Radiographic Patellofemoral Osteoarthritis Research Articles

Associations between anterior knee pain and 2-year patellofemoral cartilage worsening: The MOST study

Anterior knee pain (AKP) is associated with patellofemoral osteoarthritis (PFOA), but longitudinal studies are lacking. If AKP precedes PFOA, it may create an opportunity to identify and intervene earlier in the disease process. The purpose of this study was to examine the longitudinal relation of AKP to worsening patellofemoral (PF) cartilage over two years. Participants were recruited from the Multicenter Osteoarthritis Study, a longitudinal study of individuals with or at risk for knee osteoarthritis (OA). Exclusion criteria included bilateral knee replacements, arthritis other than OA, and radiographic PFOA. At baseline, participants completed a knee pain map questionnaire and underwent knee magnetic resonance imaging (MRI). Imaging was repeated at 2-year follow-up. Exposure was presence of frequent AKP. Outcome was worsening cartilage damage in the PF joint defined as increase in MRI Osteoarthritis Knee Score from baseline to 2 years. Log-binomial models were used to calculate risk ratios (RR). One knee from 1083 participants (age 56.7±6.6 years; body mass index 28.0±4.9kg/m2) was included. Frequent AKP and frequent isolated AKP were present at baseline in 14.5% and 3.6%, respectively. Frequent AKP was associated with an increased risk (RR: 1.78, 95% confidence interval: 1.21, 2.62) of 2-year worsening cartilage damage in the lateral PF compartment. No association was found between frequent AKP and worsening in the medial PF joint. Frequent AKP at baseline was associated with worsening cartilage damage in the lateral PF joint over 2 years.

Automatic diagnosis and grading of patellofemoral osteoarthritis from the axial radiographic view: a deep learning-based approach.

Patellofemoral osteoarthritis (PFOA) has a high prevalence and is assessed on axial radiography of the patellofemoral joint (PFJ). A deep learning (DL)-based approach could help radiologists automatically diagnose and grade PFOA via interpreting axial radiographs. To develop and assess the performance of a DL-based approach for diagnosing and grading PFOA on axial radiographs. A total of 1280 (dataset 1) axial radiographs were retrospectively collected and utilized to develop the high-resolution network (HRNet)-based classification models. The ground truth was the interpretation from two experienced radiologists in consensus according to the K-L grading system. A binary-class model was trained to diagnose the presence (K-L 2∼4) or absence (K-L 0∼1) of PFOA. A multi-class model was used to grade the stage of PFOA, i.e. from K-L 0 to K-L 4. Model performances were evaluated using the receiver operating characteristics (ROC), confusion matrix, and the corresponding evaluation metrics (positive predictive value [PPV], negative predictive value [NPV], F1 score, sensitivity, specificity, accuracy) of the internal test set (n = 129) from dataset 1 and an external validation set (dataset 2, n = 187). For the binary-class model, the area under the curve (AUC) was 0.91 in the internal test set and 0.90 in the external validation set. For grading PFOA, moderate to severe stage of PFOA exhibited a good performance in these two datasets (AUC = 0.91-0.98, PPV = 0.69-0.90, NPV = 0.92-0.99, F1 score = 0.72-0.87, sensitivity = 0.75-0.87, specificity = 0.90-0.99, accuracy = 0.87-0.98). The HRNet-based approach performed well in diagnosing and grading radiographic PFOA, especially for the moderate to severe cases.

Machine learning based texture analysis of patella from X-rays for detecting patellofemoral osteoarthritis

