Ceramic wear debris in synovial fluid allow early diagnosis of hip prosthesis failure

Abstracts / Bone 44 (2009) S253–S338

Conclusion: Balloon Kyphoplasty as an addition to oncologic treatment leads to a statistically significant reduction of pain status and improvement of physical function. Further, Balloon Kyphoplasty prevents a height loss and increase of kyphotic deformity. Conflict of interest: None declared. doi:10.1016/j.bone.2009.03.519

P094 The effect of zoledronic acid on serum Dickkopf-1, osteoprotegerin and rankl in patients with paget's disease of bone S.A. Polyzosa,*, A.D. Anastasilakisa, Z. Efstathiadoua, M. Kitaa, I. Litsasa, A. Avramidisa, G. Arsosb, E. Moralidisb, S. Gerouc, V. Pavlidouc, A. Papatheodoroud, E. Terposd a Endocrinology, Ippokration General Hospital b Nuclear Medicine, Aristotle University of Thessaloniki c Microbiology, Laboratories Analysis, Thessaloniki d Medical Research, 251 General Airforce Hospital, Athens, Greece Background: The receptor activator of nuclear factor kappaB ligand (RANKL) and osteoprotegerin (OPG) are implicated in the pathogenesis of Paget's disease of bone (PDB). Wnt/beta-catenin signaling promotes new bone formation by functioning as a positive regulator of osteoblasts and negative regulator of osteoblastdependent osteoclastogenesis, at least partially by up-regulating OPG and down-regulating RANKL on osteoprogenitors. Dickkopf (DKK)-1 is a secreted Wnt signaling antagonist. Overexpression of DKK-1 in culture of Pagetic osteoblasts resulted in stimulation of osteoclast proliferation and inhibition of osteoblast growth. Zoledronic acid (ZOL) has been introduced in the treatment of PDB, but the molecular mechanisms mediating its action are not fully elucidated. AIMS: Our hypothesis was that ZOL could affect the OPG/RANKL dipole directly or indirectly through down-regulation of DKK-1. The aim of this study was to evaluate for first time in PDB: 1) the serum levels of DKK1; 2) the association of DKK-1 with RANKL and OPG; 3) the effect of ZOL on serum DKK-1, RANKL and OPG. Methods: 11 patients with active (biochemically and scintigraphically) PDB, median aged 60 years, were prospectively recruited in the study. 12 age-gender- and BMI-matched healthy individuals were used as controls at baseline. Blood samples were obtained before treatment (baseline) and after 3, 6, 12 and 18 months following ZOL infusion in patients with PDB.Results: Patients with PDB had significantly higher RANKL (p = 0.002), OPG (p = 0.001) and bone markers (total alkaline phosphatase and CTX) compared with controls at baseline. However, there were no differences between groups in DKK-1 and RANKL:OPG ratio at baseline. Serum OPG, RANKL, RANKL:OPG ratio and DKK-1 remained unaffected throughout the study. No significant correlations were found between OPG, RANKL, RANKL:OPG ratio and DKK-1 at baseline nor between their changes during the study. Bone markers were both significantly decreased after therapy. Conclusions: Although OPG and RANKL were both increased in patients with PDB, which are indicative of increased activation of the OPG/RANKL/RANK system, ZOL had no effect on serum OPG, RANKL or DKK-1. DKK-1 was not increased in patients with PDB, was not related to OPG and RANKL and was unaffected by ZOL. Although the initial hypothesis was rejected according to the results, this study cannot exclude the effect of ZOL on DKK-1, OPG and RANKL in bone milieu in PDB. Conflict of interest: None declared. doi:10.1016/j.bone.2009.03.520

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P095 Ceramic wear debris in synovial fluid allow early diagnosis of hip prosthesis failure S. Steaa,*, F. Trainab, A. Beraudia, M. Montesia, S. Squarzonic, A. Sudaneseb, A. Tonid a Laboratorio Tecnologia Medica b i Divisione Di Ortopedia E Traumatologia, Istituto Ortopedici Rizzoli c Istituto Di Genetica Molecolare, Cnr d i Divisione Di Ortopedia E Traumatologia, Laboratorio Di Tecnologia Medica, Istituto Ortopedici Rizzoli, Bologna, Italy Ceramic on ceramic hip prosthesis represents a solution for joint pathologies particularly in young patients. While ceramic head fractures are seldom reported [1], ceramic liner fractures are not well recognized. Patients with damaged ceramic components nearly always present a noising hip. Conventional X-ray does not allow an early diagnosis because only macroscopic damage can be pointed out. CT scan can be applied to demonstrate impingement or malpositioning and represents a powerful diagnostic tool, but it cannot provide information about damage to the liner as well. Definitive demonstration of micro damage of the liner can be obtained only through the analysis of wear debris in the synovial fluid. Early recognition of clinical signs of ceramic liner fractures, is essential to avoid the wide spread of ceramic particles in the periarticular space, that can seriously damage also the new prosthesis in case of revision surgery. We have already demonstrated that patients with real noising hips (excluding snapping hip) present some ceramic particles in the fluid while control patients do not [2]. Aim of the present study is to verify if the presence of ceramic wear particles in the synovial fluid can predict a significant damage of the liner. We therefore enrolled in the study 15 ‘noising patients' and we correlated the presence of ceramic debris in the fluid with the damage observed in the liner at time of revision. 12 control patients wearing the same type of prostheses, successfully functioning represented the ‘control-patients’. Particles were isolated from synovial fluid by hypoclorite digestion, then measured and chemically identified by means of scanning electron microscopy and microanalysis as previously described [3]. No ceramic particles were isolated from control patients; on the contrary all ‘noising patients’ were positive for wear particles, as expected. In 12 out of 15 cases, liner resulted macroscopically damaged at time of revision surgery and were exchanged; intense wear and particles, at least 3 μm large, occurred in these cases. In the remaining three cases abnormal wears of both head and bottom of the liner were found; wear particles appeared smaller and less numerous. It can be concluded that the presence in synovial fluid of ceramic particles of at least 3 μm can predict liner damage in ceramic on ceramic noising hip prostheses. [1] Willmann G. 2000. Clin Orthop Relat Res 2000–379:22–8. [2] Toni A et al., 2006, J. Bone Joint Surg.88,4,65–73. [3] Visentin M., 2005 J: Biomater Appl. Oct;20(2):103–21. Conflict of interest: None declared. doi:10.1016/j.bone.2009.03.521

P096 Relationship between age and bone turnover markers in patients with active ankylosing spondylitis S. Arendsa,*, E. Brouwera, A. Spoorenbergb, T.L. Jansenb, P.M. Houtmanb, C.G. Kallenberga, P.C. Limburga, E. van der Veerc a Rheumatology, University Medical Centre Groningen, Groningen b Rheumatology, Medical Centre Leeuwarden, Leeuwarden c Laboratory Medicine, University Medical Centre Groningen, Groningen, Netherlands