Risk of knee osteoarthritis after different types of knee injuries in young adults: a population-based cohort study

Snoeker BAM, Roemer FW, Turkiewicz A, et al. Br J Sports Med. 2019. [Epub Ahead of Print].

https://www.ncbi.nlm.nih.gov/pubmed/31826861

Take-Home Message

A young adult who sustains a knee injury is almost 6 times more likely to be diagnosed with knee osteoarthritis in the subsequent 11 years than a peer without an injury.

Summary

A knee injury can compromise long-term joint health and greatly affect an individual’s short- and long-term quality of life. While we know that about 1 in 3 people will develop osteoarthritis within the first decade after an anterior cruciate ligament injury, little is known about the occurrence of osteoarthritis after other types of knee injuries. Therefore, Snoeker and colleagues performed a longitudinal cohort, using data from the Skane Health Registry in Sweden, to determine the risk of clinically diagnosed knee osteoarthritis after different types of knee injury compared to individuals without an injury. The authors included people 25 to 34 years of age between 1998 and 2007 with at least one diagnostic code during that time. The 5,247 participants with an injury had a newly diagnosed knee injury between 1999 and 2007. Injuries included ligament injury, meniscal tear, knee contusions, cartilage injury, fracture, dislocation, etc. The authors identified 142,825 people without an injury who had been evaluated by a healthcare professional during the same time period. The onset of knee osteoarthritis was defined based on medical classification codes (ICD-10 code = M17) registered by a physician at least 3 years after a reported injury and up until the year 2017. Average follow-up time for the injured and uninjured groups were 14.5 years and 14 years, respectively. Overall, the rate of diagnosed knee osteoarthritis within the first 11 years after an injury was about 5.7 times greater among people with a knee injury than not. People with an injury developed knee osteoarthritis 7 to 9 months earlier than those without an injury. These findings were fairly consistent among men and women and people older or younger than 30 years at the start of the study. The authors also noted that while all knee injuries increased the risk of knee osteoarthritis, the risk was greatest after a cruciate ligament injury, meniscal tear, a fracture of the proximal tibia or patella, or injury to multiple structures.

Viewpoints

Overall, the authors found that someone with a knee injury is at greater risk of developing knee osteoarthritis over time. Interestingly, this is the first evidence that all types of injuries among young adults increase the risk of knee osteoarthritis; however, the risk is greatest after a cruciate ligament injury, meniscal tear, or fracture. The authors also acknowledged that the difference in disease-free time between injured and uninjured people who develop knee osteoarthritis early in life was less than 1 year. This may indicate that people with osteoarthritis at a young age without an injury may have other strong factors leading to osteoarthritis (e.g., obesity). Unfortunately, the authors lacked key details about each person (e.g., body mass index). While these findings are novel and helpful it remains challenging to know what to tell younger patients in high school or college about their risk of osteoarthritis after an injury since this study only included people over 25 years of age. Despite these limitations, it is important to tell patients with a knee injury that there is consistent evidence in the literature that they maybe 3 to 6 times more like to develop knee osteoarthritis within the first decade after an injury. Based on a figure provided by the authors we can also estimate that we could probably tell patients that at least 1 in 20 patients after a knee injury (except contusions) will be diagnosed with osteoarthritis in the first 11 years after an injury. Hence, we should educate patients about what is osteoarthritis, strategies to reduce their risk, and the importance of reporting joint symptoms to their future healthcare providers.

Questions for Discussion

What do you tell a patient with regard to a knee injury and the long-term health of their joint? How might you see this study influencing that conversation if at all?

Written by: Kyle Harris

Reviewed by: Jeffrey Driban

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