Course Of Knee Osteoarthritis Research Articles

Reliability and validity of OpenPose for measuring hip-knee-ankle angle in patients with knee osteoarthritis

We aimed to assess the reliability and validity of OpenPose, a posture estimation algorithm, for measuring hip-knee-ankle (HKA) angle in patients with knee osteoarthritis, by comparing it with radiography. In this prospective study, we analysed 60 knees (30 patients) with knee osteoarthritis. We measured HKA angle using OpenPose and radiography before or after total knee arthroplasty and assessed the test–retest reliability of each method with intraclass correlation coefficient (1, 1). We evaluated the ability to estimate the radiographic measurement values from the OpenPose values using linear regression analysis and used intraclass correlation coefficients (2, 1) and Bland–Altman analyses to evaluate the agreement and error between OpenPose and radiographic measurements. OpenPose had excellent test–retest reliability (intraclass correlation coefficient (1, 1) = 1.000) and excellent agreement with radiography (intraclass correlation coefficient (2, 1) = 0.915), with regression analysis indicating a large correlation (R2 = 0.865). OpenPose also had a 1.1° fixed error and no systematic error when compared with radiography. This is the first study to validate the use of OpenPose for the estimation of HKA angle in patients with knee osteoarthritis. OpenPose is a reliable and valid tool for measuring HKA angle in patients with knee osteoarthritis. OpenPose, which enables non-invasive and simple measurements, may be a useful tool to assess changes in HKA angle and monitor the progression and post-operative course of knee osteoarthritis. Furthermore, this validated tool can be used not only in clinics and hospitals, but also at home and in training gyms; thus, its use could potentially be expanded to include self-assessment/monitoring.

The Impact of Chronic Pain, Stiffness and Difficulties in Performing Daily Activities on the Quality of Life of Older Patients with Knee Osteoarthritis.

Osteoarthritis causes a number of physical ailments, which result in the deterioration of a persons' general health and reduction of their ability to move freely. This cross-sectional study was designed to assess the impact of physical ailments in the course of knee osteoarthritis (KOA) on the quality of life (QoL) of patients in early old age. An anonymous survey was conducted by the use of the recognized research tools: Western Ontario scale and McMaster Osteoarthritis Index (WOMAC), The Index of Severity for Knee Disease (ISK) and World Health Organization Quality of Life-BEFF (WHOQOL-BREF). The study involved 300 people aged between 60 and 75 years old, including 150 patients diagnosed with gonarthrosis and 150 people without lower limb complaints. The significant intensification of the symptoms of knee osteoarthritis was associated with a worse assessment of health (p < 0.001), overall quality of life (p < 0.001) and in the following domains: physical (p < 0.001), mental (p < 0.001) and environmental (p < 0.001) in a group of patients with KOA. These findings suggest that taking measures to reduce knee pain and improve function may have an impact on improving the overall quality of the life of people in their early old age.

ASSOCIATEION BETWEEN LEVOTHYROXINE USE AND LONGITUDINAL THIGH MUSCLES QUALITY AND RISK OF KNEE OSTEOARTHRITIS INCIDENCE: OSTEOARTHRITIS INITIATIVE DATA

Purpose: Hypothyroidism can commonly cause myopathy, characterized by myalgia and weakness, affecting almost 80 percent of patients. This myopathy may be important in the course of knee osteoarthritis (KOA), in which thigh muscles play an essential role in the incidence and progression of the diseases. Despite that hypothyroidism and KOA are very common and frequently coexist in the elderly population, no conclusive evidence is available regarding the possible association of hypothyroidism with thigh muscle changes.

Baseline clinical characteristics of predicted structural and pain progressors in the IMI-APPROACH knee OA cohort

ObjectivesTo describe the relations between baseline clinical characteristics of the Applied Public-Private Research enabling OsteoArthritis Clinical Headway (IMI-APPROACH) participants and their predicted probabilities for knee osteoarthritis (OA) structural (S) progression...

