RESUMO
PURPOSE: The aim of this study was to determine whether a flexible medial meniscus prosthesis is more capable of sharing loads with the direct tibiofemoral cartilage contact than the stiffer first-generation prosthesis. Additionally, the effect of the prosthesis on the tibial pressure distribution after total meniscectomy was investigated. METHODS: In an artificial knee joint, the relative amounts of load transferred through both meniscus prostheses and the direct tibiofemoral contact were assessed with pressure-sensitive sensors. Additionally, six cadaveric knee joints were loaded in a physiological environment. Tibial contact pressures were measured with an intact native meniscus, after total meniscectomy and after implantation of the second-generation meniscus prosthesis. RESULTS: Whereas the first generation of the meniscus prosthesis transferred virtually all the load from femur to tibia, the second-generation prosthesis allowed for load sharing with the direct tibiofemoral contact. No differences in load sharing were found between the native meniscus and the second-generation meniscus prosthesis. The prosthesis decreased peak and mean pressures on the medial tibial cartilage compared to meniscectomy. No significant differences in pressure were found between the native meniscus and the meniscus prosthesis. CONCLUSIONS: The second-generation meniscus prosthesis presented in this study can share loads with the direct tibiofemoral contact, a characteristic that the first-generation prosthesis did not have. The flexible meniscus prosthesis significantly reduces the contact pressures on the medial tibial plateau after total meniscectomy. Although the biomechanical performance of the native meniscus could not be reproduced completely, the meniscus prosthesis may have the potential to relieve post-meniscectomy pain symptoms.
RESUMO
In the Dutch Arthroplasty Register (LROI), the product and batch number of prosthetic components and cement are registered for traceability. Registration of the product number provides opportunities to extend the information about a specific prosthesis. All product numbers used from the beginning of the registration in 2007 were characterized to develop and maintain an implant library.The Scientific Advisory Board developed a core-set that contains the most important characteristics needed to form an implant library. The final core-set contains the brand name, type, coating and material of the prosthesis. In total, 35 676 product numbers were classified, resulting in a complete implant library of all product numbers used in the LROI.To improve quality of the data and increase convenience of registration, the LROI implemented barcode scanning for data entry into the database. In 2017, 82% of prosthetic components and cement stickers had a GS1 barcode. The remaining product stickers used HIBCC barcodes and custom-made barcodes.With this implant library, implants can be grouped for analyses at group level, e.g. evaluation of the effect of a material of a prosthesis on survival of the implant. Apart from that, the implant library can be used for data quality control within the LROI database.The implant library reduces the registration burden and increases accuracy of the database. Such a system will facilitate new designs (learning from the past) and thus improve implant quality and ultimately patient safety. Cite this article: EFORT Open Rev 2019;4 DOI: 10.1302/2058-5241.4.180063.
RESUMO
PURPOSE: In total knee arthroplasty (TKA), the posterior tibial slope is not always reconstructed correctly, and the knee ligaments may become too tight in flexion. To release a tight flexion gap, surgeons can increase the posterior tibial slope using two surgical resection techniques: the anterior tibial cortex (ACR) or the centre of tibial plateau (CPR) referencing. It is not known how this choice affects the knee laxity and function during activities of daily living. The aim of this study was to investigate the effect of tibial slope on knee laxity, kinematics and forces during a squatting activity using computer simulation techniques. We hypothesised that the effects depend on the referencing technique utilised. METHODS: A validated musculoskeletal model of TKA was used. Knee laxity tests were simulated in flexion and extension. Then, a squat motion was simulated to calculate: movement of the tibiofemoral joint (TFJ) contact points and patello-femoral joint (PFJ) contact force. All analyses were repeated with more anterior (-3°), neutral (0°), and more posterior tibial slope (+3°, +6°, +9°), and with two referencing techniques (ACR, CPR). RESULTS: Knee laxities increased dramatically with more posterior slope with the ACR technique (up to 400%), both in flexion and in extension. The CPR technique, instead, had much smaller effects (up to 42% variations). During squatting, more slope with the ACR technique resulted in larger movements of the TFJ contact point. The PFJ contact force decreased considerably with more slope with the CPR technique (12% body weight reduction every 3° more posterior slope), thanks to the preservation of the patellar height and quadriceps-femur load sharing. CONCLUSION: ACR technique alters considerably the knee laxity, both in flexion and extensions, and surgeons should be cautious about its use. More slope with CPR technique induces more favourable TFJ kinematics and loading of the knee extensor apparatus and does not substantially alter knee laxity. Preferably, the tibial slope resection should be pre-planned thoroughly and performed using CPR technique as accurately as possible. Surgeons can directly translate the results of this study into the clinical practice.
