Total Knee Arthroplasty Implants Research Articles

Ceramic Coating in Cemented Primary Total Knee Arthroplasty is Not Associated With Decreased Risk of Revision due to Early Prosthetic Joint Infection

BackgroundProsthetic joint infection (PJI) is one of the most frequent and devastating causes of short-term revision total knee arthroplasty (TKA). In vitro evidence suggests ceramic surfaces demonstrate resistance to biofilm, but the clinical effect of bearing surface modifications on the risk of PJI remains unclear. This premier registry-based study examines the influence of ceramic bearing surface coatings on the outcome in cemented primary TKA. MethodsIn total, 117,660 cemented primary TKAs in patients with primary osteoarthritis recorded in the German arthroplasty registry since 2012 were followed up for a maximum of 3 years. The primary endpoint was risk of revision for PJI on ceramic coated and uncoated cobalt-chromium-molybdenum femoral components. Propensity score matching for age, gender, obesity, diabetes mellitus, depression and Elixhauser comorbidity index, and substratification on common design twins with and without coating was performed. ResultsIn total, 4637 TKAs (85.1% female) with a ceramic-coated femoral component were identified, 42 had been revised for PJI and 122 for other reasons at 3 years. No survival advantage due to the risk of revision for PJI could be determined for ceramic-coated components. Revision for all other reasons demonstrated a significant higher rate for TKAs with ceramic-coated components. However, the results of this were confounded by a strong prevalence (20.7% vs 0.3%) of metal sensitivity in the ceramic-coated group. ConclusionNo evidence of reduced risk for PJI due to ceramic-coated implants in cemented primary TKA was found. Further analysis for revision reasons other than PJI is required.

Ten-year outcomes of a nitrided Ti-6Al-4V titanium alloy fixed-bearing total knee replacement with a highly crosslinked polyethylene-bearing in patients with metal allergy

BackgroundMetal hypersensitivity in patients with a total knee arthroplasty (TKA) is a rare condition and a very controversial topic. Despite the lack of data concerning the real effective impact of allergy on TKA failures, most of the manufactures offer the choice of ‘non-allergenic’ implants both for primary and revision TKA, some of which provide the same designs and surgical techniques as the conventional ones. Only a few studies are available on outcomes on these ‘hypersensitivity-friendly’ implants and even fewer specifically on allergic patients with a mid- to long-term follow-up. MethodsBetween 2007 and 2015, we enrolled 72 patients (57 females, 15 males), who underwent TKA treated with a non-allergenic posterior-stabilized (PS) total knee implant for a declared and proven metal allergy.Patients were followed clinically and radiographically for a mean 10 years of follow-up. ResultsWith revision as an endpoint the Kaplan–Meier survival estimate showed a survival rate of 97.2% at five years and 95.1% at 10 years. Significant improvements in range of motion (ROM), Knee Society Scoring (KSS) and Hospital for Special Surgery (HSS) knee scores were registered at final follow-up (P < 0.0001). At final follow-up validated Patient-Reported Outcome Measures (PROMs) showed the following scores: Oxford Knee Score (OKS) 42.1, EQ5D 0.80, EQ VAS 80.1, Forgotten Joint Score 71.2. ConclusionsThis nitrided Ti-6Al-4V titanium alloy fixed-bearing total knee replacement with a highly crosslinked polyethylene-bearing showed interesting results and survival rates in patients with metal allergy at mid- to long-term follow-up.

Early Outcomes of an Alternative Bearing Surface in Primary Total Knee Arthroplasty in Patients with Self-reported Metal Allergy

