Kinematic Comparison Between Mobile-Bearing and Fixed-Bearing Inserts in NexGen Legacy Posterior Stabilized Flex Total Knee Arthroplasty

doi:10.1016/j.arth.2007.01.009

The Journal of Arthroplasty

Volume 23, Issue 2, February 2008, Pages 164-169

https://doi.org/10.1016/j.arth.2007.01.009 Get rights and content

Abstract

Femoral component rollback and tibial rotation were evaluated using lateral radiographs taken during passive knee flexion under fluoroscopy in NexGen Legacy Posterior Stabilized Flex (Zimmer, Warsaw, Ind) total knee arthroplasties (TKAs; 30 with mobile insert and 26 with fixed insert). Measured maximal flexion angle demonstrated no significant differences. Femoral component rollback was observed predominantly in TKAs with fixed insert in more than 45° flexion and correlated with maximal flexion angle in each group. Tibial internal rotation was more significant in TKAs with mobile insert in maximal flexion. However, tibial internal rotation from 90° to maximal flexion, which demonstrated correlation with maximal flexion angle in each group, did not show significant difference. The kinematic differences between 2 inserts seemed to have little relevance to the maximal flexion angle.

Section snippets

Patients

Fifty-six knees of 45 patients (7 males and 38 females) implanted with NexGen LPS-Flex were included in this study. There were 4 males and 28 females with an initial diagnosis of osteoarthritis. The remaining patients were all diagnosed as having rheumatoid arthritis. The mean age at operation was 70 years (range, 42-85 years) and the mean follow-up period was 17 months (range, 6-42 months). We had no criteria for insert selection regarding patients' preoperative characteristics such as

Results

Mean maximal flexion angle was 128.8° (100°-145°) in mobile and 130° (120°-140°) in fixed inserts. No statistically significant difference was found. No complications such as wound healing problem, infection, and pulmonary embolism were noted in all of the patients. No radiologic signs of component loosening or osteolysis were seen within the follow-up period.

Femoral component rollback was evaluated as anteroposterior translation of femoral component with increasing flexion angle and was

Discussion

In this study, we evaluated femoral rollback as well as tibial internal rotation in TKAs with both types of insert, mobile and fixed, and they were significant in deep flexion of more than 90°. Moreover, correlation with maximal flexion angle was demonstrated in both TKAs, suggesting that not only femoral rollback but also tibial internal rotation plays an important role in deep knee flexion after TKA.

Although Most et al [6] reported that there was no difference in tibial rotation between

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NexGen Complete Knee Solution Legacy Knee Posterior Stabilized (LPS) LPS-Flex Fixed Bearing Knee:...

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Cited by (23)

