No abstract

No abstract

Background:Total knee arthroplasty can be considered as a reliable surgical procedure with a good long-term clinical result. However, implant failure due to particle induced aseptic loosening as well as the aspect of hypersensitivity to metal ions still remains an emerging issue.Methods:The purpose of this prospective international multi-centre study was to evaluate the clinical and radiological outcomes and the reliability of the unconstrained Multigen Plus Total Knee System with a new BIOLOX® delta ceramic femoral component. Cemented total knee arthroplasty was performed on 108 patients (110 knees) at seven hospitals in three countries. Clinical and radiological evaluations were performed preoperatively, and after 3, 12 and 24 months postoperatively using the HSS-, WOMAC-, SF-36-score and standardised X-rays.Results:The mean preoperative HSS-Score amounted to 55.5 ± 11.5 points and improved significantly in all postoperative evaluations (85.7 ± 11.7 points at 24 months). Furthermore, improvements in WOMAC- and SF-36-score were evaluated as significant at all points of evaluation. Radiolucent lines around the femoral ceramic component at 24 months were found in four cases. Progression of radiolucent lines was not seen and no implant loosening was observed. During the 24 month follow-up eight patients underwent subsequent surgery due to reasons unrelated to the implant material.Conclusions:The observed clinical and radiological results are encouraging for a long-term survival of the ceramic femoral component. Therefore, ceramic implants could be a promising solution not only for patients with allergies against metallic implant materials, but also for the osteoarthritic knee joint. Long-term follow-up is necessary to draw conclusions regarding the superiority of the ceramic knee implants concerningin vivowear and long-term survivorship.

The wear simulator test demonstrates that wear of polyethylene inserts under third-body wear conditions, in combination with ceramic femoral components, was significantly lower than with metallic femoral components.

Small cartilage defects treated with microfracture show comparable clinical results to those treated with ACI (autologous chondrocyte implantation). Unfortunately, the regenerative tissue generated by microfracture treatment does not exhibit the structure and function of hyaline articular cartilage. Adult mesenchymal stem cells are supposed to be capable of differentiating according to mechanical stimuli, e.g. into chondrocytes, thus generating hyaline cartilage. The treatments used so far, such as the microfracture procedure, are only able to induce mechanically insufficient fibrocartilage. The purpose of the present study was to test the influence of a resorbable implant manufactured from PGLA (polyglycollic-co-lactic acid) fleece in combination with microfracture in the weight-bearing area of the femoral condyle of mature sheep on cartilage repair. Artificial chondral defects (diameter: 8 mm) were created and treated with microfracture, with a PGLA implant alone or with a combination of both (n=6 for each group). Untreated empty defects served as controls. Under thorough pain control, full weight bearing was permitted immediately after the operation. After 12 weeks, the animals were killed and the operated knees were removed and histologically processed. First, the degree of covering of the defect with regenerative tissue was measured; then, the quality of the regenerate was evaluated using the score of O'Driscoll, Keeley and Salter [(1986) J. Bone Joint Surg. Am. 68, 1017-1035], which was modified to include histochemical labelling results. The combination of PGLA implant and microfracture led to a significant improvement of the quality of the regenerate when compared with microfracturing alone.

The annual number of total knee replacement implantations is rising continuously. A progressive cutaneous hypersensitivity rate against metallic materials in the population has been registered which can lead to an increase of allergy-induced reactions associated with implant loosening in the future although the correlation with an allergic cutaneous sensitisation has not been proven in all cases. On apparent allergy against metallic implant components different alternative solutions to standard endoprostheses should be taken into account for primary implantation or revision of total knee replacement, for example the application of implant components without metallic elements (e.g. ceramics), the use of non-allergic metallic implants, such as titanium or ZrNb alloys, or potential allergy-inducing metallic materials after masking the implant surface using a suitable coating. In the case of primary or revision surgery most patients with metal allergy are treated with a Ti(Nb)N-coated knee implant made of cobalt-chrome or titanium alloys in our hospital. Within an international multi-centre study we are currently implanting a newly developed knee endoprosthesis system with a ceramic femoral component as an alternative.

Poor preoperative function may affect recovery unfavourably and lead to prolonged pain. Earlier THA in the course of functional decline may associate with better outcomes.

During follow-up no stem had to be revised. The mean preoperative HHS of the three study groups amounted to 54.6 ± 15.7 points. At the 12 months follow-up the mean HHS in the SL-Plus group (n = 22) was 88.3 ± 10.5 points, in the Hipstar group (n = 25) 83.3 ± 15.0 and the in Symax group (n = 27) 83.6 ± 15.1. Due to stress shielding the straight Hipstar stem revealed radiolucent lines in the proximal Gruen zones of about 60%, whereas the SL-Plus stem showed significantly more radiolucent lines (87%). However, subsequent long-term studies must be carried out in order to clarify if the progression of radiolucent lines may influence the clinical result and implant longevity.