Correlations Of Cartilage Volume, Structure Changes And Adipokines In Patients With Knee Osteoarthritis

Background Osteoarthritis(OA) is the most common chronic joint disease worldwide, is a major cause of disability in the elderly people. At present, radiological examination of X-ray has become the gold standard of diagnosis of OA. However, it could not to observe OA early joint structure changes, which bring a certain degree of difficulty in early diagnosis and treatment of OA. Magnetic resonance imaging(MRI) can found early and subtle structure changes; Therefore, MRI become very popular of early diagnosis and treatment of OA. In recent years, foreign research has demonstrated that the articular cartilage volume(CV) is related with the radiological changes including osteophyte(OP), joint space narrowing(JSN) and other related joint structure change. These kinds of research in China are rarely reported, especially for the patients with knee OA. Excessive joint bearing caused by obesity is a potential mechanism for the change of knee joint structure of OA, but metabolic inflammation may also play an important role. Recent studies suggest that adipose tissue, not only has the energy storage function, but also can secrete a variety of adipocytokines, such as leptin(LPT), adiponectin(ADP), resistin(RST), playing a regulatory role on chondrocyte. Now there are no reports about the relationship between knee OA and adipocytokines in our country.Objections The purpose of the study is to examine the relationship between CV and radiological changes, cartilage defect(CD), bone marrow lesions(BMLs) and other structural changes. In addition, to analysis the relationship between CV, radiographic severity and serum adipocytokines, laboratory indicators is the other purpose, in order to improve the understanding of OA, to explore the possible early diagnosis and potential therapeutic target.Methods 205 symptomatic patients with knee OA were collected from January 2012 to November 2013 in outpatient department of rheumatism, the First Affiliated Hospital of Medical University. According to the Kellgren- Laurence(KL) grades and Osteoarthritis Research Society International(OARSI) index assess the knee joint radiographic severity and the classification of OP and JSN. Using Osiri X software measure CV and assess the classification of CD and BMLs in MRI. Record the clinical and laboratory indexes of OA patients, and according to The Western Ontario and Mc Master University Osteoarthritis Index(WOMAC) evaluate knee joint pain, stiffness and joint function of patients with knee OA and measure the levels serum LPT, ADP and RST by enzyme-linked immunosorbent assay(ELISA).Results1. Correlation between CV and clinical, laboratory indicators: total CV(sum of patella, medial tibial and lateral tibial CV) positively associate with WHR(r=0.172, P=0.033); CV(patella, medial tibial, lateral tibial) between male and female has obvious difference(P < 0.05); Patients with radiological changes(ROA) have obvious difference with patients without radiological changes(non-ROA) in age, duration of disease, total CV, patella CV(P values are 0.003, 0.003, 0.026, 0.028);2. Correlation between CV and radiological changes: patella CV negative associated with lateral tibial OP(β:-0.103, 95% CI:-0.165,-0.040) and medial tibial, lateral tibial CV was significantly negative associated with JSN in specific site(β:-0.090, 95% CI:-0.171,-0.009 and β:-0.125, 95% CI:-0.219,-0.030 respectively);3. Correlation between CV and CD: there are significant associations between CV(patella, medial tibial, lateral tibial) and CD in specific site. For example, the medial tibial CV was associated with medial tibial CD before and after adjustment for age, sex, BMI and disease duration(β:-0.121, 95% CI:-0.170,-0.072 and β:-0.114, 95% CI:-0.163,-0.064 respectively);4. Correlation between CV and BMLs: there is a significantly negative association between CV of medial tibial and BMLs of medial tibial before and after adjustment for age, sex, BMI and disease duration(β:-0.042, 95% CI:-0.119,-0.024).5. Correlation between CV and serum adipocytokines: In ROA patients, LPT was significantly and positively associated with knee cartilage volume at patellar and medial tibial sites in both unadjusted and adjusted analyses(β: 6.213, 95% CI: 2.11, 10.10 for medial tibia; and β: 10.172, 95% CI: 1.30, 17.55 for patella), but ADP and RST had no significant association with cartilage volume. In non-ROA patients, LPT, ADP, RST were not significantly associated with cartilage volume at any site.6. Correlation between serum adipocytokines and KL grades: Serum ADP, not LPT and RST was significantly associated with reduced radiographic OA severity in univariable analyses and this association remained significant after adjustment for age, sex, BMI and disease duration(OR: 0.988, 95% CI: 0.979, 0.998).Conclusions1. The knee joint CV associated with other joint structure changes in OA patients. Therefore, CV may be a good clinical indicator in diagnosis OA.2. Serum levels of leptin are independently associated with increased knee cartilage volume. In addition, serum adiponectin is significantly and negatively associated with radiographic OA severity, suggesting a potentially protective effect.