper extremity: (Ab)normal
redefined.
General rights
It is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s)
and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open
content license (like Creative Commons).
Disclaimer/Complaints regulations
If you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please
let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material
inaccessible and/or remove it from the website. Please Ask the Library: https://uba.uva.nl/en/contact, or a letter
to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You
will be contacted as soon as possible.
10
194
Chapter 10
Physeal stress injuries of the shoulder, elbow and wrist can occur in young athletes as a result of repetitive stress applied to the upper extremity. Athletes with, or at risk for, these stress-related injuries should be identified as early as possible to prevent further damage from occurring and require detailed information regarding status of injury and expected time of recovery. To enable this, MRI was used to describe the normal and abnormal morphologic appearance of the distal radial physis and changes in this appearance resulting from extensive stress applied to the upper extremity. Furthermore, feasibility of several (semi-) quantitative techniques for indicating physeal stress was explored.
Chapter 1 introduces the subject and illustrates the outline of this thesis. The research in parts I and II describe MR imaging-based methods for evaluation of the distal radius and
ulna in wrist-loading athletes. Part III focuses on future directions and, in order to guide future
studies exploring imaging methods for physeal elbow and shoulder injuries, shows in which sports youth athletes are at risk for stress-related injuries of the elbow and shoulder.
As a starting point, the development of the Amsterdam MRI assessment of the physis (AMPHYS) protocol was described in chapter 2. After extracting all imaging features associated
with physeal stress injuries of the wrist from medical literature and our institution’s picture archiving system, several experts used the retrieved list of imaging features to evaluate MRI scans of gymnasts with physeal injury, asymptomatic gymnasts and non-gymnasts. To ensure the AMPHYS protocol to be useful in clinical practice, the final protocol consists of twelve imaging features on which the observers demonstrated at least fair interobserver agreement. These features include presence and characteristics of distal radial epiphyseal bone marrow edema, thickness and signal intensity of the distal radial physis and irregularity, physeal cartilage intrusions and bone marrow edema in the metaphyses of the distal radius and ulna.
Using the established AMPHYS protocol, chapter 3 and 4 explore the normal and abnormal
appearance of the periphyseal areas of the distal radius and ulna. Chapter 3 focuses on the
presence of areas with bone marrow edema-like signal intensity on MR images in 23 healthy adolescents. Results demonstrated that prevalence of these areas with a, mostly mild, increase in signal intensity on water-sensitive MR sequences was high in the distal radial epiphysis (26%), and metaphyses of the distal radius (65%) and ulna (91%). The presence of these areas appeared to be age-dependent and therefore likely the result of physiologic maturation related processes in the bone marrow.
In chapter 4 MR images of 69 wrists of healthy adolescents and gymnast with and without a
stress-related injury of the distal radial physis are used to comprehensively describe the presence of imaging features included in the AMPHYS protocol. Interestingly, all imaging features appeared to be, to some extent, present in the healthy adolescent’s wrist and can therefore not be regarded as signs of pathology straightaway. Compared to non-gymnasts, asymptomatic gymnasts had a thicker distal radial physis, suggesting that repetitive stress applied to the wrist during gymnastics affects the MR appearance of the forearm. Furthermore several features
BNW_Rik_V1.indd 194
appeared to differ between healthy and physeal injured gymnasts and can therefore be valuable for daily clinical practice; these features included signal intensity of bone marrow edema in the distal radial epiphysis and metaphyses of the distal radius and ulna, and to a lesser extent depth of physeal cartilage intrusions into the metaphysis and thickness of the distal radial physis if compared to the physis of the first metacarpal bone.
Chapters 5, 6 and 7 explore methods to quantify imaging features associated with physeal
stress injuries in the wrist. In Chapter 5 Dixon chemical shift images were used to estimate the
proportion of water signal in the bone marrow of the distal radius and ulna; subsequently the feasibility and clinical utility of this ‘water signal fraction’ as an objective measure of bone marrow edema was tested. In several regions of interest in the distal radial metaphysis, distributed from adjacent to the physis to more proximal, absolute water signal fraction was higher in injured gymnasts compared to gymnasts without clinical symptoms. Furthermore, the metaphyseal water score (the ratio between a region of interest 5-10 mm proximal to the physis and the most proximal ‘reference’ region of interest) was increased in symptomatic gymnasts as well, suggesting the proposed method can be beneficial in the assessment of physeal stress injury in the wrist.
Both chapters 6 and 7 focus on thickness of the distal radial physis as a sign of physeal
stress and utilize segmentations of distal radial physes of 27 symptomatic, 24 asymptomatic and 18 non-gymnasts. In the study portrayed in chapter 6 the segmented physes were transformed
into three-dimensional reconstructions and volume of each physis was quantified. On group level both symptomatic (971 mm3) and asymptomatic (951 mm3) gymnasts had a larger median
physeal volume compared to non-gymnasts (646 mm3). However, largest physeal volumes were
observed in the group symptomatic gymnasts.
Chapter 7 is based on the same distal radial physeal segmentations, but delves into the
spatial distribution of stress-related physeal widening as a result of repetitive wrist-loading in gymnastics. First the healthy non-gymnasts’ physes were analyzed, which showed a thin center and increasing physeal thickness towards the borders. In both gymnasts with and without wrist pain the entire surface was thicker compared to non-gymnasts. Stress-related thickening in the physes of gymnasts with a suspected injury was particularly present at the volar side, suggesting that the volar side is subject to most injurious stresses.
The morphologic and (semi-)quantitative methods explored in this thesis to identify stress-related injuries of the distal radial physis are ready to be validated in a new and larger athletic population involved in wrist-loading. To establish if the proposed methods can be used for other stress-related physeal injuries in the upper extremity as well, clinical value and feasibility of the methods have to be studied in these specific locations. As a first step in this process, Chapter 8
describes a systematic literature review to identify sports in which young athletes are at risk for stress-related injuries and pain in the elbow and shoulder. The results illustrated that incidence of overuse injuries was highest among young athletes involved in tennis, baseball and softball.
196
Chapter 10
Stress-related pain was most prevalent in the elbow in baseball players (17-45%) and in the shoulder in handball- (63%), volleyball- (52%), basketball- (47%) and baseball players (8-32%). Research projects aiming at validating (imaging) methods to identify physeal stress in the elbow and shoulder can concentrate on athletes involved in these sports.
The research in this thesis illustrates that the morphologic and quantitative appearance of the wrist on MR images is affected by repetitive stress in wrist-loading athletes. It redefined the (ab)normal MR appearance of the healthy wrist and identified imaging features affected by wrist-loading and associated with physeal stress. Especially the morphologic AMPHYS protocol is ready to be used in daily clinical practice, however, both morphologic and quantitative methods require further validation in a larger athletic population. This thesis focused on elite-athletes; establishing the value of the described imaging-based methods for accurately identifying injuries of the distal radial physis in recreational athletes as well can augment clinical utility of the proposed methods in daily practice.
Further development of an imaging-based diagnostic strategy can be bidirectional; a future longitudinal study focusing on recovery of injury-associated imaging features can provide valuable insights in the healing process of the physis during periods of rest and thus enable physicians to provide injured athletes with specific information on injury severity and return-to-play time. Furthermore, the differences in the appearance of the distal radius and ulna between injured and healthy wrist-loading athletes can be studied to assess if these changes reflect early pathology and thus facilitate the identification of physeal stress injuries in an earlier stage.
Providing that further validation and development is done, the described imaging methods can be combined with clinical data to provide injured athletes with detailed information on injury status and recovery time.
BNW_Rik_V1.indd 196
