In vivo kinematics of mobile-bearing total knee arthroplasty during deep knee bending under weight-bearing conditions

Purpose  

Little is known about the in vivo kinematics of mobile-bearing total knee arthroplasty, especially at deep knee flexion under weight-bearing conditions.     

Sagittal plane kinematics of fixed- and mobile-bearing total knee replacements

Purpose  

The objective of this prospective, randomized, patient- and observer-blinded study was to analyze, in vivo, the knee joint kinematics in the sagittal plane in a patient population that had received either a fixed or a mobile TKA.     

No differences between fixed- and mobile-bearing total knee arthroplasty

Purpose

For years, numerous studies have been performed to determine whether mobile-bearing total knee arthroplasty (MB-TKA) or fixed-bearing total knee arthroplasty (FB-TKA) is the preferential design in total knee arthroplasty. Reviews and meta-analyses on this subject have focused on a relatively small number of randomised controlled trials, possibly missing important results of smaller studies. The goal of this review was to provide a comprehensive overview of all literature comparing MB-TKA and FB-TKA in the treatment of osteoarthritis of the knee.

Methods

An extensive literature search was performed in the PubMed database. All studies that compared MB-TKA with FB-TKA and looked at one of four theorised advantages (insert wear, signs of loosening, survival rate of the prosthesis and clinical outcome) were included.

Results

The initial search yielded 258 articles, of which 127 were included after the first screening. The included studies consisted of 9 meta-analyses, 3 systematic reviews, 48 RCT’s, 44 comparative studies, 10 reviews and 13 studies that examined patients who received bilateral TKA (one MB-TKA and one FB-TKA). Combining the results of all studies showed that almost all studies found no difference between MB-TKA and FB-TKA.

Conclusions

Even when examining all different types of studies on MB-TKA and FB-TKA, the results of this review showed no difference in insert wear, risk of loosening, survivorship or clinical outcome. In daily practice, the choice between MB-TKA and FB-TKA should be based on the experience and judgment of the surgeon, since no clear differences are observed in the scientific literature.

Level of evidence

III.

     

Magnetic resonance imaging of in vivo kinematics after total knee arthroplasty

PURPOSE: To improve the quality of magnetic resonance imaging (MRI) on knees after total knee arthroplasty (TKA) by minimizing image artifacts caused by metallic implants, and to establish a method determining in vivo kinematics of TKA knees using MRI. MATERIALS AND METHODS: Two knee implants made of cobalt-chrome and oxidized zirconium were tested with different pulse sequences and imaging parameters. Then, in vivo kinematic MRI was performed on five well-functioning TKAs under simulated weight-bearing conditions. Kinematic measurements were made and a linear correlation test was run between the tibio- and patellofemoral measurements. RESULTS: The best images with minimum metallic artifacts were observed using oxidized zirconium implants, a fast spin echo sequence (FSE), thin slice thickness, and high readout gradient. TKA kinematics exhibited a large deviation from the normal kinematics and considerable patient-to-patient variability. However, significant linear correlations between tibiofemoral and patellofemoral kinematics were observed (R = -0.96, 0.92, 0.88). CONCLUSION: Metallic artifacts due to orthopedic implants can be reduced in MR images for some materials, appropriate pulse sequence, and imaging parameters selection, enabling MR quantification of knee kinematics. Tibiofemoral kinematics appears to affect patellofemoral position after total knee arthroplasty.     

Clinical and radiological outcomes of fixed- versus mobile-bearing total knee replacement: a meta-analysis

Controversy exists regarding the clinical and radiological differences in outcomes between fixed- and mobile-bearing total knee replacements (TKR). The aim of this study was to compare these two TKR designs using a meta-analysis of the electronic databases MEDLINE, EMBASE, CINAHL and AMED in addition to a review of unpublished material. All included papers were critically appraised using a modified PEDro critical appraisal tool. Thirty-three studies were eligible, assessing the outcomes of 3532 TKRs. Analysis suggested that there was no significant difference in clinical or radiological outcomes and complication rates between fixed- and mobile-bearing TKRs.     