Different Prevention and Treatment Strategies for Knee Osteoarthritis (KOA) with Various Lower Limb Exoskeletons – A Comprehensive Review

SUMMARYIt was reported that about 10% of people suffer from painful knee arthritis, and a quarter of them were severely disabled. The core activities of daily living were severely limited by knee osteoarthritis (KOA). In order to reduce knee pain and prolong the life of the knee joint, there has been an increasing demand on the development of exoskeletons, for prevention and treatment. The course of KOA was closely related to the biomechanics of knee joint, and the pathogenesis was summarized based on the biomechanics of knee joint. For the prevention and clinical treatment, exoskeletons are classified into three categories: prevention, treatment, and rehabilitation after the operation. Furthermore, the design concepts, actuators, sensors, control strategies, and evaluation criteria were presented. Finally, the shortcomings and limitations were summarized. It is useful for researchers to develop suitable exoskeletons in the future.

Multimodal approach to intraarticular drug delivery in knee osteoarthritis.

The expectations from any future disease-modifying treatment for knee osteoarthritis (KOA) are extremely high as it has to impact the joint as a whole leading to favorable alterations of diverse tissues and functions. In this light, targeting the knee only from the inside may not be biologically justified for the management of a whole joint disease such as KOA. Our hypothesis to test is whether any injectable therapeutic intervention alone can lead to disease modification of KOA which is viewed in the complexity of the modern concept of osteoarthritis (OA) as a whole joint disease. Therefore, we aimed at analyzing the intraarticular route to the KOA patient in an attempt to unveil its "biological" constraints. A comprehensive search through databases was carried out using specific keywords to add objectivity to the main messages. The literature analysis has shown that "cutting-edge" intraarticular therapies may offer a key to non-invasive symptomatic relief. Changing the course of KOA, however, may necessitate a multimodal approach towards the knee joint including a combination of intraarticular injections with interventions on multiple levels. Importantly, our understanding of OA has evolved redefining the concept of the disease, being in interaction with the human body as a whole. Any future conservative disease-modifying treatment of KOA should aim at a multimodal, holistic approach towards the knee joint including but not limited only to intraarticular injections. A combination with other interventions should be further researched.

Health-related quality of life and its influencing factors in Chinese with knee osteoarthritis.

To evaluate the health-related quality of life (HRQoL) of knee osteoarthritis (KOA) patients in China, compare their HRQoL with norm population, and examine the associations between the potential influencing factors and HRQoL. A cross-sectional study was conducted in 912 KOA patients from 4 provinces between March and November 2017. All participants were diagnosed according to the National Institute for Health and Care Excellence (NICE)'s criterion or the Chinese Medical Association (CMA)'s criterion. Recruited patients were surveyed for HRQoL using the 12-item Short Form (SF-12) and sociodemographic, disease-related factors. We assessed the associations between potential influencing factors and HRQoL using multiple linear regression models. Among the KOA patients, the mean physical component summary (PCS) of HRQoL was 40.91 ± 11.62, lower than norm (P < 0.001). And the mean mental component summary (MCS) was 50.25 ± 11.99, similar to the norm. Patients who were older (β = - 0.155, P = 0.001), women (β = - 4.589, P < 0.001), had ever been treated (β = - 2.426, P = 0.006), had longer course of KOA (β = - 0.164, P = 0.012), and were in early stage (β = - 2.968, P = 0.001) or progressive/late stage (β = - 7.636, P < 0.001) showed lower scores of PCS. Patients who lived in Hunan (β = 4.988, P < 0.001) and had education levels of junior high school (β = 3.134, P = 0.012) or senior high school and above (β = 3.050, P = 0.010) had better mental status. Those suffered from non-knee pains (β = - 2.308, P = 0.027) and with progressive or late KOA (β = - 4.690, P = 0.016) had lower MCS scores. KOA patients had worse physical condition. The mental and physical health of patients were affected by different factors. Targeted management measures should be taken to improve their HRQoL.

Natural history of knee osteoarthritis for 40 years from the matsudai knee osteoarthritis survey, Japan

Purpose: Osteoarthritis (OA) is a leading cause of disability worldwide. It brings a significant burden on the health care system and society for both men and women. In particular, knee OA is one of the frequent types of OA. Therefore, preventing knee OA is an important issue worldwide. However, knee OA is a multifactorial disease and we don't know much about the natural course of knee OA; all osteoarthritis knee would get progressed or not. To investigate the relationship between knee OA and various factors, we've conducted 9 times epidemiological survey for knee OA at one district in Japan for 40 years since 1979.

