Tibial Component In Total Knee Arthroplasty Research Articles

Metal-backed versus all-polyethylene tibial components in primary total knee arthroplasty

Background and purpose The choice of either all-polyethylene (AP) tibial components or metal-backed (MB) tibial components in total knee arthroplasty (TKA) remains controversial. We therefore performed a meta-analysis and systematic review of randomized controlled trials that have evaluated MB and AP tibial components in primary TKA.Methods The search strategy included a computerized literature search (Medline, EMBASE, Scopus, and the Cochrane Central Register of Controlled Trials) and a manual search of major orthopedic journals. A meta-analysis and systematic review of randomized or quasi-randomized trials that compared the performance of tibial components in primary TKA was performed using a fixed or random effects model. We assessed the methodological quality of studies using Detsky quality scale.Results 9 randomized controlled trials (RCTs) published between 2000 and 2009 met the inclusion quality standards for the systematic review. The mean standardized Detsky score was 14 (SD 3). We found that the frequency of radiolucent lines in the MB group was significantly higher than that in the AP group. There were no statistically significant differences between the MB and AP tibial components regarding component positioning, knee score, knee range of motion, quality of life, and postoperative complications.Interpretation Based on evidence obtained from this study, the AP tibial component was comparable with or better than the MB tibial component in TKA. However, high-quality RCTs are required to validate the results.

All-polyethylene tibial components in TKA in rheumatoid arthritis: a 25-year follow-up study

PurposeThere is renewed interest in the all-polyethylene tibial component in total knee arthroplasty (TKA). Long-term results of this prosthesis in rheumatoid arthritis (RA) patients, however, are limited. Therefore, we studied 104 primary cemented all-polyethylene tibial TKA in 80 consecutive RA patients for up to 25 years to determine the long-term survival of all-polyethylene tibial components in patients suffering from end stage RA.MethodsWe estimated revision rates according the revision rate per 100 observed component years used in national joint registries. Kaplan–Meier was used to estimate survival curves.ResultsDuring the 25-year follow-up, three revisions for tibial component loosening were performed. The mean revision rate of all-polyethylene tibial components with revision for aseptic loosening as the endpoint was 0.09 per 100 observed component years. This corresponds to a revision rate of 0.9% after ten years and 2.25% after 25 years. Survivorship according to Kaplan–Meier was 100% at ten years and 87.5% at 25 years [95% confidence interval (CI) 64.6–100)].ConclusionThis study shows good long-term results of all-polyethylene tibial TKA in patients with RA. RA patients with multiple-joint inflammation may be less physically active than osteoarthritis patients, resulting in a lower demand on the prosthesis, and these patients may, indeed, be good candidates for all-polyethylene tibial TKA. Our results suggest that all-polyethylene tibial TKA could be a successful and cost-saving treatment for end-stage knee arthritis in RA patients.

Pulsed lavage improves fixation strength of cemented tibial components

Pulsatile lavage is purported to improve radiographic survival in cemented total knee arthroplasty (TKA). Similarly, a potential improvement of fixation strength of the tibial tray has been assumed based on the increased cement penetration. In this study, the influence of pulsed lavage on fixation strength of the tibial component and bone cement penetration was evaluated in six pairs of cadaveric specimens. Following surgical preparation, the tibial surface was irrigated using pulsatile lavage on one side of a pair, while on the other side syringe lavage was applied. All tibial components were implanted using the same cementing technique. Cement penetration and bone mineral density was assessed based on computed tomography data. Fixation strength of the tibial trays was determined by a pull-out test with a material testing machine. Median pull-out forces and cement penetration were significantly (p = 0.031) improved in the pulsed lavage group as compared to the syringe lavage group. Enhanced fixation strength is suggested as being a key to improved survival of the implant. Consequently, pulsatile lavage should be considered as a mandatory preparation step when cementing tibial components in TKA.

Comparison of Bone Mineral Density Between Porous Tantalum and Cemented Tibial Total Knee Arthroplasty Components

Porous tantalum was recently introduced as a metallic implant material for total knee arthroplasty. Its porosity, low modulus of elasticity, and high frictional characteristics were expected to provide physiologic load transfer and relative preservation of bone stock. However, to our knowledge, the effect of a Trabecular Metal tibial component on bone mineral density has not been reported. The purpose of the present study was to compare the periprosthetic bone mineral density between patients managed with uncemented Trabecular Metal and cemented tibial components. Twenty-eight knees receiving a Trabecular Metal tibial component and twenty-eight knees receiving a cemented cobalt-chromium tibial component had dual x-ray absorptiometry scans at two weeks preoperatively and at two weeks and six, twelve, eighteen, and twenty-four months postoperatively, to assess periprosthetic bone mineral density. All of the operations were performed by one surgeon through a medial parapatellar approach. None of the differences between the two groups in terms of preoperative bone mineral density in the femoral neck, wrist, lumbar spine, or knee were significant. In both groups, the bone mineral density in the tibia decreased postoperatively. However, the postoperative decrease in bone mineral density in the lateral aspect of the tibia was significantly less in knees with Trabecular Metal components than in knees with cemented tibial components at twenty-four months (mean and standard deviation, -6.7% +/- 22.9% compared with -36.8% +/- 24.2%; p = 0.002). At twenty-four months postoperatively, there was no significant difference between the two groups in terms of the Knee Society score, range of motion of the knee, or bone mineral density in the lumbar spine. No prosthetic migration or periprosthetic fracture was detected in either group. The decrease in bone mineral density of the lateral tibial plateau was less in knees with a Trabecular Metal tibial component following total knee arthroplasty than in knees with a cemented tibial component. Additional research is needed to determine whether long-term clinical benefits are realized with the use of porous tantalum tibial components for total knee arthroplasty.