No difference between fixed- and mobile-bearing total knee arthroplasty in activities of daily living and pain: a randomized clinical trial

Purpose

Until now, there are no definitive conclusions regarding functional differences related to middle- and long-term everyday activities and patient pain following implantation of mobile- and fixed-platform tibial prostheses. The aim of this study was to determine whether there are middle-term differences in knee function and pain in patients undergoing fixed- and mobile-bearing total knee arthroplasty (TKA).

Methods

Eligible patients were randomized into two groups: the first group received TKA implantation with a fixed tibial platform (group A); the second group received TKA with a mobile tibial platform (group B). Patients were followed up (2 years), and their symptoms and limitations in daily living activities were evaluated using the Knee Outcome Survey—Activities of Daily Living Scale (ADLS), in addition to pain evaluation assessed using the pain visual analogue scale (VAS).

Results

There were no significant differences in function and symptoms in the ADLS and VAS between the study groups.

Conclusion

The type of platform used in TKA (fixed vs. mobile) does not change the symptoms, function or pain of patients 2 years post-surgery. Although mobile TKAs may have better short-term results, at medium- and long-term follow-up they do not present important clinical differences compared with fixed-platform TKAs. This information is important so that surgeons can choose the most suitable implant for each patient.

Level of evidence

Randomized clinical trial, Level I.

     

Comparing in vivo kinematics of anterior cruciate-retaining and posterior cruciate-retaining total knee arthroplasty

The purpose of this study was to compare knee kinematics in patients with bi-cruciate preserving total knee arthroplasty and posterior cruciate ligament (PCL) preserving total knee arthroplasty. Five knees received PCL-retaining arthroplasty and nine knees received both cruciate-retaining arthroplasty (ACL/PCL knees). We studied treadmill gait, stair stepping, and maximum flexion activities using lateral fluoroscopy and shape matching. For maximum flexion, the ACL/PCL knees showed 6 mm more posterior translation of the lateral condyle (p < 0.05). For the stair activity, posterior translations of the lateral condyle were significantly greater in the ACL/PCL knees from 30° to 70° flexion (p < 0.05). Both condyles in the ACL/PCL knees showed greater posterior translation in the stance and swing phases of gait than in the PCL knees (p < 0.05). Preserving both cruciate ligaments in total knee arthroplasty appears to maintain some basic features of normal knee kinematics in these activities.     

Gait analysis and electromyography in fixed- and mobile-bearing total knee replacement: a prospective, comparative study

Purpose  

The theoretical superiority of mobile-bearing total knee arthroplasties (TKAs) has not yet been proven in clinical studies. The aim of the current study was to compare and to analyse in a patient population that had received either a fixed or a mobile TKA differences in gait analysis electromyography and clinical scores.     

Tibio-femoral and patello-femoral joint kinematics during navigated total knee arthroplasty with patellar resurfacing

Purpose

In total knee arthroplasty, surgical navigation systems provide tibio-femoral joint (TFJ) tracking for relevant bone preparation, disregarding the patello-femoral joint (PFJ). Therefore, the important intra-operative assessment of the effect of component positioning, including the patella, on the kinematics of these two joints is not available. The objective of this study is to explore in vivo whether accurate tracking of the patella can result in a more physiological TFJ and PFJ kinematics during surgery.

Methods

Ten patients underwent navigated knee replacement with patellar resurfacing. A secondary system was used to track patellar motion and PFJ kinematics using a special tracker. Patellar resection plane position and orientation were recorded using an instrumented probe. During all surgical steps, PFJ kinematics was measured in addition to TFJ kinematics.

Results

Abnormal PFJ motion patterns were observed pre-operatively at the impaired knee. Patellar resection plane orientation on sagittal and transverse planes of 3.9° ± 9.0° and 0.4° ± 4.1° was found. A good restoration of both TFJ and PFJ kinematics was observed in all replaced knees after resurfacing, in particular the rotations in the three anatomical planes and medio-lateral patellar translation.

Conclusions

Patella tracking results in nearly physiological TFJ and PFJ kinematics in navigated knee arthroplasty with resurfacing. The intra-operative availability also of PFJ kinematics can support the positioning not only of the patellar component in case of resurfacing, but also of femoral and tibial components.

Level of evidence

II.     