Does hyaluronic acid injection prevent the progression of knee Osteoarthritis ?

Purpose: Intra-articular injection of hyaluronic acid (HA) is performed as a conservative treatment for knee osteoarthritis (OA). HA has diverse pharmacological actions. In addition to increased lubrication of joint surfaces, its actions have been reported to include inhibition of the release of inflammatory cytokines and promotion of endogenous HA production. While many reports have suggested that injection of HA is clinically effective for knee OA, the actual improvement only seems to be modest. It has also been reported that injection of HA did not prevent the progression of knee OA, but rather promoted it. Thus, there are many unanswered questions about intra-articular HA therapy. The purpose of this study is imaging evaluation of patients who received long-term treatment with intra-articular HA for knee OA was conducted. Methods: This study was conducted in accordance with all applicable requirements of our university (including IRB approval). The subjects were 42 patients/64 knees (male: 17, female: 25) who received long-term intra-articular injection of HA for knee OA at the outpatient clinic of our university. Their mean age was 74.0 years, and the mean observation period was 4 years and 7 months. Knee radiographs were assessed by the Kellgren-Lawrence (K-L) classification, and the joint space was measured on frontal and lateral views obtained with the patient in the standing semiflexion position. In addition, the height, body weight, body mass index (BMI), frequency of HA injections, and total dose of HA were evaluated. Radiographic disease progression was defined as an annual increase of at least 1 grade in the K-L score or a decrease of > 0.2 mm in knee joint cartilage thickness annually. Results: Knee OA progression was seen in 24/64 knees (37.5%), while OA did not progress or the joint space increased in 40/64 knees (62.5%) (Fig 1). Approximately half of the knees with progression of knee OA were in K-L grade 3 or higher (45.8% * χ2 test), while all grade 1 or 2 patients who showed progression were obese with a BMI ≥27 kg/m2. On the other hand, in the group without knee OA progression, more than three-fourths of the knees were K-L grade 1 and 2 (77.5% * unpaired t-test). The interval between HA injections was shorter in patients without progression of knee OA, and the total dose was larger than in patients with progression (Table 1). Conclusions: Our previous study in OA animal models indicated that intra-articular injection of HA has both symptom-modifying and disease-modifying effects. In this study, the aim was to determine whether HA has these effects in human knees, as well as to determine the long-term treatment course with intra-articular injection of HA. In the OARSI guidelines, the strength of the recommendation for intra-articular injections of HA is 64, which is lower than for intra-articular injection of corticosteroids. In the previous research, HA treatment is well tolerated and produces statistically and clinically significant improvement of symptoms in patients with mild to moderate knee OA. In this study, 37.5% of the patients showed OA progression despite continuing HA injection. Converted to the annual OA progression ratio, 7.9% of the patients were shown to have knee disease progression annually. Comparing this ratio with the natural course of knee OA, 7% was reported by the Framingham study, with 3% reported by another study. It is difficult to compare this ratio because of the different populations and study designs. However, intra-articular injection of HA may not prevent OA progression. Approximately two-thirds of patients who received intra-articular injection of HA showed no progression or improvement of knee OA. Intra-articular injection of HA may not be effective in patients with K-L grade 3 or higher or BMI ≥27 kg/m2.View Large Image Figure ViewerDownload Hi-res image Download (PPT)

The knowledge and self-management educational needs of older adults with knee osteoarthritis: A qualitative study.

Knee osteoarthritis (KOA) is closely related with ageing, physical disability and functional dependency. The course of KOA is considered progressive and irreversible. Engagement with self-management may, however, minimize the impact of KOA. To be fully engaged with self-management activities, knowledge about KOA is a prerequisite. There is limited empirical data on older adults’ understanding on KOA and their information needs about KOA. Therefore, the aims of this study were to explore older adults’ knowledge about KOA and their perspectives on the information required to enable self-management. Three focus groups were conducted with 16 older adults with KOA. The sample consisted of three men and thirteen women with the mean age 73.2 years (range from 61 to 89). Thematic content analysis revealed two themes which were understanding about KOA and information needed about KOA. Participants’ knowledge about KOA varied between individuals with many expressing that they needed more information about KOA. A targeted strategy is needed to educate older adults about KOA in order to support and prepare them for self-management.

