Knee cartilage change on magnetic resonance imaging: Should we lump or split topographical regions? A 2-year study of data from the osteoarthritis initiative.

OBJECTIVE: We challenge the paradigm that a simplistic approach evaluating anatomic regions (e.g., medial femur or tibia) is ideal for assessing articular cartilage loss on magnetic resonance (MR) imaging. We used a data-driven approach to explore whether specific topographical locations of knee cartilage loss may identify novel patterns of cartilage loss over time that current assessment strategies miss. DESIGN: We assessed 60 location-specific measures of articular cartilage on a sample of 99 knees with baseline and 24-month MR images from the Osteoarthritis Initiative, selected as a group with a high likelihood to change. We performed factor analyses of the change in these measures in two ways: (1) summing the measures to create one measure for each of the six anatomically regional-based summary (anatomic regions; e.g., medial tibia) and (2) treating each location separately for a total of 60 measures (location-specific measures). RESULTS: The first analysis produced three factors accounting for 66% of the variation in the articular cartilage changes that occur over 24 months of follow-up: (1) medial tibiofemoral, (2) medial and lateral patellar, and (3) lateral tibiofemoral. The second produced 20 factors accounting for 75% of the variance in cartilage changes. Twelve factors only involved one anatomic region. Five factors included locations from adjoining regions (defined by the first analysis; e.g., medial tibiofemoral). Three factors included articular cartilage loss from disparate locations. CONCLUSIONS: Novel patterns of cartilage loss occur within each anatomic region and across these regions, including in disparate regions. The traditional anatomic regional approach is simpler to implement and interpret but may obscure meaningful patterns of change.

The Prognostic Potential of End-Stage Knee Osteoarthritis and Its Components to Predict Knee Replacement: Data From the Osteoarthritis Initiative.

OBJECTIVE: We aimed to determine how 2 definitions of end-stage knee osteoarthritis (esKOA) and each component (knee symptoms, persistent knee pain, radiographic severity, and presence of limited mobility or instability) related to future knee replacement (KR). METHODS: We performed knee-based analyses of Osteoarthritis Initiative data from baseline to the first 4 annual follow-up visits, and data on KR from baseline until the fifth yearly contact. We calculated a base model using common risk factors for KR in logistic regression models with generalized estimating equations. We assessed model performance with area under the receiver-operating characteristic curve (AUC) and Hosmer-Lemeshow test. We then added esKOA or each component from the visit (< 12 months) before a KR and change in the year before a KR. We calculated the net reclassification improvement (NRI) index and the integrated discrimination improvement (IDI) index. RESULTS: Our sample was mostly female (58%), ≥ 65 years old, White (82%), and without radiographic knee osteoarthritis (50%). At the visit before a KR, Kellgren-Lawrence (KL) grades (ordinal scale; AUC 0.88, NRI 1.12, IDI 0.11), the alternate definition of esKOA (AUC 0.84, NRI 1.16, IDI 0.12), and a model with every component of esKOA (AUC 0.91, NRI 1.30, IDI 0.17) had the best performances. During the year before a KR, change in esKOA status (alternate definition) had the best performance (AUC 0.86, NRI 1.24, IDI 0.12). CONCLUSION: Radiographic severity may be a screening tool to find a knee that will likely receive a KR. However, esKOA may be an ideal outcome in clinical trials because a change in esKOA state predicts future KR.

Increased risk of incident knee osteoarthritis in those with greater work-related physical activity.

