About me

Paul Gerdhem became specialist in Orthopaedics 2000. He defended his thesis titled "Risc factors for falls and fractures in elderly women" 2004 and became associate professor 2005, and adjunct professor in 2019.

He is the head of the section for spinal disorders at the department of reconstructive orthopaedics at the Karolinska University Hospital since 2017.

His clinical work concerns spinal disorders with a special interest in spinal deformities.

He is the principal investigator of three national multicenter studies; on scoliosis and genetics, on conservative treatment for scoliosis, and on thoracolumbar burst fractures. He is a member of the steering committees of the national quality registers Swespine and the Swedish Fracture Register.

He is the former President of the Swedish Society of Spinal Surgeons and the former President of the Nordic Spinal Deformities Society.

Research description

Our research group perform clinical and translational studies that cover fractures, osteoporosis, spinal deformity, degenerative spinal disorders, hip and pelvic disorders, and improvement in surgical techniques. Methodologies include clinical trials, register studies, genetics, bone metabolism, bone density measurements, imaging and navigation. I will here give a summary of my ongoing research. 

Studies on scoliosis 

Spinal deformity affects around 3% of children and adolescents. About one tenth gets an aggressive variant leading to a severe deformity of the spine and thorax. Severe scoliosis leads to pulmonary dysfunction and pain.  

Despite the frequent use of braces to prevent severe scoliosis, evidence for effectiveness of the brace is based on a few studies. Data is especially scarce for braces used only night time compared to full-time brace wear (>20 hours per day). The former have proposed advantages such as better compliance and patient comfort. Postural retraining has been proposed as treatment for scoliosis, but higher quality evidence is lacking.   

Therefore, a randomised controlled trial is performed to compare the result from night time brace treatment, postural retraining and observation in patients with idiopathic scoliosis (clinicaltrials.gov: NCT01761305)18, and all 135 patients have been included into the study. The study is estimated to have come to its first final end-point in 2021. 

The only effective treatment to reduce a scoliotic curve is surgery. My research is also aimed at improving surgical positioning of implants and defining optimal number of implants in scoliosis surgery. We have performed a study with augmented reality navigation, and are now planning a randomized controlled trial. We also participate in another multicenter randomised controlled trial (clinicaltrials.gov: NCT03729947) on the use of postoperative drains in pediatric spine surgery (together with Turku university hospital, Finland).   

The hereditary component of idiopathic scoliosis is well known, but the pathogenesis of scoliosis is poorly understood and it is difficult to early identify those at risk of severe scoliosis. Our aim is to increase understanding of the genetic background in idiopathic scoliosis and to find prognostic markers for scoliosis progression by genetic studies in families, and by examining RNA expression from tissue samples collected from idiopathic scoliosis patients and controls. Significant genes and genetic pathways will be tested in a large already available cohort of patients and controls.  New insights into the aetiology and treatments may give rise to new and more personalised treatment options. The results from the treatment studies and genetic studies could also lead to trials on patients with other causes of spinal deformity.

Spine fractures

The treatment of severe spinal fractures is part of the responsibility of the Karolinska University Hospital. These may occur as single fractures or as part of the injuries sustained during a multi-trauma. The Swedish Fracture register is a relatively new resource headed to improve fracture treatment at a large scale. A first study on the reliability of the spinal fracture classification in the register has been published. A comparative study on surgical techniques and a study on non-surgical treatment are ongoing, which include a comparison on complications of different fracture treatments.  

In a national group we aim to commence large observational and randomized controlled trials using the infrastructure of the Swedish Fracture register, with the aim to involve several of the hospitals now engaged in the Fracture register. Randomized controlled trials on fracture treatment are relatively sparse, especially regarding spinal fractures. Outcome will include patient reported outcome, postoperative wound healing/infection, postoperative thrombo-embolic complications and mortality. The results will improve treatment for patients with spinal trauma.  

In low energy fractures, one of the most important risk factors besides old age is low bone density. The gold standard for bone density measurement is dual energy X-ray absorptiometry (DXA). FRAX (https://www.sheffield.ac.uk/FRAX) is an important and often used web based tool to assess fracture risk. However, it does not incorporate assessment of frailty, function and balance which are important independent risk factors, as shown by my research group. We are now also studying whether volumetric bone density will result in better assessment of fracture risk than the areal density provided by DXA in two longitudinal cohorts. 

Sacro-iliac (SI) joint pain 

Together with Oslo University hospital we have started a randomized sham-controlled trial on minimal invasive sacro-iliac joint stabilisation in the treatment of sacro-iliac joint pain, that will also study effects on the brain of pelvic pain and treatment (clinicaltrials.gov: NCT03507049). 

Sacro-iliac joint pain may be the result of pelvic trauma, pregnancy or degenerative conditions. In recent years, surgical treatment of the sacroiliac joint has again gained popularity. A majority of papers are case series mostly published by the industry or by authors with close connections to the industry, and therefore carrying a risk of being biased.  