BackgroundMost implants for total knee arthroplasty (TKA) are comprised of alloys that contain nickel. Controversy exists whether metal allergies produce negative effects and affect clinical outcomes. The purpose of this study was to retrospectively review a minimum 2-year follow-up with an ion-bombarded titanium TKA implant in patients with reported metal sensitivity. MethodsA retrospective review of patients who underwent primary TKA with the ion-bombarded titanium Vanguard (Zimmer Biomet, Warsaw, IN) implant with 2-year minimum follow-up was performed from 2008 through 2017. The query revealed 346 patients (451 knees) with minimum 2-year follow-up. The mean age was 64.7 years, the mean body mass index was 35.1 kg/m2, and 95% of patients were women. ResultsThe mean follow-up was 4.6 years. The mean range of motion improved from 109° to 112° (P = .03), University of California Los Angeles activity scale from 4.1 to 5.1 (P < .001), Knee Society Clinical scores from 36 to 89 (P < .001), and Knee Society Functional scores from 48 to 73 (P < .001). There were 5 (1.1%) revisions: 2 infections (2-staged exchange), 1 tibial revision for aseptic loosening after a fall, and 2 bearing exchanges for instability. Other surgeries were open reduction internal fixation of periprosthetic fracture, 1 arthroscopic release of snapping popliteus, and 4 local wound incision and debridement (2 superficial infections and 2 nonhealing wounds). Manipulation under anesthesia was required in 27 (6%) patients. ConclusionsThese early results are encouraging for the use of alternative metal titanium alloy implants in metal-sensitive patients undergoing primary TKA. At 4.6 years of mean follow-up, patients had substantial improvement in the range of motion and clinical outcomes with a low frequency of revision.

Résultats à court terme comparant les prothèses totales de genou de type médial pivot implantées avec alignement cinématique versus mécanique : étude cas-témoins

IntroductionThe kinematic alignment (KA) technique for total knee arthroplasty (TKA) and the medial pivot (MP) component design are two options promoting a physiologic prosthetic knee kinematics when used in combination that could improve TKA outcomes. Case-control study is initiated to compare the 1-year radio-clinical outcomes between kinematic alignment medial pivot total knee arthroplastiy (KA MP-TKAs) and mechanical alignment medial pivot total knee arthroplastiy (MA MP-TKA). Goal of a study was to answer the following questions: do KA MP-TKAs patients have improved functional outcomes compared to MA MP-TKAs patients? (Q1); do prosthetic knee and lower limb alignments differ between KA and MA patients (Q2)? And does kinematic implantation of MP TKA has higher risk of reoperations and revisions (Q3)? Material and methodsA case-control study was carried out to compare the 1-year clinical and radiographic outcomes between 24 consecutive KA-TKA patients and 24 matched MA-TKA patients. All patients had implantation with manual instruments and a cemented medial pivot TKA with excision of the PCL. All data were collected prospectively, and outcome scores were patient reported. ResultsKA patients had superior values in Forgotten Joint Score (FJS) at 1-year (KA 77 vs. MA 51) (p=0.05) follow-up. After one year, KA patients scored better in objective section of the new Knee Society Score (KSS) (p=0.02), and in sport section of the Knee Osteoarthritis Outcome Score (KOOS) (p=0.01). Eleven out of 24 patients (46%) in KA group and 7/24 patients (29%) in MA group had limb alignment out of 180±3°, whereas 17/24 (70%) of KA patients, and 14/24 (58%) of MA patients had orientation of tibial component with more than 3 of varus. No reoperation or revision occurred in either group. Discussion/conclusionThe KA of MP-TKA design seems to have a good efficacy at early-term, with some 1-year functional performance higher to the ones from MA MP-TKAs. Further research is needed to define if those early results will last over time. Level of evidenceIII, case-controlled study.

The Effects of Cyclic Loading and Motion on the Implant-Cement Interface and Cement Mantle of PEEK and Cobalt-Chromium Femoral Total Knee Arthroplasty Implants: A Preliminary Study.

This study investigated the fixation of a cemented PEEK femoral TKA component. PEEK and CoCr implants were subjected to a walking gait cycle for 10 million cycles (MC), 100,000 cycles or 0 cycles (unloaded control). A method was developed to assess the fixation at the cement–implant interface, which exposed the implants to a fluorescent penetrant dye solution. The lateral condyles of the implants were then sectioned and viewed under fluorescence to investigate bonding at the cement–implant interface and cracking of the cement mantle. When tested for 100,000 cycles, debonding of the cement–implant interface occurred in both PEEK (61%) and CoCr (13%) implants. When the duration of testing was extended (10 MC), the percentage debonding was further increased for both materials to 88% and 61% for PEEK and CoCr, respectively. The unloaded PEEK specimens were 79% debonded, which suggests that, when PEEK femoral components are cemented, complete bonding may never occur. Analysis of cracks in the cement mantle showed an absence of full-thickness cracks in the unloaded control group. For the 100,000-cycle samples, on average, 1.3 and 0.7 cracks were observed for PEEK and CoCr specimens, respectively. After 10 MC, these increased to 24 for PEEK and 19 for CoCr. This was a preliminary study with a limited number of samples investigated, but shows that, after 10 MC under a walking gait, substantial debonding was visible for both PEEK and CoCr implants at the cement–implant interface and no significant difference in the number of cement cracks was found between the two materials.

