Posterior-stabilized Designs Research Articles

Medial-pivot design does not provide superior clinical results compared to posterior-stabilized total knee arthroplasty despite kinematic differences during step-up and lunge activities: A prospective randomized controlled trial under medial tight soft tissue balance.

This study aimed to compare in vivo kinematics during weight-bearing daily activities and determine the relationship with clinical outcomes in patients undergoing total knee arthroplasty (TKA) with a medial-pivot (MP, Evolution™) versus a posterior-stabilized (PS, Persona®) design under constant conditions of intraoperative soft tissue balance. Forty patients undergoing MP or PS-TKA under similar conditions of soft tissue balance were enrolled in this prospective randomized controlled trial. Outcome measures included clinical knee society scores (KSS) and knee injury and osteoarthritis outcome scores (KOOS). A kinematic assessment was conducted while the participants performed lunge and step-up activities under fluoroscopic guidance. Eighteen patients in each arm completed 1-year follow-up and were included in the analysis. All patients experienced pain relief and satisfactory knee function postoperatively. In kinematics, in the MP arm, the medial femoral condyle remained consistent, whereas the lateral femoral condyle gradually shifted posteriorly with increasing knee flexion. Conversely, in the PS arm, paradoxical anterior movement of the medial femoral condyle accompanied the lateral pivot motion. During lunge and step-up activities, a medial-pivot motion was observed in 83% and 72% of knees in the MP arm, respectively, compared with 22% and 11% in the PS arm. Despite these differences in kinematics, there were no statistically significant differences in the KSS and KOOS between the two groups. Under weight-bearing conditions during flexion, knees that underwent Evolution™ MP-TKA did not show superior clinical results compared to Persona® PS-TKA, despite exhibiting in vivo kinematics closely resembling the normal in vivo pattern. Therapeutic studies-Level I.

Medial Stabilised Total Knee Arthroplasty: Definition and Performance

Background Medial-stabilised total knee arthroplasty (MS-TKA) usage has increased significantly over the past decade with encouraging results. MS-TKA mimics the natural knee kinematics, providing superior antero-posterior stability as compared to cruciate-retaining or posterior-stabilised designs. Its proponents suggest that MS-TKA may provide the solution to the residual dissatisfaction seen in many patients following knee replacement surgery. Methods The literature was reviewed for critical analysis of the evidence for the biomechanics of the native knee and the clinical outcomes for MS-TKA. The history of the development of the medial-stabilised knee was also reviewed. Results MS-TKA were found generally to have similar revision rates to non-MS-TKA. Studies of knee function found either similar or improved function, which may be due to increased AP stability and a lack of paradoxical movement of femur over tibia which is seen in CR and PS designs. Conclusion This review highlights the key design features needed for a total knee arthroplasty to be termed as a medial-stabilised design, summarises current clinical and kinematic evidence including an overview of its development over the past three decades and sets out the next steps needed for meaningful evaluation of long-term real-world data of individual MS-TKA implants. With longer and more detailed follow-up data emerging as MS-TKA becomes more popular, a more thorough analysis of their performance will soon be possible.

Prior Patellectomy: A Systematic Review and Meta-Analysis Comparing Cruciate-Retaining and Posterior-Stabilized Total Knee Arthroplasty Survivorship and Reported Outcomes

BackgroundIn the setting of total knee arthroplasty (TKA), prior patellectomy historically prompted the use of increased constraint implants, specifically posterior-stabilized (PS) designs. However, modern case series have reported similar outcomes utilizing cruciate-retaining (CR) implants. The primary outcome of this study was to compare implant retention rates between these 2 implant designs in prior patellectomy patients. Secondary outcomes included a comparison of patient-reported outcome scores and cause for revision. MethodsA comprehensive systematic review was performed using Web of Science, PubMed, and Scopus databases per the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Boolean operator search terms included “patellectomy AND (arthroplasty) OR (replacement).” Case reports, review articles, < 2 years of follow-up, and studies in which the implant design could not be ascertained were excluded. An initial screening of titles and abstracts for inclusion was performed, followed by a full manuscript review of eligible articles. Single-data extraction was performed, followed by subsequent statistical analysis. ResultsA total of 9 studies (209 knees) met the inclusion criteria. The average time from patellectomy to TKA was 16.1 years. While all patients had significant improvement in functional outcomes, CR implants displayed proportionally greater improvement in Knee Society Scores compared to PS implants (+108 versus +98%, P ≤ .001). However, there was a significantly greater rate of revision in the CR cohort compared to PS (18.6 versus 2.6%, P = .002). ConclusionsPrior patellectomy patients undergoing TKA have significant improvements in patient-reported functional outcomes and high midterm retention rates. While CR implant designs portend a potentially greater improvement in functional outcomes, they also have a greater risk for revision than their PS implant counterparts. However, contemporary implant designs and operative techniques likely render revision rates equivocal between CR and PS implants in postpatellectomy patients.

