Comparison of a new mobile-bearing total knee prosthesis with a fixed-bearing prosthesis: a matched pair analysis

Global mapping of institutional and hospital-based (Level II-IV) arthroplasty registries: a scoping review

PURPOSE

Four joint arthroplasty registries (JARs) levels exist based on the recorded data type. Level I JARs are national registries that record primary data. Hospital or institutional JARs (Level II-IV) document further data (patient-reported outcomes, demographic, radiographic). A worldwide list of Level II-IV JARs must be created to effectively assess and categorize these data.

METHODS

Our study is a systematic scoping review that followed the PRISMA guidelines and included 648 studies. Based on their publications, the study aimed to map the existing Level II-IV JARs worldwide. The secondary aim was to record their lifetime, publications' number and frequency and recognise differences with national JARs.

RESULTS

One hundred five Level II-IV JARs were identified. Forty-eight hospital-based, 45 institutional, and 12 regional JARs. Fifty JARs were found in America, 39 in Europe, nine in Asia, six in Oceania and one in Africa. They have published 485 cohorts, 91 case-series, 49 case-control, nine cross-sectional studies, eight registry protocols and six randomized trials. Most cohort studies were retrospective. Twenty-three per cent of papers studied patient-reported outcomes, 21.45% surgical complications, 13.73% postoperative clinical and 5.25% radiographic outcomes, and 11.88% were survival analyses. Forty-four JARs have published only one paper. Level I JARs primarily publish implant revision risk annual reports, while Level IV JARs collect comprehensive data to conduct retrospective cohort studies.

CONCLUSIONS

This is the first study mapping all Level II-IV JARs worldwide. Most JARs are found in Europe and America, reporting on retrospective cohorts, but only a few report on studies systematically.

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.

Clinical performance and survivorship of navigated floating platform mobile-bearing total knee arthroplasty: A minimum 10-year follow-up

BACKGROUND

The purpose of this study is to report the outcome of navigation-assisted cruciate-retaining total knee arthroplasty (TKA) using one type of cemented, second-generation, floating-platform (FP), mobile-bearing system.

METHODS

Forty-two patients who underwent cruciate retaining TKAs using e.motion-FP prostheses under navigational guidance were retrospectively reviewed. The preoperative diagnosis was osteoarthritis in all knees except one rheumatoid arthritis. The mean follow-up was 132.0 months (range, 120-140 months) and the mean age was 64.0 ± 4.7 years (range, 51-76 years) at the time of index surgery. Clinical and radiographic results as well as mechanical survival rate of this type of prosthesis were investigated at a minimum follow-up of 10 years.

RESULTS

The mean mechanical femorotibial angle was improved from 11.7° ± 3.3° preoperatively to 1.4° ± 1.7° at the latest follow-up. No prosthesis-related complications occurred. One knee underwent open debridement due to superficial infection at 5 weeks after surgery and the other knee experienced a periprosthetic fracture around the proximal tibia, which was successfully healed after open reduction and internal fixation.

CONCLUSIONS

The e.motion-floating platform mobile-bearing design yielded satisfactory long-term durability and implant performance under navigational guidance.

P.F.C Sigma® cruciate retaining fixed-bearing versus mobile-bearing knee arthroplasty: a prospective comparative study with minimum 10-year follow-up

AIMS

To prospectively compare long-term clinical and radiological outcomes following a cruciate retaining fixed-bearing (FB) and a mobile-bearing (MB) primary total knee replacement (TKR).

METHODS

We prospectively reviewed 113 TKRs in 99 patients (14 bilateral) with a PFC sigma cruciate retaining rotating platform system, at an average follow-up of 11.1 years (range 10-12). Results were contrasted with those from 89 TKRs in 72 patients (17 bilateral) with a PFC sigma cruciate fixed-bearing prosthesis, at an average follow-up of 12.1 years (range 10-14.1). Outcomes collected included pre- and post-operative range of motion, Oxford Knee Scores, complications encountered, as well as radiographical assessments of polyethylene wear.

RESULTS

In the MB group, mean Oxford Knee Scores improved from 16 pre-operatively to 42 at final follow-up. The mean range of motion was 115° (75-130). In the FB group, mean Oxford Knee Scores improved from 16.2 pre-operatively to 42.5 at final follow-up. The mean range of motion was 111.2 (80-135) degrees at final follow-up.

