Dr. Carsen is a Pediatric Orthopedic Surgeon, a Mid-Career Clinician-Scientist, and the Director of Research for the Division of Orthopedics at CHEO. He is an Assistant Professor of Surgery at the University of Ottawa with an active academic and research career. His clinical practice is largely focused on sports medicine, knee and hip arthroscopy, and fracture care. His research portfolio includes multi-disciplinary collaborations, focusing on sports injuries of the knee; primarily ACLs, femoroacetabular impingement and hip morphology, as well as orthopedic trauma. He is the Principal Investigator on over 10 studies at CHEO and numerous more both nationally and internationally. Dr. Carsen is the CHEO RI’s Vice Chair of the Investigator Mentorship Program. He also a member of the RI’s Innovation Committee and Scientific and Advisory Leadership Team.
Areas of Research: Hip, Sports Medicine, Bone Health
Burosumab for the treatment of cutaneous-skeletal hypophosphatemia syndrome
Cutaneous-skeletal hypophosphatemia syndrome (CSHS) is a rare bone disorder featuring skeletal and skin manifestations, caused by mosaic somatic activating RAS family pathogenic variants with mosaic effects (Lim et al., 2016). CSHS is characterized by the overproduction of fibroblast growth factor-23 (FGF23), which is secreted by osteocytes in affected dysplastic bones (Ovejero et al., 2023). FGF23 causes inhibition of renal absorption and gastrointestinal absorption of phosphate by lowering sodium phosphate cotransporter activity and limiting 1,25-dihydroxyvitamin D (1,25(OH)2D) synthesis (Lim et al., 2016). Together, these biochemical aberrations result in hypophosphatemia, causing bone pain, rickets, long bone deformity, as well as impaired growth and mobility (Ovejero et al., 2016; Lim et al., 2016). Conventional treatment of CSHS with phosphate supplementation and active vitamin D does not directly address the FGF23 over-expression (Lim et al., 2014). While phosphate supplementation brings about temporary increases in serum phosphorus levels, it also increases FGF23 production, which ultimately perpetuates the renal phosphate-wasting and fails to successfully treat rickets. Burosumab is a fully human monoclonal antibody, given subcutaneously every two weeks in children, that neutralizes FGF23. Burosumab was recently shown to be superior to conventional therapy in a phase 3 randomized controlled trial in children with X-linked hypophosphatemia (XLH), another childhood-onset condition linked to FGF23 overproduction (Imel et al., 2019).
Criteria Used to Determine Unrestricted Return to Activity After ACL Reconstruction in Pediatric and Adolescent Patients: A Systematic Review
Only 14 of the 27 reviewed studies reported using >1 criterion when determining RTA. Furthermore, few studies used patient-reported outcome measures or lower limb kinematics as RTA criteria, indicating that more research is needed to validate these metrics in the pediatric population.
Medial Discoid Meniscus in Children: A Multicenter Case Series of Clinical Features and Operative Results
Patient presentations and treatments for those with discoid medial menisci were similar to those reported for patients with discoid lateral menisci. Knees with discoid medial menisci also demonstrated instability attributed to peripheral insufficiency and posterior tears. Tears were present in over half of knees with discoid medial menisci, and reoperation was more common in knees that underwent repair of tears than those without repair.
Mitigating the Denosumab‑Induced Rebound Phenomenon with Alternating Short‑ and Long‑Acting Anti‑resorptive Therapy in a Young Boy with Severe OI Type V
From “ACAN” to “I CAN”: Restoring wellness in a boy with severe osteochondritis dissecans through diagnostic precision combined with optimal medical, surgical and rehabilitation management
The optimal management of atypical osteochondritis dissecans with multi-joint involvement and other morphological atypia requires multidisciplinary care. The inclusion of comprehensive bone health and metabolism as well as genetic investigations provided important information to help guide treatment in this case.