Medial-pivot total knee arthroplasty enhances tibiofemoral axial rotation stability in weight-bearing mid-range flexion compared to posterior-stabilised system.

Total knee arthroplasty (TKA) stands as a primary intervention for severe knee ailments, yet concerns remain regarding postoperative patient satisfaction and flexion instability. This study aims to evaluate the in-vivo kinematics of medial-pivot (MP) and posterior-stabilised (PS) designs during step-up activity, in comparison to the kinematics of the nonoperated contralateral knee. Sixteen patients with PS-TKA and 14 with MP-TKA were retrospectively examined. Clinical outcomes were assessed using patient-completed questionnaires. Motion during step-up was captured using a dual fluoroscopic system. Statistical analysis was applied to evaluate the in-vivo tibiofemoral six-degree-of-freedom kinematics and articular contact positions between the two groups. Despite being older, patients in the MP group reported higher postoperative subjective scores for weight-bearing functional activities. The axial rotation centres of MP-TKA located on the medial tibial plateau exhibited less variance compared to PS-TKA and contralateral knees. Compared to the contralateral knee (contralateral to medial-pivot [C-MP] or contralateral to posterior-stabilised [C-PS]), the MP group exhibited limited range of motion in terms of anteroposterior translation (MP: 3.6 ± 1.3 mm vs. C-MP: 7.4 ± 2.5 mm, p < 0.01) and axial rotation (MP: 6.6 ± 1.9° vs. C-MP: 10.3 ± 4.9°, p = 0.02), as well as in the PS group for anteroposterior translation (PS: 3.9 ± 1.7 mm vs. C-PS: 7.2 ± 3.7 mm, p < 0.01). The MP group with better postoperative ratings demonstrated a more stable MP axial rotation pattern during step-up activity compared to the PS group, underscoring the pivotal role of prosthetic design in optimising postoperative rehabilitation and functional recovery. Level III.

Effect of Surgical Technique, Implant Design, and Time of Examination on Contact Kinematics: A Study of Bicruciate-Stabilized and Posterior-Stabilized Total Knee Arthroplasty

BackgroundBicruciate-stabilized (BCS) total knee arthroplasty (TKA) designs attempt to approximate natural knee mechanics. Multiple surgical techniques, including gap balancing (GB) and measured resection (MR), have been developed to provide optimal implant positioning and soft-tissue balance. The goal of this study was to determine the effect of surgical technique on BCS TKA contact kinematics. Secondary goals included investigating the change of kinematics over time and comparing BCS TKA kinematics to a posterior-stabilized (PS) design. MethodsThe study included the BCS-GB, BCS-MR, and PS-MR groups. The BCS-GB and BCS-MR groups underwent weight-bearing radiostereometric analysis for multiple knee flexion angles at 3 months and 1 year postoperatively, whereas the PS-MR group was imaged at 1 year postoperatively. The medial and lateral contact kinematics were determined from implant poses. ResultsThere were no differences in BCS TKA kinematics between the GB and MR techniques. There were differences in the mid-flexion ranges when comparing the 3-month and 1-year kinematics of the BCS design; however, they were less than 1.5 mm. Differences existed between the kinematics of the BCS and PS designs at all flexion angles for the medial condyle (P < .0006) and at 0° of flexion on the lateral condyle (P < .0001). ConclusionsContact kinematics for a BCS design were similar for both surgical techniques, suggesting both are appropriate for this design. Small, likely clinically insignificant differences were found between 3-month and 1-year kinematics. The BCS TKA kinematics differed from the PS design; however, it is unclear whether these differences improve clinical outcomes.

Accurate surgical posterior tibial slope alteration can be achieved in total knee arthroplasty regardless of surgeon skill level or local soft tissue thickness-A retrospective radiograph-based study.