Fluoroscopic and Computed Tomographic Analysis of Knee Kinematics During Very Deep Flexion After Total Knee Arthroplasty

We examined the relative motion of femoral and tibial total knee arthroplasty components and the difference between 2 different tibial inserts (9 flat types and 7 dish types) in patients sitting in very deep flexion. X-ray, fluoroscopic examination, and computed tomography were used to analyze liftoff, and rotation. During seiza-style sitting, one knee (11%) with the flat insert lifted off on the medial side and 5 knees (71%) with the dish-type insert showed liftoff. The tibial internal rotation angles were 17.2° ± 4.1° (flat type) and 11.7° ± 3.1° (dish type) ( P < .05). The flat type showed less liftoff at the medial side and more internal rotation. For very deep flexion, components that tolerate larger rotational freedom are favorable.

Experimental Analysis of Model-Based Roentgen Stereophotogrammetric Analysis (MBRSA) on Four Typical Prosthesis Components

Classical marker-based roentgen stereophotogrammetric analysis (RSA) is an accurate method of measuring in vivo implant migration. A disadvantage of the method is the necessity of placing tantalum markers on the implant, which constitutes additional manufacturing and certification effort. Model-based RSA (MBRSA) is a method by which pose-estimation of geometric surface-models of the implant is used to detect implant migration. The placement of prosthesis markers is thus no longer necessary. The accuracy of the pose-estimation algorithms used depends on the geometry of the prosthesis as well as the accuracy of the surface models used. The goal of this study was thus to evaluate the experimental accuracy and precision of the MBRSA method for four different, but typical prosthesis geometries, that are commonly implanted. Is there a relationship existing between the accuracy of MBRSA and prosthesis geometries? Four different prosthesis geometries were investigated: one femoral and one tibial total knee arthroplasty (TKA) component and two different femoral stem total hip arthroplasty (THA) components. An experimental phantom model was used to simulate two different implant migration protocols, whereby the implant was moved relative to the surrounding bone (relative prosthesis-bone motion (RM)), or, similar to the double-repeated measures performed to assess accuracy clinically, both the prosthesis and the surrounding bone model (zero relative prosthesis-bone motion (ZRM)) were moved. Motions were performed about three translational and three rotational axes, respectively. The maximum 95% confidence interval (CI) for MBRSA of all four prosthesis investigated was better than -0.034 to 0.107 mm for in-plane and -0.217 to 0.069 mm for out-of-plane translation, and from -0.038 deg to 0.162 deg for in-plane and from -1.316 deg to 0.071 deg for out-of-plane rotation, with no clear differences between the ZRM and RM protocols observed. Accuracy in translation was similar between TKA and THA components, whereas rotational accuracy about the long axis of the hip stem THA components was worse than the TKA components. The data suggest that accuracy and precision of MBRSA seem to be equivalent to the classical marker-based RSA method, at least for the nonsymmetric implant geometries investigated in this study. The model-based method thus allows the accurate measurement of implant migration without requiring prosthesis markers, and thus presents new opportunities for measuring implant migration where financial or geometric considerations of marker placement have thus far been prohibitive factors.

The accuracy of computed tomography for determining femoral and tibial total knee arthroplasty component rotation

Patellofemoral complications, instability, and tibial polyethylene wear after total knee arthroplasty (TKA) resulting from malrotation of the tibial or femoral components (or both) may be difficult to diagnose based on physical examination and standard knee radiographs. The preoperative assessment of implant rotational alignment is critical in planning treatment because the femoral or tibial component (or both) may need to be revised if malpositioned. The purpose of this study was to ascertain the accuracy of computed tomography (CT) scan for determining rotational alignment of femoral and tibial components in TKA. TKA components were inserted in human cadaver specimens at neutral and 5° of external or internal rotation. For each position, the amount of rotation, determined from digital photographs, was compared with CT scan. The correlation coefficient between these two values averaged 0.87, which was significant at P <.05. The CT scan protocol described in this study can be applied clinically to patients with patellofemoral complaints to confirm or rule out the presence of component malrotation.