Knee Kinetics Of Patients With Different Types Of Total Knee Arthroplasty Implants During Downhill Walking

Ramping walking is a common daily activity that is often incorporated in rehabilitation for total knee arthroplasty (TKA) patients. However, no studies have investigated knee biomechanics of patients with total knee arthroplasty (TKA), and comparisons between posterior stabilized (PS), cruciate retaining (CR) and bi-cruciate stabilized (BCS) TKA implants during ramp walking. PURPOSE: To examine the differences in knee biomechanics between patients with the three different types of TKA implants and healthy controls during downhill walking on a 10° ramp. METHODS: Five BCS, 10 CR, 10 PS TKA patients and 10 healthy controls performed five downhill walking trials at their self-selected pace, on a 10° instrumented ramp mounted through rigid contact surface structures mounted onto two force platforms (AMTI). Three-dimensional kinematic data (240 Hz, Vicon) were collected in conjunction with ground reaction force data (1200 Hz). A 2 × 4 (limb × group) mixed design ANOVA was used to examine selected knee joint kinematic and kinetic variables. RESULTS: In downhill walking, a significant limb effect was found in peak loading-response (p=0.005) and push-off knee extension moment (KEM, p=0.015). Peak loading-response KEMs were smaller (p=0.006) in replaced limbs (0.94 Nm/kg) than non-replaced limbs (0.97 Nm/kg). Similar findings were seen in peak push-off (p=0.015) KEMs. Peak loading-response knee abduction moment (KAbM) were mostly similar between the replaced limbs of three TKA groups and healthy controls in downhill walking. Peak loading-response KAbMs were smaller in non-replaced limbs of BCS (-0.34 Nm/kg, p=0.018) and PS (-0.37 Nm/kg, p=0.001) patients compared to that in their non-replaced limbs (BCS: -0.53 Nm/kg & PS: -0.49 Nm/kg). CONCLUSION: The results from this study showed that during downhill walking, peak KEMs were lower in replaced limbs than non-replaced limbs for all TKR patients, suggesting a deficit in knee extensor strength regardless of TKA designs. Post-surgery rehabilitation should focus on eccentric strength training of quadriceps for their replaced knees to reduce the asymmetry in knee movement and loading. BCS and PS patients may need additional attention in strengthening of quadriceps and hamstrings of the replaced limbs.

Cementless Tritanium Baseplate Total Knee Arthroplasty: Survivorship and Outcomes at 5-Year Minimum Follow-Up.

Newer generation cementless total knee arthroplasty (TKA) designs have provided stronger osteointegration between the implant and bone. Despite excellent survivorship and outcomes with cemented TKAs, areas of concern within the bone-cement interface remain a concern and necessitate studies on alternative constructs. This study assesses: (1) implant survivorship; (2) clinical outcomes; and (3) complications with radiographic outcomes at a 5-year minimum follow-up of cementless highly porous titanium-coated baseplates in TKAs. Part of this study has been reported. We retrospectively reviewed a prospectively collected database at a single high-volume institution between July 1, 2013 and June 30, 2014 for patients who underwent a primary TKA using cementless highly porous titanium-coated baseplate implants. Patients were evaluated clinically at postoperative follow-up visits at a minimum of 5 years. To calculate the survivorship, Kaplan-Meier analysis was performed to determine all-cause, aseptic, and septic implant survivorship at each final follow-up for all patients. A total of 228 TKAs were performed and followed for a minimum of 5 years (range, 5-6 years). As of the latest follow-up, one case of septic loosening of the patellar button and one case of patellar dislodgment secondary to physical manipulation were recorded and revised. Overall, the cohort displayed implant survivorship of 99.5% at 5-year minimum follow-up. Improvements were seen in both Knee Society pain and function scores and were 37 points (range, 17-60 points) and 28 points (range, 15-47 points), respectively. The mean improvement in flexion was 17.8 (range, -20 to 40 degrees) and mean improvement in extension was -5.5 (range, -30 to 5 degrees). Cementless TKAs serve as strong alternative choice to cemented TKAs. Although cemented fixation is commonly known as the gold standard, results of this study confirm the findings of previous investigations on the survivorship of cementless TKA implants. Therefore, patients who undergo primary TKA with a cementless tritanium baseplate can expect excellent clinical outcomes at a 5-year minimum follow-up.