Does mobile-bearing have better flexion and axial rotation than fixed-bearing in total knee arthroplasty? A randomised controlled study based on gait
2020, Journal of Orthopaedic Translation
To analyse the 6 degrees of freedom of the knee and gait data of patients with medial knee osteoarthritis before and after fixed-bearing (FB) and mobile-bearing (MB) total knee arthroplasty (TKA) and examine the influence of TKA on gait characteristics and the difference between FB and MB prosthesis. We also sought to explore the prosthesis options available for TKA in these patients.
Thirty patients who underwent TKA at the Department of Orthopedics at our hospital from June to October 2017 were included. All patients had a lower limb mechanical axis (hip-knee-ankle angle) of less than 180° which were regarded as genu varum knees and had medial knee osteoarthritis. Patients were randomised divided into the FB group and the MB group according to the knee prosthesis implanted. An infrared navigation three-dimensional portable knee motion analysis system (Opti-Knee®, Shanghai Innomotion, Inc.) was used to acquire data on the 6 degrees of freedom of both knees when walking on flat ground before and after surgery (angle of tibia relative to femur parameters: flexion-extension, internal rotation–external rotation, abduction–adduction; displacement parameters: anterior–posterior, proximal–distal, medial–lateral). Postoperative follow-up efficacy was assessed using the Oxford Knee Score system.
There were significant differences in the maximum values of the internal/external rotation and flexion/extension angle between patients post-TKA and the healthy population, p values were 0.007 and <0.001,respectively. The postoperative maximum values of genu varum and internal rotation in both FB [(−9.49 ± 5.99°), (−5.77 ± 3.42°), respectively] and MB [(−9.64 ± 4.83°), (−7.54 ± 4.51°), respectively] groups were lower than the preoperative ones [FB (−15.13 ± 6.78°), (−8.28 ± 4.83°); MB (−13.28 ± 3.98°), (−9.46 ± 4.99°), respectively] (p ≤ 0.001), while the postoperative maximum values of flexion angle and anterior displacement in both FB [(46.11 ± 4.14°), (0.71 ± 0.35 cm), respectively] and MB [(49.33 ± 3.98°), (0.75 ± 0.89 cm), respectively] groups were larger than the preoperative ones [FB (43.15 ± 3.77°), (0.26 ± 0.74 cm); MB (44.62 ± 5.92°), (0.33 ± 0.79°), respectively] (p ≤ 0.001). The postoperative range of flexion/extension angle in both FB (40.13 ± 4.14°) and MB (45.82 ± 3.76°) groups was significantly larger than the preoperative one [FB (36.17 ± 6.07°), MB (37.09 ± 3.93°), respectively] (p ≤ 0.001). There were also significant increases in range of anterior–posterior displacement in the FB group (0.85 ± 0.32 cm) postoperatively compared with the preoperative one (0.71 ± 0.92 cm) (p = 0.016) and significant increases in range of medial-lateral displacement (0.64 ± 0.73 cm) in the MB group postoperatively compared with the preoperative one (0.52 ± 0.91 cm) (p = 0.025). The mean flexion/extension angle of the MB group was significantly greater than the FB group after surgery in both the stance phase and the swing phase (p < 0.001). There were significant differences in postoperative knee axial rotation during the gait cycle between the MB and FB groups (p = 0.028) and that postoperative internal rotation of the tibia relative to the femur increased in the MB group. The Oxford Knee Score at the last follow-up visit about 7.5 months after surgery was 15.6 ± 1.3 and 15.1 ± 1.1 points for FB and MB groups, respectively. This difference was not significant (p = 0.428).
TKA can make the parameters of knee gait characteristics closer to the normal population. Medial knee osteoarthritis patients who received a MB prosthesis in TKA had better joint flexion function and axial rotation than the FB one. However, there is insufficient evidence to suggest that the MB prosthesis is a better option for patients with medial knee osteoarthritis.
To date, no consensus for prosthesis selection in TKA has been established. This study found significant differences in joint flexion/extension angle and internal/external rotation during gait post-TKA surgery in medial knee osteoarthritis patients who received different prostheses. This will provide some references for prosthesis selection for a large number of genu varum patients in clinical practice.
Comparison of High-Flexion Fixed-Bearing and High-Flexion Mobile-Bearing Total Knee Arthroplasties—A Prospective Randomized Study
2018, Journal of Arthroplasty
Citation Excerpt :
Bistolf et al [29] reported that NexGen LPS-Flex Mobile Bearing TKA provided reliable and durable clinical results with a survivorship of over 98% at 10 years, in unselected patients regardless of age, sex, severity of disease, and patellar treatment. Shi et al [30] compared the kinematics between NexGen LPS-Flex Fixed and Mobile Bearing TKAs. They suggested that the kinematic differences between two inserts had little relevance to a clinical setting in the long run.