OBJECTIVE: Occupations involving greater physical activity may increase risk for knee osteoarthritis (OA). Existing studies have not evaluated work-related physical activity before OA onset. Hence, we aimed to evaluate the association between work-related physical activity and knee OA incidence. METHODS: We performed a person-based longitudinal study using Osteoarthritis Initiative (OAI) data among people who volunteered or worked for pay without baseline radiographic knee OA or knee pain. Bilateral knee radiographs were obtained at baseline and annual follow-ups. We defined radiographic OA as Kellgren-Lawrence grade ≥2. Questions from the Physical Activity Scale for the Elderly at baseline and annual OAI visits provided information about work-related physical activity level and hours. We performed logistic regression with work-related physical activity level ( mainly sitting , standing and some walking , walking while handling some materials ) and hours as predictors. The outcome was incident person-based radiographic OA within the ensuing 12 months, over 48 months. RESULTS: Among 951 participants (2819 observations), higher work-related physical activity levels had greater adjusted ORs for incident radiographic OA (people with jobs with standing and some walking : 1.11 (0.60-2.08), and walking while handling some materials : 1.90 (1.03-3.52), when compared with those with mainly sitting work-related activity ). There was no association between number of hours worked and incident radiographic OA. CONCLUSIONS: People performing work that require walking while handling some materials have greater odds of incident knee OA than those with jobs mostly involving sitting. Strategies are needed to mitigate risk factors predisposing them to radiographic OA.

A novel approach to studying early knee osteoarthritis illustrates that bilateral medial tibiofemoral osteoarthritis is a heritable phenotype: an offspring study.

To assess the potential of studying offspring of people with and without knee osteoarthritis to understand the risk factors and heritability for knee osteoarthritis. We selected two groups of Osteoarthritis Initiative (OAI) participants from one clinical site: (1) participants with bilateral radiographic medial tibiofemoral osteoarthritis and (2) those without tibiofemoral osteoarthritis. We then invited biological offspring ≥ 18 years old to complete an online survey that inquired about osteoarthritis risk factors and symptoms. Among the survey respondents, we recruited ten offspring of members from each group for a clinic visit with bilateral knee posterior-anterior radiographs and magnetic resonance imaging of the right knee. We established contact with 269/413 (65%) eligible OAI participants. Most (227/269, 84%) had ≥ 1 eligible biological offspring, and 213 (94%) were willing to share information about the new family study with their offspring. Our survey was completed by 188 offspring from 110 OAI participants: mean age of 43.0 (10.4) years, mean body mass index of 23.7 (5.9) kg/m2, 65% female. Offspring obesity (OR = 2.7, 95% CI 1.0-7.3), hypertension (OR = 3.7, 95% CI 1.2-11.3), and Heberden's nodes (OR = 3.6, 95% CI 1.0-13.2) were associated with parental osteoarthritis status; however, adjusted models were not statistically significant. Radiographic tibiofemoral osteoarthritis (16/18 knees vs. 2/20 knees) and meniscal abnormalities (7/9 vs. 2/10 index knees) were more common among offspring with parental osteoarthritis status than not. We established the potential of a novel offspring study design within the OAI, and our results are consistent with bilateral radiographic medial tibiofemoral osteoarthritis being a heritable phenotype of osteoarthritis.

The incidence and characteristics of accelerated knee osteoarthritis among women: the Chingford cohort.

BACKGROUND: Prior research on accelerated knee osteoarthritis (AKOA) was primarily confined to the Osteoarthritis Initiative, which was enriched with people with risk factors for knee osteoarthritis (KOA). It is unclear how often AKOA develops in a community-based cohort and whether we can replicate prior findings from the Osteoarthritis Initiative in another cohort. Hence, we determined the incidence and characteristics of AKOA among women in the Chingford Study, which is a prospective community-based cohort. METHODS: The Chingford Study had 1003 women with quinquennial knee radiographs over 15 years. We divided the 15-year observation period into three consecutive 5-year phases. Within each 5-year phase, we selected 3 groups of participants among women who started a phase without KOA (Kellgren-Lawrence [KL] < 2): 1) incident AKOA developed KL grade ≥ 3, 2) typical KOA increased radiographic scoring (excluding AKOA), and 3) no KOA had the same KL grade over time. Study staff recorded each participant's age, body mass index (BMI), and blood pressure at baseline, 5-year, and 10-year study visits. We used multinomial logistic regression models to test the association between groups (outcome) and age, BMI, and blood pressure at the start of each phase. The cumulative incidences and odds ratios (OR) from each phase were pooled using a fixed-effect meta-analysis model. RESULTS: The person-based cumulative incidence of AKOA was 3.9% over 5 years (pooled estimate across the three 5-year phases). Among incident cases of KOA, AKOA represented ~ 15% of women with incident KOA. Women with AKOA were older than those with typical (OR = 1.56, 95%CI = 1.16-2.11) or no KOA (OR = 1.84, 95%CI = 1.40-2.43). Women with AKOA had a greater BMI than those without KOA (OR = 1.52, 95%CI = 1.17-1.97). We observed no association between group and blood pressure. CONCLUSIONS: In a community-based cohort, > 1 in 7 women with incident KOA had AKOA. Like the Osteoarthritis Initiative, people with AKOA were more likely to have greater age and BMI.