Patellofemoral kinematics during deep knee flexion after total knee replacement: a computational simulation

Purpose

Actions requiring deep knee flexion, such as kneeling and squatting, are challenging to perform after total knee replacement (TKR), though many manufactures emphasize that their knee prostheses could safely achieve high flexion. Little is known about the patellofemoral kinematics during deep flexion. This study aimed to track the movement of the patella during kneeling and squatting through dynamic computational simulation.

Methods

A validated knee model was used to analyse the patellar kinematics after TKR, including shifting, tilting and rotation. The data were captured from full extension to 135° of knee flexion. For kneeling, an anterior force of 500 N was applied perpendicularly on the tibial tubercle as the knee flexed from 90° to 135°. For squatting, a ground reaction force was applied through the tibia from full extension to 135° of flexion.

Results

This study found that patellar shifting and rotation in kneeling were similar to those while squatting. However, during kneeling, the patella had a greater medial tilt and showed signs of abrupt patellar tilt owning to an external force being concentrated on the tibial tubercle.

Conclusions

In terms of squatting and kneeling movements, the latter is a more strenuous action for the patellofemoral joint after TKR due to the high forces acting on the tibial tubercle. It is suggested that overweight patients or those requiring high flexion should try to avoid kneeling to reduce the risk of the polyethylene wear. Further modification of trochlear geometry may be required to accommodate abrupt changes in patellar tilting.

Level of evidence

II.     

Muscle activity around the knee and gait performance in unicompartmental knee arthroplasty patients: a comparative study on fixed- and mobile-bearing designs

Purpose

Unicompartmental knee arthroplasty (UKA) offers clinical and functional advantages over total knee arthroplasty. The aim of this study was to compare the functional recovery of patients with mobile UKA versus fixed-bearing designs by state-of-the-art gait analysis and, in particular, by assessing muscular activity.

Methods

Ten patients with the Oxford (mobile bearing) and ten patients with Optetrak (fixed bearing) UKA were evaluated at a minimum follow-up of 1?year post-operatively by gait analysis, which includes the main time–distance parameters, kinematics and kinetics of the replaced knee, and muscular activity of the main relevant muscles. Twenty healthy young subjects were used as controls.

Results

The mean International Knee Society score was 92.7?±?11.2 for all 20 UKA knees; for the Oxford UKA, it was 94.1?±?9.5; and for the Optetrak UKA, it was 91.5?±?12.9, although follow-up was significantly lower for the latter. Time–distance parameters showed a slower gait in both groups compared with that of controls, and the Oxford group had values closer to the controls. Knee joint flexion was similar to that of controls at initial contact and loading response with no differences between groups. In all patients, the joint moments were smaller to that of controls. Residual abnormalities such as the prolonged rectus femoris activity were present in both designs, and the only difference distinguishing the Optetrak group from the others was the combined co-contraction of the hamstrings.

Conclusions

A good restoration of gait was achieved by most unicompartmental knee patients independently of the UKA design, although some abnormalities persisted in muscle activity around the knee.

Level of evidence

Retrospective comparative study, Level III.     

Comparison of patellar retention versus resurfacing in LCS mobile-bearing total knee arthroplasty

Purpose  

The aim of this retrospective study was to compare clinical outcomes of total knee arthroplasty (TKA) with and without patellar resurfacing using the Low Contact Stress (LCS) mobile-bearing prosthesis in 275 osteoarthritic knees (199 patients) after a minimum of 7 years of follow-up.     

Patellofemoral kinematics in mobile-bearing and fixed-bearing posterior stabilised total knee replacements: a cadaveric study

Purpose  

The aim was to compare the patellar kinematics in the normal knee, fixed-bearing (FB) and mobile-bearing total knee replacement (MB-TKR). The hypothesis that a mobile-bearing TKR has a more natural patellar movement was tested.     

Posterior tibial slope impacts intraoperatively measured mid-flexion anteroposterior kinematics during cruciate-retaining total knee arthroplasty

Purpose

Posterior tibial slope (PTS) for cruciate-retaining (CR) total knee arthroplasty (TKA) is usually pre-determined by the surgeon. Limited information is available comparing different choices of PTS on the kinematics of the CR TKA, independent of the balancing of the extension gap. This study hypothesized that with the same balanced extension gap, the choice of PTS significantly impacts the intraoperatively measured kinematics of CR TKA.