To retrospectively report on the impact of local soft tissue thickness and surgeon skill level on the accuracy of surgical posterior tibial slope (PTS) alteration achieved in patients undergoing total knee arthroplasty (TKA) utilising lateral knee radiographs. Pre- and postoperative radiographs of 82 patients undergoing primary TKA using conventional mechanical alignment technique were measured by two observers and subjected to quality criteria for accurate measurement of the PTS. All patients underwent a standardised surgical approach for PTS alteration: cruciate-retaining (CR) cases with preoperative PTS ≤ 10° were set for reconstruction of the preoperative PTS. Cases indicated for posterior-stabilised (PS) design and/or with a preoperative PTS > 10° were set for 3° of postoperative PTS. Pretibial subcutaneous fat (PSF) and surgeon skill level were analysed for their predictive quality regarding the accuracy of surgical PTS alteration achieved. The overall mean postoperative PTS was significantly lower than the preoperative values (6.2°, SD 2.7 vs. 7.7°, SD 3.2; p = 0.002103). Neither local soft tissue thickness, namely PSF, nor surgeon skill level was found to be a predictor of the accuracy of surgical PTS alteration achieved. Among cases set for PTS reconstruction, 25.9% and 42.6% achieved a postoperative PTS within ±1° and ±2° of preoperative values, respectively. In patients with a PTS > 10° or those indicated for PS design, slope reduction was achieved with a mean postoperative PTS of 6.5°. Furthermore, 14.3% and 32.1% of cases were within ±1° and ±2° of 3, respectively. This study demonstrates that accurate surgical alteration of the PTS is possible in TKA regardless of local knee soft tissue thickness or surgeon skill level. This proves the clinical feasibility of both targeted reduction as well as reconstruction of the PTS in TKA. Level III, retrospective cohort study.

Ultracongruent Polyethylene Liners Do Not Affect Survival of Total Knee Arthroplasty for Valgus Deformity

BackgroundValgus knee deformity is observed in nearly 10% of patients undergoing total knee arthroplasty (TKA). The degree of polyethylene constraint required to balance a valgus knee remains controversial, and historically, posterior-stabilized (PS) designs have been favored. This study evaluated the survivorship of TKA done in valgus knees based on implant design and specifically compared posterior-stabilized (PS) and ultracongruent (UC) liners. MethodsA total of 549 primary TKAs performed on valgus knees by fellowship-trained arthroplasty surgeons from 2013 to 2019 were reviewed. Demographics, comorbidities, degrees of preoperative deformity, implants used, and all-cause revisions until final follow-up were recorded. Cox regression analyses evaluated survival to all-cause revision in each cohort. The mean follow-up was 4.9 years (range, 2 to 9). ResultsThere were 403 UC liners compared to 146 PS liners. There was no difference in patient age (68 versus 67 years; P = .30), body mass index (30.9 versus 30.4; P = .36), or degree of deformity (8.6 versus 8.8 degrees; P = .75) between the cohorts. At final follow-up, there were 5 revisions in the PS cohort (3.4%) versus 11 revisions in the UC cohort (2.7%) (P = .90). The most common reason for revision in both cohorts was periprosthetic joint infection (4 PS; 8 UC). Multivariable regression analyses controlling for age, body mass index, Elixhauser comorbidity score, sex, and degree of deformity demonstrated UC polyethylene liners were not associated with revision (hazard ratio 0.76; 95% confidence interval [CI] 0.26 to 2.21; P = .62). There was no difference in eight-year survivorship to all-cause revision, including aseptic and septic failure. ConclusionsAlternative polyethylene liners from the historically utilized PS liners for TKA for valgus deformity did not reduce survivorship. With modern polyethylene designs, UC inserts can be utilized for this deformity without increasing the risk of failure.

INCIDENCE AND SURGICAL TREATMENT OF COMPONENT BREAKAGE AFTER UNICOMPARTMENTAL AND TOTAL KNEE ARTHROPLASTY: A SINGLE-CENTRE LONG-TERM EXPERIENCE

Fractures of the prosthetic components after total knee arthroplasty (TKA) are rare but dangerous complications, sometimes difficult to diagnose and to manage. Aim of this study is to evaluate the incidence of component breakage and its treatment in our single institution's experience. We retrospectively review our institution registry. From 605 revision knee arthroplasties since 2000 to 2018, we found 8 cases of component breakage, of these 3 belonged to UKA, and 5 belonged to TKA. The UKA fractures were all on the metal tibial component; while 4 TKA fractures were ascribed to the liner (2 Posterior-Stabilized designs and 2 constrained designs) and only one case was on the femoral component. For every patient a revision procedure was performed, in two cases a tibial tubercle osteotomy was performed, while in one case (where the fracture was of the post cam) an arthroscopy was performed prior to the arthrotomy. All of the UKA fractures were treated with a standard revision implant. As regard the TKA, 2 liner fractures were treated with the only liner exchange, while the other 2 liner fractures and the fracture of the metallic component were treated with total knee revision. No intra- and post-operative complications were found. Component breakage after TKA is a serious complication. Its treatment, always surgical, can hide pitfalls, especially if the timing is not correct; indeed apart from the revision of one or more components, the surgeons must address any issues of management of bone defect and ligamentous stability.

