Total anti-oxidant status and C-reactive protein values in Nigerians with symptomatic primary osteoarthritis of the knee joint – an initial report

Osteoarthritis is a degenerative as well as an inflammatory disorder of joints. The joint inflammation in this disease (as with inflammation in other organs of the body) leads to the production of acute phase proteins like C-reactive protein (CRP) along with the release of cytokines and neutrophils. The lysosomes released from the activated neutrophils result in the production of large amounts of free radicals which are harmful to the human body. Antioxidants on the other hand are substances that when present even in low concentrations avidly react with and annihilate free radicals before oxidative damage is inflicted on vital components of the cells. This case-control study was aimed at investigating the influence of age; body mass index, total antioxidant status (an indirect measure of total free radicals) and c-reactive protein (an acute phase reactant) on symptomatic osteoarthritis of the knee. Thirty five subjects with clinical and radiological features of osteoarthritis of the knee were recruited from the Orthopaedic clinic of the University College Hospital, Ibadan. Twenty healthy age-matched controls were recruited from the Surgical Outpatient Clinic of the same hospital. Informed consent, biodata and body mass indices were obtained after which venous blood samples were obtained from each subject. Total plasma antioxidant status (TAS) was estimated spectrophotometrically by the Koracevic method while the CRP concentration was measured using Humatex CRP kit® (Human GmbH, Germany). The mean ages of the test and control groups were 58.8±12.0 and 52.3±7.9 years respectively. Osteoarthritic patients demonstrated significantly higher (p <0.05) BMI (32.2±6.9 kg/m²) compared to controls (26.1±3.4 kg/m²). The mean TAS was significantly lower (p <0.05) in the test (1.09±0.38 mmol/l) compared to the controls (1.61±0.09 mmol/l). CRP was positive in 19 (54.3%) of the test subjects but negative in all the control. There was an inverse correlation between the BMI and TAS (p <0.05) as well as between age and TAS (p <0.05). This study shows that Nigerian patients with symptomatic osteoarthritis of the knee tend to be obese and have a lower total antioxidant status. Antioxidant supplementation of the diet as a means of minimizing the severity of osteoarthritis and other free radical-mediated diseases in older Nigerian adults is advocated.

Keywords
Osteoarthritis; anti-oxidants; c-reactive protein; acute phase reactants; Nigeria.