<p>The epidemiology of pelvic and acetabular fractures has been sparsely described and up-to date information on incidence, demographic distributions and treatment are lacking. Surgical treatment of pelvic and acetabular fractures is often considered for patients after high-energy trauma and/or in acetabular fractures with intraarticular incongruency. The surgery is associated with numerous complications, which has not been properly described for unselected cohorts of patients. Further knowledge regarding the healing process after surgical treatment of pelvic fractures is also needed.</p><p>Aim: The aim of this thesis was first to determine the epidemiology of pelvic and acetabular fractures in the Swedish adult population, including the rate of surgical treatment. Second, surgical treatment of both pelvic and acetabular fractures was independently explored to establish rates of complications with particular focus on reoperations. Finally, Computed Tomography Micromotion Analysis was used in the follow-up of surgically treated patients with pelvic fracture. The primary aim here was to investigate the practicability of the method, and secondarily to try to quantify movement in the pelvis during the healing process.</p><p>Methods: The National Patient Register was used to acquire data for the epidemiological analysis (Study I). In the analysis of complications after pelvic and acetabular fracture surgery, all adult patients treated for a pelvic or an acetabular fracture at the Karolinska University Hospital in Stockholm, Sweden during a ten-year period were included (Study II+III). To investigate the usability of Computed Tomography Micromotion Analysis, a prospective clinical study was conducted including ten patients surgically treated for a pelvic fracture. All patients were followed with computed tomography for one year (Study IV).</p><p>Results: The incidence of pelvic and acetabular fractures increased from 64 to 80 per 100,000 person-years in the Swedish adult population from 2001 to 2016. 2% of all pelvic fractures were surgically treated, compared to 15% for acetabular fractures. The rate of surgical treatment was higher for males (Study I).</p><p>A total of 194 patients with surgically treated pelvic fractures and 229 patients with surgically treated acetabular fractures with a median follow-up of 4.9 years were analysed. For the pelvic fracture patients, the rate of reoperation was 25% with infection being the most common cause of reoperation. In the acetabular fracture cohort, reoperation rate was 21%, with arthrosis as the most common indication. Surgical treatment with primary Total Hip Arthroplasty was associated with a reduced risk for reoperation, as was male gender, for the acetabular fracture patients (Study II+III). The follow-up of surgically treated pelvic fracture patients with Computed Tomography Micromotion Analysis demonstrated largest movement between 0-6 weeks postoperatively, with reduced movement thereafter (Study IV).</p><p>Conclusions: The incidence of pelvic and acetabular fractures increased markedly during 2001-2016, indicating a potential upsurge of patients in need of treatment. Reasons for this increase remains unclear but cannot solely be attributed to an ageing population. Surgical treatment of pelvic and acetabular fractures was associated with a high risk of reoperation and other subsequent complications, and measures need to be taken to try to reduce this risk. Gender discrepancies seemed to exist, both regarding rate of surgical treatment but also possibly in risk of reoperation after acetabular fracture surgery. These differences need further scrutiny. Computed Tomography Micromotion Analysis was a valid tool for investigating motion in the pelvis after surgical treatment of pelvic fracture patients. This method has potential to aid in the determination of fracture healing.</p><h3>List of scientific papers</h3><p>I. Lundin N, Huttunen TT, Enocson A, Marcano AI, Felländer-Tsai L, Berg HE. Increasing incidence of pelvic and acetabular fractures. A nationwide study of 87,308 fractures over a 16-year period in Sweden. Injury. 2021;52(6):1410-1417. <br><a href="https://doi.org/10.1016/j.injury.2021.03.013">https://doi.org/10.1016/j.injury.2021.03.013</a><br><br> </p><p>II. Lundin N, Enocson A. Complications after surgical treatment of pelvic fractures: a five year follow-up of 194 patients. Eur J Orthop Surg Traumatol. 2022. Published online 10 February 2022. <br><a href="https://doi.org/10.1007/s00590-022-03215-0">https://doi.org/10.1007/s00590-022-03215-0</a><br><br> </p><p>III. Lundin N, Berg HE, Enocson A. Complications after surgical treatment of acetabular fractures: a 5-year follow-up of 229 patients. Eur J Orthop Surg Traumatol. 2022. Published online 20 May 2022. <br><a href="https://doi.org/10.1007/s00590-022-03284-1">https://doi.org/10.1007/s00590-022-03284-1</a><br><br> </p><p>IV. Lundin N, Olivecrona H, Bakhshayesh P, Gordon Murkes L, Enocson A. Computed Tomography Micromotion Analysis in the follow-up of patients with surgically treated pelvic fractures – A prospective clinical study. Eur J Orthop Surg Traumatol. 2023. Published online 14 April 2023. <br><a href="https://doi.org/10.1007/s00590-023-03542-w">https://doi.org/10.1007/s00590-023-03542-w</a><br><br> </p>