Effect of physical therapy on early knee osteoarthritis with medial meniscal posterior tear assessed by MRI T2 mapping and 3D-to-2D registration technique: A prospective intervention study

Objectives: The purpose of this study was to verify that exercise aimed at improving knee kinematics in early-stage knee osteoarthritis (OA) patients with medial meniscus posterior root tears (MMPRTs) reduces knee adduction angle during gait and prevents rapid cartilage degeneration in the medial compartment of the knee.Methods: Subjects were randomly assigned to an adapting alignment exercise (AAE) group, with the goal of improving knee kinematics, and a muscle training and exercise (MTE) group. Before the start of the six-month intervention and following its completion, we performed an analysis of knee kinematics during gait using a 3D-to-2D registration technique and identified the area of cartilage degeneration using MRI T2 mapping.Results: The amount of change between pre- and post-intervention measurements of the maximum angle of adduction was 0.48° (95% CI: −0.14, 1.09) in the MTE group and −0.40° (−0.84, 0.04) in the AAE group (p = .039). The amount of change in the area of cartilage degeneration according to MRI T2 mapping expressed as MTE/AAE group was 7.7 mm2 (−0.4, 15.8)/−2.7 mm2 (−10.8, 5.3) at the posterior knee (p = .043).Conclusion: AAE could be a potential treatment method that improves the natural course of knee OA with MMRPTs.

Should Platelet-Rich Plasma or Stem Cell Therapy Be Used to Treat Osteoarthritis?

Osteoarthritis is the most common form of arthritis and unfortunately lacks disease-modifying treatments. This has led to a growing demand for more effective nonoperative treatment options. Platelet-rich plasma and mesenchymal stem cell therapy offer the potential to modify the natural course of knee osteoarthritis using cell-based technology. Because of the lack of high-quality evidence and the large degree of heterogeneity, in terms of study designs and measured outcomes, the use of platelet-rich plasma or mesenchymal stem cell therapy to treat knee osteoarthritis cannot be recommended at this time.

Modifiable risk factors in knee osteoarthritis: treatment implications.

Optimal management of knee osteoarthritis (KOA) should include, where possible, modification of risk factors through targeted interventions. The objectives of the present narrative review were to identify, summarize, and cluster all the potentially modifiable risk factors that influence the course of KOA, and discuss their susceptibility to alteration via personal, clinical, and public strategy. For this purpose, Pubmed and Scopus databases were queried using the terms "knee osteoarthritis", "risk factors" and "improvement". Six main categories of modifiable risk factors were identified: (1) obesity and overweight, (2) comorbidity, (3) occupational factors, (4) physical activity, (5) biomechanical factors, (6) dietary exposures. In the era of age- and obesity-related diseases, the combined effects of local and systemic risk factors should be managed by combined measures. Femoral muscle-strengthening physical activities, complemented with proper diet, weight loss, vocational rehabilitation, management of comorbidities (especially diabetes and depression), and biomechanical support may add up to the holistic therapeutic approach towards the patient with KOA. An individual risk factor modification program should be developed in accordance with patient preferences and habits, workplace, medical history, and overall health condition. Due to its great impact on a wide range of functions and tissues, interventions on modifiable risk factors improve not only the symptoms of KOA but also affect the osteoarthritic joint as a whole.

