The possible diagnostic value of new biochemical markers in aseptic loosening of hip endoprosthesis

Aseptic loosening of endoprosthesis is the most important problem in total hip arthroplasty. The diagnosis of aseptic loosening is based on anamnesis,the clinical findings, the radiography and scintigraphy. Despite the mul titude of diagnostic possibilities it is still a problem to get an exact and early diagnosis. The process of loosening in the bone interface always leads to a change of bone structure of the surrounding bone tissue. In a prospective study we measured biochemical markers of bone metabolism in serum and urine to evaluate a possible change occuring parallel to endoprotheic loosening. 37 patients with severe signs of loosening (later intraoperativly confirmed) and 30 patients without any clinical or radiological signs of loosening (control group) were included. Gender, age and model of endoprosthesis were similar in both groups. Parameters of bone formation (osteocalcin, alkaline phosphatase, procollagen I C-terminal extension peptide) and bone resorption (Cross-linked n-terminal telopetide) were measured. The cross-linked n-terminal telopetide (NTX) was significant increased in the loosening group (p < 0.001). Of the measured bone formation markers only osteocalcin showed a significantly higher level in patients with endoprosthetic loosening (p < 0.002). All other measured parameters of the bone metabolism showed no significant differences between the both groups. Our results show, that biochemical markers can provide relevant information of endoprosthesic loosening. We are now analysing in a prospective longitudinal study wheather these parameters are also suitable to detect.arly endoprosthetic loosening.