A two-stage approach to primary TKA using articulating antibiotic-loaded spacers improve function and eradicate infection in septic arthritic knees.

The treatment of an infected arthritic knee might be challenging. The failure rate has been reported to be high for open or arthroscopic debridement. A subsequently high rate of infection has been noted in these patients undergoing primary total knee arthroplasty (TKA). In the present study, a two-stage approach using an articulating spacer was used. The hypothesis was that the procedure would eradicate the infection and improve pain and function in these patients. A total of 16 consecutive patients were enrolled in this retrospective study. The mean follow-up time was 6.1years (range 2.0-9.9years). Patients with advanced osteoarthritis and infection of the knee were included. All patients had previously undergone one or more failed arthroscopic or open procedures for the eradication of infection. All patients received the same homemade metal-on-plastic articulating antibiotic spacer. Double antibiotic therapy was given for 2weeks intravenously and orally for 4weeks. TKA implantation was performed 6weeks after the first stage. The infection was eradicated without recurrence in all patients. The functional results were significantly improved, and pain was significantly reduced after spacer and TKA implantation. The mean amount of knee flexion was 95 ± 30° preoperatively, and it increased to 109 ± 14° (p = 0.012) after spacer implantation and to 119 ± 10° (p = 0.002) after TKA implantation. The mean KSS objective was 58 ± 12 preoperatively, and it increased to 75 ± 14 (p < 0.0001) after spacer implantation and to 96 ± 3 (p < 0.0001) after TKA implantation. The mean KSS function was 17 ± 11 preoperatively, and it increased to 46 ± 10 (p < 0.0001) after spacer implantation and to 86 ± 6 (p < 0.0001) after TKA implantation. The mean VAS score was 65 ± 11 preoperatively, and it decreased to 2 ± 4 (p < 0.0001) after spacer implantation and to 1 ± 2 (p < 0.0001) after TKA implantation. The two-stage procedure for the treatment of infected arthritic knees after failed eradication surgery was effective in all patients. Using an antibiotic articulating metal-on-plastic cement spacer showed improved functional results between the stages and at the final follow-up. No intra- or postoperative complications occurred.

Functional Flexion Instability After Rotating-Platform Total Knee Arthroplasty.

We sought to define "at risk" loading conditions associated with rotating-platform total knee arthroplasty (TKA-RP) implants that predispose to insert subluxation and spinout and to quantify tolerances for flexion-extension gap asymmetry and laxity in order to prevent these adverse events. Biomechanical testing was performed on 6 fresh-frozen cadaveric limbs with a TKA-RP implant with use of a gap-balancing technique, followed by sequential femoral component revision with variable-thickness polyethylene inserts to systematically represent 5 flexion-extension mismatch and asymmetry conditions. Each configuration was subjected to mechanical loading at 0°, 30°, and 60°. Rotational displacement of the insert on the tibial baseplate, lateral compartment separation, and insert concavity depth were measured with use of a digital caliper. Yield torque, a surrogate for ease of insert rotation and escape of the femoral component, was calculated with use of custom MATLAB code. Design-intended insert rotation decreased with increasing knee flexion angles in each loading configuration. Likewise, yield torque increased with increasing joint flexion and decreased with increasing joint laxity in all testing configurations. Insert instability and femoral condyle displacement were reproduced in positions of increasing knee flexion and asymmetrical flexion gap laxity. The depth of lateral polyethylene insert concavity determined femoral condylar capture and defined a narrow tolerance of <2 mm in the smallest implant sizes for flexion gap asymmetry leading to rotational insert instability. Decreased femoral-tibial articular surface conformity with increasing knee flexion and asymmetrical flexion gap laxity enable paradoxical motion of the femoral component on the upper insert surface rather than the undersurface, as designed. Mobile-bearing TKA-RP is a technically demanding procedure requiring a snug symmetrical flexion gap. As little as 2 mm of asymmetrical lateral flexion laxity can result in decreased conformity, condyle liftoff, and insert subluxation. Flexion beyond 30° decreases bearing surface contact area and predisposes to reduced insert rotation and mechanical malfunction.