New insights into the natural course of knee osteoarthritis: early regulation of cytokines and growth factors, with emphasis on sex-dependent angiogenesis and tissue remodeling. A pilot study

This study was conducted to identify cytokine profiles associated with radiographic phenotypes of knee osteoarthritis (rKOA) with a focus on early stage of the disease. The pilot population study involved 60 middle-aged patients (mean age 50±7.3y.). Standardized weight-bearing anteroposterior and axial radiographs were used to assess rKOA severity in tibiofemoral (TFJ) of patellofemoral joint (PFJ) by grading system (grades 0-3). Luminex (xMAP®) technology was used to simultaneously assess 60 biomarkers (BMs). Several pathways of angiogenic (CXCL10/IP-10, FGF1/2, PDGF-AA/BB, ANG1, RANTES), tissue remodeling/fibrosis (MMP1/3, TIMP2/3/4, TGFβ), and fat tissue (leptin) BMs associated with rKOA severity already in very early phase (grade 1). We identified several sets of cytokines as key markers of early knee osteoarthritis (KOA) predicting radiographic features in logistic-regression models (AUC=0.80-0.97). Marked sex-specificity of rKOA course was detected: upregulation of angiogenesis dominated in females, whereas the activation of tissue remodeling was dominant in males. Several of these shifts, e.g., decrease of CXCL10/IP-10, took place only in grade 1 KOA and disappeared or reversed in later stages. OA of different knee-joint compartments has distinct profiles of cytokines. A broad list of BMs (TIMP2/3/4, MMP1/3, TGFβ1/2, vWF-A2, sE-selectin and leptin) associated with OA in the PFJ. Our results demonstrate that substantial and time-limited shifts in the angiogenic and TIMP/MMP systems occur in the early stage of KOA. Our study findings highlight the sex-, grade- and compartment-dependent shifts in above processes. The data may contribute to the individualized prevention of KOA in the future.

The effect of different treatments on the clinical course of knee osteoarthritis

Purpose: To study the effect of different groups of drugs on the clinical course of gonarthrosis as well as to develop an algorithm for selection of therapeutic approach depending on clinical and radiation signs of this disease. Methods: 122 patients with unilateral knee osteoarthritis in the age of 30-70 years old were examined. The patients were randomized in 4 groups comparable by age, BMI and clinical and radiation signs. Patients of the first group (n = 30) received chondroitin sulfate 1,200 mg/day and glucosamine 1,500 mg/day (Theraflex®). The second group (n = 31) received chondroitin sulfate 1,200 mg/day and glucosamine 1,500 mg/day in combination with oral strontium ranelate 2 g a day. The third group (n = 30) – chondroitin sulfate 1,200 mg/day and glucosamine 1,500 mg/day in combination with oral diacerein 50 mg twice a day. The fourth group (n = 31) – chondroitin sulfate 1,200 mg/day and glucosamine 1,500 mg/day in combination with intra-articular administration of 1.5% sodium hyaluronate 2.0 ml No. 4 courses per course with interval of 7 days. Duration of oral therapy was 12 months (Fig. 1). The diagnosis of osteoarthrosis was established in accordance with American College of Rheumatology criteria. Roentgenological stage was assessed in accordance with Kellgren and Lawrence classification. At randomization roentgenologic stage I was registered in 79 patients (64.75 %), stage II – in 43 (32.25 %). All study participants were examined by three times: before treatment and after 6 and 12 months of treatment. Magnetic Resonance Imaging (MRI, 3 Tesla) with colour mapping of the knee cartilage tissue and calculation of T2-reaxation time were performed. The patients assessed degree of pain syndrome and disease course by 100-point Visual Analogue Scale (VAS); functional activity of joints was determined by Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) (Fig.2). Results: This is the first study conducted with the use of MRI with colour T2-mapping of the cartilage to verify structural changes of the knee cartilage in early stages of osteoarthritis in dynamics. It was established that both bone marrow edema (osteitis) and decrease of bindings between collagen-proteoglycan complex and water molecules which is reflected by such critical parameter as the change of T2-signal relaxation time detected using T2-mapping method play a special role in this stage of the disease (Fig. 1).Fig. 2Dynamics of Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) in study groups at baseline and after 6 and 12 months.View Large Image Figure ViewerDownload Hi-res image Download (PPT) Conclusions: It was established that both bone marrow edema (osteitis) and decrease of bindings between collagen-proteoglycan complex and water molecules which is reflected by such critical parameter as the change of T2-signal relaxation time detected using T2-mapping method play a special role in this stage of the disease. Combination of oral CS and G (Theraflex®) and intra-articular administration of sodium hyaluronate was the most effective in treatment of knee osteoarthritis.

