Rotating Platform Knee Prosthesis Research Articles

The Outcome of Posterior-Stabilized, Rotating Platform Total Knee Arthroplasty at a Minimum Ten-Year Follow-Up, a Middle East Institution Experience.

Posterior-stabilized, rotating platform knee prosthesis design was aimed to decrease polyethylene wear for the sake of improving implant survivorship. The purpose of the present prospective study was to evaluate the long-term clinical and radiographic results as well as the survival rate after using a rotating platform, posterior-stabilized knee prosthesis at a minimum of 10 years at a Middle East institution. We compared the results with reports in the literature on western populations. From January 2002 to June 2008, 96 patients (106 knees) underwent total knee arthroplasty (TKA) using a cemented rotating platform posterior-stabilized knee prosthesis. At a mean of 11.5 ± 1.3 years, 85 patients (95 TKAs) were available for clinical, radiographic, and implant survival analysis. At the final follow-up, 78.9% of the patients had excellent Knee Society Scoring system score, the average knee flexion was 110 ± 17 degrees, the average anatomical knee coronal alignment was 186 ± 2 degrees and 187 ± 3 degrees for varus and valgus knees, respectively. Five (5.2%) knees were revised of these: two for bearing dislocation, two for aseptic loosening, and one for infection. The Kaplan-Meier survival rate was 94.7% for all revisions and 97.8% when only revision for aseptic loosening considered as the end point. At a long-term follow-up, reasonable clinical and radiographic outcomes had been achieved after using a rotating platform, posterior-stabilized knee prosthesis in our population with acceptable survival rate reaching up to 95%, which is comparable to reports from the western population.

The process of designing a rotating platform artificial knee prosthesis with posterior stabilizers by finite element analysis

The purpose of this paper is to design a rotating platform knee prosthesis with posterior stabilizers. This design is based on reverse engineering and interactive acquisition and reconstruction of 3D models combined with the finite element method. A 3D geometric model of a healthy knee joint was created from an anatomical knee model by using an active acquisition system based on a 3D scanner. This healthy model comprises a portion of the long bones (femur, tibia and fibula), as well as the transverse ligament, medial collateral ligament, posterior cruciate ligament, anterior cruciate ligament, medial meniscus and cartilage. The digital model that was obtained was repaired and converted to an engineering drawing format by use of CATIA© software. Also, based on the foregoing format, a rotating platform knee prosthesis was designed and assembled by this software. Once the healthy and artificial models were repaired, the Mentat Marc© software was used to develop the healthy and artificial knee FE models. From the anthropometry of the human body, a combination of loads and positions were obtained by use of 3D Static Strength Prediction software. The normal stresses, Von Mises stresses and all relative displacements of the healthy and artificial knee FE model were determined. The Von Mises stresses on both the cortical and the trabecular bone of the artificial and healthy knee FE model were analyzed and compared. The prosthesis was designed for the knee of a male patient of height and body weight of 190 cm and 120 kg, respectively.

Does mobile-bearing knee arthroplasty motion change with activity?

BackgroundThe purpose of this study was to evaluate the effect of mobile-bearing implant design and activity on knee arthroplasty kinematics during three activities of daily living. MethodsIn vivo kinematics were analyzed using 3D model registration from fluoroscopic images of non-weightbearing knee flexion-extension, weight-bearing squatting and stair activities in 20 knees in 10 patients with bilateral total knee arthroplasty. Each patient had one rotating-platform and one meniscal-bearing variant of the same prosthesis design. ResultsAnteroposterior translations in meniscal-bearing knees were larger than those in rotating-platform knees for the different dynamic conditions. Meniscal-bearing knees showed more posterior femoral locations with activities that increased demand on the quadriceps. Condylar translations changed little in rotating-platform knees with different activities. ConclusionsActivity dynamics can have a significant influence on knee kinematics, and have a greater effect on the kinematics of unconstrained meniscal-bearing prostheses than rotating-platform knee prostheses. Level of evidenceLevel II.