High incidence of radiolucent lines at the implant–cement interface of a new total knee replacement

Recently introduced total knee arthroplasty (TKA) implants have been linked with the early development of periprosthetic radiolucency (PPRL). The aim of this study was to carry out a retrospective clinical and radiographical analysis of a consecutive series of a new TKA, and to assess the incidence and distribution of PPRL. A retrospective review of all new TKA implants performed by a single surgeon at a single hospital between March 2013 and October 2017 was performed. The minimum follow-up period was 3 months, with ongoing patient review at 6, 12 and 36 months. Sequential post-operative radiographs were performed to determine the presence of PPRL. A total of 122 TKAs were identified in 112 patients over the 4.5-year study period. The average follow-up time was 21 months (range 3-51 months). PPRL was noted in 29 TKAs (23.8%). When comparing the PPRL group to those without PPRL, there was a difference in body mass index, with body mass index associated with an increased likelihood of PPRL (P = 0.003). There was no difference in constraint of implant (P = 0.818), cement type (P = 0.340), patella resurfacing (P = 0.286), age (P = 0.984) gender (P = 0.376) or initial mechanical axis deviation (P = 0.054) between groups. PPRL were most commonly seen in tibial anterior-posterior (AP) zone 1 and zone 2 (96.6%), followed by femoral lateral zone 5 (58.6%), tibia lateral zone 1 (55.2%) and tibial lateral zone 2 (53.2%). No patients have required revision surgery. A high incidence of early PPRL is seen in patients undergoing primary TKA using a new implant system, mainly involving the tibial component. Ongoing clinical and radiological assessment for patients seems warranted based on these findings.

Short-term follow-up of kinematically vs. mechanically aligned total knee arthroplasty with medial pivot components: A case-control study

IntroductionThe kinematic alignment (KA) technique for total knee arthroplasty (TKA) and the medial pivot (MP) component design are two options promoting a physiologic prosthetic knee kinematics when used in combination that could improve TKA outcomes. Case-control study is initiated to compare the 1-year radio-clinical outcomes between kinematic alignment medial pivot total knee arthroplasty (KA MP-TKAs) and mechanical alignment medial pivot total knee arthroplasty (MA MP-TKA). Goal of a study was to answer the following questions: Do KA MP-TKAs patients have improved functional outcomes compared to MA MP-TKAs patients? (Q1); Do prosthetic knee and lower limb alignments differ between KA and MA patients (Q2)? And does kinematic implantation of MP TKA has higher risk of reoperations and revisions (Q3)? Material and methodsA case-control study was carried out to compare the 1-year clinical and radiographic outcomes between 24 consecutive KA-TKA patients and 24 matched MA-TKA patients. All patients had implantation with manual instruments and a cemented medial pivot TKA with excision of the PCL. All data were collected prospectively, and outcome scores were patient reported. ResultsKA patients had superior values in Forgotten Joint Score (FJS) at 1-year (KA 77 vs. MA 51) (p=0.05) follow-up. After one year KA patients scored better in objective section of the new Knee Society Score (KSS) (p=0.02), and in sport section of the Knee Osteoarthritis Outcome Score (KOOS) (p=0.01). Eleven out of 24 patients (46%) in KA group and 7/24 patients (29%) in MA group had limb alignment out of 180°±3°, whereas 17/24 (70%) of KA patients, and 14/24 (58%) of MA patients had orientation of tibial component with more than 3° of varus. No reoperation or revision occurred in either group. Discussion/ConclusionThe KA of MP TKA design seems to have a good efficacy at early-term, with some 1-year functional performance higher to the ones from MA MP TKAs. Further research is needed to define if those early results will last over time. Level of evidenceIII, case-controlled study.

Hydroxyapatite-coated implants provide better fixation in total knee arthroplasty. A meta-analysis of randomized controlled trials.