L’efficacité de la conservation du ligament croisé postérieur versus la stabilisation postérieure sur les fonctions du genou et de l’appareil extenseur chez les patients après une arthroplastie totale bilatérale simultanée du genou : une étude de suivi rétrospective de deux ans

IntroductionThe importance of the posterior cruciate ligament in knee functionality is known; however, the effect of preserving the posterior cruciate ligament in total knee arthroplasty (TKA) on extensor mechanism function and knee function is not clear. We aimed to compare extensor mechanism function and knee function between patients operated with the cruciate-retaining and posterior-stabilized designs for simultaneous bilateral TKA. HypothesisPatients operated with the cruciate-retaining design would produce better outcomes than those operated with the posterior-stabilized design. Materials and methodsA total of 104 patients were divided into two groups as the cruciate-retaining (n=52) and posterior-stabilized (n=52) groups. The groups were compared for extensor mechanism function (chair-rise test) and knee function (Hospital for Special Surgery [HSS] knee score). The follow-up points were six weeks, three months, six months, one year, and two years. ResultsNo statistically significant effect on chair-rise performance of the group-by-time interaction (χ2 [5,N=104]=5.32, p=0.37) or of group (χ2 [1,N=104]=1.69, p=0.19). In the HSS knee score, the group-by-time interaction was statistically significant (F [5,510]=6.24, p<0.001). A statistically significant difference of 7.4 points in favor of the posterior-stabilized group was found at six weeks (p=0.002). No statistically significant differences were found between the groups at the other follow-up points. DiscussionThe cruciate-retaining and posterior-stabilized designs have similar outcomes with regard to extensor mechanism function and knee function in the long-term period in patients who underwent simultaneous bilateral TKA. In the short-term period, the posterior-stabilized design shows better knee function than the cruciate-retaining design. Level of evidenceIII; a retrospective study.

The effectiveness of cruciate-retaining versus posterior-stabilized designs on extensor mechanism function and knee function in patients after simultaneous bilateral total knee arthroplasty: A two-year retrospective follow-up study

IntroductionThe importance of the posterior-cruciate ligament in knee functionality is known; however, the effect of preserving the posterior-cruciate ligament in total knee arthroplasty (TKA) on extensor mechanism function and knee function is not clear. We aimed to compare extensor mechanism function and knee function between patients operated with the cruciate-retaining and posterior-stabilized designs for simultaneous bilateral TKA. HypothesisPatients operated with the cruciate-retaining design would produce better outcomes than those operated with the posterior-stabilized design. Materials and methodsA total of 104 patients were divided into two groups as the cruciate-retaining (n=52) and posterior-stabilized (n=52) groups. The groups were compared for extensor mechanism function (chair-rise test) and knee function (Hospital for Special Surgery [HSS] knee score). The follow-up points were six weeks, three months, six months, one year and two years. ResultsNo statistically significant effect on chair-rise performance of the group-by-time interaction (χ2 [5, n=104]=5.32, p=.37) or of group (χ2 [1, n=104]=1.69, p=.19). In the HSS knee score, the group-by-time interaction was statistically significant (F [5.510]=6.24, p<.001). A statistically significant difference of 7.4 points in favor of the posterior-stabilized group was found at six weeks (p=.002). No statistically significant differences were found between the groups at the other follow-up points. DiscussionThe cruciate-retaining and posterior-stabilized designs have similar outcomes with regard to extensor mechanism function and knee function in the long-term period in patients who underwent simultaneous bilateral TKA. In the short-term period, the posterior-stabilized design shows better knee function than the cruciate-retaining design. Level of evidenceIII; a retrospective study.

International primary knee arthroplasty registry review: findings from current reports.

International joint registries provide high volumes of information in relation to the performance of total knee arthroplasty on a global scale. Distillation of this data can be challenging, particularly with the establishment of more arthroplasty registries on a yearly basis. We therefore aim to present key information from these registries in relation to primary total knee arthroplasty. The specific questions of interest include: Which fixation type is superior in TKA? Does the level of constraint impact on clinical performance? How do partial knee replacements perform in the registries? Does patellar resurfacing lead to superior results? Are there any specific implants which perform particularly well or poorly? A comprehensive review of the major English-speaking knee arthroplasty registries across the globe was performed. Given the expanding large number of registries worldwide, it was not possible to perform a comprehensive review of all registries and so, a detailed review of the major English-speaking knee arthroplasty registries was included. Key trends and developments in implant performance were identified and presented in the current article. Total knee replacements have lower revision rates than both unicompartmental and patellofemoral joint replacement procedures. Patellofemoral joint replacements have the highest failure rate of all knee replacement procedures. Cruciate-Retaining (CR) TKR designs have superior outcomes to Posterior-Stabilized (PS) designs across all registries. Patellar resurfacing appears to confer an advantage over non-resurfaced patellas in primary TKR. We present current global trends in the utility and performance of TKA based on data from English-speaking arthroplasty registries.

