BackgroundClinical decision-making around intramuscular tendon injuries of the hamstrings is a controversial topic in sports medicine. For this injury, MRI at return to play (RTP) might improve RTP decision-making; however, no studies have investigated this.ObjectiveOur objectives were to describe MRI characteristics at RTP, to evaluate healing and to examine the association of MRI characteristics at RTP with reinjury for clinically recovered hamstring intramuscular tendon injuries.MethodsWe included 41 athletes with hamstring intramuscular tendon injuries and an MRI at baseline and RTP. For both MRIs, we used a standardised scoring form that included intramuscular tendon injury characteristics. We recorded reinjuries during 1-year follow-up.ResultsAt RTP, 56% of the intramuscular tendons showed a partial or complete thickness tendon discontinuity. Regarding healing from injury to RTP, 18 of 34 (44% overall) partial-thickness tendon discontinuities became continuous and 6 out of 7 (15% overall) complete thickness tendon discontinuities became partial-thickness tendon discontinuities. Waviness decreased from 61% to 12%, and 88% of tendons became thickened. We recorded eight (20%) reinjuries within 1 year. Intramuscular tendon characteristics at RTP between participants with or without a reinjury were similar.ConclusionComplete resolution of an intramuscular tendon injury on MRI is not necessary for clinically successful RTP. From injury to RTP, the intramuscular tendon displayed signs of healing. Intramuscular tendon characteristics of those with or without a reinjury were similar.

Introduction: Malignant hyperthermia (MH) and exertional rhabdomyolysis (ERM) have long been considered episodic phenotypes occurring in response to external triggers in otherwise healthy individuals with variants in RYR1. However, recent studies have demonstrated a clinical and histopathological continuum between patients with RYR1-related congenital myopathies and those with ERM or MH susceptibility. Furthermore, animal studies have shown non-neuromuscular features such as a mild bleeding disorder and an immunological gain-of-function associated with MH/ERM related RYR1 variants raising important questions for further research. Awareness of the neuromuscular disease spectrum and potential multisystem involvement in RYR1-related MH and ERM is essential to optimize the diagnostic work-up, improve counselling and and future treatment strategies for patients affected by these conditions. This study will examine in detail the nature and severity of continuous disease manifestations and their effect on daily life in patients with RYR1-related MH and ERM.Methods: The study protocol consists of four parts; an online questionnaire study, a clinical observational study, muscle imaging, and specific immunological studies. Patients with RYR1-related MH susceptibility and ERM will be included. The imaging, immunological and clinical studies will have a cross-sectional design, while the questionnaire study will be performed three times during a year to assess disease impact, daily living activities, fatigue and pain. The imaging study consists of muscle ultrasound and whole-body magnetic resonance imaging studies. For the immunological studies, peripheral mononuclear blood cells will be isolated for in vitro stimulation with toll-like receptor ligands, to examine the role of the immune system in the pathophysiology of RYR1-related MH and ERM.This study is funded by the Radboudumc Regional Junior Researcher Grant in collaboration with the Canisius Wilhelmina Hospital. The Radboudumc and Canisius Wilhelmina Hospital were not involved in the design of the study and will not be involved in collection, analysis, and interpretation of data and in writing manuscripts.The authors have no conflicts of interest to disclose.Ethics approval and consent to participate: This study protocol was approved by the regional medical ethics committee (CMO Arnhem-Nijmegen, registration number 2020-6251). All study subjects will need to give written informed consent before participation in this study.Data access statement: The datasets generated during and/or analyzed during the present study are available on reasonable request. The authors declare that they have no competing interestsThe datasets generated during and/or analyzed during the present study are available from the corresponding author on reasonable request. Data sharing not applicable to this article as no datasets were generated or analyzed during the present study.

Background SELENON (SEPN1)-related myopathy (SELENON-RM) is a rare congenital myopathy characterized by slowly progressive proximal muscle weakness, early onset spine rigidity and respiratory insufficiency. A muscular dystrophy caused by mutations in the LAMA2 gene (LAMA2-related muscular dystrophy, LAMA2-MD) has a similar clinical phenotype, with either a severe, early-onset due to complete Laminin subunit α2 deficiency (merosin-deficient congenital muscular dystrophy type 1A (MDC1A)), or a mild, childhood- or adult-onset due to partial Laminin subunit α2 deficiency. For both muscle diseases, no curative treatment options exist, yet promising preclinical studies are ongoing. Currently, there is a paucity on natural history data and appropriate clinical and functional outcome measures are needed to reach trial readiness. Methods LAST STRONG is a natural history study in Dutch-speaking patients of all ages diagnosed with SELENON-RM or LAMA2-MD, starting August 2020. Patients have four visits at our hospital over a period of 1.5 year. At all visits, they undergo standardized neurological examination, hand-held dynamometry (age ≥ 5 years), functional measurements, questionnaires (patient report and/or parent proxy; age ≥ 2 years), muscle ultrasound including diaphragm, pulmonary function tests (spirometry, maximal inspiratory and expiratory pressure, sniff nasal inspiratory pressure; age ≥ 5 years), and accelerometry for 8 days (age ≥ 2 years); at visit one and three, they undergo cardiac evaluation (electrocardiogram, echocardiography; age ≥ 2 years), spine X-ray (age ≥ 2 years), dual-energy X-ray absorptiometry (DEXA-)scan (age ≥ 2 years) and full body magnetic resonance imaging (MRI) (age ≥ 10 years). All examinations are adapted to the patient’s age and functional abilities. Correlation between key parameters within and between subsequent visits will be assessed. Discussion Our study will describe the natural history of patients diagnosed with SELENON-RM or LAMA2-MD, enabling us to select relevant clinical and functional outcome measures for reaching clinical trial-readiness. Moreover, our detailed description (deep phenotyping) of the clinical features will optimize clinical management and will establish a well-characterized baseline cohort for prospective follow-up. Conclusion Our natural history study is an essential step for reaching trial readiness in SELENON-RM and LAMA2-MD. Trial registration This study has been approved by medical ethical reviewing committee Region Arnhem-Nijmegen (NL64269.091.17, 2017–3911) and is registered at ClinicalTrial.gov (NCT04478981).

Growth arrest at the secondary growth plate, also known as the acrophysis, is a rare phenomenon with only very few known published case reports. We report on a case of formation of ghost secondary ossification centers at the acrophyses of the knee joint in a 14-year-old female, who survived early childhood acute lymphoblastic leukemia. The patient suffered from severe side effects from both disease and subsequent treatment strategies with a 10-month immobilization period as a consequence at the age of 3 years. The ghost secondary ossification centers were encountered on radiographs and MRI 10 years later, when she presented for evaluation of chronic pain in her left knee related to sports activities, due to a meniscal cyst. Awareness of this phenomenon is nevertheless important, because it seems that endochondral bone growth recovery at the acrophyses might be different from recovery in physes, because we found no concomitant sequelae of growth arrest in the metaphyses.