High flexion total knee arthroplasty - mid-term follow up of 5 years

Minimum 5-year follow-up results and functional outcome of rotating-platform high-flexion total knee arthroplasty: A prospective study of 701 knees

BACKGROUND

To evaluate the midterm clinical outcome, functional outcome, associated complications, and survivorship of high-flexion posterior-stabilized rotating-platform total knee arthroplasty.

METHODS

We prospectively analyzed 701 knees in 501 patients, who underwent total knee arthroplasty using high-flexion posterior-stabilized rotating-platform prosthesis. Patients were assessed preoperatively and postoperatively for their ability to kneel, do full squats, do half squats, and sit cross-legged by using a patient-administered questionnaire.

RESULTS

Significant improvement was seen in patient-reported outcomes at the mean follow-up of 5.5 (range, 5-7) years. Mean flexion achieved postoperatively was 135° (range, 120°-150°) from a mean preoperative flexion of 108.8° (range, 90°-120°). Ninety-five percent of patients were able to sit cross-legged, 90% were able to kneel, 70% were able to perform a half squat, and 20% were able to perform a full squat.

CONCLUSIONS

Posterior-stabilized, rotating-platform, high-flexion design provides good postoperative flexion, functional outcome, and good midterm survivorship.

Performing high flexion activities does not seem to be crucial in developing early femoral component loosening after high-flexion TKA

Background

It is still unclear whether high flexion (HF) activities correlated with the early loosening of the femoral component and whether HF activities are possible. We investigated what is the capability for performing various HF activities, and whether high flexion activities increase the chance of aseptic loosening after HF-TKA.

Methods

We retrospectively analysed 260 patients who underwent HF-TKA using the NexGen LPS Flex between 2001 and 2009. The mean follow-up was 6.7 years (range, 5–13). We evaluated range of motion, Knee Society scores, WOMAC, and serial radiographs for aseptic loosening. Responses to questions on individual HF activities were recorded on 5-point Likert scales based on difficulty (0–4). Patients were divided two groups based on their responses to squatting and kneeling, which were important weight-bearing HF activities in Asian population (HF group vs. non-HF group) for comparisons of aseptic loosening and clinical outcomes.

Results

More than 80 % of patients positively responded for various HF activities. The capability of HF activities showed that cross-legged sitting, squatting, and kneeling were 97.7, 51.1 and 52.7 % at the latest follow-up, respectively. Aseptic loosening was identified in two tibial components (0.8 %) but none in femoral components in non-HF group. There was no significant difference of aseptic loosening based on HF activities (0.8% vs. 0%, p = 0.063).

Conclusions

The results of this study suggest that HF activities do not seem to be associated with aseptic loosening of femoral component after HF-TKA.

Clinical Outcomes in Men and Women following Total Knee Arthroplasty with a High-Flex Knee: No Clinical Effect of Gender

While it is generally recognized that anatomical differences exist between the male and female knee, the literature generally refutes the clinical need for gender-specific total knee prostheses. It has been found that standard, unisex knees perform as well, or better, in women than men. Recently, high-flex knees have become available that mechanically accommodate increased flexion yet no studies have directly compared the outcomes of these devices in men and women to see if gender-based differences exist. We retrospectively compared the performance of the high-flex Vanguard knee (Biomet, Warsaw, IN) in 716 male and 1,069 female knees. Kaplan-Meier survivorship was 98.5% at 5.6–5.7 years for both genders. After 2 years, mean improvements in Knee Society Knee and Function scores for men and women (50.9 versus 46.3; 26.5 versus 23.1) and corresponding SF-12 Mental and Physical scores (0.2 versus 2.2; 13.7 versus 12.2) were similar with differences not clinically relevant. Postoperative motion gains as a function of preoperative motion level were virtually identical in men and women. This further confirms the suitability of unisex total knee prostheses for both men and women.