Total Knee Arthroplasty in Patients Who had a Prior Anterior Cruciate Ligament Reconstruction: Balancing Remains the Issue

BackgroundFollowing anterior cruciate ligament (ACL) injury, 20% of patients will develop osteoarthritis. Despite this, there remains a paucity of data describing outcomes of total knee arthroplasty (TKA) after prior ACL reconstruction. We aimed to describe survivorships, complications, radiographic results, and clinical outcomes of TKA after ACL reconstruction in one of the largest series to date. MethodsWe identified 160 patients (165 knees) who underwent primary TKA following prior ACL reconstruction between 1990 and 2016 using our total joint registry. The mean age at TKA was 56 years (range, 29-81), 42% were women, and their mean body mass index was 32. Ninety percent of knees were posterior-stabilized designs. Survivorship was assessed using the Kaplan-Meier method. The mean follow-up was 8 years. ResultsThe 10-year survivorships free of any revision and any reoperation were 92 and 88%, respectively. Seven patients were revised for instability (6 global and 1 flexion), 4 for infection, and 2 for other reasons. There were 5 additional reoperations: 3 manipulations under anesthesia, 1 wound debridement, and 1 arthroscopic synovectomy for patellar clunk. Nonoperative complications occurred in 16 patients, 4 of which were flexion instability. Radiographically, all nonrevised knees were well-fixed. Knee Society Function Scores significantly improved from preoperative to 5 years postoperative (P < .0001). ConclusionSurvivorship of TKA in post-ACL reconstruction knees was lower than expected with instability being the most common reason for revision. In addition, the most common nonrevision complications were flexion instability and stiffness requiring manipulations under anesthesia, indicating that achieving soft tissue balance in these knees may be difficult.

Comparison of the in-vivo kinematics of three different knee prosthesis designs during a step-up movement

BackgroundThere is no consensus on the importance of the kinematics of the prosthetic joint for the clinical outcome after total knee arthroplasty. A 3-armed randomized controlled trial was done to determine and compare the in vivo kinematics of a posterior cruciate-retaining and two posterior cruciate-sacrificing (Anterior-Stabilized and Posterior-Stabilized) prosthetic designs from the same total knee arthroplasty system. Since the anterior-stabilized and posterior-stabilized designs are posterior cruciate ligament-sacrificing designs, we hypothesized they would have similar contact-point kinematics. Further, we hypothesized that the cruciate-retaining design would have contact-point kinematics different from the anterior-stabilized and the posterior-stabilized designs, but comparable to a native knee. MethodsThirty-nine patients with a well-functioning total knee arthroplasty one year postoperatively underwent kinematic analysis of a weight-bearing step-up movement under fluoroscopic recording. Model-based radiostereometric analysis was used to determine anteroposterior contact-point translations and rotations through the movement path to assess knee kinematics. FindingsThe cruciate-retaining and anterior-stabilized groups' medial and lateral contact-points displayed similar paradoxical posterior translations during step-up in the magnitude of 7 and 2 mm, respectively. In contrast, the posterior-stabilized group's contact-points translated anteriorly by 4 and 10 mm throughout the movement and were significantly more posterior than the cruciate-retaining and the anterior-stabilized groups from >100° to 40° of flexion. The femur rotated internally with all designs. InterpretationThe cruciate-retaining and anterior-stabilized designs displayed similar contact-point translation patterns during a step-up movement. Only the posterior-stabilized design showed a pattern comparable to native knees. Conversion from a cruciate-retaining to an anterior-stabilized design because of posterior cruciate ligament insufficiency will not change knee kinematics.

Tibial sagittal and rotational alignment reduce patellofemoral stresses in posterior stabilized total knee arthroplasty