BackgroundThe potential advantages of hydroxyapatite (HA)-coated cementless total knee arthroplasty (TKA) implants are bone stock preservation and biological fixation. Studies comparing the outcomes of HA-coated cementless, non HA-coated cementless (uncemented) and cemented TKA implants reported contradictory data. Our aim was to provide a comparison of the effects of HA coating of tibial stem on the stability and functionality of TKA implants.MethodsA systematic literature search was performed using MEDLINE, Scopus, EMBASE and the CENTRAL databases up to May 31st, 2019. The primary outcome was Maximum Total Point Motion (MTPM) of the tibial stem. This parameter is determined by radiosterometric analysis and refers to the migration pattern of the prosthesis stems. The clinical outcomes of the implanted joints were evaluated by the Knee Society Knee Score (KSS) and the Knee Society Function Score (KFS). Weighted mean difference (WMD) with 95% confidence interval (CI) were calculated with the random-effects model.ResultsAltogether, 11 randomized controlled trials (RCTs) with 902 patients for primary TKA implants were included. There was a statistically significant difference in the MTPM values with the use of HA-coated and uncoated uncemented implants (WMD = +0.28, CI: +0.01 to +0.56, P<0.001). However, HA-coated stems showed significantly higher migration when compared with the cemented prostheses (WMD = -0.29, CI: -0.41 to -0.16, P<0.001). The KSS values of HA-coated implants were significantly higher than those for the uncemented implants; moreover, KSS and KFS outcome scores were statistically not different between the HA-coated and cemented prosthesis cases.ConclusionHA-coating yields better stability than other, uncemented prostheses. More importantly, the HA-coating is not outperformed by cemented prosthesis in providing good functional outcome.

Summary of knee implant one, three, five, and 10-year revision risk reported by national and regional arthroplasty registries: a valuable source of evidence for clinical decision-making.

Optimal implant selection is a major component of high-quality arthroplasty care, and revision risk is an important parameter characterizing knee arthroplasty implant clinical performance.National and regional arthroplasty registries are essential sources of revision risk data, but these data are often difficult to find because they are buried within extensive annual reports. Summarizing total knee arthroplasty (TKA) implant revision risks as presented in registry reports can maximize the usefulness of registry data for orthopaedic surgeons.The findings summarize the revision risk data found in national arthroplasty reports from the Australian, Danish, Finnish, and the England, Wales, Northern Ireland and the Isle of Man registries, and in regional arthroplasty reports from the Emilia-Romagna Region (Italty), and the Michigan Arthroplasty Registry Collaborative Quality Initiative (MARCQI) registries.The six supplemental summary tables present revision risk data for TKA implants by cemented, uncemented, hybrid, and unreported fixation types. Additional summary tables are presented for revision risk of unicondylar (UKA) and patellofemoral joint (PFJ) revisions. Within TKA fixation categories, revision risks at 10 years ranged from 2.4% to 35.7% (cemented), 2.8% to 25.0% (uncemented), 2.0% to 9.2% (hybrid), and 0.0% to 39.7% (unreported). Unicondylar 10-year revision risk ranged from 4.9% to 17.2%. Patellofemoral joint 10-year revision risk ranged from 15.2% to 21.7%.There is substantial variation in one, three, five, and 10-year revision risk across implants, which suggests surgeons should choose implants carefully.Cite this article: EFORT Open Rev 2020;5:268-272. DOI: 10.1302/2058-5241.5.190053

Does Unicompartmental Knee Replacement Offer Improved Clinical Advantages Over Total Knee Replacement in the Treatment of Isolated Lateral Osteoarthritis? A Matched Cohort Analysis From an Independent Center

BackgroundThe purpose of this study is to compare the functional and radiographic results, perioperative complications, satisfaction rate, and mid-term survivorship after unicompartmental knee arthroplasty (UKA) and total knee arthroplasty (TKA) for the treatment of lateral compartmental knee osteoarthritis (LCKO). MethodsBetween March 2007 and September 2017, we identified 35 patients with primary TKAs and 121 patients with lateral UKAs (LUKAs) for LCKO with a minimum follow-up of 2 years (mean 5.3 years, range 2-12.4). The matched variables were age, gender, operation side, body mass index, American Society of Anesthesiologist grade, initial diagnosis, osteoarthritis grade in lateral compartment, and follow-up time. All patients were assessed using the Oxford Knee Score, Hospital for Special Surgery score, range of motion, length of hospital stay, satisfaction, and complications. Survivorship of UKA and TKA implants was also compared. ResultsAt last follow-up, LUKA had a significantly better postoperative Oxford Knee Score, Hospital for Special Surgery score, range of motion, shorter length of hospital time, and higher satisfaction rate than matched TKA group. There were significant differences regarding patellar tendon injury (P = .043), superficial wound infection (P = .028), patellar snapping or impingement (P = .047), and stiffness (P < .001). Five-year survivorships free from revision were similar in both groups (99.2% vs 97.1%, P = .347). ConclusionLUKA for LCKO demonstrated more favorable 5-year results in comparison with TKA. Furthermore, LUKA achieved comparable mid-term survivorship and was less likely to suffer from wound infection and knee stiffness, although not overall surgical complications.