Composite quantitative knee structure metrics predict the development of accelerated knee osteoarthritis: data from the osteoarthritis initiative.

BACKGROUND: We aimed to determine if composite structural measures of knee osteoarthritis (KOA) progression on magnetic resonance (MR) imaging can predict the radiographic onset of accelerated knee osteoarthritis. METHODS: We used data from a nested case-control study among participants from the Osteoarthritis Initiative without radiographic KOA at baseline. Participants were separated into three groups based on radiographic disease progression over 4 years: 1) accelerated (Kellgren-Lawrence grades [KL] 0/1 to 3/4), 2) typical (increase in KL, excluding accelerated osteoarthritis), or 3) no KOA (no change in KL). We assessed tibiofemoral cartilage damage (four regions: medial/lateral tibia/femur), bone marrow lesion (BML) volume (four regions: medial/lateral tibia/femur), and whole knee effusion-synovitis volume on 3 T MR images with semi-automated programs. We calculated two MR-based composite scores. Cumulative damage was the sum of standardized cartilage damage. Disease activity was the sum of standardized volumes of effusion-synovitis and BMLs. We focused on annual images from 2 years before to 2 years after radiographic onset (or a matched time for those without knee osteoarthritis). To determine between group differences in the composite metrics at all time points, we used generalized linear mixed models with group (3 levels) and time (up to 5 levels). For our prognostic analysis, we used multinomial logistic regression models to determine if one-year worsening in each composite metric change associated with future accelerated knee osteoarthritis (odds ratios [OR] based on units of 1 standard deviation of change). RESULTS: Prior to disease onset, the accelerated KOA group had greater average disease activity compared to the typical and no KOA groups and this persisted up to 2 years after disease onset. During a pre-radiographic disease period, the odds of developing accelerated KOA were greater in people with worsening disease activity [versus typical KOA OR (95% confidence interval [CI]): 1.58 (1.08 to 2.33); versus no KOA: 2.39 (1.55 to 3.71)] or cumulative damage [versus typical KOA: 1.69 (1.14 to 2.51); versus no KOA: 2.11 (1.41 to 3.16)]. CONCLUSIONS: MR-based disease activity and cumulative damage metrics may be prognostic markers to help identify people at risk for accelerated onset and progression of knee osteoarthritis.

Risk factors and the natural history of accelerated knee osteoarthritis: a narrative review.