ObjectiveTo assess the ability of texture features for detecting radiographic patellofemoral osteoarthritis (PFOA) from knee lateral view radiographs. DesignWe used lateral view knee radiographs from The Multicenter Osteoarthritis Study (MOST) public use datasets (n = 5507 knees). Patellar region-of-interest (ROI) was automatically detected using landmark detection tool (BoneFinder), and subsequently, these anatomical landmarks were used to extract three different texture ROIs. Hand-crafted features, based on Local Binary Patterns (LBP), were then extracted to describe the patellar texture. First, a machine learning model (Gradient Boosting Machine) was trained to detect radiographic PFOA from the LBP features. Furthermore, we used end-to-end trained deep convolutional neural networks (CNNs) directly on the texture patches for detecting the PFOA. The proposed classification models were eventually compared with more conventional reference models that use clinical assessments and participant characteristics such as age, sex, body mass index (BMI), the total Western Ontario and McMaster Universities Arthritis Index (WOMAC) score, and tibiofemoral Kellgren-Lawrence (KL) grade. Atlas-guided visual assessment of PFOA status by expert readers provided in the MOST public use datasets was used as a classification outcome for the models. Performance of prediction models was assessed using the area under the receiver operating characteristic curve (ROC AUC), the area under the precision-recall (PR) curve -average precision (AP)-, and Brier score in the stratified 5-fold cross validation setting. ResultsOf the 5507 knees, 953 (17.3%) had PFOA. AUC and AP for the strongest reference model including age, sex, BMI, WOMAC score, and tibiofemoral KL grade to predict PFOA were 0.817 and 0.487, respectively. Textural ROI classification using CNN significantly improved the prediction performance (ROC AUC = 0.889, AP = 0.714). ConclusionWe present the first study that analyses patellar bone texture for diagnosing PFOA. Our results demonstrates the potential of using texture features of patella to predict PFOA.

Relationship of Patellofemoral Osteoarthritis to Changes in Performance-based Physical Function Over 7 Years: The Multicenter Osteoarthritis Study.

To determine the relationship of patellofemoral osteoarthritis (PFOA) to changes in performance-based function over 7 years. There were 2666 participants (62.2 ± 8.0 yrs, BMI 30.6 ± 5.9 kg/m2, 60% female) from the Multicenter Osteoarthritis Study with knee radiographs at baseline who completed repeated chair stands and a 20-meter walk test (20MWT) at baseline, 2.5, 5, and 7 years. Generalized linear models assessed the relation of radiographic PFOA and radiographic PFOA with frequent knee pain to longitudinal changes in performance-based function. Analyses were adjusted for age, sex, BMI, tibiofemoral OA, and injury/surgery. Linear models demonstrated a significant group-by-time interaction for the repeated chair stands (P = 0.04) and the 20MWT (P < 0.0001). Those with radiographic PFOA took 1.01 seconds longer on the repeated chair stands (P = 0.02) and 1.69 seconds longer on the 20MWT (P < 0.0001) at 7 years compared with baseline. When examining the relation of radiographic PFOA with frequent knee pain to performance-based function, there was a significant group-by-time interaction for repeated chair stands (P = 0.05) and the 20MWT (P < 0.0001). Those with radiographic PFOA with frequent knee pain increased their time on the repeated chair stands by 1.12 seconds (P = 0.04) and on the 20MWT by 1.91 seconds (P < 0.0001) over 7 years. Individuals with radiographic PFOA and those with radiographic PFOA with frequent knee pain have worsening of performance-based function over time. This knowledge may present opportunities to plan for early treatment strategies for PFOA to limit functional decline over time.

Automated detection of patellofemoral osteoarthritis from knee lateral view radiographs using deep learning: data from the Multicenter Osteoarthritis Study (MOST)

To assess the ability of imaging-based deep learning to detect radiographic patellofemoral osteoarthritis (PFOA) from knee lateral view radiographs. Knee lateral view radiographs were extracted from The Multicenter Osteoarthritis Study (MOST) public use datasets (n=18,436 knees). Patellar region-of-interest (ROI) was first automatically detected, and subsequently, end-to-end deep convolutional neural networks (CNNs) were trained and validated to detect the status of patellofemoral OA. Patellar ROI was detected using deep-learning-based object detection method. Atlas-guided visual assessment of PFOA status by expert readers provided in the MOST public use datasets was used as a classification outcome for the models. Performance of classification models was assessed using the area under the receiver operating characteristic curve (ROC AUC) and the average precision (AP) obtained from the Precision-Recall (PR) curve in the stratified 5-fold cross validation setting. Of the 18,436 knees, 3,425 (19%) had PFOA. AUC and AP for the reference model including age, sex, body mass index (BMI), the total Western Ontario and McMaster Universities Arthritis Index (WOMAC) score, and tibiofemoral Kellgren-Lawrence (KL) grade to detect PFOA were 0.806 and 0.478, respectively. The CNN model that used only image data significantly improved the classifier performance (ROC AUC=0.958, AP=0.862). We present the first machine learning based automatic PFOA detection method. Furthermore, our deep learning based model trained on patella region from knee lateral view radiographs performs better at detecting PFOA than models based on patient characteristics and clinical assessments.