Aseptic Loosening of Porous Metaphyseal Sleeves and Tantalum Cones in Revision Total Knee Arthroplasty: A Systematic Review.

Bone loss often complicates revision total knee arthroplasty (TKA). Management of metaphyseal defects varies, with no clearly superior technique. Two commonly utilized options for metaphyseal defect management include porous-coated metaphyseal sleeves and tantalum cones. A systematic review was conducted according to the international Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. We combined search terms "Total knee arthroplasty" AND/OR "Sleeve," "Cone" as either keywords or medical subject heading (MeSH) terms in multiple databases according to PRISMA recommendations. All retrieved articles were reviewed and assessed using defined inclusion and exclusion criteria. A total of 27 studies (12 sleeves and 15 cones) of revision TKAs were included. In the 12 studies on sleeve implantation in revision TKAs, 1,617 sleeves were implanted in 1,133 revision TKAs in 1,025 patients. The overall rate of reoperation was 110/1,133 (9.7%) and the total rate of aseptic loosening per sleeve was 13/1,617 (0.8%). In the 15 studies on tantalum cone implantation in revision TKAs, 701 cones were implanted into 620 revision TKAs in 612 patients. The overall rate of reoperation was 116/620 (18.7%), and the overall rate of aseptic loosening per cone was 12/701 (1.7%). Rates of aseptic loosening of the two implants were found to be similar, while the rate of reoperation was nearly double in revision TKAs utilizing tantalum cones. Variability in the selected studies and the likely multifactorial nature of failure do not allow for any definitive conclusions to be made. This review elucidates the necessity for additional literature examining revision TKA implants.

No clinical differences at the 2-year follow-up between single radius and J-curve medial pivot total knee arthroplasty in the treatment of neutral or varus knees.

Modern total knee arthroplasty (TKA) systems are designed to reproduce the normal knee kinematics and improve patient outcome. The authors compared two different third-generation medial pivot TKA implants, having a single-radius or a J-curve design in their sagittal plane, hypothesizing no clinical differences. Two cohorts of 50 patients who underwent primary TKA were first preoperatively matched by sex, deformity, body mass index (BMI), Oxford Knee Score (OKS), Knee society score (KSS) and range of motion (ROM) and then statistically analyzed at a minimum follow-up (FU) of 2years. An identical surgical technique, which aimed to reproduce a slightly tighter medial than lateral compartment, was used in all knees. At a minimum follow-up of 2years (range 24-34months) there were no statistically significant differences in OKS and KSS between the two implant groups. The final ROM differed statistically between the two groups: the average maximum active flexion was 123° in the J-curve femoral design group with an adapted "medially-congruent" polyethylene insert, and 116° in the single radius femoral design with a medial "ball-in-socket" articulation. No clinical and radiological differences were found when the two cohorts of patients were compared. This study showed that the implant design played a minor role in the final outcome as opposed to a precise surgical technique. Retrospective case-control study, Level III.

Osteo-Compatibility of 3D Titanium Porous Coating Applied by Direct Energy Deposition (DED) for a Cementless Total Knee Arthroplasty Implant: in Vitro and in Vivo Study.

Direct energy deposition (DED) technology has gained increasing attention as a new implant surface technology that replicates the porous structure of natural bones facilitating osteoblast colonization and bone ingrowth. However, concerns have arisen over osteolysis or chronic inflammation that could be caused by Cobalt-chrome (CoCr) alloy and Titanium (Ti) nanoparticles produced during the fabrication process. Here, we evaluated whether a DED Ti-coated on CoCr alloy could improve osteoblast colonization and osseointegration in vitro and in vivo without causing any significant side effects. Three types of implant CoCr surfaces (smooth, sand-blasted and DED Ti-coated) were tested and compared. Three cell proliferation markers and six inflammatory cytokine markers were measured using SaOS2 osteoblast cells. Subsequently, X-ray and bone histomorphometric analyses were performed after implantation into rabbit femur. There were no differences between the DED group and positive control in cytokine assays. However, in the 5-bromo-2′-deoxyuridine (BrdU) assay the DED group exhibited even higher values than the positive control. For bone histomorphometry, DED was significantly superior within the 1000 µm bone area. The results suggest that DED Ti-coated metal printing does not affect the osteoblast viability or impair osseointegration in vitro and in vivo. Thus, this technology is biocompatible for coating the surfaces of cementless total knee arthroplasty (TKA) implants.