CONCLUSION

We failed to elicit an objectively demonstrable clinical difference between the MB- and FB-implanted knees. Similarly, radiological benefits of the MB implants with regard to polyethylene wear were not evident at a minimum 10-year follow-up.

Comparison of ultra-congruent mobile- and fixed-bearing navigation-assisted total knee arthroplasty with minimum 5-year follow-up

PURPOSE

The purpose of this study was to compare the midterm outcomes between fixed and mobile ultra-congruent (UC) bearings in total knee arthroplasty (TKA).

METHODS

This is a retrospective matched-pairs case-control study of patients who underwent primary navigation-assisted TKA with a minimum 5-year follow-up. A total of 182 cases involved the fixed UC bearing system as Group 1 and 101 cases involved mobile UC bearing system group as Group 2. After 1:1 matching, 73 knees in each group were enrolled. Clinical and radiographic outcomes were evaluated.

RESULTS

The overall survival was 143 of 146 cases (97.9 %) at final follow-up, and 72 of 73 cases (96.3 %) in Group 1 and 71 of 73 cases (95.8 %) in Group 2 at final follow-up based on an endpoint of revision surgery. The reasons of revision TKA were periprosthetic fracture in Group 1, infection and bearing dislocation in Group 2. There was no statistical difference in Hospital for Special Surgery (HSS) scores, Knee Society Scores (KSS), WOMAC index score evaluations between groups.

CONCLUSIONS

This study demonstrated that the fixed-bearing UC prosthesis could provide satisfactory performance compared with that of the mobile-bearing UC prosthesis with minimum 5-year follow-up. The fixed-bearing UC prosthesis could be considered in navigation-assisted TKA with theoretical advantages of UC design.

LEVEL OF EVIDENCE

IV.

No difference in clinical and radiologic outcomes after total knee arthroplasty with a new ultra-congruent mobile bearing system and rotating platform mobile bearing systems after minimum 5-year follow-up

We retrospectively compared the clinical and radiographic results between 76 primary total knee arthroplasties (TKAs) using the e.motion Ultra-Congruent prosthesis and 155 primary TKAs using the Low Contact Stress rotating platform. All patients had a minimum 5-year follow-up. Range of motion, Hospital for Special Surgery score, Knee Society Knee Score and Knee Society Functional Score significantly increased in both groups postoperatively, but there was no significant difference between the two groups. The mechanical femorotibial angle improved in both groups postoperatively. Coronal and sagittal component angles were well maintained at the final follow-up. This study demonstrates that a new mobile-bearing prosthesis, designed to be highly congruent with a rotating bearing, could be considered with theoretical advantages and comparable outcomes of established mobile-bearing prostheses.

Differences in anatomy and kinematics in Asian and Caucasian TKA patients: influence on implant positioning and subsequent loading conditions in mobile bearing knees

The objective of our study was to determine the mechanical stress conditions under tibiofemoral loading with an overlay of knee kinematics in deep flexion on two different mobile bearing designs in comparison to in vivo failure modes. This study investigates the seldom but severe complication of fatigue failure of polyethylene components at mobile bearing total knee arthroplasty designs. Assuming a combination of a floor-based lifestyle and tibial malrotation as a possible reason for a higher failure rate in Asian countries we developed a simplified finite element model considering a tibiofemoral roll-back angle of 22° and the range of rotational motion of a clinically established floating platform design (e.motion FP) at a knee flexion angle of 120° in order to compare our results to failure modes found in retrieved implants. Compared to the failure mode observed in the clinical retrievals the locations of the occurring stress maxima as well as the tensile stress distribution show analogies. From our observations, we conclude that the newly introduced finite element model with an overlay of deep knee flexion (lateral roll-back) and considerable internally rotated tibia implant positioning is an appropriate analysis for knee design optimizations and a suitable method to predict clinical failure modes.

A systematic review of clinical outcomes and survivorship after total knee arthroplasty with a contemporary modular knee system

A systematic review appraising the clinical performance and safety of the primary SIGMA modular knee system (DePuy-Synthes, Warsaw, Ind.) found 5 registry reports and 53 journal publications reporting survivorship or postoperative increase in Knee Society scores on 241632 primary SIGMA knee arthroplasties. Pooled data from national joint registries and clinical studies on primary SIGMA knee survivorship were comparable. Both were higher than for all other knees in 5 national joint registries up to 5 years. Compared with pooled data from 2 independent systematic reviews of primary non-SIGMA knees, the SIGMA system provided comparable postoperative changes in Knee Society knee score and a nonsignificant trend of higher postoperative changes in Knee Society function score. This finding suggests that this knee system provides excellent durable results.