Are merchant views useful for patellofemoral osteoarthritis?

Purpose: To evaluate the effectiveness of merchant view radiographs (MVR) to identify and grade patellofemoral osteoarthritis (PFOA) relative to MRI. Methods: A cohort of patients who underwent partial meniscectomy at a single large institution aged at least 45 years with a knee MRI within the preceding 6 months and with MVR within the preceding year was selected. PFOA was evaluated on MVR using KL grading (0-4) and minimum joint space width (mJSW) by a musculoskeletal (MSK) radiologist or a trained medical student. Size and depth of cartilage loss in the patellofemoral compartment was graded on MRI by an MSK radiologist using clinically used grading systems. MRI findings were classified into none, mild, moderate, or severe categories apriori. Positive and negative predictive values (PPV and NPV) and ROC curves for KL grading were calculated for detecting PFOA on MRI as none or mild (negative) versus moderate or severe (positive). Prediction models were built for comparing ROC curves for KL and mJSW variables. Results: 442 patients were identified with MVR and MRI. MVR KL grades of 0 or 1 had relatively good NPV for OA on MRI (81.3%, 95% CI: [75.1%, 78.5%]). MVR KL grades of 4 had similarly good PPV (86.7%, 95% CI: [69.5%,99%] ). MVR KL grades of 2 had relatively poor NPV (68.0%) and KL grades of 3 had similarly poor PPV (69.0%). MVR KL grades of 2 and 3 accounted for 62.6% of the radiographs. ROC areas were poor to fair for KL grading (ROC area 0.696) and for a mJSW model (ROC area 0.686). A model with both KL and JSW (ROC area 0.709) was not significantly better than just KL grading (p=0.623). Conclusions: MVR may be diagnostically useful for PFOA when they are essentially normal (KL 0 or 1) or very abnormal (KL 4). MRI should be more strongly considered if there is mild to moderate radiographic PFOA (KL 2 or 3), as radiographs are less accurate at these grades.Tabled 1MRI vs X-ray PFOAKL grade PF = 0KL grade PF = 1KL grade PF = 2KL grade PF = 3KL grade PF = 4MEDIAN JSW_PFMRI=non213059717.6MRI=mild2942901117.1MRI=moderate713461326.4MRI=severe262427115.4 Open table in a new tab

Radiographic and Symptomatic Knee Osteoarthritis 32 to 37 Years After Acute Anterior Cruciate Ligament Rupture

Background: The long-term prevalence of knee osteoarthritis (OA) after anterior cruciate ligament (ACL) injury is unknown, especially in patients without a history of ACL surgery. Purpose: To (1) describe the prevalence of radiographic OA, symptomatic OA, and knee replacement surgery 32 to 37 years after acute ACL injury and to (2) compare the prevalence of radiographic OA, symptomatic OA, and knee symptoms between patients allocated to early ACL surgery or no ACL surgery and patients who crossed over to ACL surgery. Study Design: Cohort study; Level of evidence, 2. Methods: Participants aged 15 to 40 years at the time of ACL injury were allocated to surgical (augmented or nonaugmented ACL repair) or nonsurgical ACL treatment within 14 days of injury. At 32 to 37 years after the initial injury, 153 participants were followed up with plain weightbearing radiographs and completed 4 subscales from the Knee injury and Osteoarthritis Outcome Score (KOOS). Radiographic OA was defined as Kellgren and Lawrence grade 2 or higher. Symptomatic OA was defined as radiographic OA plus knee symptoms measured with the KOOS. Results: Participants allocated to ACL surgery (n = 64) underwent surgery at a mean ± SD of 5 ± 4 days (range, 0-11 days) after injury. Of the 89 participants allocated to no ACL surgery, 53 remained nonsurgically treated, 27 had ACL surgery within 2 years, and 9 had ACL surgery between 3 and 21 years after injury. In the total sample, 95 participants (62%) had radiographic tibiofemoral OA, including 11 (7%) who had knee replacement. The prevalence of radiographic tibiofemoral OA was lower in the group allocated to ACL surgery compared with the group who never had ACL surgery (50% vs 75%; P = .005). The prevalence of symptomatic OA (50% in the total sample) and patellofemoral radiographic OA (35% in the total sample) was similar between groups. Conclusion: Patients allocated to early ACL surgery, performed a mean 5 days after injury, had a lower prevalence of tibiofemoral radiographic OA at 32 to 37 years after injury compared with patients who never had ACL surgery. The prevalences of symptomatic OA, radiographic patellofemoral OA, and knee symptoms were similar irrespective of ACL treatment. Overall, the prevalence of OA after ACL injury was high. Registration: NCT03182647 (ClinicalTrials.gov identifier)