Patellofemoral joint complications remain an important issue in total knee arthroplasty. We compared the patellofemoral contact status between cruciate-retaining and posterior-stabilized designs with varying degrees of tibial sagittal and rotational alignment using a computer simulation to ensure proper alignments in total knee arthroplasty. Knee kinematics, patellofemoral contact force and quadriceps force were computed using a musculoskeletal modeling program (LifeMOD/KneeSIM 2010; LifeModeler, Inc., San Clemente, California) during a weight-bearing deep knee bend. Two different posterior tibial slope (PTS)s (3° and 7°) and five different tibial tray rotational alignments (neutral, internal 5° and 10°, and external 5° and 10°) were simulated. Patellofemoral contact area and stresses were next computed using finite element analysis. The patellofemoral contact force for the posterior-stabilized design was substantially lower than the cruciate-retaining design after post-cam contact because of increasing femoral roll-back. Neutral rotational alignment of the tibial component resulted in smaller differences in patellofemoral contact stresses between cruciate-retaining and posterior-stabilized designs for PTSs of 3° or 7°. However, the patellar contact stresses in the cruciate-retaining design were greater than those in posterior-stabilized design at 120° of knee flexion with PTS of 3° combined with internal rotation of the tibial component. Our study provides biomechanical evidence implicating lower PTSs combined with internal malrotation of the tibial component and the resultant increase in patellofemoral stresses as a potential source of anterior knee pain in cruciate-retaining design.

Medial Pivot Versus Posterior-Stabilized Prosthesis Design in Primary Total Knee Arthroplasty: A Systematic Review and Meta-Analysis.

Studies of clinical outcomes that compare the Medial Pivot design (MP) with the Posterior-Stabilized design (PS) were controversial. The meta-analysis was performed to summarize existing evidence, aiming to determine whether MP was superior to PS prosthesis. Search strategies followed the recommendations of the Cochrane collaboration. Electronic searches such as PubMed, Embase, Web of Science, and Cochrane were systematically searched for publications concerning medical pivot and posterior stabilized prosthesis from the inception date to April 2021. Authors also manually checked and retrieved a reference list of included publications for potential studies, which the electronic searches had not found. Two investigators independently searched, screened, and reviewed the full text of the article. Disagreements generated throughout the process were resolved by consensus, and if divergences remain, they were arbitrated by a third author. Subsequently, patients were divided into the MP and PS groups. This study included 18 articles, comprising a total of 2614 patients with a similar baseline. The results showed the PS group had a higher risk of the patellar clunk or crepitus. However, the theoretical advantages of MP prosthesis could not translate to the difference in knee function, clinical complications, revision rate and satisfaction. Similarly, the shape and mechanism of prostheses could not affect the implant position and postoperative alignment. The MP prosthesis can reduce the patellar clunk or crepitus rate. However, choices between the MP and PS prosthesis would not affect knee function, clinical complications, revision rate, patient satisfaction, implant position, and postoperative alignment.

Higher use of fixed-bearing over mobile-bearing and posterior-stabilized over medial pivot designs in total knee arthroplasty (TKA): a systematic comparative analysis using worldwide arthroplasty registers from England and Wales, Australia, Norway, New Zealand, Germany and Switzerland

IntroductionThe aim of this study was to compare the use of mobile-bearing, fixed-bearing, posterior-stabilized (PS) and medial pivot design to describe epidemiological differences and subsequent outcomes.Materials and methodsA systematic literature search was performed using the NORE website to identify the relevant arthroplasty registers. Inclusion criteria were the following: (1) reports had to be publicly available, (2) reports had to be written in German or English language, (3) differentiation between mobile- and fixed-bearing, posterior-stabilized, and if possible, medial pivot designs had to be possible from the present reports, and (4) data had to be reported for at least three consecutive years and the latest report had to be from the year 2020 to retrieve recent data.ResultsSix registries (England and Wales, Australia, Norway, New Zealand, Germany, Switzerland) offered sufficient data according to the inclusion criteria. In all countries, the dominant type of bearing used for total knee arthroplasty (TKA) was fixed-bearing, with percentages ranging from 60.8% to 84.1% in 2018, 63.6% to 85.7% in 2019 and 66.2% to 87.4% in 2020. A large variation was observed concerning mobile-bearing design, which showed a range from 2.8% to 39.2% in 2018, 2.6% to 36.4% in 2019 and 2.9% to 33.8% in 2020. Some variation was found regarding the use of PS TKA, as its percentage frequency ranged from 9.7% to 29.2% in 2018, 9.8% to 29.4% in 2019 and 10.1% to 28.5% in 2020. Medial pivot design had a share of 9.1% in 2018, 8.6% in 2019 and 8.4% in 2020 in Australia, while it only accounted for 1.4% in 2018, 2.1% in 2019 and 2.5% in 2020 in Germany.ConclusionThe comparison of arthroplasty registers from England and Wales, Australia, Norway, New Zealand, Germany and Switzerland revealed large differences regarding the application of posterior-stabilized designs, but also common ground considering the overwhelming use of fixed-bearing inserts, which, when inserted correctly, eradicate the potential complication of bearing dislocation. Arthroplasty registers offer a real-world clinical perspective with the aim to improve quality and patient safety.

Factors Affecting the Risk of Aseptic Patellar Complications in Primary TKA Performed with Cemented All-Polyethylene Patellar Resurfacing.