BACKGROUND: Osteoarthritis is generally a slowly progressive disorder. However, at least 1 in 7 people with incident knee osteoarthritis develop an abrupt progression to advanced-stage radiographic disease, many within 12 months. We summarize what is known - primarily based on findings from the Osteoarthritis Initiative - about the risk factors and natural history of accelerated knee osteoarthritis (AKOA) - defined as a transition from no radiographic knee osteoarthritis to advanced-stage disease < 4 years - and put these findings in context with typical osteoarthritis (slowly progressing disease), aging, prior case reports/series, and relevant animal models. Risk factors in the 2 to 4 years before radiographic manifestation of AKOA (onset) include older age, higher body mass index, altered joint alignment, contralateral osteoarthritis, greater pre-radiographic disease burden (structural, symptoms, and function), or low fasting glucose. One to 2 years before AKOA onset people often exhibit rapid articular cartilage loss, larger bone marrow lesions and effusion-synovitis, more meniscal pathology, slower chair-stand or walking pace, and increased global impact of arthritis than adults with typical knee osteoarthritis. Increased joint symptoms predispose a person to new joint trauma, which for someone who develops AKOA is often characterized by a destabilizing meniscal tear (e.g., radial or root tear). One in 7 people with AKOA onset subsequently receive a knee replacement during a 9-year period. The median time from any increase in radiographic severity to knee replacement is only 2.3 years. Despite some similarities, AKOA is different than other rapidly progressive arthropathies and collapsing these phenomena together or extracting results from one type of osteoarthritis to another should be avoided until further research comparing these types of osteoarthritis is conducted. Animal models that induce meniscal damage in the presence of other risk factors or create an incongruent distribution of loading on joints create an accelerated form of osteoarthritis compared to other models and may offer insights into AKOA. CONCLUSION: Accelerated knee osteoarthritis is unique from typical knee osteoarthritis. The incidence of AKOA in the Osteoarthritis Initiative and Chingford Study is substantial. AKOA needs to be taken into account and studied in epidemiologic studies and clinical trials.

Effusion-synovitis and infrapatellar fat pad signal intensity alteration differentiate accelerated knee osteoarthritis.

OBJECTIVES: To determine whether greater effusion-synovitis volume and infrapatellar fat pad (IFP) signal intensity alteration differentiate incident accelerated knee OA (KOA) from a gradual onset of KOA or no KOA. METHODS: We classified three sex-matched groups of participants in the Osteoarthritis Initiative who had a knee with no radiographic KOA at baseline (recruited 2004-06; Kellgren-Lawrence <2; n = 125/group): accelerated KOA: ⩾1 knee progressed to Kellgren-Lawrence grade ⩾3 within 48 months; common KOA: ⩾1 knee increased in radiographic scoring within 48 months; and no KOA: both knees had the same Kellgren-Lawrence grade at baseline and 48 months. The observation period included up to 2 years before and after when the group criteria were met. Two musculoskeletal radiologists reported presence of IFP signal intensity alteration and independent readers used a semi-automated method to segment effusion-synovitis volume. We used generalized linear mixed models with group and time as independent variables, as well as testing a group-by-time interaction. RESULTS: Starting at 2 years before disease onset, adults who developed accelerated KOA had greater effusion-synovitis volume than their peers (accelerated KOA: 11.94 ± 0.90 cm3, KOA: 8.29 ± 1.19 cm3, no KOA: 8.14 ± 0.90 cm3) and have greater odds of having IFP signal intensity alteration than those with no KOA (odds ratio = 2.07, 95% CI = 1.14-3.78). Starting at 1 year prior to disease onset, those with accelerated KOA have greater than twice the odds of having IFP signal intensity alteration than those with common KOA. CONCLUSION: People with IFP signal intensity alteration and/or greater effusion-synovitis volume in the absence of radiographic KOA may be at high risk for accelerated KOA, which may be characterized by local inflammation.

Early pre-radiographic structural pathology precedes the onset of accelerated knee osteoarthritis.