Can radiographic patellofemoral osteoarthritis be diagnosed using clinical assessments?

The aim of this study was to determine whether participant characteristics and clinical assessments could identify radiographic osteoarthritis (OA) in individuals with clinically diagnosed, symptomatic patellofemoral osteoarthritis (PFOA). Participant characteristics and clinical assessments were obtained from 179 individuals aged 50 years and over with clinically diagnosed symptomatic PFOA, who were enrolled in a randomised trial. Anteroposterior, lateral, and skyline X-rays were taken of the symptomatic knee. The presence of radiographic PFOA was defined as "no or early PFOA" (Kellgren and Lawrence [KL] grade ≤1 in the PF compartment) or "definite PFOA" (KL grade ≥2). Diagnostic test statistics were applied to ascertain which participant characteristics and clinical assessments could identify the presence of definite radiographic PFOA. A total of 118 participants (66%) had definite radiographic PFOA. Univariate analysis identified that older age (>61 years), female sex, higher body mass index (BMI) (>29 kg/m2 ), longer pain duration (>2.75 years), higher maximum knee pain during stair ambulation (>47/100 mm), and fewer repeated single step-ups to pain onset (<21) were associated with the presence of definite radiographic PFOA. Multivariate logistic regression indicated that BMI, pain duration, and repeated single step-ups to pain onset were independently associated with radiographic PFOA and identified the presence of definite radiographic PFOA with an overall accuracy of 73%. In individuals over 50 years of age with a clinical diagnosis of PFOA, higher BMI, longer pain duration, and fewer repeated single step-ups to pain onset increased the likelihood of radiographic PFOA. However, overall diagnostic accuracy was modest, suggesting that radiographic PFOA cannot be confidently identified using these tests.

High prevalence of patellofemoral osteoarthritis in China: a multi-center population-based osteoarthritis study.

To describe the prevalence and risk factors of patellofemoral osteoarthritis (PFOA) among Chinese residents. A multi-center population-based osteoarthritis study was conducted in 2014. Residents aged ≥ 50years old were recruited using a cluster sampling method. Subjects completed a home interview and physical examination and had skyline view of radiographs at patellofemoral (PF) joints. Radiographs were read by two trained musculoskeletal researchers, and discordance of a subject's PFOA status between two readers was adjudicated with a third musculoskeletal researcher present. Radiographic OA at PF joint was defined if osteophytes (OST) score was ≥ 2 or if joint space narrowing (JSN) score was ≥ 2 with concurrent grade 1 OST in the PF joint. Of 3446 subjects (63.0% women) included in this analysis, the prevalence of radiographic PFOA was 23.9% (20.5% men vs. 25.8% women). Prevalence of lateral radiographic OA was higher than medial radiographic OA at PF joint. Grades of both osteophytes and joint space narrowing in the lateral patellofemoral compartment were higher than those in the medial patellofemoral compartment (all P values < 0.001). Women, older age, higher BMI, and fewer years of education were significantly associated with higher prevalence of radiographic PFOA, osteophytes, and joint space narrowing. Prevalence of radiographic PFOA was high among Chinese population. Key Points • The multi-center population-based osteoarthritis study shows the prevalence of radiographic PFOA was high among Chinese population. • Older age, female gender, obesity, and few years of education were associated with a high risk of PFOA. • Prevalence of lateral radiographic OA was higher than medial radiographic OA at PF joint.