The placebo effect after surgery has been shown to be an important factor in short-term efficacy. This has particularly been shown in trials where surgery is aimed at treating chronic pain. In fact, in a meta-analysis, surgery was not better than sham treatment in chronic pain conditions. Since invasive interventions are frequently associated with larger placebo-effects (compared to non-invasive treatments), there is a large risk that surgery trials give biased results unless they include a sham control comparison. Therefore, it is important to determine to what degree the positive effects are due to specific efficacy of the surgical intervention or to non-specific factors such as the placebo effect. Although surgical treatment of the SI- joint has been shown to have effect superior to conservative care, it is still unclear if these effects can be explained by placebo mechanisms. We are therefore undertaking a study that has a placebo comparison group. In total about 60 individuals (30 at Karolinska) with SI-joint pain will be randomized to minimal invasive SI-joint stabilisation or sham surgery. Effects on the brain of pain and treatment are studied with functional MRI as well.   

Studies on degenerative disorders 

Lumbar disc herniation is a common cause of low back and leg pain. When non-surgical treatment fails, surgery gives relief from symptoms for the majority, but as much as one fourth are reporting an unsatisfactory result. We look for the reason for this and study the long term prevalence of disc degeneration and additional surgery after disc herniation and compare our findings to controls. As in the study on sacro-iliac joint pain, functional brain MRI is performed to study long term effects of pain.   

The incidence of surgery for degenerative spinal disorders varies with country, also in the Western world. Between the Nordic countries there is a 30-60% difference in surgical incidence. Using data in three Nordic national spine registers we are studying indications and patient reported outcome after surgery for different degenerative disorders. The variation in incidence seems not associated with outcome differences. In lumbar spinal stenosis a simpler technique generates the same outcome as a more costly and complicated technique.  These findings are similar to others done in my research group;  newer and more complicated techniques have difficulties showing an improved outcome. 

Osteoarthritis is a degenerative condition which affects both the spine and the hip. Most patients with osteoarthritis in the hip undergo non-surgical treatment. When non-surgical treatment is insufficient a total hip replacement can be performed. Concomitant low back pain is common, and about 3% out of all patients who have undergone a total hip replacement also have spinal surgery. Previous reports have suggested poorer outcome (higher dislocation and revision rate) among patients with total hip replacement when both lumbar fusion and total hip replacement have been performed. Together with Ted Eneqvist, Södersjukhuset, Stockholm, data from both the Swedish spine register and hip register will be used to further expand the current knowledge of the hip-spine relationship.  

In an extension of the above project, we will study the relationship between the hip and spine in children with cerebral palsy, who often have hip and spinal deformity problems. Hip migration is seen in 30-60% of the children with more severe cerebral palsy. Whether hip migration/dislocation and spinal deformity are caused by one another or coexistent is debated. By use of the Swedish Spine register and the Cerebral palsy register/follow-up program we hope to disentangle this question.  


Teaching portfolio

Paul Gerdhem is involved in the supervision of undergraduate students at medical school and PhD-students. He was Director/Co-director of PhD-studies at CLINTEC 2008-2017.


Teaching interests

Orthopaedics, osteoporosis, spinal disorders.

Teaching includes supervision of students during theses projects (15-30 credits) and lectures. Paul Gerdhem is the course leader of courses in spinal disorders and basic orthopaedic skills for residents with about 2 courses per year. 

Academic honours, awards and prizes


ASBMR Young Investigator Award (first author of abstract) (American Society for Bone and Mineral Research), September, 2003, in Minneapolis, USA 

John Sevastik Award for best abstract in the category etiology and genetics at the ”International Research Society of Spinal Deformities” in Montreal, Canada, 1-3 juli, 2010 (senior author of abstract) 

Best abstract / Highest ranked abstract among 800 submissions during Eurospine/Spineweek 2012 (senior and presenting author). 

Nominated to best abstract, Nordic SpinalDeformity Society, Oslo 26-28 Aug, 2014 (first and presenting author).  

Best podium presentation / Highest ranked abstract among more than 1000 submissions during Eurospine, Berlin, 5-7 Oct, 2016 (senior author of abstract) 

Nominated to Best abstract presentation during Eurospine, Barcelona, 19-21 Sep, 2018 (as 7 out of more than 1000 submitted abstracts nominated) (senior and presenting author of abstract).  

Co-author of the book “Ortopedi-patofysiologi, sjukdomar och trauma hos barn och vuxna” which was acknowledged as the best textbook 2018 by the publisher “Studentlitteratur”  

Hibbs basic science award at the Scoliosis Research Society, Montreal, Canada, 18-21 Sep, 2019 (co-author of abstract). 

Positions of trust and honor (selected) 

Appointed member of the Doctoral Dissertation committee at the Karolinska Institutet (2010-2016). 

Elected Scientific Secretary of the Swedish Society of Spine Surgeons (2006-2008). 

Elected Vice President of the Swedish Society of Spine Surgeons (2010-2012). 

Elected President of the Swedish Society of Spine Surgeons (2012-2014) 

Member of the steering committee of the Swedish Spine Register (2014-ongoing) 

Member of the steering committee of the Swedish Fracture Register (2014-ongoing) 

Secretary of the Swedish Study Group on Early Onset Scoliosis (2014- ongoing) 

Appointed member of the committee for academic evaluation of physicians applying for a position at the Karolinska University Hospital (2007-2017) 

President of the Nordic Spinal Deformities Society (2017-2019)