Scan-rescan precision of subchondral bone curvature maps from routine 3D DESS water excitation sequences: Data from the Osteoarthritis Initiative

BackgroundSubchondral bone (SCB) undergoes changes in the shape of the articulating bone surfaces and is currently recognized as a key target in osteoarthritis (OA) treatment. The aim of this study was to present an automated system that determines the curvature of the SCB regions of the knee and to evaluate its cross-sectional and longitudinal scan-rescan precision MethodsSix subjects with OA and six control subjects were selected from the Osteoarthritis Initiative (OAI) pilot study database. As per OAI protocol, these subjects underwent 3T MRI at baseline and every twelve months thereafter, including a 3D DESS WE sequence. We analyzed the baseline and twenty-four month images. Each subject was scanned twice at these visits, thus generating scan-rescan information. Images were segmented with an automated multi-atlas framework platform and then 3D renderings of the bone structure were created from the segmentations. Curvature maps were extracted from the 3D renderings and morphed into a reference atlas to determine precision, to generate population statistics, and to visualize cross-sectional and longitudinal curvature changes. ResultsThe baseline scan-rescan root mean square error values ranged from 0.006mm−1 to 0.013mm−1, and from 0.007mm−1 to 0.018mm−1 for the SCB of the femur and the tibia, respectively. The standardized response of the mean of the longitudinal changes in curvature in these regions ranged from −0.09 to 0.02 and from −0.016 to 0.015, respectively. ConclusionThe fully automated system produces accurate and precise curvature maps of femoral and tibial SCB, and will provide a valuable tool for the analysis of the curvature changes of articulating bone surfaces during the course of knee OA.

Changes in proprioceptive weighting in women with knee osteoarthritis during quiet standing compared to healthy controls

Purpose: Knee osteoarthritis (OA) is highly prevalent in people above the age of 60 and is associated with pain, muscle weakness, and proprioceptive deficits at the knee joint. Muscle-tendon vibration has been used in different populations such as elderly and patients with low back pain, to assess the use of proprioceptive information from different body parts in postural control. One recent study by Shanahan et al, used muscle vibration to assess the proprioceptive weighting in a group of subjects with knee osteoarthritis (KL grade 3 or 4). To the best of our knowledge this has not been done in patients with early medial knee OA. Therefore, to better understand the progression of proprioceptive impairments with the natural course of knee OA, we aimed to investigate the proprioceptive reweighting in group of subjects with early OA according to the classification criteria of Luyten (so beginning joint degeneration on MRI), and compare them to their healthy peers and patients with established OA. Methods: Standing was challenged by vibrating ankle muscles (i.e. tibialis anterior (TA) and triceps surae (TS)) and knee musculature (vastus medialis (VM)) in 27 women with early OA, 24 with established OA, and 27 healthy controls. Two muscle vibrators were utilized bilaterally with a frequency of 70 Hz and amplitude of approximately 0.5 mm. These specific vibration characteristics are used to induce a maximum illusory motion. Each trial lasted for 45 seconds, where muscle-tendon vibration was applied during the middle 15 seconds. Center of pressure (CoP) displacement was recorded using a force plate (1000 Hz). CoP position was calculated and averaged over the first 15 s of the trial (pre-vibration), during the 15 s of vibration, and after the cessation of vibration (post-vibration). The absolute difference in mean CoP position before and during vibration was then calculated as the response to muscle vibration. Also, the postural recovery from muscle vibration was defined and calculated as the absolute difference in mean CoP position during and after vibration. The ratio between the response to vibration of the VM and TS (TS/ (TS + VM) and VM and TA (TA/ (TA + VM)) was calculated as measure of proprioceptive weighting. Results: Both early and established OA groups showed significantly different postural control strategies compared to healthy controls in favor of ankle muscle proprioceptive control (ratio closer to 1) ( TS/VM= 0.87, P =0.033 and TS/VM= 0.89, P =0.015, respectively). Vibration of triceps surae resulted in a significantly larger effect on CoP both at response and recovery, in the early (PResponse=0.023 and PRecovery˂0.001) and established (PResponse=0.006 and PRecovery=0.003) OA groups compared to the healthy controls. Conclusions: The results from this study suggest that knee OA might lead to down weighting of the proprioceptive information from knee muscles. In conclusion, Subjects with knee OA seem to rely more on ankle proprioceptive input, as previously found in elderly, which suggests alterations in postural control that might be present early in the disease process.