Functionality and Safety of an Ultra-Congruent Rotating Platform Knee Prosthesis at 5.6 Years: More than 5- Year Follow-Up of the e.motion® UC-TKA

Background:Mobile bearing TKA prostheses were designed to minimize polyethylene wear by increasing implant conformity and reducing stresses between the articulating prosthesis components. It is the purpose of this study to assess the mid-term functionality and clinical outcome associated with a highly congruent mobile platform design, the e.motion® UC total knee prosthesis.Material and Methods:Functional and clinical outcomes were assessed after an average of 5.6 years (5.1 – 6.0 years) after total knee arthroplasty in 28 patients (24 women), aged 77.8±7.5 years. The Knee injury and Osteoarthritis Outcome Score (KOOS) was assessed. Secondary outcomes included the Knee Society Score (KSS), radiological evaluation of radiolucent lines and recording of adverse events.Results:The average KOOS subscore for the activities of daily life was 77.8 points after 5.6 years. Both the clinical and functional KSS improved at 2.4 and 5.6 years. Two patients showed radiolucent lines at 5.6 years. Adverse events over 5.6 years included 3 subluxations, 1 tilting and 1 misalignment of the patella. None of the prostheses were revised.Conclusion:This pilot study shows promising outcomes for the e.motion® UC prosthesis. In the small sample, the implant performed comparably to the LCS prosthesis (the gold standard). There were no loosenings or revisions observed at 5.6 years.

Microscratching Characterization of the Wear-in of UHMW Polyethylene in Prostheses

A new measurement technique of prosthesis wear by microscratching has been demonstrated. The technique has been applied in a study of the backside wear of a UHMW polyethylene tibial insert of a rotating platform knee prosthesis. Four disc-shaped UHMW polyethylene plugs, prepared with 5-μm deep microscratches, were carefully recessed into the backside of the tibial insert. It was demonstrated that the scratches are not affected by creep under static load. A realistic in vitro wear simulation experiment was performed over 0.8 × 106 flexion cycles. SEM and AFM show that following the experiment the initial microscratches are effectively absent in all four locations with only residual depressions observed. This implies that typically at least 5 μm of polyethylene material was worn over the first 0.8 × 106 cycles by processes other than creep. Evidence from AFM and SEM indicates the in-fill and reintegration of polyethylene wear particles into residual scratch depressions. This supports a two-phase model of the wear process that has been independently confirmed by radioisotope tracing. For an initial wear-in phase, the model implies large, but rapidly decreasing, wear, resulting from abrasive wear and a competition between the loss and the reintegration of wear particles. The in vitro wear-in of the backside may typically produce a wear debris volume of 8.5 mm3. In addition to wear-in, the model assumes a much lower, constant long-term wear rate. The model has been used to correct published backside wear rates for the effects of the wear-in phase. A best estimate of 0.7 mm3/106 cycles has been determined for the long-term in vitro backside wear rate of a tibial insert in a rotating platform design.

Long-Term Clinical Outcomes and Survivorship After Total Knee Arthroplasty Using a Rotating Platform Knee Prosthesis: A Meta-Analysis

A systematic search identified 29 papers reporting survivorship and clinical and function Knee Society Scores (KSS) of 6437 total knee replacements using the Low Contact Stress (LCS) Rotating Platform (RP) mobile bearing knee. Low Contact Stress RP survivorship and KSS outcomes were compared with non-LCS knees in the Swedish knee registry at comparable time periods and in 2 independent systematic reviews of knee arthroplasty outcomes. There is a substantial body of mainly observational evidence supporting the LCS RP knee. Knee Society Score outcomes were comparable for LCS RP and non-LCS RP knees at up to 15 years of follow-up, with mean clinical and function scores ranging from 72 to 96 and 58 to 90, respectively. Survivorship of LCS RP knees up to 14 years was higher than that for all knees in the Swedish Knee Registry.