There is none, to our knowledge, about comparison of high-flexion fixed-bearing and high-flexion mobile-bearing total knee arthroplasties (TKAs) in the same patients. The purpose of this study was to determine whether clinical results; radiographic and computed tomographic scan results; and the survival rate of a high-flexion mobile-bearing TKA is better than that of a high-flexion fixed-bearing TKA.
The present study consisted of 92 patients (184 knees) who underwent same-day bilateral TKA. Of those, 17 were men and 75 were women. The mean age at the time of index arthroplasty was 61.5 ± 8.3 years (range 52-65 years). The mean body mass index was 26.2 ± 3.3 kg/m² (range 23-34 kg/m²). The mean follow-up was 11.2 years (range 10-12 years).
The Knee Society knee scores (93 vs 92 points; P = .531) and function scores (80 vs 80 points; P = 1.000), WOMAC scores (14 vs 15 points; P = .972), and UCLA activity scores (6 vs 6 points; P = 1.000) were not different between the 2 groups at 12 years follow-up. There were no differences in any radiographic and CT scan parameters between the 2 groups. Kaplan-Meier survivorship of the TKA component was 98% (95% confidence interval, 93-100) in the high-flexion fixed-bearing TKA group and 99% (95% confidence interval, 94-100) in the high-flexion mobile-bearing TKA group 12 years after the operation.
We found no benefit to mobile-bearing TKA in terms of pain, function, radiographic and CT scan results, and survivorship. Longer-term follow-up is necessary to prove the benefit of the high-flexion mobile-bearing TKA over the high-flexion fixed-bearing TKA.
Is High-Flexion Total Knee Arthroplasty a Valid Concept? Bilateral Comparison With Standard Total Knee Arthroplasty
2016, Journal of Arthroplasty
Citation Excerpt :
Internal rotation of tibia is also essential in deep knee flexion, and it is observed during deep flexion in normal knee opposite to “screw-home” movement of full extension [22]. Shi et al [38] evaluated femoral rollback and tibial internal rotation in different bearings of high-flexion PS design knees. They found that femoral rollback and tibial internal rotation correlated with maximum flexion angle.
The purpose of this study was to determine whether the high-flexion total knee prosthesis significantly improves knee flexion in vivo.
Forty-four patients undergoing same-day bilateral total knee arthroplasty for primary osteoarthritis of both knees were randomized to receive a standard posterior-stabilized knee prosthesis (P.F.C. Sigma; DePuy Johnson & Johnson, Warsaw, IN) in one knee and a high-flexion concept posterior-stabilized knee prosthesis (LOSPA; Corentec, Inc, Seoul, Korea) in the other knee and were followed up for 2 years postoperatively.
The mean postoperative range of motion was 128.8° (range, 100°-144°) in the LOSPA group and 128.5° (range, 100°-142°) in the P.F.C. Sigma group (P = .744). There were no significant differences in the postoperative mean Knee Society score and Western Ontario and McMaster Universities Osteoarthritis Index score between the LOSPA and P.F.C. Sigma groups (P = .839 and P = .972, respectively).
Despite theoretical range of motion advantages of high-flexion prosthesis, there were no group differences with regard to range of motion, clinical outcomes, and the incidence of radiolucent lines at final follow-up assessment.
In vivo kinematic comparison between mobile-bearing and fixed-bearing total knee arthroplasty during step-up activity
2014, Journal of Arthroplasty
Citation Excerpt :
Garling et al [17] attributed the limited axial rotation of the mobile-bearing inserts in the NexGen LPS mobile to the anterior location of the trunion. Shi et al [12] used lateral radiographs to compare the anterior location of the femoral component in mobile- and fixed-bearing TKA. It is possible that the femoral component of the mobile-bearing TKA moves anteriorly with rotation of the polyethylene insert due to the anterior location of the trunion.
Mobile-bearing total knee arthroplasty (TKA) expects high conformity and low contact stress. It is designed to correct the rotational mismatch between femoral and tibial components. We examined the difference in weight-bearing knee kinematics in patients with mobile-bearing and fixed-bearing TKA performing step-up activities. We randomly assigned 40 knees (37 patients) to mobile-bearing TKA (n = 20) or fixed-bearing TKA (n = 20). Using fluoroscopic imaging we evaluated knee kinematics during step-up activity one year after surgery. The total extent of rotation was not different for the two TKAs. Due to the axial rotation of the polyethylene insert, patients with mobile-bearing TKA had a wider range of absolute axial rotation. The position of the medial and the lateral condyles was significantly more posterior in the fixed-bearing TKA. There were only minor kinematic differences between the two TKAs. The polyethylene insert in the mobile-bearing TKA moved as designed especially with respect to the self-alignment feature.