Does vitamin D affect femoral cartilage thickness? An ultrasonographic study

This study aims to investigate the association between vitamin D levels and distal femoral cartilage thickness in healthy subjects. Eighty patients who were admitted to our outpatient clinic between May and July 2013 were classified into three subgroups according to their 25-OH vitamin D levels of <10, 10-20, and ≥20 ng/mL. Distal femoral cartilage thickness was measured from the midpoints of the right medial condyle (RMC), right lateral condyle (RLC), right intercondylar area (RIA), left medial condyle (LMC), left lateral condyle (LLC), and left intercondylar area (LIA) by using musculoskeletal ultrasound (US). The group with severe vitamin D deficiency (<10 ng/mL) had thinner femoral cartilage thickness at LMC (p = 0.005). Positive correlations were determined only between vitamin D levels and US measurements in the severe vitamin D deficiency group at RLC (r = 444, p = 0.020), LMC (r = 357, p = 0.067), and LLC (r = 568, p = 0.002). Low levels of vitamin D seem to affect the femoral cartilage thickness, adversely. Further studies are necessary to ascertain the clinical relevance of this change in cartilage thickness and whether vitamin D supplementation can reverse the cartilage thinning process or the allied clinical symptoms in the course of knee osteoarthritis.

Editorial: Valgus alignment and lateral compartment knee osteoarthritis: A biomechanical paradox or new insight into knee osteoarthritis?

The paper by Felson and colleagues (1) in this issue reports that valgus malalignment increases the risk of knee osteoarthritis (OA) x-ray progression, and incidence of lateral cartilage damage. Furthermore the paper suggests that even a relatively slight valgus alignment may cause lateral compartment osteoarthritis (OA), in part, by increasing the risk of meniscal damage. Given that the major percentage of the ambulatory load during walking is transferred to the medial compartment of the knee even for knees with slight valgus alignment, this study raises some important questions regarding the role of static frontal plane alignment and more specifically of ambulatory forces in the natural course of knee OA. Does this study present a possible biomechanical paradox or do these results point to the need for a deeper understanding of the role of ambulatory load in the pathomechanics of knee OA? This editorial will address this potential paradox by examining the role of mechanical factors in OA across scales ranging from full body ambulation to cell biology.

The value of cartilage biomarkers in progressive knee osteoarthritis: cross-sectional and 6-year follow-up study in middle-aged subjects

To determine the possible diagnostic and prognostic value of cartilage biomarkers in early-stage progressive and nonprogressive knee osteoarthritis (OA) in a population-based cohort of middle-aged subjects with chronic knee pain. Design tibiofemoral (TF) and patellofemoral (PF) radiographs were graded in 128 subjects (mean age at baseline, 45 ± 6.2 years) in 2002, 2005, and 2008. Cartilage degradation was assessed by urinary C-telopeptide fragments of type II collagen (uCTx-II), synthesis by serum type II A procollagen N-terminal propeptide (sPIIANP), and articular tissue turnover in general by cartilage oligomeric matrix protein (sCOMP). Several diagnostic associations were found between all studied biomarkers and progressive osteophytosis. COMP and CTx-II had a predictive value for subsequent progressive osteophytosis in multiple knee compartments and in case of CTx-II-also for progressive JSN. Over the first 3 years (2002-2005), significant associations were observed between COMP and progressive osteophytosis, whereas 3 years later (2005-2008) between CTx-II and progressive JSN. Thus, the associations between cartilage markers (COMP, CTx-II) and progression of radiographic OA features--osteophytes and JSN--were different between 2002-2005 and 2005-2008. Logistic regression revealed that for every unit increase in COMP level, there was 33 % higher risk for TF osteophyte progression. During early-stage OA, the presence and progression of osteophytosis is accompanied by increased level of cartilage biomarkers. This is the first study to demonstrate biochemical differences over the course of knee OA, illustrating a phasic nonpersistent character of OA with periods of progression and stabilization.