Sasha Carsen

Scientist, CHEO Research Institute

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

Research Projects

  1. How Is Variability in Femoral and Acetabular Version Associated With Presentation Among Young Adults With Hip Pain?


    Based on the central acetabular version and femoral version as measured by Murphy, hips were grouped according to their rotational profile into four groups: unstable rotational profile: high (high acetabular version with high femoral version) or moderate (high acetabular version with normal femoral version or normal acetabular version with high femoral version); normal rotational profile (normal acetabular version with femoral version); compensatory rotational profile (low acetabular version with high femoral version or high acetabular version with low femoral version); and impingement rotational profile (low acetabular version with low femoral version): high (low acetabular version with low femoral version) or moderate (low acetabular version with normal femoral version or normal acetabular version with low femoral version). Radiographic assessments were manually performed on digitized images by two orthopaedic residents, and 25% of randomly selected measurements were repeated by the senior author, a fellowship-trained hip preservation and arthroplasty surgeon. Interobserver and intraobserver reliabilities were calculated using the correlation coefficient with a two-way mixed model, showing excellent agreement for Murphy technique measurements (intraclass correlation coefficient 0.908 [95% confidence interval 0.80 to 0.97]) and Reikerås technique measurements (ICC 0.938 [95% CI 0.81 to 0.97]). Patient-reported measures were recorded using the International Hip Outcome Tool (iHOT-33) (0 to 100; worse to best).

  2. The evolving role and technique of hip arthroscopy in children and adolescents


    Hip arthroscopy has come a long way from the initial description of the endoscopic visualization of the hip joint nearly a century ago. The development of pediatric and adolescent hip arthroscopy has largely paralleled, and trailed shortly behind, the recent growth and technical development in adult hip arthroscopy over the last twenty years. In the adult or general literature, large randomized controlled trials, observational cohorts, and national registries have made hip arthroscopy one of the most closely studied surgical techniques in orthopaedics, and have demonstrated that hip arthroscopy provides efficacy and clinically important benefit in specific indications. Although similar evidence is not yet available for pediatric and adolescent patients, the growing experience and opportunity in the area have led to incredible development in the field and further embrace of hip arthroscopy as a surgical tool and technique with important pediatric impact and even more so future potential.

  3. Predictors of True Scaphoid Fractures in Children


    This study is a retrospective cohort study of children presenting to a tertiary pediatric hospital with hand or wrist injuries. Patients were grouped based on the presence of a true scaphoid fractures (confirmed on imaging) or those with clinical suspicion of a scaphoid fracture alone (no radiographic evidence of fracture). Demographic and clinical characteristics were compared with univariate and multivariate statistics to identify fracture predictors.

  4. 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).

  5. 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.