Mid-term outcomes of floating platform mobile-bearing total knee arthroplasty under navigational guidance with a minimum 4-year follow-up

We evaluated 106 knees that underwent primary total knee arthroplasty (TKA) with the navigation-assisted gap balancing technique using an e.-motion cruciate retaining floating platform (FP) mobile-bearing prosthesis to prospectively assess the survival of the e.-motion FP system after a minimum follow-up of 4 years. There was no evidence of any complications, including dissociation or breakage of the polyethylene liner or component loosening at last follow up (5.1 ± 0.6 years). Four knees, however, required re-operation, three for distal femoral fracture, and one for infection. The estimated 5-year prosthesis survival rates without revision for any reason and for prosthesis-associated problems were 96.2% and 100%, respectively. The e.-motion floating platform, with a cruciate retaining design under navigation guidance, demonstrated excellent clinical results and 5-year survival rate.

Influence of gap balance on the sagittal movement of a specific mobile bearing floating platform design in total knee arthroplasty

We analyzed 119 knees implanted with mobile bearing floating platform prostheses using the navigation-assisted gap balancing technique to analyze the relationship between intraoperative sagittal movement of floating platforms and soft tissue balancing. The 95 (79.8%) knees were classified into the positive rollback group (mean insert posterior rollback 5.86 ± 1.24 mm), and the remaining 24 (20.2%) into the negative rollback group. Lateral flexion gap (LFG) differed significantly between knees with positive and negative rollback (20.5 ± 1.7 mm vs 22.1 ± 1.7 mm, P = .021). Only LFG significantly influenced the occurrence of bearing sagittal movement. Sagittal translation of the insert occurred in about 80% of knees implanted with mobile bearing floating platforms in TKA, and was affected by flexion gaps, especially on the lateral side.

Single-radius, multidirectional total knee replacement

PURPOSE

The present study was designed to evaluate the mid-term (5- to 8-year) survival rate of a new total knee replacement (TKR) with a single-radius femoral component and a multidirectional, highly congruent tibial component, in comparison with an historical group (TKR with multi-radius design and fixed bearing).

METHODS

Four hundred and thirty patients were included, of which 369 patients (86 %) completed the 5-year follow-up with Knee Society Score evaluation and radiograph examination (study group = 387, control group = 83).

RESULTS

There was a significant improvement for all analysed items between pre-operative status and late follow-up. Mean knee score was 93 ± 9 points in the study group and 88 ± 16 points in the control group (p < 0.001). Mean flexion angle was not different (118 ± 11 vs. 114 ± 13 degrees). Mean functional score was 87 ± 16 points in the study group and 71 ± 24 points in the control group (p < 0.001). Survival rate at 5-year follow-up was 98.8 % (vs. 98.0 %) for mechanical revisions only, and 96.4 % (vs. 98.1 %) for all revisions.

CONCLUSIONS

The new TKR allowed obtaining significantly better results than the fixed-bearing TKR. These results are in line with the best series published in the current literature, but there was no evidence of any superiority of this TKR against already published standards.

Mobile vs fixed-bearing total knee arthroplasty performed by a single surgeon: a 4- to 6.5-year randomized, prospective, controlled, double-blinded study

The superiority between posterior-stabilized mobile-bearing and fixed-bearing designs still remains controversial. Fifty-six consecutive patients undergoing primary, unilateral knee arthroplasty for osteoarthritis were randomly assigned to receive either a mobile-bearing (29 patients) or fixed-bearing (27 patients) prosthesis. We report the results at 4 to 6.5 years (mean, 5.5) follow-up. The Knee Society knee scores, pain scores, functional scores and Oxford knee scores were not statistically different (P > 0.05) between the two groups. Mean postoperative range-of-motion of mobile-bearing knees was significantly greater than that of fixed-bearing knees (127º versus 111º, P = 0.011). 72% of patients could sit cross legged, 48% could sit on the floor, and 17% could squat. Kaplan-Meier survival rate was 100%. No spin-out of mobile bearing was observed. The radiological analysis showed no osteolysis or implant loosening.