180° rotatory dislocation of the rotating platform of a posterior-stabilized mobile-bearing knee prosthesis; possible complication after closed reduction of a posterior dislocation--a case report

Dislocation of the rotating platform is a significant early complication of mobile-bearing total knee arthroplasty. The authors report an unusual case of acute 180° rotatory dislocation of the rotating platform after closed reduction of a posterior dislocation of a posterior-stabilized mobile-bearing total knee prosthesis. A 71-year-old male with knee osteoarthritis underwent TKRA using a posterior-stabilized mobile-bearing prosthesis. Posterior dislocation of the prosthesis occurred at 5 weeks postoperatively, and closed reduction of the posterior dislocation resulted in complete 180° rotatory dislocation of the rotating platform. The patient was treated by open exploration and polyethylene exchange for a larger component. This case illustrates that dislocation of a posterior-stabilized mobile-bearing total knee prosthesis can occur given valgus laxity and causes a 90° spin-out of the polyethylene insert, and that closed reduction attempts may contribute to complete 180° rotatory dislocation of the rotating platform. Special attention should be given to both AP and lateral views to ensure that the platform is truly reduced and not rotated by 180°. Plain digital radiography, which enhances the density of polyethylene, or arthrography is helpful for diagnosing this complication.

Seven-year survivorship and functional outcomes of the high-flexion Vanguard complete knee system

Certain recreational, cultural, occupational, and religious practices may require knee flexion exceeding typical daily living activity needs. Some total knee prostheses mechanically accommodate high flexion to help meet such demands, e.g., the Vanguard knee (Biomet, Inc., Warsaw, IN) which can mechanically achieve 140°-145°. This multicenter, prospective clinical study of 957 Vanguard knees (865 patients) examined mid-term outcomes. The Kaplan-Meier survivorship estimate was 97.8% (95% CI: 96.5-98.7%) at 7.0 years. For patients with ≥ 2-year follow-up (n=627), mean peak flexion increased from 116.8° to 124.8° (P<0.001). For knees with pre-operative flexion of <95°, 95°-105°, and >105°, the mean increases were 27.8°, 22.0°, and 3.6°, respectively. Mean Knee Society Knee and Function scores increased from 45.9 and 45.5 points to 92.0 and 73.8 points, respectively (P<0.001).

High-flexion posterior-stabilized total knee prosthesis: is it worth the hype?

High-flexion knee prosthesis was introduced with the aim of obtaining higher degree of flexion and good survivorship in patients with high functional demands or those requiring squatting, kneeling, etc., which is more common in Asians. Based on all the research and experience with this prosthesis, it was concluded that high flexion designs meet the need of deeper degrees of flexion in selected sets of patients only. Results were equal and comparable to the traditional standard posterior-stabilized total knee arthroplasty design and superior to it in terms of gaining more flexion and fulfilling activities, such as squatting, kneeling, and sitting cross-legged.

No better flexion or function of high-flexion designs in Asian patients with TKA

BACKGROUND

Recently, high-flexion PCL-retaining (CR) and -substituting (PS) knee prostheses were designed to allow greater and safer flexion after TKA. However, the advantages of high-flexion TKA over standard design have been debated in terms of early maximal flexion. A recent study reported a high incidence of early loosening of the femoral component related to the deep flexion provided by high-flexion PS TKA.

QUESTIONS/PURPOSES

We determined whether high-flexion fixed bearing CR and PS prostheses would provide (1) a better flexion, (2) a better function, and (3) a higher incidence of radiographic loosening than TKA performed using standard fixed bearing CR prostheses in Asian patients.

METHODS

From a total of 182 patients with primary unilateral TKA, we retrospectively reviewed 137 TKAs: 47 with high-flexion CR, 42 with high-flexion PS, and 48 with standard CR designs. ROM, Knee Society scores, and WOMAC scores were evaluated and compared among the three groups. Radiographically, we assessed radiolucent zones and component loosening. Minimum followup was 5 years (mean, 6.2 years; range, 5-8 years).

RESULTS

We found no differences among the three groups in mean maximal flexion (high-flexion CR: 135°; high-flexion PS: 134°; standard CR: 136°), Knee Society scores, and WOMAC scores at last followup. Also, there were no differences among the three groups in terms of radiolucent lines around the prosthesis. No patient in any group had loosening of the femoral component.

CONCLUSIONS

The high-flexion CR or PS design had no advantages over the standard CR design with respect to ROM, clinical scores, and radiolucent lines around the femoral or tibial component after 5 years' followup.

Brief followup report: Does high-flexion total knee arthroplasty allow deep flexion safely in Asian patients?

