THE SERUM LEVELS OF RECEPTOR ACTIVATOR OF NUCLEAR FACTORκB LIGAND, BONE-SPECIFIC ALKALINE PHOSPHATASE, OSTEOCALCIN AND OSTEOPROTEGERIN DO NOT CORRELATE WITH THE RADIOGRAPHICALLY ASSESSED SEVERITY OF IDIOPATHIC HIP AND KNEE OSTEOARTHRITIS

Abstract

Objective: The clinical significance of biochemical bone markers in the diagnosis and severity of Osteoarthritis remains still unknown. The relationship between biochemical bone turnover markers and commonly recognizable radiographic features of knee and hip osteoarthritis remains unclear.

Purpose: We evaluated the serum levels of Receptor Activator of Nuclear Factor-κB Ligand (RANKL), Bone-specific Alkaline Phosphatase (b-ALP), Osteocalcin and Osteoprotegerin in two groups of patients suffering from osteoarthritis of the Knee or Hip respectively, aiming to correlate these results with the radiographically assessed severity of the disease and the patients’ age. The results between the two groups were also compared.

Patients-Methods: Between March 2007 and February 2009, a total of 175 patients suffering from Knee or Hip Osteoarthritis were enrolled in the study. Following proper radiographic evaluation, the osteoarthritic changes of patients were graded by 3 orthopaedic surgeons according to the system of Kellgren and Lawrence; at the same time the serum levels of biochemical markers were determined.

Results: Osteoprotegerin was found to be positively correlated with age in both the Knee (r=0.376, p=0.000) and Hip (r=0.425, p=0.001) group, whether Osteocalcin was significantly correlated with the age in the group of Knee Osteoarthritis(r=0.218, p=0.02). No other significant correlation was noted between the serum level of markers and age of patients in both groups. There was not significant difference in the mean serum level of biochemical markers among patients belonging to each of the four different levels of severity of hip and knee OA. There was no significant impact of the type of Osteoarthritis, to the serum level of all biochemical markers.

Conclusions: Based on our results, it seems that none of the serum biochemical markers studied can be used (either independently or in combination with the others) as surrogates for radiographic imaging in Hip and Knee osteoarthritis.