Methods

Navigated CR TKAs were performed on seven fresh-frozen cadavers with healthy knees and intact posterior cruciate ligament (PCL). A custom designed tibial baseplate was implanted to allow in situ modification of the PTS, which altered the flexion gap but maintained the extension gap. Knee kinematics were measured by performing passive range of motion (ROM) tests from full extension to 120° of flexion on the intact knee and CR TKAs with four different PTSs (1°, 4°, 7°, and 10°). The measured kinematics were compared across test conditions to assess the impact of PTS.

Results

With a consistent extension gap, the change of PTS had significant impact on the anteroposterior (AP) kinematics of the CR TKA knees in mid-flexion range (45°–90°), but not so much for the high-flexion range (90°–120°). No considerable impacts were found on internal/external (I/E) rotation and hip–knee–ankle (HKA) angle. However, the findings on the individual basis suggested the impact of PTS on I/E rotation and HKA angle may be patient-specific.

Conclusions

The data suggested that the choice of PTS had the greatest impact on the mid-flexion AP translation among the intraoperatively measured kinematics. This impact may be considered while making surgical decisions in the context of AP kinematics. When using a tibial component designed with “center” pivoting PTS, a surgeon may be able to fine tune the PTS to achieve proper mid-flexion AP stability.

     

The Rotaglide mobile-bearing total knee arthroplasty: no difference between cemented and hybrid implantation

Purpose

The optimal fixation of the Rotaglide total knee arthroplasty’s (TKA) components is controversial. It is hypothesized that the hybrid fixation (cementless femoral component) in a mobile-bearing TKA system might cause increased rate of loosening—especially in the femoral part—and finally failure of the arthroplasty. Consequently, the aim of this study was to compare the survival and revision rates and also the clinical and radiological outcomes of the cemented and hybrid fixation of the Rotaglide TKA.

Methods

One hundred patients, who underwent TKA with the Rotaglide prosthesis, were randomly placed in two groups. In the first group, the prosthesis was cemented, and in the second group, the hybrid technique was used. Revision and mortality rates were compared after 8–12 years of follow-up. Knee and Osteoarthritis Outcome Score (KOOS) questionnaire and the Knee Society Roentgenographic Evaluation and Scoring System were used to demonstrate clinical and radiographic differences.

Results

There were no statistically significant differences in revision (n.s.) or mortality (n.s.) rates between the two treatment arms. The clinical outcome at the time of last follow-up (mean 9.5 years, SD ±1.4) ranged from very good to excellent (77.8 ± 17.5 for the cemented group and 77.2 ± 20.4 for the hybrid group). No statistically significant differences in all KOOS subscales. Radiographs showed no significant difference in prosthesis alignment and no evidence of loosening between groups.

Conclusion

The hypothesis that the hybrid fixation in a mobile-bearing TKA system might cause increased rate of loosening and finally failure of the arthroplasty was not confirmed. The fixation technique (cemented or hybrid) had no influence on the prosthesis’s survivorship, and also on mortality rates, clinical and radiographic outcomes in a mean follow-up time of 9.5 ± 1.4 years. The Rotaglide TKA is a safe and reliable prosthesis regardless the fixation technique.

Level of evidence

Prospective comparative study, II.     

Staged bilateral mobile-bearing and fixed-bearing total knee arthroplasty in the same patients: a prospective comparison of a posterior-stabilized prosthesis

Mobile-bearing total knee arthroplasty (TKA) has several theoretical advantages over fixed-bearing TKA. We conducted a prospective randomized trial to compare the results of mobile-bearing and fixed-bearing posterior-stabilized TKA in the same patients using the same femoral component design of a mobile-bearing prosthesis in one knee and a fixed-bearing prosthesis in the other knee in 25 patients with osteoarthritis. The mean follow-up was 40 months. No significant differences were found in the mobile-bearing and fixed-bearing knees in terms of clinical and radiographic results. No osteolysis, loosening, or revision occurred. One knee with a mobile-bearing prosthesis had a dislocation of the rotating bearing; however, spontaneous reduction occurred and the dislocation did not recur. Satisfactory early results can be achieved in both mobile-bearing and fixed-bearing knees. We could not demonstrate an advantage of a mobile-bearing TKA.