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Gewählte Publikation:

Friesenbichler, J.
Serum metal ion concentrations following total knee arthroplasty using hinged prostheses: Comparison between fixed and rotating hinge devices
Doktoratsstudium der Medizinischen Wissenschaft; Humanmedizin; [ Dissertation ] ; 2015. pp.71. [OPEN ACCESS]


Autor*innen der Med Uni Graz:
Friesenbichler Jörg
Leithner Andreas
Maurer-Ertl Werner
Szkandera Joanna

Background: Serum metal ion concentrations of cobalt (Co) and chrome (Cr), indicating the wear behaviour of orthopaedic implants, are a critically discussed field of research due to potential harmful effects caused by their elevated systemic exposure. The aim of the study was to determine the values of cobalt, chromium and molybdenum (Mo) in the serum of patients after reconstruction of the knee using a fixed hinge megaprostheses following tumour resection. The metal ion concentrations of Co and Cr were then compared to those of patients treated with rotating hinge knee prostheses. Materials &Methods: Howmedica Modular Resection System (HMRSTM): Between 1998 and 2006, 19 patients were treated with wide resection and reconstruction of the lower extremity using the fixed hinge HMRSTM tumour prostheses for primary malignant bone tumours in the distal femur or the proximal tibia. Out of this group, 11 patients were available for the determination of serum metal ion concentrations. Limb Preservation System (LPSTM) and S-ROM®NoilesTM: Fifty-five patients underwent total knee replacement using the modular LPSTM megaprosthesis or the S-ROM®NoilesTM revision device from 2003 to 2008, after a tumour resection or revision TKA. Both implants consist of a rotating hinge articulation. Out of this group, blood was taken from 25 patients treated with these devices (LPSTM: n=17; S-ROM®NoilesTM: n=8). Serum metal ion determination: Blood was taken from all patients using stainless-steel needles attached to 9 ml no- additive plastic vacuum tubes (VACUETTE®). All needles and tubes were from the same batch and blood was taken under equal conditions by one observer. Furthermore none of the patients had a history of renal impairment. The concentrations of Co, Cr and Mo were determined using electrothermal graphite furnace atomic absorption spectrometry (ET ASS) at an external laboratory. Results: Determining the serum metal ions concentrations in patients following megaprosthetic reconstruction with a fixed hinge articulation showed a mean concentration for Co of 0.47 µg/dl (range, 0.04-1.28 µg/dl), for Cr of 0.401 µg/dl (range, 0.148-0.891 µg/dl), and for Mo of 0.06 µg/dl (range, 0.01-0.09 µg/dl) after an average follow-up of 108 months (range, 67 to 163 months). The values for Co and Cr were tenfold and twofold, respectively, increased compared to the upper values from the reference laboratory, while the Mo concentrations were within the limits. Patients treated with a LPSTM megaprosthesis also showed fifteen-fold and twofold, respectively, increased Co and Cr concentrations after an average follow-up of 34 months (range, 9 to 67 months), while the concentrations in the S-ROM®NoilesTM rotating hinge group were within the limits after nearly the same time of follow-up (mean 37, range, 15 to 62 months). The differences for Co and Cr levels between the implant groups were statistically significant (Co: p=0.010, Cr: p<0.001). Discussion: Determining the concentration of metal ions following fixed hinge total knee arthroplasty revealed significant increments for Co and Cr. The same effects could also be observed in the rotating hinge group but only in case of megaprostheses. Referring to the most recent AAOS and EFORT guidelines released for total hip arthroplasties with metal-on-metal articulation, we recommend as well close and periodic follow-ups for all other orthopaedic devices with a metal-on-metal or metal-on-polyethylene articulation with plain radiographs and serum including metal ion determination at least once. Although there was no case of an adverse reaction to metal debris in the current series, the revision of fixed hinge implants should be considered in case of high serum metal ion levels.

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