The impact of radiographic patellofemoral osteoarthritis on symptomatic, physical and psychosocial features in individuals with persistent patellofemoral pain

Purpose: Patellofemoral pain (PFP) is a common, burdensome condition across the lifespan, that often starts in adolescence and persists into adulthood. There is increasing suggestion that persistent PFP may be related to patellofemoral osteoarthritis (PFOA). Understanding the characteristics of people with persistent PFP, and how these relate to the presence of radiographic PFOA, may help us develop targeted treatments to improve patient outcomes. The aim of this study was to explore how symptomatic, psychosocial and physical characteristics differ in those with persistent PFP based on the presence or absence of radiographic PFOA.

Associations of trochlea morphology and patellofemoral alignment with prevalent radiographic patellofemoral osteoarthritis

To investigate the relation of trochlea morphology and patellofemoral alignment to prevalent radiographic patellofemoral osteoarthritis (PFOA). A within-person knee-matched case-control study was performed. Participants with unilateral radiographic PFOA were selected from the Multicenter Population-based Osteoarthritis Study (MPOA) in three towns in northern China that was approved by Peking University Health Science Center Ethics Committee (2018PHB166-01). Radiographic PFOA, radiographic tibiofemoral OA, sulcus angle, patellofemoral index and patella displacement were assessed using posterio-anterior and skyline views of the knee. We classified sulcus angle, patellofemoral index and patella displacement into quarters and investigated the relation of each of these measures to prevalent radiographic PFOA. Among 451 participants (mean age: 65.2 years, women: 66.8%) with unilateral radiographic PFOA, a reverse J-shaped relationship was observed between sulcus angle and prevalent radiographic PFOA (P=0.039 for quadratic term). Both higher patellofemoral index and patella displacement were associated with higher prevalent radiographic PFOA. Adjusted odds ratios (ORs) of prevalent radiographic PFOA in the highest quarter of patellofemoral index and patella displacement were 4.69 and 3.60 (Pfor trend <0.001), respectively, compared with the lowest quarter of each measurement. A similar relationship was observed between sulcus angle with either prevalent radiographic lateral or medial PFOA. Higher values of patellofemoral index and patella displacement were statistically significantly associated with higher prevalent radiographic lateral (ORs=5.07 and 4.59, respectively), but not medial PFOA (ORs=0.58 and 0.76, respectively). Extreme sulcus angles as well as higher values of patellofemoral index and patella displacement were associated with higher prevalent radiographic PFOA.

Obesity is related to incidence of patellofemoral osteoarthritis: the Cohort Hip and Cohort Knee (CHECK) study.

To determine the longitudinal association of baseline body mass index and change in body mass index over 8years to incident of patellofemoral osteoarthritis at the 8-year follow-up. A sample of 528 women and men, aged 45-65years, with knee complaints and without radiographic evidence of patellofemoral and tibiofemoral osteoarthritis at baseline, were selected from the Cohort Hip and Cohort Knee cohort. Incidence of patellofemoral osteoarthritis was defined as presence of radiographic patellofemoral osteoarthritis (with or without tibiofemoral osteoarthritis) at the 8-year follow-up. Baseline body mass index data were categorized into normal, overweight, and obese weight-categories. Logistic regression analyses, adjusted for age and sex, were conducted to determine the association of baseline body mass index and change in body mass index to patellofemoral osteoarthritis incidence 8years later. Obesity was associated with greater odds of radiographic patellofemoral osteoarthritis incident (odds ratio: 1.8 [95% CI 1.1, 3.1]) 8years later. There were no significant associations observed between body mass index change over 8years and incidence of radiographic patellofemoral osteoarthritis in overweight and obese individuals. Obesity is associated with increased odds of developing radiographic patellofemoral osteoarthritis 8years later.