BACKGROUND: Accelerated knee osteoarthritis (AKOA) is characterized by more pain, impaired physical function, and greater likelihood to receive a joint replacement compared to individuals who develop the typical gradual onset of disease. Prognostic tools are needed to determine which structural pathologies precede the development of AKOA compared to individuals without AKOA. Therefore, the purpose of this manuscript was to determine which pre-radiographic structural features precede the development of AKOA. METHODS: The sample comprised participants in the Osteoarthritis Initiative (OAI) who had at least one radiographically normal knee at baseline (Kellgren-Lawrence [KL] grade < 1). Participants were classified into 2 groups based on radiographic progression from baseline to 48 months: AKOA (KL grade change from < 1 to > 3) and No AKOA. The index visit was the study visit when participants met criteria for AKOA or a matched timepoint for those who did not develop AKOA. Magnetic resonance (MR) images were assessed for 12 structural features at the OAI baseline, and 1 and 2 years prior to the index visit. Separate logistic regression models (i.e. OAI baseline, 1 and 2 years prior) were used to determine which pre-radiographic structural features were more likely to antedate the development of AKOA compared to individuals not developing AKOA. RESULTS: At the OAI baseline visit, degenerative cruciate ligaments (Odds Ratio [OR] = 2.2, 95% Confidence Interval [CI] = 1.3,3.5), infrapatellar fat pad signal intensity alteration (OR = 2.0, 95%CI = 1.2,3.2), medial/lateral meniscal pathology (OR = 2.1/2.4, 95%CI = 1.3,3.4/1.5,3.8), and greater quantitative knee effusion-synovitis (OR = 2.2, 95%CI = 1.4,3.4) were more likely to antedate the development of AKOA when compared to those that did not develop AKOA. These results were similar at one and two years prior to disease onset. Additionally, medial meniscus extrusion at one year prior to disease onset (OR = 3.5, 95%CI = 2.1,6.0) increased the likelihood of developing AKOA. CONCLUSIONS: Early ligamentous degeneration, effusion/synovitis, and meniscal pathology precede the onset of AKOA and may be prognostic biomarkers.

Accelerated knee osteoarthritis is associated with pre-radiographic degeneration of the extensor mechanism and cruciate ligaments: data from the Osteoarthritis Initiative.

BACKGROUND: To determine if adults with incident accelerated knee osteoarthritis (KOA) are more likely to have degenerative knee ligaments or tendons compared to individuals with typical or no KOA. METHODS: We identified 3 sex-matched groups among Osteoarthritis Initiative participants who had a knee without radiographic KOA at baseline (Kellgren-Lawrence [KL] < 2): 1) accelerated KOA: at least 1 knee had KL grade ≥ 3 in ≤48 months, 2) typical KOA: at least 1 knee increased in radiographic scoring within 48 months, 3) no KOA: both knees had the same KL grade at baseline and 48 months. We evaluated knee magnetic resonance images up to 2 years before and after a visit when the accelerated or typical KOA criteria were met (index visit). Radiologists reported degenerative signal changes for cruciate and collateral ligaments, and extensor mechanism and proximal gastrocnemius tendons. We used generalized linear mixed models with 2 independent variables: group and time. RESULTS: Starting at least 2 years before onset, adults with accelerated KOA were twice as likely to have degenerative cruciate ligaments than no KOA (odds ratio = 2.10, 95% CI = 1.18, 3.74). A weaker association (not statistically significant) was detected for adults with accelerated versus typical KOA (OR = 1.72, 95%CI = 0.99, 3.02). Regardless of time, adults with accelerated (odds ratio = 2.13) or typical KOA (odds ratio = 2.16) were twice as likely to have a degenerative extensor mechanism than no KOA. No other structural features were statistically significant. CONCLUSIONS: Degenerative cruciate ligaments or extensor mechanism antedate radiographic onset of accelerated KOA. Hence, knee instability may precede accelerated KOA, which might help identify patients at high-risk for accelerated KOA and novel prevention strategies.

Diffuse tibiofemoral cartilage change prior to the development of accelerated knee osteoarthritis: Data from the osteoarthritis initiative.

We compared the spatial distribution of tibiofemoral cartilage change between individuals who will develop accelerated knee osteoarthritis (KOA) versus typical onset of KOA prior to the development of radiographic KOA. We conducted a longitudinal case-control analysis of 129 individuals from the Osteoarthritis Initiative. We assessed the percent change in tibiofemoral cartilage on magnetic resonance images at 36 informative locations from 2 to 1 year prior to the development of accelerated (n = 44) versus typical KOA (n = 40). We defined cartilage change in the accelerated and typical KOA groups at 36 informative locations based on thresholds of cartilage percent change in a no KOA group (n = 45). We described the spatial patterns of cartilage change in the accelerated KOA and typical KOA groups and performed a logistic regression to determine if diffuse cartilage change (predictor; at least half of the tibiofemoral regions demonstrating change in multiple informative locations) was associated with KOA group (outcome). There was a non-significant trend that individuals with diffuse tibiofemoral cartilage change were 2.2 times more likely to develop accelerated knee OA when compared with individuals who develop typical knee OA (OR [95% CI] = 2.2 [0.90-5.14]. Adults with accelerated or typical KOA demonstrate heterogeneity in spatial distribution of cartilage thinning and thickening. These results provide preliminary evidence of a different spatial pattern of cartilage change between individuals who will develop accelerated versus typical KOA. These data suggest there may be different mechanisms driving the early structural disease progression between accelerated versus typical KOA. Clin. Anat. 32:369-378, 2019. © 2018 Wiley Periodicals, Inc.

