Evaluation of different coatings of the tibial tray in uncemented total knee arthroplasty. A randomized controlled trial with 5 years follow-up with RSA and DEXA

BackgroundRegenerex® is a porous titanium construct with a 3D interconnecting pore structure and biomechanical characteristics close to that of normal trabecular bone. This study aimed to compare the Regenerex (VR) to the non-interconnecting pore structure Porous Plasma Spray (VP) on tibial implants for total knee arthroplasty (TKA) at 5 years.MethodsWe enrolled and randomized 61 patients (mean age = 63(49–71) years, Female/Male = 35/26) who were planned for an uncemented Vanguard TKA (Biomet, Warsaw, Indiana, USA) to receive either a VR or a VP coated tibial component (31/29). We performed radiostereometric analysis (RSA) and Dual Energy X-ray Absorptiometry (DEXA) postoperatively, and at three, six, 12, 24 and 60 months with measurements of migration. In total 55 patients attended the 5-year follow-up.ResultsOne patient died and four were reoperated during the 60-months period; none due to aseptic loosening. All reoperations were in the VR-group. The mean (range) 60-months MTPM was 1.4 mm (0.5–3.7) for the VP-group and 1.8 mm (0.4–4.9) for the VR-group (p = 0.8). The 24 to 60-months mean (range) MTPM was −0.3 mm (−5 to 1.24) in the VP-group and 0.2 mm (−0.4 to 3.5) in the VR-group (p = 0.8).ConclusionWe did not find any statistically significant differences between the VP- and VR-group and both groups show recognizable migration. We will continue to follow the groups for years to come.     

The outcome of cemented vs. cementless fixation of a femoral component in total knee replacement (TKR) with the identification of radiological signs for the prediction of failure

A survival analysis and radiological review were performed on a series of femoral total knee arthroplasty (TKA) prostheses either cemented (150 cases) or cementless, press-fit (201 cases). The internal surface of the femoral components were shot-blast CoCr alloy. The incidence of loosening of the femoral component at 6 years was 9.8% with cementless fixation and 0.6% with cement (P<0.05) at 6 years. Amongst uncemented prostheses, there was no difference in the survival or radiological outcome with the use of a stem as against two condylar pegs. The clinical need for revision may be predicted radiologically 3 years after operation in symptomless patients by noting a change in component position combined with progressive radiolucent lines and osteolysis. Thus, radiological follow-up should be continued for a minimum of 3 years after knee replacement. The use of a stem enabled the detection of radiolucent lines which we believe were missed around prostheses with condylar pegs. Thus, the use of a stem improves the prediction of failure (but does not improve fixation).     

Clinical and radiologic outcomes of total knee arthroplasty using the Advance Medial Pivot prosthesis. A mean 7 years follow-up

BackgroundMedial Pivot total knee prosthesis has been designed according to studies on normal knee kinematics aiming to replicate physiological knee movement. The purpose of this study was to evaluate clinical and radiologic results of the Advance Medial Pivot Total Knee Arthroplasty, at a mean follow-up of seven years.MethodsOne hundred seventy two Medial Pivot total knee arthroplasties in 160 consecutive patients have been evaluated using the American Knee Society Score and the Knee Society Total Knee Arthroplasty Roentgenographic Evaluation and Scoring System. Statistical analysis was performed using the Student's t-test and the Wilcoxon matched-pairs signed-rank (Mann–Whitney) test in order to evaluate the significance of differences within the groups of patients. Patients compliance was 93.75% thus only six patients (3.75%) lost to follow-up and four patients (2.5%) died for reasons unrelated to the surgery.ResultsThe mean Knee Society score and range of motion was improved from 77.6 points and 97.7° to 152.8 points and 112.5° respectively (p < .001). In total 85.8% and 82.4% of the knees had an excellent (≥ 80) or good (70–79) functional and knee scores respectively. Relief of pain was satisfactory in 88.9% of the patients, while 96% of the patients return to age-related daily life activities. Stability and comfort during walking was subjectively judged by the patients as satisfactory in about 90%. Anterior knee pain was observed in eight patients (5.4%). The Kaplan–Meier survivorship analysis showed a cumulative success rate of 98.6%.ConclusionsThe results are encouraging but longer follow-up of this cohort is necessary in the study of this specific design.Level of evidence IV     

Results of total knee replacement with a cruciate-retaining model for severe valgus deformity—A study of 48 patients followed for an average of 9 years

The objectives of the present study were to find out the results and the factors affecting survival after primary knee arthroplasty with a cruciate-retaining prosthesis in severe valgus deformity. Forty-eight patients (52 knees) participated in the current follow-up study. All patients were followed at least 5 years or to first revision. Mean follow-up time was 9 years (range, 1 to 17 years).The Kaplan-Meier analysis revealed 79% (95% CI 68% to 91%) survival rate with revision for any reason and 81% (95% CI 70% to 93%) survival rate with revision for instability as an endpoint at 10 years. Preoperatively TFA was 23° (range, 15°-51°) in valgus and 7° (range, 21° valgus-4° varus) in valgus postoperatively. Of the 14 re-operated patients, eight were revised because of progressive postoperative medial collateral ligament instability. All re-operations were performed during the first 4 years of the follow-up. The mean TFA was 15.5° valgus postoperatively for those eight and the odds ratio for a revision was 2 (95% CI 1-3, p = 0.025) when compared to the rest of the study population. The residual valgus deformity increases the risk of re-operation and it should be avoided. If proper soft-tissue balance cannot be achieved or there is no functional medial collateral ligament present more constrained implants should be used. In selected cases where both bony correction and ligament balancing have properly been achieved the use of a cruciate-retaining type of prosthesis is justified.