Original ArticleKinematic Comparison Between Mobile-Bearing and Fixed-Bearing Inserts in NexGen Legacy Posterior Stabilized Flex Total Knee Arthroplasty
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
References (9)
- et al.
The effects of early rollback in total knee arthroplasty on stair stepping
J Arthroplasty
(2002) - et al.
Tibiofemoral movement 3: full flexion in the living knee studied by MRI
J Bone Joint Surg Br
(2000) - et al.
Anteroposterior and rotational movement of femur during knee flexion
Clin Orthop
(1999) - NexGen Complete Knee Solution Legacy Knee Posterior Stabilized (LPS) LPS-Flex Fixed Bearing Knee:...
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 TranslationComparison of High-Flexion Fixed-Bearing and High-Flexion Mobile-Bearing Total Knee Arthroplasties—A Prospective Randomized Study
2018, Journal of ArthroplastyCitation 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.
Is High-Flexion Total Knee Arthroplasty a Valid Concept? Bilateral Comparison With Standard Total Knee Arthroplasty
2016, Journal of ArthroplastyCitation 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.
In vivo kinematic comparison between mobile-bearing and fixed-bearing total knee arthroplasty during step-up activity
2014, Journal of ArthroplastyCitation 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.
Matched comparison of kinematics in knees with mild and severe varus deformity using fixed- and mobile-bearing total knee arthroplasty
2012, Clinical BiomechanicsCitation 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).
No benefits or funds were received in support of the study.