Association of subchondral bone texture on magnetic resonance imaging with radiographic knee osteoarthritis progression: data from the Osteoarthritis Initiative Bone Ancillary Study.

OBJECTIVES: To assess whether initial or 12-18-month change in magnetic resonance imaging (MRI) subchondral bone texture is predictive of radiographic knee osteoarthritis (OA) progression over 36 months. METHODS: This was a nested case-control study including 122 knees/122 participants in the Osteoarthritis Initiative (OAI) Bone Ancillary Study, who underwent MRI optimised for subchondral bone assessment at either the 30- or 36-month and 48-month OAI visits. Case knees (n = 61) had radiographic OA progression between the 36- and 72-month OAI visits, defined as ≥ 0.7 mm minimum medial tibiofemoral radiographic joint space (minJSW) loss. Control knees (n = 61) without radiographic OA progression were matched (1:1) to cases for age, sex, body mass index and initial medial minJSW. Texture analysis was performed on the medial femoral and tibial subchondral bone. We assessed the association of texture features with radiographic progression by creating a composite texture score using penalised logistic regression and calculating odds ratios. We evaluated the predictive performance of texture features for predicting radiographic progression using c-statistics. RESULTS: Initial (odds ratio [95% confidence interval] = 2.13 [1.41-3.40]) and 12- 18-month change (3.76 [2.04-7.82]) texture scores were significantly associated with radiographic OA progression. Combinations of texture features were significant predictors of radiographic progression using initial (c-statistic [95% confidence interval] = 0.65 [0.64-0.65], p = 0.003) and 12-18-month change (0.68 [0.68-0.68], p < 0.001) data. CONCLUSIONS: Initial and 12-18-month changes in MRI subchondral bone texture score were significantly associated with radiographic progression at 36 months, with better predictive performance for 12-18-month change in texture. These results suggest that texture analysis may be a useful biomarker of subchondral bone in OA. KEY POINTS: • Subchondral bone MRI texture analysis is a promising knee osteoarthritis imaging biomarker. • In this study, subchondral bone texture was associated with knee osteoarthritis progression. • This demonstrates predictive and concurrent validity of MRI subchondral bone texture analysis. • This method may be useful in clinical trials with interventions targeting bone.

Inflammation and glucose homeostasis are associated with specific structural features among adults without knee osteoarthritis: a cross-sectional study from the osteoarthritis initiative.