BACKGROUND

The long-term survivorship of TKA in Asian countries is comparable to that in Western countries. High-flexion TKA designs were introduced to improve flexion after TKA. However, several studies suggest high-flexion designs are at greater risk of femoral component loosening compared with conventional TKA designs. We previously reported a revision rate of 21% at 11 to 45 months; this report is intended as a followup to that study.

QUESTIONS/PURPOSES

Do implant survival and function decrease with time and do high-flexion activities increase the risk of premature failure?

METHODS

We prospectively followed 72 Nexgen LPS-flex fixed TKAs in 47 patients implanted by a single surgeon between March 2003 and September 2004. We determined the probability of survival using revision as an end point and compared survival between those who could and those who could not perform high-flexion activities. Minimum followup was 0.9 years (median, 6.5 years; range, 0.9-8.6 years).

RESULTS

Twenty-five patients (33 knees) underwent revision for aseptic loosening of the femoral component at a mean of 4 years (range, 1-8 years). The probability of revision-free survival for aseptic loosening was 67% and 52% at 5 and 8 years, respectively. Eight-year cumulative survivorship was lower in patients capable of squatting, kneeling, or sitting crosslegged (31% compared with 78%). There were no differences in the pre- and postoperative mean Hospital for Special Surgery scores and maximum knee flexion degrees whether or not high-flexion activities could be achieved.

CONCLUSIONS

Overall midterm high-flexion TKA survival in our Asian cohort was lower than that of conventional and other high-flexion designs. This unusually high rate of femoral component loosening was associated with postoperative high-flexion activities.

High-flexion total knee arthroplasty: survivorship and prevalence of osteolysis: results after a minimum of ten years of follow-up

BACKGROUND

We are aware of no information about the mid-term performance of the high-flexion total knee arthroplasty, although early results have been reported. The purpose of this study was to evaluate the mid-term results of high-flexion and conventional knee prostheses.

METHODS

We prospectively compared the results of 100 patients with osteoarthritis who had received a NexGen Legacy Posterior Stabilized (NexGen LPS) prosthesis in one knee and a NexGen Legacy Posterior Stabilized-Flex (NexGen LPS-Flex) prosthesis in the other. Seventy-five patients (150 knees) were women and twenty-five (fifty knees) were men. The mean age was sixty-five years (range, forty-eight to eighty-five years) at the time of the index procedure. The mean duration of follow-up was 10.3 years (range, ten to 10.6 years). The patients were assessed with radiographs, with the rating system of the Knee Society, and with the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score at three months, one year, and annually thereafter.

RESULTS

Total knee scores, knee function scores, pain scores, WOMAC scores, knee motion, and activity scores did not differ significantly between the two designs of the implants, on the basis of the numbers studied, either preoperatively or at the time of final follow-up. One knee in the NexGen LPS-Flex group was revised because of recurrent infection. No knee in either group had aseptic loosening of the components. The Kaplan-Meier survivorship at ten years postoperatively, with revision defined as the end point, was 100% (95% confidence interval, 94 to 100) for the NexGen LPS prosthesis and 99% (95% confidence interval, 93 to 100) for the NexGen LPS-Flex prosthesis.

CONCLUSIONS

After a minimum duration of follow-up of ten years, there were no significant differences between the two groups with regard to implant survivorship, functional outcome, knee motion, or prevalence of osteolysis.

MODERN TRENDS IN ORTHOPEDICS: THE KNEE ARTHROPLASTY

Using PubMed the authors analyzed publications dedicated to knee arthroplasty that were published in 2011. The modern trends of knee joint replacement include improvement of implants and instruments; partial knee replacement as alternative to TKA; reducing of surgical trauma due to less-invasive approaches; achieving of deep flexion after TKA; using of computer navigation and individual cutting blocks to make surgery more precise; optimization of rehabilitation process in pre-, intra-and postoperative period; including multimodal pain control; development of complex strategies for prevention of intra- and postoperative complications. In this review the attention was attracted to the most discussed in 2011 subjects: development of new designs and materials of knee implants; navigation, robotics and individualized resection blocks; partial knee replacement; infection, blood loss and venous thromboembolism after TKA; influence of different factors on arthroplasty outcomes, especially components and leg alignment, patella resurfacing, PCL retention or substitution, uncemented fixation, mobility of PE insert, severe pre-op deformities or stiffness, previous intra-articular fractures and tibia or femur osteotomies, soft tissue deficit etc.