Cruciate ligament injury : crunching the numbers

Cruciate Ligament (CL) injury is a serious injury that occurs primarily during activities like soccer, handball, floorball, alpine skiing, etc. Patients are generally young and the injury often results in early discontinuation of activity and an early onset of osteoarthritis (OA). The optimal treatment of CL injury is under continuous debate, where surgical reconstruction is recommended for patients engaged in high-level sports. Non-surgical treatment is considered to have a satisfactory outcome in the general population. CL injuries are one of the most studied topics within the field of sports medicine. Over 20,000 articles have been published, however none of these studies have hitherto used a national register-based approach.

The overall aim of this thesis was to study the incidence, treatment and long-term effects of patients with CL injury in Sweden using a register-based approach. The thesis includes four studies, each with a specific aim. The first aim was to calculate the incidence of CL injuries in the general population. Earlier studies have focused on patients at risk or on the reported cases in a smaller geographical setting. Thus, the incidence in the general population has been unknown. For a long time, an argument for CL reconstruction (CL-R) has been that it prevents development of post traumatic OA, however, studies investigating this have presented conflicting results. Therefore, the second aim of this thesis was to study if this argument could be proven using a register-based approach. The third aim was to study what impact socioeconomic status (SES) has on the choice of treatment for these injuries. For other conditions, higher SES has been associated with a higher access to and utilization of surgical treatments, but its effect on patients with CL injury has never been studied. The fourth aim was to study how choice of treatment for a CL injury influenced changes in SES. This approach to create a new alternative outcome for symptomatic surgical procedures is essential in the process to develop new tools and methods for personalized medicine.

This thesis shows that the incidence of CL injury in Sweden is 78 per 100,000 inhabitants. More than 50% of the patients are younger than 30 years and 60% are males. Overall, 36% are treated with surgical reconstruction and this option was more common among younger patients. Preventing post-traumatic OA is not a valid argument for CL-R. On the contrary patients going through surgical reconstruction had a 22% increased risk of developing symptomatic OA compared with those treated non-operatively. Ten percent of the patients developed symptomatic OA, and a concomitant meniscus injury increased this risk threefold. Even though CL-R is done with the aim to create a stable knee, SES had a big impact on which treatment the patient was admitted to. Patients with university education had a 29% increased likelihood of undergoing CL-R compared with those who had not graduated from high-school. The choice of treatment did not significantly affect the salary of a patient five years after injury. However, this thesis presents a multivariate model for an alternative outcome for symptomatic surgery where individual variables, such as socioeconomic outcome variables, are considered. This sets the foundation for future studies about symptomatic surgery, and the creation of decision tools to offer a more personalized treatment.

List of scientific papers

I. Nordenvall R, Bahmanyar S, Adami J, Stenros C, Wredmark T, Felländer-Tsai L. A Population-Based Nationwide Study of Cruciate Ligament Injury in Sweden, 2001-2009: Incidence, Treatment, and Sex Differences. The American Journal of Sports Medicine. 2012 Aug; 40(8), 1808-13.
https://doi.org/10.1177/0363546512449306

II. Nordenvall R, Bahmanyar S, Adami J, Mattila VM, Felländer-Tsai L. Cruciate Ligament Reconstruction and Risk of Knee Osteoarthritis: The Association between Cruciate Ligament Injury and Post-Traumatic Osteoarthritis - A Population-Based Nationwide Study in Sweden, 1987–2009. PLOS one. August 2014, Volume 9, Issue 8, e104681.
https://doi.org/10.1371/journal.pone.0104681

III. Nordenvall R, Marcano AI, Adami J, Palme M, Mattila VM, Bahmanyar S, Felländer-Tsai L. The Impact of Socioeconomic Status on Choice of Treatment for Patients with Cruciate Ligament Injuries in The Knee. The American Journal of Sports Medicine. 2016 Nov 11.
https://doi.org/10.1177/0363546516672651

IV. Nordenvall R, Marcano AI, P Karlsson, Gerdin M, Adami J, Palme M, Mattila VM, Bahmanyar S, Felländer-Tsai L. The Socioeconomic Impact of Treatment for Cruciate Ligament Injuries – A Population-Based Cohort Study of Patients on the Workforce. [Manuscript]