BACKGROUND: Greater age and body mass index are strong risk factors for osteoarthritis (OA). Older and overweight individuals may be more susceptible to OA because these factors alter tissue turnover in menisci, articular cartilage, and bone via altered glucose homeostasis and inflammation. Understanding the role of inflammation and glucose homeostasis on structural features of early-stage OA may help identify therapeutic targets to delay or prevent the onset of OA among subsets of adults with these features. We examined if serum concentrations of glucose homeostasis (glucose, glycated serum protein [GSP]) or inflammation (C-reactive protein [CRP]) were associated with prevalent knee bone marrow lesions (BMLs) or effusion among adults without knee OA. METHODS: We conducted a cross-sectional study using baseline data from the Osteoarthritis Initiative. We selected participants who had no radiographic knee OA but were at high risk for knee OA. Blinded staff conducted assays for CRP, GSP, and glucose. Readers segmented BML volume and effusion using semi-automated programs. Our outcomes were prevalent BML (knee with a BML volume > 1 cm3) and effusion (knee with an effusion volume > 7.5 cm3). We used logistic regression models with CRP, GSP, or glucose concentrations as the predictors. We adjusted for age, sex, body mass index (BMI), and Physical Activity Scale for the Elderly (PASE) scores. RESULTS: We included 343 participants: mean age = 59 ± 9 years, BMI = 27.9 ± 4.5 kg/m2, PASE score = 171 ± 82, and 64% female. Only CRP was associated with BML prevalence (odds ratio [OR] = 1.43, 95% confidence interval [CI] = 1.09 to 1.87). For effusion, we found an interaction between BMI and CRP: only among adults with a BMI <25 kg/m2 was there a significant trend towards a positive association between CRP and effusion (OR = 1.40, 95% CI = 1.00 to 1.97). We detected a U-shaped relationship between GSP and effusion prevalence. Fasting glucose levels were not significantly associated with the presence of baseline effusion or BML. CONCLUSIONS: Among individuals without knee OA, CRP may be related to the presence of BMLs and effusion among normal weight individuals. Abnormal GSP may be associated with effusion. Future studies should explore whether inflammation and glucose homeostasis are predictive of symptomatic knee OA.

Characterizing the distinct structural changes associated with self-reported knee injury among individuals with incident knee osteoarthritis: Data from the osteoarthritis initiative.

We aimed to characterize the agreement between distinct structural changes on magnetic resonance (MR) imaging and self-reported injury in the 12 months leading to incident common or accelerated knee osteoarthritis (KOA). We conducted a descriptive study using data from baseline and the first 4 annual visits of the Osteoarthritis Initiative. Knees had no radiographic KOA at baseline (Kellgren-Lawrence [KL]<2). We classified two groups: (1) accelerated KOA: a knee developed advanced-stage KOA (KL = 3 or 4) within 48 months and (2) common KOA: a knee increased in radiographic severity (excluding those with accelerated KOA). Adults were 1:1 matched based on sex. The index visit was when a person met the accelerated or common KOA criteria. We limited our sample to people with MR images and self-reported injury data at index visit and year prior. Among 226 people, we found fair agreement between self-reported injuries and distinct structural changes (kappa = 0.24 to 0.31). Most distinct structural changes were medial meniscal pathology. No distinct structural changes (e.g., root or radial tears) appeared to differ between adults who reported or did not report an injury; except, all subchondral fractures occurred in adults who developed accelerated KOA and reported an injury. While there is fair agreement between self-reported knee injuries and distinct structural changes, there is some discordance. Self-reported injury may represent a different construct from distinct structural changes that occur after joint trauma. Clin. Anat. 31:330-334, 2018. © 2018 Wiley Periodicals, Inc.

A single recent injury is a potent risk factor for the development of accelerated knee osteoarthritis: data from the osteoarthritis initiative.

We examined the association between previously reported modifiable risk factors for accelerated knee osteoarthritis (AKOA) at the Osteoarthritis Initiative's (OAI) baseline and 48-month visits among adults who develop AKOA between the 48- and 96-month visits. We conducted a case-control study using data from the OAI baseline to the 96-month visit. Participants had no radiographic knee osteoarthritis (KOA) in the index knee at OAI baseline and 48-month visits [Kellgren-Lawrence (KL) <2]. We classified 2 groups: (1) AKOA: >1 knee developed advance-stage KOA (KL = 3 or 4) between 48- and 96-month visits and (2) No KOA: no KOA and no change in radiographic severity bilaterally over 96 months. We used logistic regression models to evaluate the association between the outcome of AKOA (versus no KOA) and several modifiable risk factors collected at OAI baseline and 48-month visits [body mass index (BMI), systolic blood pressure, comorbidity score, and NSAID use]. We also explored a new injury from baseline to 48 months and from 48- to 96 months. Adults with greater baseline and 48-month BMI were more likely to develop AKOA. Injury was only associated with AKOA onset when it occurred within 4 years of developing AKOA [prior 2 years: odds ratio = 6.21; 95% confidence interval (CI) 3.40, 11.35; 2-4 years prior: odds ratio = 4.42, 95% CI 2.06, 9.50]. BMI may consistently predispose an adult to AKOA, but certain injuries are likely a catalyst for AKOA.