Patellar complications are a consequential cause of failure of primary total knee arthroplasty (TKA). The purpose of this study was to evaluate the association of demographic and patient factors with the long-term risk of patellar complications as a function of time in a very large cohort of primary TKAs performed with patellar resurfacing. We identified 27,192 primary TKAs utilizing cemented all-polyethylene patellar components that were performed at a single institution from 1977 through 2015. We evaluated the risk of any aseptic patellar complication and any aseptic patellar reoperation or revision, subanalyzed risks of reoperation or revision for loosening, maltracking/instability, and wear, and evaluated the risk of clinical diagnosis of patellar fracture and clunk/crepitus. The mean age at TKA was 68 years (range, 18 to 99 years); 57% of the patients were female. The mean body mass index (BMI) was 32 kg/m2. The primary diagnosis was osteoarthritis in 83%, and 70% of the TKAs were posterior-stabilized. Median follow-up was 7 years (range, 2 to 40 years). Risk factors for each outcome were evaluated with Cox regression models. Nine hundred and seventy-seven knees with all-polyethylene patellae developed patellar complications. Survivorship free from any aseptic patellar complication was 93.3% at 20 years. Twenty-year survivorship free from any aseptic patellar reoperation was 97.3% and free from any aseptic patellar revision was 97.4%. Fifteen-year survivorship for the same end points for procedures performed from 2000 to 2015 was 95.7%, 99.2% and 99.3% respectively, representing substantial improvements compared with implants placed before 2000. Univariate analysis demonstrated that male sex (hazard ratio [HR], 1.4), an age of <65 years (HR, 1.3), and a BMI of ≥30 kg/m2 (HR, 1.2) were associated with increased risk of patellar complications (all p ≤0.01). Posterior-stabilized designs were associated with fewer patellar reoperations and revisions overall (HR, 0.4 and 0.4; p < 0.001) but higher risk of patellar clunk/crepitus (HR, 14.1; p < 0.001). The 20-year survivorship free from any aseptic patellar complication in this series of cemented all-polyethylene patellae was 93%. Important risk factors for any aseptic patellar complication were male sex, an age of <65 years, a BMI of ≥30 kg/m2, and a patella implanted before 2000. Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Do TKAs in Patients with Higher BMI Take Longer, and is the Difference Associated with Surgeon Volume? A Large-database Study from a National Arthroplasty Registry.

Increased surgical time in TKA may impact economic costs and clinical outcomes. Prior work has found that TKAs in patients with high BMI take longer, and these patients may be at greater risk for postoperative complications like infection. However, these studies included small numbers of patients and surgeons from single institutions and they did not consider surgeon volume. Using the New Zealand Joint Registry (NZJR), we asked: (1) Is there a relationship between increasing patient BMI and TKA operative time? (2) Is the effect of BMI on surgical time less pronounced among surgeons who perform more TKAs per year than those who perform fewer? Data were collected from the NZJR between January 2010 and December 2018 as it is the only national registry that records both BMI and surgical time. Primary TKA performed for osteoarthritis by surgeons with more than 50 TKAs over the period of the study were identified. BMI and operative time (skin incision to closure in minutes) were recorded. Patients with the following were excluded: lateral parapatellar or minimally invasive approaches; navigated, patient-specific instrumentation, or robot-assisted TKA; uncemented or hybrid fixation; those with procedures performed by a trainee (all or part); or a nonosteoarthritic indication. Of 64,108 TKAs performed during the study period, a total of 42% (27,057) met our inclusion criteria. The primary outcome was the effect of BMI on operative time. Operative time is expressed in minutes as a mean for each single-unit BMI increase across all surgeons, controlled for other variables that might influence operative time such as patella resurfacing and cruciate-retaining versus posterior-stabilized designs. Overall, the mean operative time (skin incision to closure) was 79 ± 22 minutes. Surgical experience was assessed by subdividing surgeons into six groups according to the number of TKAs performed annually (< 10, 10 to 24, 25 to 49, 50 to 74, 75 to 99, and > 100). Statistical analyses were performed including a general linear model to assess the independent association between BMI and operative time, allowing for the effects of other patient and surgical features. In addition, linear regression analyses explored the associations between BMI and operative time in the whole group and within surgical volume groups. There was an association between increasing BMI and increasing surgical duration. The mean operative time increased from 75 ± 22 minutes in patients with a normal BMI of 25 kg/m2 to 87 ± 24 minutes in patients with a BMI of 40 kg/m2 to 94 ± 28 minutes in patients with a BMI > 50 kg/m2 (p < 0.001). Surgeons performing fewer than 25 TKAs per year took 14% longer to perform a TKA on a patient with a BMI of 40 kg/m2 than on a patient with a normal BMI of 25 kg/m2. However, surgeons performing greater than 25 TKAs per year took 10% longer. In this study, an increase BMI was associated with increased surgical time in TKA. Surgical duration for high-volume surgeons appears less influenced by increases in BMI than lower volume surgeons. Although the absolute increase in duration was small, prolonged surgical time may reduce theater productivity. Even though the issues around managing patients with high BMI are multifactorial and complex, considerations from these findings include ensuring appropriate theater scheduling and possibly referring patients with high BMI to specialist centers. Further studies should focus on assessing the effectiveness of such measures in reducing complications and improving outcomes in patients with elevated BMI. Level III, therapeutic study.