Gender Differences in Contribution of Smoking, Low Physical Activity, and High BMI to Increased Risk of Early Reoperation After TKA

BackgroundThe reliable preoperative identification of patients at a high risk of early reoperations (<2 years after primary surgery) after total knee arthroplasty (TKA) could lead to adjustments of the surgical procedure and counseling, thus lowering the percentage of revision surgeries. MethodsThe unselected cohort consisted of 1885 patients (695 men and 1190 women) who underwent TKA implantation between September 2010 and April 2017 at a single tertiary orthopedic center. Multivariate patient similarity networks were applied to identify patient groups at a high risk of early reoperations based on 25 preoperative parameters. ResultsEarly reoperations (109 cases, 5.8%) were less frequent in women (4.4%; median time to reoperation, 2.0 months) than in men (8.2%; 7.5 months), reaching the highest incidence in younger men (10.9%; <66 years). Of the tested preoperative parameters, the risk of reoperation in men was more likely associated with smoking or obesity (body mass index [BMI] > 30). In women, low physical activity and high BMI were the most likely risk factors for early reoperations. Other factors did not affect the risk of early reoperations, including the primary diagnosis, comorbidities, and surgeon-implanting TKA. ConclusionThis study demonstrates the effect of smoking, physical activity, and BMI on the risk of early reoperation after TKA, with the different contribution in men/women. Identification of patient subgroups with a higher risk of early revision after TKA is needed for clinical implementation of precision medicine in orthopedics.

Titanium Porous Coating Using 3D Direct Energy Deposition (DED) Printing for Cementless TKA Implants: Does It Induce Chronic Inflammation?

Because of the recent technological advances, the cementless total knee arthroplasty (TKA) implant showed satisfactory implant survival rate. Newly developed 3D printing direct energy deposition (DED) has superior resistance to abrasion as compared to traditional methods. However, there is still concern about the mechanical stability and the risk of osteolysis by the titanium (Ti) nanoparticles. Therefore, in this work, we investigated whether DED Ti-coated cobalt-chrome (CoCr) alloys induce chronic inflammation reactions through in vitro and in vivo models. We studied three types of implant surfaces (smooth, sand-blasted, and DED Ti-coated) to compare their inflammatory reaction. We conducted the in vitro effect of specimens using the cell counting kit-8 (CCK-8) assay and an inflammatory cytokine assay. Subsequently, in vivo analysis of the immune profiling, cytokine assay, and histomorphometric evaluation using C57BL/6 mice were performed. There were no significant differences in the CCK-8 assay, the cytokine assay, and the immune profiling assay. Moreover, there were no difference for semi-quantitative histomorphometry analysis at 4 and 8 weeks among the sham, smooth, and DED Ti-coated samples. These results suggest that DED Ti-coated printing technique do not induce chronic inflammation both in vitro and in vivo. It has biocompatibility for being used as a surface coating of TKA implant.

No clinical benefit from gender-specific total knee replacement implants: a systematic review

Introduction: Total knee arthroplasty (TKA) remains the treatment of choice for severe osteoarthritis of the knee and nearly 60% of patients undergoing TKA are women. Females present three notable anatomic differences. Thus, gender-specific (GS) components were introduced to accommodate the females’ anatomic differences. No systematic review has been published since 2014. The aim of this study was to perform a recent systematic review of the literature to determine whether there is any clinical benefit of gender-specific implants compared to conventional unisex implants in total knee arthroplasty (TKA). Methods: This study included prospective randomized controlled trials (PRCTs) comparing clinical and radiological outcomes, and complications in TKA with gender-specific implants and conventional implants. All studies had a minimum follow-up of two years. Results: Three PRCTs published between 2010 and 2012 were included. These studies showed a low risk of bias and were of very high quality. We did not find superior clinical outcomes for gender-specific prostheses compared to conventional prostheses. However, gender-specific TKA reduced the number of patients with femoral component overhang compared to conventional TKA. Conclusion: In our systematic review, despite a lower overhang rate, gender-specific implants in female TKA showed no clinical benefit over standard unisex implants. Good clinical results with significant improvement were observed with both designs. There is a notable absence of new studies on this subject in recent years, and further research needs to be performed using various gender-specific implant designs to further define the role of gender-specific implants. Level of evidence: Systematic review, Level IV