Imaging features in incident radiographic patellofemoral osteoarthritis: the Beijing Shunyi osteoarthritis (BJS) study

BackgroundThe present study aims to describe the imaging features in incident radiographic patellofemoral osteoarthritis (RPFOA) population in a Chinese suburban area.MethodsThe Beijing Shunyi osteoarthritis (BJS) study was a population-based, longitudinal and prospective study. Residents were recruited by randomized cluster sampling in 2014 and were followed 3 years later. Home interviews and clinical examinations were performed; weight-bearing posterior-anterior semi-flexed (45-degree) views of the tibiofemoral (TF) joints and skyline (45-degree) views of the patellofemoral (PF) joints were included. For each batch of study films (n = 100), 20 films from the year 2014 and 20 previously read PF radiographs were fed back to test inter−/intra-reader repeatability. The imaging features of incident RPFOA were analyzed. Narrative statistics, independent-sample t-tests, and nonparametric tests were performed.ResultsA total of 1295 participants (2590 knees) were recruited at baseline in 2014, and 967 (74.7%) residents were followed in 2017. Of all the knees (n = 1537) without RPFOA at baseline, 139 knees (13.3%) across 119 people developed incident RPFOA. Compared with the whole population, age (p = 0.031), body mass index (BMI, p = 0.042), and incidence of knee pain symptoms (p < 0.01) were significantly different in the incident RPFOA population, while range of motion (ROM, p = 0.052) and gender (0/1, p = 0.203) showed no significance. In the incident population, the changes of each imaging indicator grade were evaluated—lateral patellofemoral osteophyte (LPOST, increased by 1.02), medial patellofemoral osteophyte (MPOST, increased by 0.49), lateral joint space narrowing (LJSN, increased by 0.30), medial joint space narrowing (MJSN, increased by 0.06); indicator grade progress decreases, respectively. The progress of LPOST was the fastest among the four indicators (p < 0.01).ConclusionsIn this population-based longitudinal study, among the incident RPFOA population, the imaging indicators show that marginal patellofemoral osteophyte is more pronounced than patellofemoral joint space narrowing. LPOST is the fastest-progressing indicator among all the radiographic features, which is also the most common imaging manifestation of RPFOA. In the incident RPFOA population, the proportion of elders, women, higher-BMI individuals, and people suffering knee pain is more than the normal population.

Prevalence of Radiographic and Magnetic Resonance Imaging Features of Patellofemoral Osteoarthritis in Young and Middle-Aged Adults With Persistent Patellofemoral Pain.

To describe the prevalence of radiographic features of patellofemoral (PF) osteoarthritis (OA) in adults with persistent PF pain, to describe the prevalence of magnetic resonance imaging (MRI)-defined PF OA and compare it to that in age- and sex-matched controls, and to explore the prevalence of radiographic and MRI-defined PF OA across age, sex, and body mass index (BMI) groups. This cross-sectional study included 84 individuals with PF pain ≥3 months duration and 26 age- and sex-matched controls. In participants with PF pain, posteroanterior, lateral, and skyline radiographs were obtained. Radiographic OA features were scored using Kellgren/Lawrence (K/L) criteria and a radiographic atlas, with K/L grade ≥2 defined as OA, and K/L grade 1 as early OA. Both groups underwent 3.0 Tesla MRI scans, scored using the MRI Osteoarthritis Knee Score criteria. Compartmental prevalence of MRI OA features was based on cartilage lesions, bone marrow lesions (BMLs), and osteophytes. Overall, 20 participants (24%) with PF pain had radiographic PF OA (K/L grade ≥2), and 36 participants (43%) had early PF OA (K/L grade 1). MRI-defined PF OA was more prevalent in participants with PF pain (16-29%) than in controls (4-12%), irrespective of how PF OA was defined. Within the PF pain group, the prevalence of PF OA on radiographs and MRI was greater in participants who were older or female or who had a higher BMI. Features of radiographic and MRI-defined PF OA were evident in 20-30% of adults ages 26-50 years with persistent PF pain, with greater prevalence observed in those who were older, or female, or who had a higher BMI. MRI-defined PF OA was more prevalent in individuals with PF pain than in pain-free controls, especially when defined as a full-thickness cartilage lesion with BML.