A comparative analysis between fixed bearing total knee arthroplasty (PFC Sigma) and rotating platform total knee arthroplasty (PFC-RP) with minimum 3-year follow-up

BACKGROUND

Since the introduction of mobile bearing total knee designs nearly 30 years back, many studies have been done to evaluate its long-term result. Comparison with fixed bearing designs has been done in the past, but the studies were confounded by variables such as disease, surgeon, bone quality, pain tolerance, etc. We attempt to eliminate these variables in this study.

METHODS

A total of 50 patients who had bilateral arthritis of the knee with similar deformity and pre-operative range of motion on both sides agreed to have one knee replaced with mobile bearing total knee design (PFC-RP) and the other with a fixed bearing design (PFC Sigma) were prospectively evaluated. Comparative analysis of both the designs was done at a mean follow-up of 40 months, minimizing patient, surgeon and observer related bias. Clinical and radiographic outcome, survival and complication rates were compared.

RESULTS

At a mean follow-up of 40 months (range 36-47 months), no benefit of mobile bearing (PFC-RP) over fixed bearing design (PFC Sigma) could be demonstrated with respect to Knee Society scores, pain scores, range of flexion, subject preference or patello-femoral complication rates. Radiographs showed no difference in prosthetic alignment. No patient required a revision surgery till last follow-up.

CONCLUSIONS

Our study demonstrated no advantage of the mobile-bearing arthroplasty over fixed bearing arthroplasty with regard to clinical results at short-term follow-up. However, longer follow-up is necessary to confirm whether these results are sustained.

Early mechanical complications of a multidirectional mobile-bearing total knee replacement

Between April 2004 and July 2007, we performed 241 primary total knee replacements in 204 patients using the e.motion posterior cruciate-retaining, multidirectional mobile-bearing prosthesis. Of these, 100 were carried out using an image-free navigation system, and the remaining 141 with the conventional technique. We conducted a retrospective study from the prospectively collected data of these patients to assess the early results of this new mobile-bearing design.

At a mean follow-up of 49 months (32 to 71), 18 knees (7.5%) had mechanical complications of which 13 required revision. Three of these had a peri-prosthetic fracture, and were removed from the study. The indication for revision in the remaining ten was loosening of the femoral component in two, tibiofemoral dislocation in three, disassociation of the polyethylene liner in four, and a broken polyethyene liner in one. There were eight further mechanically unstable knees which presented with recurrent disassociation of the polyethylene liner. There was no significant difference in the incidence of mechanical instability between the navigation-assisted procedures (8 of 99, 8.1%) and the conventionally implanted knees (10 of 139, 7.2%).

In our view, the relatively high rate of mechanical complications and revision within 30 months precludes the further use of new design of knee replacement.

Early clinical outcomes of floating platform mobile-bearing TKA: longitudinal comparison with fixed-bearing TKA

This study was conducted to longitudinally compare a new floating platform mobile-bearing (MB) prosthesis with an established fixed-bearing (FB) system with respect to early clinical outcomes in patients with bilateral TKAs using the MB prosthesis in one knee and the FB prosthesis in the other. Clinical outcomes (ROM, AKS and WOMAC scores, and side preference), evaluated at 6, 12 and 24 months postoperatively, were compared between knees fitted with the MB prosthesis (e.motion-FP) or the FB prosthesis (Genesis II) in 66 patients who underwent bilateral TKA. In addition, the same comparisons between the knees fitted with the MB prosthesis and the knees with the FB prosthesis were made separately in the subgroup of 33 patients implanted with a cruciate retaining FB (FB-CR) prosthesis and the other subgroup of 33 patients with a posteriorly stabilized FB (FB-PS) prosthesis in a knee. The floating platform MB prosthesis achieved comparable clinical outcomes to the FB prosthesis. No significant differences were found between the FB- and MB-implanted sides at any time with respect to the outcome scales, and temporal patterns were similar. However, comparisons of FB-CR and FB-PS patient groups revealed different temporal patterns. In the FB-CR group, most outcome scales were improved at 6 months, peaked at 12 months and then remained at this level at 24 months. In contrast, outcomes in the FB-PS group improved much faster to almost peak at 6 months, and then remained at this level. In the FB-CR group, more patients preferred the knee with fitted with a MB prosthesis at 6 months. In contrast, in the FB-PS group, no side preference for the MB prosthesis was observed, and more patients preferred knees implanted with the FB prosthesis at 12 and 24 months. This study demonstrates that this new mobile-bearing prosthesis, designed as a floating platform, provides satisfactory clinical performances that are comparable to those achieved using the established fixed-bearing prosthesis in terms of clinical outcomes.

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.