Knee Injuries Are Associated with Accelerated Knee Osteoarthritis Progression : Data from the Osteoarthritis Initiative

Objective—We aimed to evaluate if a recent knee injury was associated with accelerated knee osteoarthritis (KOA) progression. Methods—In the Osteoarthritis Initiative (OAI) we studied participants free of KOA on their baseline radiographs (Kellgren-Lawrence [KL]<2). We compared three groups: 1) individuals with accelerated progression of KOA: defined as having at least one knee that progressed to endstage KOA (KL Grade 3 or 4) within 48 months, 2) common KOA progression: at least one knee increased in radiographic scoring within 48 months (excluding those defined as accelerated KOA), and 3) no KOA: no change in KL grade in either knee. At baseline, participants were asked if their knees had ever been injured and at each annual visit they were asked about injuries during the prior 12 months. We used multinomial logistic regressions to determine if a new knee injury was associated with the outcome of accelerated KOA or common KOA progression after adjusting for age, sex, body mass index, static knee malalignment, and systolic blood pressure. Results—A knee injury during the total observation period was associated with accelerated KOA progression (n=54, odds ratio [OR]=3.14) but not common KOA progression (n=187, OR=1.08). Furthermore, a more recent knee injury (within a year of the outcome) was associated with accelerated (OR=8.46) and common KOA progression (OR=3.12). Conclusion—Recent knee injuries are associated with accelerated KOA. Most concerning is that certain injuries may be associated with a rapid cascade towards joint failure in less than one year. While knee osteoarthritis is typically a slowly progressive disorder, it has recently been appreciated that 5 to 17% of knees have a rapid progression of structural damage (e.g. from normal to end-stage disease within 4 years) (1, 2). Characterization of the structural aspects of this phenomenon and its risk factors may provide insights into the nature of osteoarthritis progression and allow us to identify an at-risk subset for intervention. Identification of knee osteoarthritis phenotypes, such as those with accelerated knee osteoarthritis progression, may allow us to refine sampling for clinical studies (2-5) and develop interventions targeted at specific subtypes. Corresponding Author: Jeffrey Driban, PhD, ATC, CSCS, Division of Rheumatology, Tufts Medical Center, 800 Washington Street, Box 406, Boston, MA 02111 Phone: 617-636-7449; Fax: 617-636-1542; jdriban@tuftsmedicalcenter.org. The authors have no other conflicts of interest with regard to this work. NIH Public Access Author Manuscript Arthritis Care Res (Hoboken). Author manuscript; available in PMC 2015 November 01. Published in final edited form as: Arthritis Care Res (Hoboken). 2014 November ; 66(11): 1673–1679. doi:10.1002/acr.22359. N IH -P A A uhor M anscript N IH -P A A uhor M anscript N IH -P A A uhor M anscript Individuals with a history of joint trauma are 3 to 6 times more likely to develop knee osteoarthritis (6, 7) and are diagnosed approximately 10 years earlier than individuals without a history of joint trauma (8). Within 5 years of injury, knees have structural changes reflective of altered joint health (e.g., altered cartilage composition, altered bone structure) (9-12). Knee injuries are a strong risk factor for knee osteoarthritis and may distinguish knees with accelerated knee osteoarthritis from common knee osteoarthritis progression or knees with no knee osteoarthritis. We aimed to evaluate if a recent knee injury was associated with accelerated knee osteoarthritis. Furthermore, we conducted preliminary analyses to determine if participants with accelerated knee osteoarthritis progression, common knee osteoarthritis progression, and no knee osteoarthritis differed based on key baseline characteristics, which we selected a priori. These preliminary analyses helped us verify which variables should be adjusted for in our primary analyses. Patients and Methods To assess the association between recent knee injuries and accelerated knee osteoarthritis we used data from the Osteoarthritis Initiative (OAI). The OAI is a multicenter observational cohort study of knee osteoarthritis that collected longitudinal clinical and image data (13) as well as biospecimens from 4,796 participants over an eight-year follow-up period. The primary variables (presence of radiographic knee progression and knee injuries) were from baseline and the first four annual OAI visits (months 0 to 48). OAI data are available for public access (14). Participant Selection Among participants with no baseline radiographic knee osteoarthritis (Kellgren-Lawrence [KL] Grade<2) in either knee (n = 1,930) we evaluated three groups that we defined based on radiographic definitions of OA: 1) accelerated knee osteoarthritis: at least one knee progressed to end-stage knee osteoarthritis (KL Grade 3 or 4) within 48 months, 2) common knee osteoarthritis progression: at least one knee increased in radiographic scoring within 48 months (excluding those defined as accelerated knee osteoarthritis progression), and 3) no knee osteoarthritis: no change in KL grade in either knee at baseline and 48-month followup. We omitted 364 (18.9%) individuals from the analyses because missing radiographic data made it impossible to determine group assignment (19 potential individuals with common knee osteoarthritis progression, 345 potential individuals with no knee osteoarthritis). Self-Reported Knee Injury At baseline, participants were asked during an initial eligibility interview: “Have you ever injured your right knee badly enough to limit your ability to walk for at least two days? ”. A similar question was asked for the left knee. At each annual visit participants were asked “Since your last annual visit to the OAI clinic about 12 months ago, have you injured your right knee badly enough to limit your ability to walk for at least two days? ”. A similar question was asked for the left knee. Among individuals with accelerated or common knee osteoarthritis progression we focused on injuries to the knee that progressed. Among Driban et al. Page 2 Arthritis Care Res (Hoboken). Author manuscript; available in PMC 2015 November 01. N IH -P A A uhor M anscript N IH -P A A uhor M anscript N IH -P A A uhor M anscript individuals with no knee osteoarthritis we evaluated if the participant had a knee injury to either knee. We focused on injuries at 4 time points: 1) prior to the OAI baseline, 2) during the total observation period, 3) within one year of the study outcome, and 4) between 1 and 2 years prior to the study outcome. We defined the study outcome visit for each group as follows: 1) accelerated knee osteoarthritis: the first visit with a KL grade of 3 or 4, 2) common knee osteoarthritis progression: the first visit with an increase in KL grade, and 3) no KOA: the 48-month OAI visit. The total observation period was defined as beginning at the OAI baseline and ending at the visit with the study outcome (ranging from 12 months to 48 months). For example if a participant had a knee with KL=1 at baseline and year one, KL=2 at year 3, and KL=3 at year 4, they would meet criteria for the accelerated group, and year 4 would be the outcome study visit. However, if a participant's knee stayed at KL=2 at 48 months, they would be considered to have common knee osteoarthritis and year 3 would be the study outcome visit. Finally, if the participant stayed at KL=1, then year 4 would be the study outcome visit.