Two approaches to evaluate the associations between patellofemoral joint alignment, morphology, radiographic osteoarthritis and anterior knee pain: the most study

Purpose: To evaluate the cross-sectional associations between patellofemoral joint alignment, trochlear morphology, radiographic osteoarthritis (OA), and frequent isolated anterior knee pain (AKP). Methods: We evaluated participants from the Multicenter Osteoarthritis Study (MOST), a cohort of 3026 individuals aged 50 - 79 years who had, or were at risk of, knee OA at enrollment. At the 60-month visit, we assessed patellar alignment and trochlear morphology from MR images (bisect offset , patellar tilt angle, sulcus angle, lateral trochlear inclination, medial trochlear inclination, trochlear angle) or lateral radiographs (Insall-Salvati ratio). Radiographic OA was defined on the lateral view (patellofemoral) as any osteophyte ≥ Grade 2, or joint space narrowing ≥ Grade 2 plus any osteophyte, sclerosis or cyst ≥ Grade 1; and OA on the postero-anterior view (tibiofemoral) radiographs was defined as Kellgren & Lawrence ≥ Grade 2. Frequent isolated AKP was defined as: (i) a response of ‘yes’ to the question “During the past 30 days, have you had pain, aching, or stiffness in your knee on most days?”; and (ii) the pain was reportedly isolated to the anterior knee region using a knee pain map. We used two different study designs. Our first design was a within-person, knee-matched evaluation of participants with frequent isolated AKP in one knee and no pain in the other knee (conditional logistic regression). We selected individuals with unilateral knee pain at the 60-month visit, or at the 84-month visit if they did not meet these criteria at 60 months. Our second design was a traditional cohort approach using data from the 60-month study visit, in which we evaluated the relation of the various exposures to presence of frequent isolated AKP to knees without pain (binomial regression). Results: The within-person knee-matched design (n=110, 64% women, mean [SD] age 70 [8], BMI 30.9 [6.3]) revealed no associations between patellofemoral alignment, morphology, or tibiofemoral OA and frequent isolated AKP. Patellofemoral OA was associated with frequent isolated AKP, odds ratio 5.3 (95% CI 1.6, 18.3) (see Table 1). The cohort design (n=1818, 59% women, age 68 [8], BMI 30.4 [5.9]) revealed similar results: only patellofemoral OA was associated with frequent isolated AKP, prevalence ratio 2.2 (1.4, 3.4) (see Table 2). Conclusions: Patellofemoral alignment and trochlear morphology were not associated with frequent isolated anterior knee pain in individuals with, or at risk for, knee OA. Radiographic patellofemoral OA, but not tibiofemoral OA, was associated with frequent isolated anterior knee pain. Features of patellofemoral OA, more so than mechanical alignment or morphology features or tibiofemoral OA, may contribute to localized anterior knee pain.View Large Image Figure ViewerDownload Hi-res image Download (PPT)

Incidence, related risk factors, imaging characteristics analysis and prediction model of radiographic patellofemoral osteoarthritis in a Chinese suburban area: Shunyi osteoarthritis study

Incidence, related risk factors, imaging characteristics analysis and prediction model of radiographic patellofemoral osteoarthritis in a Chinese suburban area: Shunyi osteoarthritis study

Inverted Rearfoot posture in subjects with coexisting patellofemoral osteoarthritis in medial knee osteoarthritis: an exploratory study

BackgroundWhile abnormal rearfoot posture and its relationship to patellofemoral (PF) pain has been thoroughly discussed in the literature, its relationship to patellofemoral osteoarthritis (PFOA) has not been determined. This study aimed to examine whether rearfoot posture is associated with a higher prevalence of radiographic PFOA in a compartment-specific manner in patients with medial tibiofemoral osteoarthritis (TFOA).MethodsParticipants from orthopedic clinics (n = 68, age 56–90 years, 75.0% female), diagnosed with radiographic medial TFOA (Kellgren/Lawrence [K/L] grade ≥ 2) were included in this study. The presence of PFOA and static rearfoot posture were evaluated using a radiographic skyline view and a footprint automatic measurement apparatus, respectively. The relationship between rearfoot posture and PFOA was examined using analysis of covariance and propensity score-adjusted logistic regression analysis.ResultsOn average, patients with coexisting PFOA and medial TFOA (n = 39) had an inverted calcaneus 3.1° greater than those with isolated medial TFOA (n = 29). Increased calcaneus inverted angle was significantly associated with a higher probability of the presence of medial PFOA (odds ratio: 1.180, 95% confidence interval: [1.005, 1.439]; p = 0.043). Calcaneus inverted angle was not associated with higher odds of lateral PFOA presence based on the adjusted values.ConclusionsThe presence of an inverted rearfoot was associated with PFOA. Although these findings do not clearly indicate a biomechanical link between rearfoot posture and PFOA, this study shed light on the potential relationship between altered rearfoot posture and PFOA, as can be seen between rearfoot abnormality and PF pain.