Contemporary Mortality Rate and Outcomes in Nonagenarians After Primary Total Knee Arthroplasty

BackgroundNonagenarians (90-99 years) have experienced the fastest percent growth in primary total knee arthroplasty (TKA) utilization recently. However, there are limited data on the results of the procedure in this population. The goals of this study are to determine the mortality rate, implant survivorship, clinical outcomes, and complications of primary TKAs in nonagenarians. MethodsOur institutional total joint registry was used to identify 105 nonagenarians who underwent 119 primary cemented TKAs for osteoarthritis between 1997 and 2017. Mean age was 92 years, with 58% being female. Mortality, revision, and reoperation were assessed using cumulative incidence with death as a competing risk and Cox regression methods. Clinical outcomes were assessed using Knee Society Scores. A posterior-stabilized design was used in 88%. Mean follow-up was 4 years. ResultsThe mortality rates were 0%, 2%, 9%, and 47% at 90 days, 1 year, 2 years, and 5 years, respectively. The 5-year cumulative incidences of any revision and reoperation were 0% and 3%, respectively. The reoperations included 2 internal fixations for periprosthetic fracture and 1 hardware removal. The mean Knee Society Score improved significantly from 34 preoperatively to 80 at 5 years (P < .001). The 5-year cumulative incidence of any nonmortality complication was 66%. The most common complications were urinary tract infections and retention (8%) in the early postoperative period, and acquired idiopathic stiffness (10%) later. ConclusionNonagenarians undergoing primary TKA had low mortality rates at 90 days (0%) and 1 year (2%) with substantial functional improvements. The cumulative incidences of revision and reoperation were low at 5 years. Level of EvidenceLevel IV, retrospective cohort.

Primary total knee arthroplasty in tibial plateau fractures: Literature review and our institutional experience

BackgroundDisplaced proximal tibia fractures in the elderly may be very difficult to manage. If osteosynthesis represents the standard of care in the younger patients, in the aged population this solution is controversial because a significant failure rate has been reported after internal fixation. Moreover, osteoarthritis progression following tibial plateau fractures is common, often requiring a subsequent total knee arthroplasty (TKA). In recent years, in order to overcome the fracture healing problems and to allow immediate full weight bearing, primary TKA after tibial plateau fractures in elderly patients has gained popularity. Material and methodsfrom 2015 to 2019, 11 tibial plateau fractures in elderly patients with pre-existing osteoarthritis were treated with a primary TKA. Age, gender, mechanism of trauma, pre-operative autonomy level, fractures classification, degree of osteoarthritis and intraoperative data (ligamentous stability and type of implant) were collected. After a mean follow-up of 28 months, Knee Society Score (KSS), post-operative autonomy level and Forgotten Joint Score (FJS) were evaluated. The radiological assessment (signs of loosening, limb axis and patellar height indices) and complications were also recorded. Resultsaccording to fracture type and ligamentous competence, 6 cases of posterior-stabilized (PS) design and 5 cases of semi-constrained TKA were implanted. At the final follow up, mean KSS knee score was 83±16 and mean KSS functional score was 74±15. Mean pre-operative autonomy level assessed with the Parker scale, was significantly higher than the post-operative one (7.5±1.4 vs 5.6 ± 1.3). Mean FJS was 66 ± 14. No lines of radiolucency or limb malalignment were found at the final radiological follow-up. One major complication was recorded: one acute periprosthetic infection. One patient reported a periprosthetic femoral fracture after 26 months. ConclusionBased on our and results and those reported on literature, primary TKA is a suitable option in case of tibial plateau fractures in elderly patients with pre-existing osteoarthritis and poor bone quality, in which osteosynthesis outcome may be poor. Unlike ORIF, primary TKA may allow immediate weightbearing and a faster recovery. Nevertheless, it is a demanding surgery with a significant complications rate and should be reserved for selected patients and experienced surgeons.