Mobile-bearing total knee arthroplasty: More rotation is evident during more demanding tasks
2014, Knee
Some reports showed few but significant more axial femorotibial rotation in favor of mobile-bearing (MB) versus fixed-bearing (FB) total knee arthroplasty (TKA), mostly during knee bend fluoroscopic studies. The goal of the current study was to submit MB and FB groups of TKA patients to a turning activity, in which additional rotation was to be expected.
Two consecutive cohorts of patients after TKA (10 FB and 11 MB knees in a total of 18 patients) were assessed using motion analysis five year postoperatively, while performing gait and sit-to-walk (STW) movements with and without turning steps.
Mean range of rotation in the FB group increased from 9.7° during gait, to 11.7° during STW straight, and to 14.3° during STW turning. Mean range of rotation in the MB group increased from 13.4° during gait to 21.0° during STW straight, and stayed at 21.1° during STW turning.
Too many uncontrolled variables in the current study hinder a meaningful discrimination of MB from FB TKA rotation. However, the study does illustrate how more demanding task loads could be helpful in exploring the geometric constraints of TKA variants.
Level III, therapeutic study.
Matched comparison of kinematics in knees with mild and severe varus deformity using fixed- and mobile-bearing total knee arthroplasty
2012, Clinical Biomechanics
Citation Excerpt :
Most et al. (2003) conducted a cadaveric study and reported that there was no difference in the amount of femoral axial rotation between mobile- and fixed-bearing prostheses of the same design. Some studies have reported greater amounts of axial rotation in mobile-bearing prostheses, but there were small differences in the articular geometry between fixed- and mobile-bearing implants (Delport et al., 2006; Ranawat et al., 2004; Shi et al., 2008). Shi et al. reported that average tibial internal rotation was greater in mobile-bearing (7.9°) than in fixed-bearing (5.2°) variants of the same design in passive, non-weightbearing maximum flexion, but their methods were quite different from those used in the present study (Shi et al., 2008).
We examined knee kinematics in three 16-knee cohorts with the same implant design to clarify the influence of bearing mobility and preoperative deformity on the kinematics of posterior-stabilized knee arthroplasty. Compared to knees with mild deformity and a fixed-bearing implant, we hypothesized that a matched group of knees with mobile-bearing prostheses would show greater tibial axial rotation. We hypothesized that knees with the same fixed-bearing implant, but severe preoperative deformity, would have less axial rotation.
A total of 58 knees in 48 patients were involved in this study from a consecutive single-surgeon total knee arthroplasty series. Sixteen knees received mobile-bearing prostheses, and a best-matched cohort of knees with fixed-bearing implants was selected. The 16 fixed-bearing knees with most severe preoperative deformity were selected as a third group. All knees were examined at least 1.5 years after surgery. Flexion, femoral external rotation, anteroposterior translation of both femoral condyles during squatting and deep knee flexion activities were evaluated using model-image registration techniques.
We found some statistically significant, but small differences among the three groups in dynamic and static knee kinematics. In squatting, total femoral rotation for knees with fixed- and mobile-bearing implants, and knees with fixed-bearing implants after severe preoperative varus deformity, was not significantly different. [7° (SD3°), 9° (SD3°), 8° (SD3°), respectively, P = 0.08].
Similar kinematic results for knees with different tibial bearing surfaces and preoperative deformities indicate a robust treatment with this posterior stabilized implant. However, knees did not exhibit normal femoral rotations or functional flexion ranges.

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Original ArticleKinematic Comparison Between Mobile-Bearing and Fixed-Bearing Inserts in NexGen Legacy Posterior Stabilized Flex Total Knee Arthroplasty

Abstract

Section snippets

Patients

Results

Discussion

J Arthroplasty

Tibiofemoral movement 3: full flexion in the living knee studied by MRI

J Bone Joint Surg Br

Anteroposterior and rotational movement of femur during knee flexion

Clin Orthop

Original Article
Kinematic Comparison Between Mobile-Bearing and Fixed-Bearing Inserts in NexGen Legacy Posterior Stabilized Flex Total Knee Arthroplasty