Coronal tibial slope is associated with accelerated knee osteoarthritis: data from the Osteoarthritis Initiative.

BACKGROUND: Accelerated knee osteoarthritis may be a unique subset of knee osteoarthritis, which is associated with greater knee pain and disability. Identifying risk factors for accelerated knee osteoarthritis is vital to recognizing people who will develop accelerated knee osteoarthritis and initiating early interventions. The geometry of an articular surface (e.g., coronal tibial slope), which is a determinant of altered joint biomechanics, may be an important risk factor for incident accelerated knee osteoarthritis. We aimed to determine if baseline coronal tibial slope is associated with incident accelerated knee osteoarthritis or common knee osteoarthritis. METHODS: We conducted a case-control study using data and images from baseline and the first 4 years of follow-up in the Osteoarthritis Initiative. We included three groups: 1) individuals with incident accelerated knee osteoarthritis, 2) individuals with common knee osteoarthritis progression, and 3) a control group with no knee osteoarthritis at any time. We did 1:1:1 matching for the 3 groups based on sex. Weight-bearing, fixed flexion posterior-anterior knee radiographs were obtained at each visit. One reader manually measured baseline coronal tibial slope on the radiographs. Baseline femorotibial angle was measured on the radiographs using a semi-automated program. To assess the relationship between slope (predictor) and incident accelerated knee osteoarthritis or common knee osteoarthritis (outcomes) compared with no knee osteoarthritis (reference outcome), we performed multinomial logistic regression analyses adjusted for sex. RESULTS: The mean baseline slope for incident accelerated knee osteoarthritis, common knee osteoarthritis, and no knee osteoarthritis were 3.1(2.0), 2.7(2.1), and 2.6(1.9); respectively. A greater slope was associated with an increased risk of incident accelerated knee osteoarthritis (OR = 1.15 per degree, 95 % CI = 1.01 to 1.32) but not common knee osteoarthritis (OR = 1.04, 95 % CI = 0.91 to 1.19). These findings were similar when adjusted for recent injury. Among knees with varus malalignment a greater slope increases the odds of incident accelerated knee osteoarthritis; there is no significant relationship between slope and incident accelerated knee osteoarthritis among knees with normal alignment. CONCLUSIONS: Coronal tibial slope, particularly among knees with malalignment, may be an important risk factor for incident accelerated knee osteoarthritis.

Meniscal extrusion or subchondral damage characterize incident accelerated osteoarthritis: Data from the Osteoarthritis Initiative.

Knee osteoarthritis (KOA) is typically a slowly progressive disorder; however, a subset of knees progress with dramatic rapidity. We aimed to describe magnetic resonance imaging (MRI) findings that are associated with accelerated KOA. We conducted a longitudinal descriptive study in the Osteoarthritis Initiative cohort. We selected participants who had no radiographic KOA at baseline with one of the following in the most severe knee: (1) accelerated KOA (progressed to end-stage KOA within 48 months), (2) common KOA, and (3) no KOA at all visits. We enriched the sample by selecting knees with a self-reported or suspected knee injury. A musculoskeletal radiologist blinded to group assignments but not to time sequence performed MRI readings for the visit before and after an injury. We assessed 38 participants (knees), 66% were female, mean age 61 (9) years, and mean body mass index 28.5 (4.9) kg/m(2). Fifteen of 20 knees with no or common KOA, had no incident findings consistent with acute damage. Among the 18 knees with accelerated KOA most had incident findings: 13 (72%) had incident medial meniscal pathology with extrusion and 5 (28%) knees had subchondral damage. Incident MRI findings that are associated with incident accelerated KOA are characterized by structural damage that compromises subchondral bone or the function of the meniscus. Recognizing meniscal extrusion and/or change in shape, lateral meniscal tear, or acute subchondral damage may be vital for identifying individuals at risk for accelerated KOA.