Do Gait Patterns Differ based on Radiographic Patellofemoral Osteoarthritis Disease Severity in Individuals with Mild Tibiofemoral Osteoarthritis?

Do Gait Patterns Differ based on Radiographic Patellofemoral Osteoarthritis Disease Severity in Individuals with Mild Tibiofemoral Osteoarthritis?

Incidence, prevalence, natural course and prognosis of patellofemoral osteoarthritis: the Cohort Hip and Cohort Knee study.

To examine the proportion of isolated patellofemoral osteoarthritis (PFOA) compared to tibiofemoral osteoarthritis (TFOA) in middle-aged participants with early osteoarthritis (OA) symptoms of the knee; to describe the natural course of PFOA compared with that of TFOA and to identify whether patients with PFOA have a different phenotype compared to patients with TFOA, or with combined PFOA and TFOA (combined osteoarthritis (COA)). Participants with early OA symptoms of the knee were selected, completed questionnaires, underwent physical examination, and had knee radiographs at baseline, and at 2 and 5 years follow-up. Based on radiographs, participants were classified as having isolated TFOA, isolated PFOA, COA, or no radiographic OA. Multivariate logistic regression was used to identify participant characteristics associated with a specific group of OA at 2 years follow-up. The cohort comprised 845 participants (mean age 55.9 years). At baseline, 116 had PFOA, none had TFOA or COA. Of these 116 participants, 66.3% had developed COA at 5 years follow-up. At 2 years follow-up, PFOA, TFOA and COA were present in 77 (10.8%), 39 (5.5%) and 83 (11.6%) participants, respectively. Multivariate regression analyses at 2 years follow-up showed that participants with radiographic PFOA or TFOA were not significantly different from each other with respect to signs and symptoms. These results suggest that OA is more likely to start in the patellofemoral joint and then progress to COA in individuals with symptoms of early knee OA. No differences in TFOA and PFOA phenotypes were determined with respect to signs and symptoms.

Anterior knee pain following anterior cruciate ligament reconstruction does not increase the risk of patellofemoral osteoarthritis at 15- and 20-year follow-ups

To prospectively evaluate the relationship between the presence or persistence of anterior knee pain (AKP) during the first 2-years following anterior cruciate ligament reconstruction (ACLR) and patellofemoral osteoarthritis (PFOA) at 15- and 20-years. This study was ancillary to a long-term prospective cohort study of 221 participants following bone-patellar-tendon-bone ACLR. AKP was assessed at 1- and 2-years post-ACLR using part of the Cincinnati knee score with an additional pain location question (persistence defined as presence at both follow-ups). Radiographic PFOA (definite patellofemoral osteophyte) and symptomatic PFOA (patellofemoral osteophyte, with knee pain during past 4weeks) was assessed at 15- and 20-years follow-up. We used generalized linear models with Poisson regression to assess the relationship between AKP and PFOA. Of the 181 participants (82%) who were assessed at 15-years post-ACLR (age 39±9 years; 42% female), 36 (24%) and 33 (22%) had AKP at 1- and 2-years, respectively, while 14 (8%) reported persistent AKP. Radiographic and symptomatic PFOA was observed at 15-years in 130 (72%) and 70 (39%) participants, respectively, and at 20-years in 115 (80%) and 60 (42%) participants, respectively. Neither the presence nor persistence of AKP at 1- and/or 2-years post-ACLR was associated with significantly higher risk of radiographic or symptomatic PFOA at 15- or 20-years (risk ratios <2.1). Although AKP and PFOA were prevalent, AKP does not appear to be associated with long-term PFOA following ACLR.